KR20240144847A - Dry electrode, Preparation method of dry electrode and Lithium battery containing dry electrode - Google Patents

Abstract

A method for manufacturing a dry electrode is provided, comprising: a step of preparing a first laminate by disposing one or more intermediate layers on one or both sides of an electrode current collector; a step of preparing a second laminate by disposing a dry electrode film having a larger area than an area of the intermediate layer on the first laminate, the dry electrode film including a first region disposed on the intermediate layer and a second region extending from the first region exceeding an outer periphery of the intermediate layer; and a step of pulling at least a portion of the second region of the dry electrode film to separate the second region from the first region, thereby providing a dry electrode, wherein the dry electrode film has anisotropic tensile strength, the dry electrode includes a dry electrode active material layer disposed on the intermediate layer, and in the dry electrode, a dry electrode active material layer directly disposed on the electrode current collector is free.

Description

Dry electrode, preparation method of dry electrode and lithium battery containing dry electrode}

The present invention relates to a dry electrode, a method for manufacturing a dry electrode, and a lithium battery including the same.

In order to meet the miniaturization and high performance of various devices, in addition to miniaturization and weight reduction of lithium batteries, high energy density is becoming important. In other words, high-capacity lithium batteries are becoming important.

To realize a lithium battery suitable for the above applications, electrodes with high loading are being examined.

In the process of manufacturing an electrode with high loading, the thickness of the electrode active material layer increases, and thus, the possibility of defects such as collapse of the electrode active material layer increases during the process of introducing the electrode active material layer onto the electrode current collector.

A method for easily introducing an electrode active material layer having a high loading onto an electrode current collector is required.

One aspect is to provide a dry electrode and a method for manufacturing the same, which can easily control the position of a dry electrode film introduced onto an electrode collector.

Another aspect is to provide a dry electrode and a method for manufacturing the same, which can easily introduce various types of dry electrode films without damaging the electrode collector.

Another aspect is to provide a method for manufacturing the dry electrode.

Another aspect is to provide a lithium battery comprising the above dry electrode.

On one side,

Electrode current collector;

A dry electrode film disposed on one or both sides of the electrode collector; and

An intermediate layer disposed between the electrode current collector and the dry electrode film,

The intermediate layer includes an outer periphery region arranged along at least a portion of an outer periphery of the intermediate layer and an intermediate region excluding the outer periphery region,

A dry electrode is provided, the thickness of the outer peripheral region being thicker than the thickness of the middle region.

On the other hand,

A step of preparing a first laminate by arranging an intermediate layer on an electrode collector;

A step of preparing a second laminate by arranging a dry electrode film having a larger area than the area of the intermediate layer on the first laminate, the dry electrode film including a first region where the dry electrode film is arranged on the intermediate layer and a second region extending from the first region beyond the outer periphery of the intermediate layer; and

A step of pulling at least a portion of the second region of the dry electrode film to separate the second region from the first region to provide a dry electrode,

The intermediate layer includes an outer periphery region arranged along at least a portion of an outer periphery of the intermediate layer and an intermediate region excluding the outer periphery region,

A method for manufacturing a dry electrode is provided, wherein the thickness of the outer region is thicker than the thickness of the middle region.

On another note,

A cathode; an electrolyte disposed between the cathode and the anode,

A lithium battery is provided, wherein at least one of the positive and negative electrodes comprises the dry electrode described above.

According to one aspect, by selectively removing the dry electrode film by utilizing the difference in the thickness of the intermediate layer, various shapes of electrode active material layers can be provided without damage to the electrode current collector during the dry electrode manufacturing process.

According to another aspect, by arranging an intermediate layer between the electrode current collector and the dry electrode film, the position and shape of the dry electrode film introduced onto the electrode current collector can be easily controlled.

Figures 1a and 1b are cross-sectional views of a dry electrode according to an exemplary embodiment.
Figures 1c and 1d are perspective views of a dry electrode according to an exemplary embodiment.
FIGS. 2A and 2B are cross-sectional views of a first assembly according to an exemplary embodiment.
FIGS. 2c and 2d are perspective views of a first assembly according to an exemplary embodiment.
FIGS. 3a and 3b are cross-sectional views of a second assembly according to an exemplary embodiment.
FIGS. 3c and 3d are perspective views of a second assembly according to an exemplary embodiment.
FIGS. 4A and 4B are perspective views of a second assembly according to an exemplary embodiment.
Figures 5a to 5e are plan views of dry electrodes according to exemplary embodiments.
Figures 6a to 6q are plan views of an arrayed pattern of dry electrodes according to an exemplary embodiment.
Figure 7 is a schematic diagram of a lithium battery according to an embodiment.
Figure 8 is a schematic diagram of a lithium battery according to an embodiment.
Figure 9 is a schematic diagram of a lithium battery according to an embodiment.
Figure 10 is a scanning electron microscope image of a cross-section of a dry cathode active material layer manufactured in Example 1.

The present inventive concept described below can undergo various transformations and have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present inventive concept to specific embodiments, but should be understood to include all transformations, equivalents, or substitutes included in the technical scope of the present inventive concept.

The terminology used below is only used to describe specific embodiments and is not intended to limit the present creative idea. The singular expression includes the plural expression unless the context clearly indicates otherwise. Hereinafter, the terms "comprises" or "has" and the like are intended to indicate the presence of a feature, number, step, operation, component, part, ingredient, material or a combination thereof described in the specification, but should be understood to not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, ingredients, materials or combinations thereof. The "/" used below may be interpreted as "and" or "or" depending on the context.

In order to clearly express various layers and regions in the drawings, the thickness is shown enlarged or reduced. Similar parts are designated by the same drawing reference numerals throughout the specification. When a part such as a layer, film, region, or plate is referred to as being “on” or “over” another part throughout the specification, this includes not only the case where it is directly above the other part, but also the case where there is another part in between. The terms first, second, etc. may be used throughout the specification to describe various components, but the components should not be limited by the terms. The terms are used only to distinguish one component from another. In the present specification and the drawings, components having substantially the same functional configuration are referred to by the same reference numerals, and redundant descriptions are omitted.

In the present disclosure, the "particle diameter" of a particle refers to the average diameter when the particle is spherical, and refers to the average major axis length when the particle is non-spherical. The particle diameter of a particle can be measured using a particle size analyzer (PSA). The "particle diameter" of a particle is, for example, the average particle diameter. The average particle diameter is, for example, the median particle diameter (D50). The median particle diameter (D50) is the size of a particle corresponding to 50% of the cumulative volume, calculated from the side of particles having a small particle size in a size distribution of particles measured by, for example, laser diffraction.

As used herein, “metal” includes both metals and metalloids such as silicon and germanium, in either an elemental or ionic state.

As used herein, “alloy” means a mixture of two or more metals.

In the present disclosure, “positive electrode active material” means a positive electrode material capable of undergoing lithiation and delithiation.

In the present disclosure, “negative electrode active material” means a negative electrode material capable of undergoing lithiation and delithiation.

In the present disclosure, “lithiation” and “lithiating” mean a process of adding lithium to a positive electrode active material or a negative electrode active material.

In the present disclosure, “delithiation” and “delithiate” mean a process of removing lithium from a positive electrode active material or a negative electrode active material.

In this disclosure, “charging” and “charging” mean a process of providing electrochemical energy to a battery.

In this disclosure, “discharging” and “discharging” mean the process of removing electrochemical energy from a battery.

In the present disclosure, “positive electrode” and “cathode” mean an electrode at which electrochemical reduction and lithiation occur during a discharge process.

In the present disclosure, “cathode” and “anode” mean electrodes at which electrochemical oxidation and delithiation occur during a discharge process.

Dry electrodes according to exemplary implementations are described in more detail below.

Figures 1a and 1b are cross-sectional views of a dry electrode according to an exemplary embodiment. Figures 1c and 1d are perspective views of a dry electrode according to an exemplary embodiment.

A dry electrode (500) according to one aspect includes: an electrode current collector (100); a dry electrode film (300) disposed on one or both sides of the electrode current collector (100); and an intermediate layer (200) disposed between the electrode current collector (100) and the dry electrode film (300), wherein the intermediate layer (200) includes an outer periphery region (220) disposed along at least a portion of an outer periphery (250) of the intermediate layer (200) and an intermediate region (210) excluding the outer periphery region (220), and the thickness of the outer periphery region (220) may be thicker than the thickness of the intermediate region (210).

Middle layer

For example, in the process of laminating a dry electrode film (300) on an intermediate layer (200), a portion of the dry electrode film (300) may be exposed outside the intermediate layer (200), and a process of removing the exposed dry electrode film (200) is required. In this case, since the thickness of the intermediate layer (200) in the past was constant, a step was absolutely necessary to distinguish between an area of the dry electrode film (130) disposed on the intermediate layer (200) and a portion exposed to the outside of the intermediate layer (200), and this caused a problem in that the dry electrode (500) manufacturing process was delayed.

On the other hand, since the thickness of the outer region (220) of the dry electrode (500) is thicker than the thickness of the middle region (210), the region disposed on the middle layer (200) of the dry electrode film (300) and the region exposed to the outside of the middle layer (200) can be more easily distinguished during the manufacturing process of the dry electrode (500). Accordingly, the region exposed to the outside of the middle layer (200) of the dry electrode film (300) can be more easily removed without an additional procedure for distinguishing the region disposed on the middle layer (200) of the dry electrode film (300) and the region exposed to the outside of the middle layer (200), thereby improving the manufacturing efficiency of the dry electrode (100). In addition, by controlling the region where the outer region (220) is disposed, the patterned dry electrode film (300) can be more easily formed on the electrode current collector (100).

For example, the outer periphery (260) of the middle layer may mean a boundary line that divides an area where the middle layer is formed and an area where the middle layer is not formed. The outer periphery (260) may mean a boundary line arranged at the outermost edge of the middle layer (200). For example, the outer periphery (260) may include a first outer periphery (261) parallel to the machine (X) direction and a second outer periphery (262) parallel to the width (Y) direction.

For example, the machine direction is, for example, the x direction, the width direction is, for example, the y direction, and the thickness direction is, for example, the z direction. For example, the machine direction is, for example, the direction in which the dry electrode film (300a, 300b, 300) is stretched during the manufacture of the dry electrode film (300a, 300b, 300). Referring to FIGS. 1c and 1d, the machine direction is, for example, the x-axis direction. The direction perpendicular to the machine direction is the width direction (transverse direction). The width direction is, for example, the y direction perpendicular to the x direction. The direction in which the electrode collector (100), the intermediate layer (200), and the dry electrode film (300) are laminated is the thickness direction. The thickness direction is, for example, the z direction.

For example, the outer region (220) may be arranged along at least a portion of the outer periphery (260). For example, the outer region (220) may be arranged continuously or discontinuously along at least a portion of the outer periphery (260).

For example, the outer peripheral portion (260) may include a first outer peripheral portion (261) parallel to the machine (X) direction and a second outer peripheral portion (262) parallel to the width (Y) direction.

Referring to FIG. 1c, the outer peripheral region (220) may be arranged along the first outer peripheral portion (261). The outer peripheral region (220) may be arranged parallel to the machine direction. In this case, when the outer peripheral region (220) is arranged parallel to the machine direction, the stretching direction of the dry electrode film (300) and the direction in which the outer peripheral region (220) is arranged are identical, so that the region exposed to the outside of the intermediate layer (200) among the dry electrode film (300) can be removed more easily. For example, the outer peripheral region (220) may be arranged only along the first outer peripheral portion (261) parallel to the machine direction.

According to another embodiment, the outer region (220) may be arranged along the second outer portion (262). The outer region (220) may be arranged parallel to the width direction. For example, the outer region (220) may be arranged only along the second outer portion (261) parallel to the width direction.

Referring to FIG. 1d, the outer peripheral region (220) may be arranged along the outer peripheral portion (260). For example, the outer peripheral region (220) may be arranged along the entire outer peripheral portion (260). For example, the outer peripheral region (220) may be arranged along both the first outer peripheral portion (261) parallel to the machine (X) direction and the second outer peripheral portion (262) parallel to the width (Y) direction. In this case, the position at which the outer peripheral region (220) is arranged may be more easily controlled, so that the patterned dry electrode film (300) may be more easily formed on the electrode current collector (100).

According to one embodiment, the ratio of the area of the outer region (220) to the total area of the intermediate layer (200) may be 1 to 20%. For example, when the area of the outer region (220) satisfies the above range, during the manufacturing process of the dry electrode (500), the area of the dry electrode film (300) disposed on the intermediate layer (200) and the area outside the intermediate layer (200) can be more easily distinguished. For example,

According to one embodiment, the ratio of the area of the outer peripheral region (220) to the total area of the intermediate layer (200) may be 5 to 20%, 1 to 15%, 5 to 15%, 1 to 10% or 5 to 10%.

According to one embodiment, the ratio of the thickness of the outer region (220) to the thickness of the intermediate region (210) may be greater than 1 and less than or equal to 5. For example, when the ratio of the thickness of the outer region (220) to the thickness of the intermediate region (210) satisfies the above range, the dry electrode film (300) disposed outside the intermediate layer (200) can be removed more easily.

For example, the ratio of the thickness of the outer region (220) to the thickness of the middle region (210) may be greater than 1 and less than or equal to 4, greater than 1 and less than or equal to 3, or greater than 1 and less than or equal to 2.

According to one embodiment, the interlayer (200) may be disposed on, for example, one or both sides of the electrode collector (100).

Referring to FIGS. 1A and 1B, the interlayer (200a, 200b, 200) may be directly disposed on, for example, one side or both sides of the electrode current collector (100). Accordingly, no other layer may be disposed between the electrode current collector (100) and the interlayer (200a, 200b, 200). By directly disposing the interlayer (200a, 200b, 200) on one side or both sides of the electrode current collector (100), the bonding strength between the electrode current collector (100) and the dry electrode film (300a, 300b, 300) may be further improved.

The thickness of the intermediate layer (200a, 200b, 200) is, for example, 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, 5% or less, or 3% or less of the thickness of the electrode current collector (100).

For example, the thickness of the intermediate layer (200a, 200b, 200) is 0.01 to 30 %, 0.1 to 30 %, 0.5 to 30 %, 1 to 25 %, 1 to 20 %, 1 to 15 %, 1 to 10 %, 1 to 5 %, or 1 to 3 % of the thickness of the electrode current collector (100). The thickness of the intermediate layer (200a, 200b, 200) is, for example, 10 nm to 5 ㎛, 50 nm to 5 ㎛, 200 nm to 4 ㎛, 500 nm to 3 ㎛, 500 nm to 2 ㎛, 500 nm to 1.5 ㎛, or 700 nm to 1.3 ㎛. Since the intermediate layer (200a, 200b, 200) has a thickness within this range, the bonding force between the electrode current collector (100) and the dry electrode film (300a, 300b, 300) is further improved, and an increase in interface resistance is suppressed.

According to one embodiment, the intermediate layer (200a, 200b, 200) may include, for example, a binder. By including the binder in the intermediate layer (200a, 200b, 200), the bonding strength between the electrode current collector (100) and the dry electrode film (300a, 300b, 300) may be further improved.

For example, the binder included in the intermediate layer (200a, 200b, 200) is a conductive binder or a non-conductive binder. The conductive binder is, for example, an ion-conductive binder and/or an electron-conductive binder. A binder having both ion-conductive and electron-conductive properties may belong to both the ion-conductive binder and the electron-conductive binder.

For example, ion conducting binders include polystyrene sulfonate (PSS), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polyethylene oxide (PEO), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyethylenedioxythiophene (PEDOT), polypyrrole (PPY), polyacrylonitrile (PAN), polyaniline, and polyacetylene.

For example, the ion conducting binder may include polar functional groups. Ion conductive binders containing polar functional groups include, for example, Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP, sulfonated poly(ether ether ketone) (SPEEK), sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS), sulfonated poly(aryl ether ketone) (SPAEK), poly[bis(benzimidazobenzisoquinolinones)] (SPBIBI), poly(styrene sulfonate) (PSS), lithium Examples of the electron-conductive binder include lithium 9,10-diphenylanthracene-2-sulfonate (DPASLi ⁺ ). Examples of the electron-conductive binder include polyacetylene, polythiophene, polypyrrole, poly(p-phenylene), poly(phenylenevinylene), poly(phenylenesulfide), polyaniline, etc. The intermediate layers (200a, 200b, 200) may be conductive layers including, for example, conductive polymers.

According to one embodiment, the binder included in the intermediate layer (200a, 200b, 200) may be selected from the binders included in the dry electrode film (300a, 300b, 300) to be described later. For example, the intermediate layer (200a, 200b, 200) may include the same binder as the dry electrode film (300a, 300b, 300) to be described later. For example, the binder included in the intermediate layer (200a, 200b, 200) may be a fluorine-based binder.

According to one embodiment, the fluorine-based binder included in the intermediate layers (200a, 200b, 200) may be polyvinylidene fluoride (PVDF). The intermediate layers (200a, 200b, 200) are disposed on the electrode current collector (100) in a dry or wet manner, for example. The intermediate layers (200a, 200b, 200) may be, for example, a binding layer including a binder.

According to one embodiment, the intermediate layer (200a, 200b, 200) may further include, for example, a carbon-based conductive material. The carbon-based conductive material included in the intermediate layer (200a, 200b, 200) may be selected from the carbon-based conductive materials included in the dry electrode film (300a, 300b, 300). The intermediate layer (200a, 200b, 200) may include the same carbon-based conductive material as the electrode active material layer. Since the intermediate layer (200a, 200b, 200) includes a carbon-based conductive material, the intermediate layer (200a, 200b, 200) may be, for example, a conductive layer. The intermediate layer (200a, 200b, 200) may be, for example, a conductive layer including a binder and a carbon-based conductive material.

The intermediate layers (200a, 200b, 200) can be disposed on the electrode current collector (100) in a dry manner, for example, by deposition such as CVD or PVD. The intermediate layers (200a, 200b, 200) can be disposed on the electrode current collector (100) in a wet manner, for example, by spin coating, dip coating, or the like. The intermediate layers (200a, 200b, 200) can be disposed on the electrode current collector (100) in a wet manner, for example, by deposition of a carbon-based conductive material on the electrode current collector (100).

The dry-coated intermediate layer (200a, 200b, 200) may be made of a carbon-based conductive material and may not include a binder. Alternatively, the intermediate layer (200a, 200b, 200) may be disposed on the electrode current collector (100) by, for example, coating a composition including a carbon-based conductive material, a binder, and a solvent on the surface of the electrode current collector (100) and drying it. The intermediate layer (200a, 200b, 200) may have a single-layer structure or a multi-layer structure including a plurality of layers.

According to one embodiment, the composition of the intermediate region (210) of the intermediate layer (200) may be the same as the composition of the outer peripheral region (220). In this case, the intermediate layer (200) can be easily formed on the electrode current collector (100) using a single composition.

According to one embodiment, the composition of the intermediate region (210) of the intermediate layer (200) may be different from the composition of the outer peripheral region (220). In this case, the strength of the outer peripheral region (220) of the intermediate layer (200) may be greater than the strength of the intermediate region (210). Accordingly, the dry electrode film (300) exposed to the outside of the intermediate layer (200) can be more easily separated and removed during the manufacturing process of the dry electrode (500).

Dry electrode film (300)

Referring to FIGS. 1a to 1d, a dry electrode film (300a, 300b, 300) can be placed on an intermediate layer (200).

According to one embodiment, the thickness of the region disposed on the middle region (210) among the dry electrode films (300a, 300b, 300) may be thicker than the thickness of the region disposed on the outer region (220).

For example, the sum of the thicknesses of the region disposed on the middle region (210) and the middle region (210) among the dry electrode films (300a, 300b, 300) may be equal to the sum of the thicknesses of the region disposed on the outer region (220) and the outer region (210) among the dry electrode films (300a, 300b, 300). Accordingly, the overall thickness of the dry electrode (500) to be manufactured may be constant.

Referring to FIGS. 1A to 1D, the dry electrode films (300a, 300b, 300) may be, for example, self-standing films. The dry electrode films (300a, 300b, 300) may, for example, maintain a film form without a support. Accordingly, the dry electrode films (300a, 300b, 300) may be prepared as separate self-standing films and then placed on the electrode current collector (100).

For example, since the dry electrode film (300a, 300b, 300) is manufactured in a dry manner, it does not include an intentionally added process solvent. For example, it does not include a residual processing solvent. Although a trace amount of unintended solvent may remain in the dry electrode film (300a, 300b, 300), such solvent is not an intentionally added process solvent. Therefore, the dry electrode film (300a, 300b, 300) manufactured from the dry electrode film (300a, 300b, 300) is distinguished from a wet electrode active material layer manufactured by mixing electrode components and a process solvent and then removing part or all of the process solvent by drying.

The dry electrode film (300a, 300b, 300) includes a dry electrode active material. The dry electrode active material is, for example, an electrode active material that is not impregnated, dissolved, or dispersed in a process solvent. The dry electrode active material is, for example, an electrode active material that includes a process solvent or does not come into contact with a process solvent. The dry electrode active material is, for example, an electrode active material that does not come into contact with a process solvent during the manufacturing process of the dry electrode film (300a, 300b, 300) and the dry electrode (500).

Dry electrode active materials are, for example, dry cathode active materials.

The cathode active material may be, for example, lithium metal oxide, and any material commonly used in the art may be used without limitation.

The cathode active material may be, for example, at least one of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof, and specific examples thereof include Li _a A _1-b B' _b D ₂ (wherein 0.90 ≤ a ≤ 1, and 0 ≤ b ≤ 0.5); Li _a E _1-b B' _b O _2-c D _c (wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE _2-b B' _b O _4-c D _c (wherein 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li _a Ni _1-bc Co _b B' _c D _α (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _1-bc Co _b B' _c O _2-α F' _α (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _1-bc Co _b B' _c O _2-α F' _α (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _1-bc Mn _b B' _c D _α (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _1-bc Mn _b B' _c O _2-α F' _α (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _1-bc Mn _b B' _c O _2-α F' ₂ (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _b E _c G _d O ₂ (wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li _a Ni _b Co _c Mn _d G _e O ₂ (wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li _a NiG _b O ₂ (wherein 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li _a CoG _b O ₂ (wherein 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li _a MnG _b O ₂ (wherein 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li _a Mn ₂ G _b O ₄ (wherein 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); QO ₂ ; QS ₂ ; LiQS ₂ ; V ₂ O ₅ ; LiV ₂ O ₅ ; LiI'O ₂ ; LiNiVO ₄ ; Li _(3-f) J ₂ (PO ₄ ) ₃ (0 ≤ f ≤ 2); Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0 ≤ f ≤ 2); Any compound represented by the chemical formula LiFePO ₄ can be used:

In the chemical formula representing the compound described above, A is Ni, Co, Mn, or a combination thereof; B' is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F' is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I' is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

It is also possible to use a compound having a coating layer added to the surface of the above-described compound, and it is also possible to use a mixture of the above-described compound and the compound having a coating layer added. The coating layer added to the surface of the above-described compound includes, for example, a coating element compound of an oxide, a hydroxide, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, or a hydroxycarbonate of the coating element of the coating element. The compound forming the coating layer is amorphous or crystalline. The coating elements included in the coating layer are Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The method for forming the coating layer is selected within a range that does not adversely affect the properties of the positive electrode active material. The coating method is, for example, spray coating, dipping, etc. Since the specific coating method is well understood by those engaged in the relevant field, a detailed description thereof will be omitted.

The cathode active material is, for example, a composite cathode active material.

The composite cathode active material includes, for example, a core including a lithium transition metal oxide; and a shell disposed along a surface of the core, wherein the shell includes at least one first metal oxide represented by the chemical formula M _a O _b (0<a≤3, 0<b<4, when a is 1, 2, or 3, b is not an integer); and graphene, wherein the first metal oxide is disposed within a graphene matrix, wherein M is at least one metal selected from groups 2 to 13, 15, and 16 of the Periodic Table of Elements, and the lithium transition metal oxide contains nickel, and the nickel content is 80 mol% or more with respect to the total mole number of transition metals. The shell including the first metal oxide and graphene is disposed on the core of the composite cathode active material.

Conventional graphene is difficult to uniformly coat on the core due to agglomeration. In contrast, the composite cathode active material uses a composite including a plurality of first metal oxides arranged in a graphene matrix, thereby preventing agglomeration of graphene and disposing a uniform shell on the core. Accordingly, contact between the core and the electrolyte is effectively blocked, thereby preventing side reactions due to contact between the core and the electrolyte. In addition, reduction of nickel ions (Ni ³⁺ -> Ni ²⁺ ) and cation mixing by the electrolyte are suppressed, thereby suppressing the generation of a resistance layer such as a NiO phase. In addition, dissolution of nickel ions is also suppressed. Since the shell including graphene is flexible, it easily accommodates changes in the volume of the composite cathode active material during charge and discharge, thereby suppressing the occurrence of cracks inside the composite cathode active material. Since graphene has high electronic conductivity, the interfacial resistance between the composite cathode active material and the electrolyte is reduced. Accordingly, the internal resistance of the lithium battery is maintained or reduced despite the introduction of the shell including graphene. In addition, since the first metal oxide has withstand voltage, deterioration of the lithium transition metal oxide included in the core can be prevented during charge/discharge at high voltage. As a result, the cycle characteristics and high-temperature stability of the lithium battery including the composite cathode active material are improved. The shell may include, for example, one kind of the first metal oxide or two or more different first metal oxides. In addition, in the composite cathode active material, the lithium transition metal oxide has a high nickel content of 80 mol% or more with respect to the total mole number of transition metals, and can simultaneously provide high discharge capacity and cycle characteristics by disposing the shell including the first metal oxide and graphene on the core. Therefore, the composite cathode active material having a high nickel content of 80 mol% or more can provide improved capacity compared to a composite cathode active material having a relatively low nickel content, while still providing excellent life characteristics. The metal included in the first metal oxide may be, for example, one or more selected from Al, Nb, Mg, Sc, Ti, Zr, V, W, Mn, Fe, Co, Pd, Cu, Ag, Zn, Sb, and Se.

The first metal oxide may be, for example, at least one selected from Al ₂ O _z (0<z<3), NbO _x (0<x<2.5), MgO _x (0<x<1), Sc ₂ O _z (0<z<3), TiO _y (0<y<2), ZrO _y (0<y<2), V ₂ O _z (0<z<3), WO _y (0<y<2), MnO _y (0<y<2), Fe ₂ O _z (0<z<3), Co ₃ O _w (0<w<4), PdO _x (0<x<1), CuO _x (0<x<1), AgO _x (0<x<1), ZnO _x (0<x<1), Sb ₂ O _z (0<z<3), and SeO _y (0<y<2). By arranging the first metal oxide within the graphene matrix, the uniformity of the shell arranged on the core is improved, and the withstand voltage of the composite cathode active material is further improved. For example, the shell includes Al ₂ O _x (0<x<3) as the first metal oxide. The shell may further include one or more second metal oxides represented by the chemical formula M _a O _c (0<a≤3, 0<c≤4, when a is 1, 2, or 3, c is an integer). The M is one or more metals selected from groups 2 to 13, 15, and 16 of the periodic table of elements. For example, the second metal oxide includes the same metal as the first metal oxide, and the ratio of a and c, c/a, of the second metal oxide has a larger value than the ratio of a and b, b/a, of the first metal oxide. For example, c/a >b/a. The second metal oxide is selected from, for example, Al ₂ O ₃ , NbO, NbO ₂ , Nb ₂ O ₅ , MgO, Sc ₂ O ₃ , TiO ₂ , ZrO ₂ , V ₂ O ₃ , WO ₂ , MnO ₂ , Fe ₂ O ₃ , Co ₃ O ₄ , PdO, CuO, AgO, ZnO, Sb ₂ O ₃ , and SeO ₂ . The first metal oxide is a reduction product of the second metal oxide. The first metal oxide is obtained by reducing part or all of the second metal oxide. Therefore, the first metal oxide has a lower oxygen content and a higher oxidation number of the metal than the second metal oxide. For example, the shell includes the first metal oxide Al ₂ O _x (0<x<3) and the second metal oxide Al ₂ O ₃ . In the composite cathode active material, for example, the graphene included in the shell and the transition metal of the lithium transition metal oxide included in the core are chemically bound through a chemical bond. The carbon atom (C) of the graphene included in the shell and the transition metal (Me) of the lithium transition metal oxide are chemically bound through, for example, a CO-Me bond (for example, a CO-Ni bond) mediated by an oxygen atom. The core and the shell are composited by chemically bonding the graphene included in the shell and the lithium transition metal oxide included in the core. Therefore, it is distinguished from a simple physical mixture of graphene and lithium transition metal oxide. In addition, the first metal oxide included in the shell and the graphene are also chemically bound through a chemical bond. Here, the chemical bond is, for example, a covalent bond or an ionic bond. The covalent bond is, for example, a bond including at least one of an ester group, an ether group, a carbonyl group, an amide group, a carbonate anhydride group, and an acid anhydride group. The ionic bond is a bond including, for example, a carboxylic acid ion, an ammonium ion, an acyl cation group, etc. The thickness of the shell is, for example, 1 nm to 5 um, 1 nm to 1 um, 1 nm to 500 nm, 1 nm to 200 nm, 1 nm to 100 nm, 1 nm to 90 nm, 1 nm to 80 nm, 1 nm to 70 nm, 1 nm to 60 nm, 1 nm to 50 nm, 1 nm to 40 nm, 1 nm to 30 nm, 1 nm to 20 nm, or 1 nm to 10 nm. When the shell has a thickness in this range, an increase in the internal resistance of a lithium battery including the composite cathode active material is suppressed.

The content of the composite included in the composite cathode active material may be 3 wt% or less, 2 wt% or less, 1 wt% or less, 0.5 wt% or less, or 0.2 wt% or less based on the total weight of the composite cathode active material. The content of the composite may be 0.01 wt% to 3 wt%, 0.01 wt% to 1 wt%, 0.01 wt% to 0.7 wt%, 0.01 wt% to 0.6 wt%, 0.1 wt% to 0.5 wt%, 0.01 wt% to 0.2 wt%, 0.01 wt% to 0.1 wt%, or 0.03 wt% to 0.07 wt% based on the total weight of the composite cathode active material. When the composite cathode active material includes the composite in this range, the cycle characteristics of a lithium battery including the composite cathode active material are further improved. The average particle size of at least one selected from the first metal oxide and the second metal oxide included in the composite may be 1 nm to 1 um, 1 nm to 500 nm, 1 nm to 200 nm, 1 nm to 100 nm, 1 nm to 70 nm, 1 nm to 50 nm, 1 nm to 30 nm, 3 nm to 30 nm, 3 nm to 25 nm, 5 nm to 25 nm, 5 nm to 20 nm, or 7 nm to 20 nm. Since the first metal oxide and/or the second metal oxide has particle sizes in this nano-range, they can be more uniformly distributed within the graphene matrix of the composite. Accordingly, the composite can be uniformly coated on the core without agglomeration to form a shell. In addition, since the first metal oxide and/or the second metal oxide has particle sizes in this range, they can be more uniformly arranged on the core. Therefore, the withstand voltage characteristics can be more effectively exhibited by uniformly arranging the first metal oxide and/or the second metal oxide on the core. The average particle diameter of the first metal oxide and the second metal oxide is measured using, for example, a measuring device of a laser diffraction method or a dynamic light scattering method. The average particle diameter is measured using, for example, a laser scattering particle size distribution meter (for example, Horiba LA-920), and is the value of the median particle diameter (D50) when 50% is accumulated from the small particle side in volume conversion.

The core included in the composite cathode active material includes, for example, a lithium transition metal oxide represented by the following chemical formulas 1 to 8:

<Chemical Formula 1>

Li _a Co _x M _y O _2-b A _b

In the above chemical formula 1,

1.0≤a≤1.2, 0≤b≤0.2, 0.9≤x≤1, 0≤y≤0.1, and x+y=1,

M is manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B), or a combination thereof,

A is F, S, Cl, Br or a combination of these,

<Chemical formula 2>

Li _a Ni _x Co _y M _z O _2-b A _b

In the above chemical formula 2,

1.0≤a≤1.2, 0≤b≤0.2, 0.8≤x<1, 0≤y≤0.3, 0<z≤0.3, and x+y+z=1,

M is manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B), or a combination thereof,

A is F, S, Cl, Br or a combination of these,

<Chemical Formula 3>

LiNi _x Co _y Mn _z O ₂

<Chemical Formula 4>

LiNi _x Co _y Al _z O ₂

In the above chemical formulas 3 and 4, 0.8≤x≤0.95, 0≤y≤0.2, 0<z≤0.2, and x+y+z=1.

<Chemical Formula 5>

LiNi _x Co _y Mn _z Al _w O ₂

In the above chemical formula 5, 0.8≤x≤0.95, 0≤y≤0.2, 0<z≤0.2, 0<w≤0.2, and x+y+z+w=1.

<Chemical Formula 6>

Li _a Ni _x Mn _y M' _z O _2-b A _b

In the above chemical formula 6,

1.0≤a≤1.2, 0≤b≤0.2, 0<x≤0.3, 0.5≤y<1, 0<z≤0.3, and x+y+z=1,

M' is cobalt (Co), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B), or a combination thereof,

A is F, S, Cl, Br or a combination of these,

<Chemical Formula 7>

Li _a M1 _x M2 _y PO _4-b X _b

In the above chemical formula 7, 0.90≤a≤1.1, 0≤x≤0.9, 0≤y≤0.5, 0.9<x+y<1.1, 0≤b≤2,

M1 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), or a combination thereof,

M2 is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), zinc (Zn), boron (B), niobium (Nb), gallium (Ga), indium (In), molybdenum (Mo), tungsten (W), aluminum (Al), silicon (Si), chromium (Cr), vanadium (V), scandium (Sc), yttrium (Y) or a combination thereof, and X is O, F, S, P or a combination thereof.

<Chemical Formula 8>

Li _a M3 _z PO ₄

In the above chemical formula 8, 0.90≤a≤1.1, 0.9≤z≤1.1,

M3 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), or a combination thereof.

Dry electrode active materials are, for example, dry negative electrode active materials.

Any negative electrode active material that is used as a negative electrode active material of a lithium battery in the relevant technical field can be used. For example, it includes at least one selected from the group consisting of lithium metal, metals alloyable with lithium, transition metal oxides, non-transition metal oxides, and carbon-based materials. Metals alloyable with lithium include, for example, Si, Sn, Al, Ge, Pb, Bi, Sb Si-Y alloy (wherein Y is an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, a transition metal, a rare earth element, or a combination thereof, but not Si), Sn-Y alloy (wherein Y is an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, a transition metal, a rare earth element, or a combination thereof, but not Sn), etc. The element Y is, for example, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof. The transition metal oxide is, for example, lithium titanium oxide, vanadium oxide, lithium vanadium oxide, etc. The non-transition metal oxide is, for example, SnO ₂ , SiO _x (0<x<2), etc. The carbonaceous material is, for example, crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon is, for example, graphite, such as natural graphite or artificial graphite in the form of amorphous, platelet, flake, spherical, or fiber. Amorphous carbon includes, for example, soft carbon (low-temperature calcined carbon), hard carbon, mesophase pitch carbide, and calcined coke.

The dry electrode film (300a, 300b, 300) includes, for example, a dry binder. The dry binder is, for example, a binder that is not impregnated, dissolved, or dispersed in a process solvent. The dry binder is, for example, a binder that includes a process solvent or does not come into contact with a process solvent. The dry binder is, for example, a binder that does not come into contact with a process solvent during the manufacturing process of the dry electrode film (300a, 300b, 300) and the dry electrode. The dry binder is, for example, a fibrillized binder. The fibrillized binder can serve as a matrix that supports and binds the dry electrode active material and other components included in the dry electrode film (300a, 300b, 300). The fibrillized binder can be confirmed to have a fibrous form, for example, as shown in a scanning electron microscope image of a cross-section of an electrode. The fibrous binder has an aspect ratio of, for example, greater than 10, greater than 20, greater than 50, or greater than 100.

The dry binder may be, but is not limited to, any binder used in the manufacture of the dry electrode (500), such as, but not limited to, polytetrafluoroethylene (PTFE), polyvinylidene fluoride-hexapropylene (PVDF-HFP) copolymer, polyvinylidene fluoride (PVDF), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, cellulose, polyvinylpyrrolidone, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, or copolymers thereof. The dry binder may include, in particular, a fluorinated binder. Fluorinated binders include, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride-hexapropylene (PVDF-HFP) copolymer, or polyvinylidene fluoride (PVDF).

The content of the dry binder included in the dry electrode film (300a, 300b, 300) is, for example, 1 to 10 wt%, or 1 to 5 wt%, based on the total weight of the dry electrode film (300a, 300b, 300). Since the dry electrode film (300a, 300b, 300) includes the dry binder in this range, the bonding force of the dry electrode film (300a, 300b, 300) is improved, and the dry electrode (500) manufactured can maintain a high energy density.

The dry electrode film (300a, 300b, 300) may further include, for example, a conductive material. The conductive material is, for example, a dry conductive material. The dry conductive material is, for example, a conductive material that is not impregnated, dissolved, or dispersed in a process solvent. The dry conductive material is, for example, a conductive material that includes a process solvent or does not come into contact with a process solvent. The dry conductive material includes, for example, a carbon-based conductive material. The carbon-based conductive material may be, but is not limited to, carbon black, graphite particles, natural graphite, artificial graphite, acetylene black, Ketjen black, carbon fibers; carbon nanotubes; and the like, and any material used as a carbon-based conductive material in the relevant technical field may be used.

The content of the dry conductive material included in the dry electrode film (300a, 300b, 300) is, for example, 1 to 10 wt%, or 1 to 5 wt%, based on the total weight of the electrode active material layer. When the dry electrode film (300a, 300b, 300) includes the dry conductive material in this range, the conductivity of the dry electrode (500) manufactured is improved, and the cycle characteristics of the lithium battery including the dry electrode (500) can be improved.

Electrode collector (100)

The material constituting the electrode current collector (100) may be any material that does not react with lithium, i.e., does not form an alloy or compound with lithium, and is conductive. The electrode current collector (100) may be, for example, a metal or an alloy. The electrode current collector (100) may be made of, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

The electrode current collector (100) may have a form selected from, for example, a sheet, a foil, a film, a plate, a porous body, a mesoporous body, a body containing through holes, a polygonal ring body, a mesh body, a foam body, and a non-woven body, but is not necessarily limited to such a form, and any form used in the relevant technical field is possible.

The electrode current collector (100) may have a reduced thickness compared to the electrode current collector (100) included in a conventional electrode. Therefore, the electrode according to one embodiment is distinguished from a conventional electrode including a thick film current collector, for example, by including a thin film current collector. Since the electrode according to one embodiment employs a thin film current collector having a reduced thickness, the thickness of the electrode active material layer in the electrode including the thin film current collector is relatively increased. As a result, the energy density of a lithium battery employing such an electrode is increased. The thickness of the electrode current collector (100) may be, for example, less than 15 um, 14.5 um or less, or 14 um or less. The thickness of the electrode collector (100) may be, for example, 0.1 um to less than 15 um, 1 um to 14.5 um, 2 um to 14 um, 3 um to 14 um, 5 um to 14 um, or 10 um to 14 um.

The electrode current collector (100) has a reduced surface roughness compared to the electrode current collector (100) included in a conventional electrode. Since the surface of the electrode current collector (100) has a reduced surface roughness, the electrode current collector (100) can form a uniform interface with the electrode active material layer and/or the intermediate layer (200a, 200b, 200). As a result, local side reactions and/or non-uniform electrode reactions at the interface between the electrode current collector (100) and other layers are suppressed, and the cycle characteristics of a lithium battery including such an electrode are improved.

The maximum roughness depth (R _max ) of the surface of the electrode collector (100) may be, for example, 3 um or less, 2 um or less, 1 um or less, 0.5 um or less, or 0.1 um or less. The maximum roughness depth (R _max ) of the surface of the electrode collector (100) may be, for example, 10 nm to 3 um, 10 nm to 2 um, 10 nm to 1 um, 10 nm to 0.5 um, or 10 nm to 0.1 um.

The average roughness (R _a ) of the surface of the electrode collector (100) may be, for example, 2 um or less, 1 um or less, 0.5 um or less, or 0.1 um or less. The average roughness (R _a ) of the surface of the electrode collector (100) may be, for example, 10 nm to 2 um, 10 nm to 1 um, 10 nm to 0.5 um, or 10 nm to 0.1 um.

The root mean square (RMS) roughness (R _q ) of the surface of the electrode collector (100) may be, for example, 2 um or less, 1 um or less, 0.5 um or less, or 0.1 um or less. The root mean square roughness (R _q ) of the surface of the electrode collector (100) may be, for example, 10 nm to 2 um, 10 nm to 1 um, 10 nm to 0.5 um, or 10 nm to 0.1 um.

The electrode current collector (100) may include, for example, a base film and a metal layer disposed on one or both sides of the base film. The electrode current collector (100) includes a substrate, and the substrate may have a structure including, for example, a base film and a metal layer disposed on one or both sides of the base film. The above-described intermediate layer may be additionally disposed on the metal layer. The base film may include, for example, a polymer. The polymer may be, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. Since the base film includes a thermoplastic polymer, the base film may melt when a short circuit occurs, thereby suppressing a rapid increase in current. The base film may be, for example, an insulator. The metal layer may include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or an alloy thereof. The metal layer may act as an electrochemical fuse and may be cut off when overcurrent occurs to prevent a short circuit. The limit current and the maximum current may be controlled by controlling the thickness of the metal layer. The metal layer may be plated or deposited on the base film. When the thickness of the metal layer becomes thinner, the limit current and/or the maximum current of the electrode current collector (100) decrease, so that the stability of the lithium battery in the event of a short circuit may be improved. A lead tab may be added on the metal layer for connection to the outside. The lead tab may be welded to the metal layer or the metal layer/base film laminate by ultrasonic welding, laser welding, spot welding, or the like. When the base film and/or the metal layer are melted during welding, the metal layer may be electrically connected to the lead tab. In order to make the welding of the metal layer and the lead tab more solid, a metal chip may be added between the metal layer and the lead tab. The metal chip may be a thin piece of the same material as the metal of the metal layer. The metal chip may be, for example, a metal foil, a metal mesh, etc. The metal chip may be, for example, aluminum foil, copper foil, SUS foil, etc. By arranging the metal chip on the metal layer and then welding it with the lead tab, the lead tab may be welded to the metal chip/metal layer laminate or the metal chip/metal layer/base film laminate. During welding, the base film, the metal layer, and/or the metal chip may be melted, so that the metal layer or the metal layer/metal chip laminate may be electrically connected to the lead tab. The metal chip and/or the lead tab may be added to a portion of the metal layer. The thickness of the base film may be, for example, 1 to 50 ㎛, 1.5 to 50 ㎛, 1.5 to 40 ㎛, or 1 to 30 ㎛. When the base film has a thickness in this range, the weight of the electrode assembly can be reduced more effectively. The melting point of the base film can be, for example, 100 to 300°C, 100 to 250°C or less, or 100 to 200°C. When the base film has a melting point in this range, the base film can be melted during the process of welding the lead tab and easily bonded to the lead tab. In order to improve the adhesion between the base film and the metal layer, a surface treatment such as corona treatment can be performed on the base film. The thickness of the metal layer can be, for example, 0.01 to 3 ㎛, 0.1 to 3 ㎛, 0.1 to 2 ㎛, or 0.1 to ㎛. When the metal layer has a thickness in this range, the stability of the electrode assembly can be secured while maintaining conductivity. The thickness of the metal piece can be, for example, 2 to 10 ㎛, 2 to 7 ㎛, or 4 to 6 ㎛. Since the metal piece has a thickness in this range, the connection between the metal layer and the lead tab can be performed more easily. Since the electrode current collector (100) has this structure, the weight of the electrode can be reduced, and as a result, the energy density can be improved. The electrode current collector (100) can be, for example, a positive electrode current collector. The electrode current collector (100) can be, for example, a negative electrode current collector.

Referring to FIGS. 1a to 1d, the area of the intermediate layer (200a, 200b, 200) may be smaller than the area of the electrode collector (100). A dry electrode film (300a, 300b, 300) directly disposed on the electrode collector (100) may be absent (free).

Method for manufacturing dry electrode

Referring to FIGS. 2a to 2d, FIGS. 3a to 3d, FIGS. 4a and 4b, a method for manufacturing a dry electrode according to one embodiment will be described.

FIGS. 2A and 2B are cross-sectional views of a first assembly according to an exemplary embodiment. FIGS. 2C and 2D are perspective views of a first assembly according to an exemplary embodiment. FIGS. 3A and 3B are cross-sectional views of a second assembly according to an exemplary embodiment. FIGS. 3C and 3D are perspective views of a second assembly according to an exemplary embodiment. FIGS. 4A and 4B are perspective views of a second assembly according to an exemplary embodiment.

Referring to FIGS. 2A to 2D, first, a first laminate (250) is prepared by arranging one or more intermediate layers (200a, 200b, 200) on one side or both sides of an electrode current collector (100). The intermediate layers (200a, 200b, 200) may be arranged on one side of the electrode current collector (100) or on opposite sides of the electrode current collector (100), respectively. The intermediate layers (200a, 200b, 200) may be arranged on part or all of one side or both sides of the electrode current collector (100). The intermediate layers (200a, 200b, 200) may cover part or all of the surface of the electrode current collector (100) on one side of the electrode current collector (100). The intermediate layer (200a, 200b, 200) may cover all or part of the surface of the electrode collector (100) on both sides of the electrode collector (100). In this case, the intermediate layer (200) includes an outer periphery region (220) arranged along at least a part of an outer periphery (outer periphery, 260) of the intermediate layer and an intermediate region (210) excluding the outer periphery region (220), and the thickness of the outer periphery region (220) may be thicker than the thickness of the intermediate region (210).

The first laminate (250) can be manufactured, for example, by the following method.

The step of preparing a first laminate (250) by arranging one or more intermediate layers (200a, 200b, 200) on one side or both sides of an electrode current collector (100) includes, for example, a step of providing an electrode current collector (100); and a step of arranging an intermediate layer (200a, 200b, 200) on one side or both sides of the electrode current collector (100). The material of the electrode current collector (100) refers to the electrode current collector (100) part described above. The positive electrode current collector may be, for example, aluminum foil. The negative electrode current collector may be, for example, copper foil. The step of arranging one or more intermediate layers (200a, 200b, 200) on one side or both sides of the electrode current collector (100) dry or wet arranges the intermediate layers (200a, 200b, 200) on one side or both sides of the electrode current collector (100). Dry coating coats, for example, a carbon-based conductive material and/or a precursor thereof on one or both sides of an electrode current collector (100) by deposition, etc. The deposition is performed at a temperature of room temperature to high temperature and a pressure of normal pressure to vacuum. The intermediate layer (200a, 200b, 200) disposed by dry coating may not include a binder if it is made of a carbon-based material. Wet coating coats, for example, a composition including a carbon-based conductive material and a binder on one or both sides of an electrode current collector (100). The composition includes, for example, a carbon-based conductive material, a binder, and a process solvent. For the carbon-based conductive material and the binder, refer to the electrode section described above. The process solvent may be selected from solvents used in the preparation of an electrode slurry. The process solvent is removed by drying after the composition is coated on the electrode current collector (100). The coating method may be spin coating, dip coating, or the like, but is not limited thereto, and any coating method used in the relevant technical field may be used.

For example, the method of forming the outer region (220) within the intermediate layer (200) is not particularly limited, and can be applied without limitation as long as the thickness of the outer region (220) can be formed greater than that of the intermediate region (210). For example, the intermediate layer (200) can be formed by coating one type of intermediate layer forming composition on the electrode current collector (100). In this case, in order to form the outer region (220), a relatively excessive amount of the intermediate layer forming composition can be applied along the outer periphery (260) of the intermediate layer to form the outer region (220).

For example, the intermediate layer (200) may be formed using two types of intermediate layer forming compositions. In this case, the first intermediate layer forming composition may be applied along the outer periphery (260) to form an outer region (220), and then the second intermediate layer forming composition may be applied to the remaining region except for the portion where the outer region is formed to form an intermediate region (210).

Referring to FIGS. 3a to 3d, next, a second laminate (350) is prepared by placing a dry electrode film (300a, 300b, 300) having a wider area than the area of the intermediate layer (200a, 200b, 200) on the first laminate (250). The dry electrode film (300a, 300b, 300) includes a first region (A1) placed on the intermediate layer (200a, 200b, 200) and a second region (A2) extending from the first region (A1) beyond the outer periphery of the intermediate layer (200a, 200b, 200). The second region (A2) of the dry electrode film (300a, 300b, 300) is, for example, a region where the intermediate layer (200a, 200b, 200) is free between the dry electrode film (300a, 300b, 300) and the electrode current collector (100). The second region (A2) of the dry electrode film (300a, 300b, 300) is, for example, a region of the dry electrode film (300a, 300b, 300) that does not contact the intermediate layer (200a, 200b, 200). The second region (A2) of the dry electrode film (300a, 300b, 300) is, for example, a region of the dry electrode film (300a, 300b, 300) that does not contact the intermediate layer (200a, 200b, 200). After arranging the dry electrode film (300a, 300b, 300) having a wider area than the area of the intermediate layer (200a, 200b, 200) on the first laminate (250), the second laminate (350) can be prepared, for example, by rolling. A dry electrode film (300a, 300b, 300) is placed on one side or both sides of a first laminate (250) and rolled to manufacture a second laminate (350) having a dry electrode film (300a, 300b, 300) placed on one side or both sides of the first laminate (250). For example, a second laminate (350) having a structure disclosed in FIG. 3a can be prepared by placing a dry electrode film (300a, 300b, 300) on one side of the first laminate (250) and rolling. Alternatively, a second laminate (350) having a structure disclosed in FIG. 3b can be prepared by placing a dry electrode film (300a, 300b, 300) on each side of the first laminate (250) and rolling. Rolling may be, for example, a roll press, a flat plate press, etc., but is not necessarily limited thereto. The pressure during rolling is, for example, 1.0 to 10.0 ton/cm. If the pressure during rolling increases excessively, cracks in the electrode current collector (100) may occur. If the pressure during rolling is excessively low, the bonding strength between the electrode current collector (100) and the dry electrode film (300a, 300b, 300) may be low.

Referring to FIGS. 3A to 3D and 4A to 4B, the dry electrode film (300a, 300b, 300) may further include a cut line (600a, 600b, 600) arranged along at least a portion of the boundary between the first region (A1) and the second region (A2), for example. Since the dry electrode film (300a, 300b, 300) further includes the cut line (600a, 600b, 600), the second region (A2) can be more effectively and easily separated from the first region (A1). The cut line (600a, 600b, 600) is, for example, a line region that is cut continuously or intermittently in advance along the boundary between the first region (A1) and the second region (A2).

For example, as the outer peripheral region (220) of the intermediate layer (200) is arranged along the outer peripheral portion (260) of the intermediate layer (200), the cutting line (600a, 600b, 600) may be formed at least in a part of the boundary between the first region (A1) and the second region (A2) during the process of arranging and rolling the dry electrode film (300a, 300b, 300) on the first laminate (250). In the dry electrode film (300a, 300b, 300), the cutting line (600a, 600b, 600) may be arranged along, for example, at least a part of the outer peripheral portion of the intermediate layer (200a, 200b, 200). Since the cutting lines (600a, 600b, 600) are arranged along at least a part of the outer periphery of the intermediate layer (200a, 200b, 200), the process of introducing the cutting lines (600a, 600b, 600) into the dry electrode film (300a, 300b, 300) can be simplified. As a result, the manufacturing process of the dry electrode (500) can be simplified. For example, since the cutting lines (600a, 600b, 600) are arranged along a part of the outer periphery of the intermediate layer (200a, 200b, 200), a dry electrode film (300a, 300b, 300) of a simple shape can be easily manufactured. Alternatively, the cutting lines (600a, 600b, 600) may be arranged along the entire outer periphery of the intermediate layer (200a, 200b, 200). By arranging the cutting lines (600a, 600b, 600) along the entire outer periphery of the intermediate layer (200a, 200b, 200), the second region (A2) can be more effectively separated from the first region (A1). For example, by arranging the cutting lines (600a, 600b, 600) along the entire outer periphery of the intermediate layer (200a, 200b, 200), dry electrode films (300a, 300b, 300) having various types of patterns can be easily manufactured.

The length of the cut lines (600a, 600b, 600) may be, for example, 40% or less, 35% or less, or 30% or less of the total length of the boundary between the first region (A1) and the second region (A2). The length of the cut lines (600a, 600b, 600) may be, for example, 40% or less, 35% or less, or 30% or less of the total length of the outer periphery of the middle layer (200a, 200b, 200). The length of the cut lines (600a, 600b, 600) may be, for example, 40% or less, 35% or less, or 30% or less of the total machine direction length of the dry electrode film (300a, 300b, 300). The length of the cutting line (600a, 600b, 600) may be, for example, 40% or less, 35% or less, or 30% or less of the total length in the width direction of the dry electrode film (300a, 300b, 300). For example, when the dry electrode film (300a, 300b, 300) includes the cutting line (600a, 600b, 600), the manufacturing of the dry electrode (500) can be performed more easily by pulling a part of the second region (A2) along the cutting line (600a, 600b, 600) to separate it from the first region (A1).

Referring to FIGS. 4A and 4B, at least a portion of a second region (A2) of a dry electrode film (300a, 300b, 300) is pulled to separate the second region (A2) from the first region (A1), thereby providing a dry electrode (500). For example, a portion of the second region (A2) at one end of the dry electrode film (300a, 300b, 300) is folded at an angle of 90 degrees to 180 degrees and then pulled to separate the second region (A2) from the first region (A1). Since the dry electrode film (300a, 300b, 300) has anisotropic tensile strength, the second region (A2) is selectively separated from the dry electrode film (300a, 300b, 300). A dry electrode (500) can be prepared by separating the second region (A2).

Referring to FIG. 4a, the dry electrode film (300a, 300b, 300) includes a first region (A1) and a second region (A2), and the second region (A2) can be separated from the first region (A1) along, for example, the machine direction (MD) of the dry electrode film (300a, 300b, 300). For example, the second region (A2) can be separated from the first region (A1) along a cutting line (600a, 600b) arranged along the machine direction (MD) of the dry electrode film (300a, 300b, 300).

The machine direction is, for example, the direction in which the dry electrode film (300a, 300b, 300) is stretched during the manufacture of the dry electrode film (300a, 300b, 300). Referring to FIGS. 4a and 4b, the machine direction is, for example, the x-axis direction. The direction in which the electrode film is stretched can be confirmed from an electron microscope image of a surface or cross-section of the dry electrode film (300a, 300b, 300). For example, the direction in which the stretched binder is oriented on the surface or cross-section of the dry electrode film may be the machine direction of the dry electrode film (300a, 300b, 300). The stretched binder includes, for example, a fiberized binder. The direction in which the fiberized binder is oriented may be, for example, the machine direction of the dry electrode film (300a, 300b, 300). The direction perpendicular to the machine direction is the transverse direction. Referring to FIGS. 4a and 4b, the transverse direction is, for example, the y-axis direction. Since the second region (A2) is separated from the first region (A1) along the machine direction of the dry electrode film (300a, 300b, 300), the second region (A2) can be separated more easily from the dry electrode film (300a, 300b, 300).

Referring to FIG. 4b, the dry electrode film (300a, 300b, 300) includes a first region (A1) and a second region (A2), and the second region (A2) can be separated from the first region (A1) along, for example, an outer periphery of the intermediate layer (200a, 200b, 200). For example, the second region (A2) can be separated from the first region (A1) along a cutting line (600) arranged along the outer periphery of the intermediate layer (200a, 200b, 200).

Since the second region (A2) is separated from the first region (A1) along the outer periphery of the intermediate layer (200a, 200b, 200), a dry electrode film (300a, 300b, 300) can be selectively disposed on the intermediate layer (200a, 200b, 200). The position and/or shape of the dry electrode film (300a, 300b, 300) disposed on the intermediate layer (200a, 200b, 200) can be selected depending on the position and/or shape of the intermediate layer (200a, 200b, 200).

For example, a dry electrode film (300a, 300b, 300) having the same shape as the intermediate layer (200a, 200b, 200) but having a larger area is disposed on an intermediate layer (200a, 200b, 200) having a square shape, and the dry electrode film (300a, 300b, 300) includes a first region (A1) having the same shape and area as the intermediate layer (200a, 200b, 200) and a second region (A2) extending from the first region (A1) beyond the outer periphery (260) of the intermediate layer (200a, 200b, 200) and disposed around the first region (A1). By pulling the second region (A2) of the dry electrode film (300a, 300b, 300), the second region (A2) is selectively separated from the first region (A1) along the outer periphery of the intermediate layer (200a, 200b, 200), and a dry electrode film (300a, 300b, 300) having the same shape and area as the intermediate layer (200a, 200b, 200) is disposed on the intermediate layer (200a, 200b, 200).

Referring to FIGS. 4a and 4b, the dry electrode films (300a, 300b, 300) may have, for example, a first area (S1). The intermediate layer (200a, 200b, 200) may have, for example, a second area. The ratio (S2/S1) of the second area (S2) to the first area (S1) may be 0.5 to 0.99, 0.6 to 0.98, 0.7 to 0.97, 0.8 to 0.96, or 0.9 to 0.95. Since the ratio (S2/S1) of the second area (S2) to the first area (S1) has a value within this range, the second area (A2) can be more effectively removed from the dry electrode film (300a, 300b, 300), and the dry electrode film (300a, 300b, 300) can be more effectively disposed on the intermediate layer (200a, 200b, 200). If the ratio (S2/S1) of the second area (S2) to the first area (S1) is too large, it may be difficult to remove the second area (A2) from the dry electrode film (300a, 300b, 300). If the ratio (S2/S1) of the area (S2) and the first area (S1) is too small, the area of the second area (A2) separated and removed from the dry electrode film (300a, 300b, 300) may increase excessively.

Referring to FIGS. 4a and 4b, the electrode current collector (100) may have, for example, a third area (S3). The intermediate layer (200a, 200b, 200) may have, for example, a second area (S2). The ratio (S2/S3) of the second area (S2) to the third area (S3) may be 0.5 to 0.99, 0.6 to 0.98, 0.7 to 0.97, 0.8 to 0.96, or 0.9 to 0.95. Since the ratio (S2/S3) of the second area (S2) to the third area (S3) has a value within this range, various forms of dry electrode films (300a, 300b, 300) may be introduced onto the electrode current collector (100). If the ratio (S2/S3) of the second area (S2) and the third area (S3) is too large, the dry electrode film (300a, 300b, 300) disposed spaced apart from the electrode current collector (100) is formed, so that the structural stability of the dry electrode (500) may deteriorate. If the ratio (S2/S3) of the second area (S2) and the third area (S3) is too small, the area of the dry electrode film (300a, 300b, 300) disposed on the electrode current collector (100) becomes too small, so that the energy density of the dry electrode (500) may deteriorate.

Referring to FIG. 5a, a dry electrode (500) manufactured by a method for manufacturing a dry electrode (500) according to one embodiment may include, for example, a plurality of dry electrode films (300a, 300b, 300) that are spaced apart from each other along the width direction of the electrode current collector (100) on one side or both sides of the electrode current collector (100). Each of the plurality of dry electrode films (300a, 300b, 300) may have, for example, a first machine direction length (MDL1) and a first width direction length (TDL1). The electrode current collector (100) may have, for example, a second machine direction length (MDL2) and a second width direction length (TDL2). Referring to FIG. 5a, the machine direction is, for example, the x direction, the width direction is, for example, the y direction, and the thickness direction is, for example, the z direction. The ratio (MDL1/TDL1) of the machine direction first length (MDL1) of the dry electrode film (300a, 300b, 300) to the width direction first length (TDL1) of the dry electrode film (300a, 300b, 300) may be, for example, 20 or more, 30 or more, 50 or more, or 100 or more. The ratio (TDL1/TDL2) of the width direction first length (TLD1) of the dry electrode film (300a, 300b, 300) to the width direction second length (TDL2) of the electrode current collector (100) may be, for example, 0.3 or less, 0.2 or less, or 0.1 or less. Accordingly, a plurality of dry electrode films (300a, 300b, 300) are spaced apart and arranged along the width direction of the electrode current collector (100) to form a dry electrode (500) in a stripe shape. An intermediate layer (200a, 200b, 200) is arranged between the plurality of dry electrode films (300a, 300b, 300) and the electrode current collector (100).

Referring to FIG. 5b, a dry electrode (500) manufactured by a method for manufacturing a dry electrode (500) according to one embodiment may include, for example, a dry electrode film (300a, 300b, 300) disposed along the machine direction of the electrode current collector (100) on one side or both sides of the electrode current collector (100). The dry electrode film (300a, 300b, 300) may have, for example, a third machine direction length (MDL3) and a third width direction length (TDL3). The electrode current collector (100) may have, for example, a fourth machine direction length (MDL4) and a fourth width direction length (TDL4). Referring to FIG. 5b, the machine direction is, for example, the x direction, the width direction is, for example, the y direction, and the thickness direction is, for example, the z direction. The longitudinal ends of the dry electrode films (300a, 300b, 300) may be in contact with, for example, the longitudinal ends of the electrode collector (100). The machine direction third length (MDL3) of the dry electrode films (300a, 300b, 300) may be, for example, 99 % to 101 %, 99.5 % to 100.5 %, 99.8 % to 100.2 %, or 99.9 % to 100.1 % of the machine direction fourth length (MDL4) of the electrode collector (100). The width direction ends of the dry electrode films (300a, 300b, 300) may be arranged to be spaced apart from, for example, the width direction ends of the electrode collector (100). The third widthwise length (TDL3) of the dry electrode film (300a, 300b, 300) may be, for example, 60% to 99%, 70% to 99%, 80% to 99%, or 90% to 99% of the fourth widthwise length (TDL4) of the electrode current collector (100).

Referring to FIG. 5c, a dry electrode (500) manufactured by a method for manufacturing a dry electrode (500) according to one embodiment may include, for example, a dry electrode film (300a, 300b, 300) disposed along the machine direction of the electrode current collector (100) on one side or both sides of the electrode current collector (100). The dry electrode film (300a, 300b, 300) may have, for example, a fifth machine direction length (MDL5) and a fifth width direction length (TDL5). The electrode current collector (100) may have, for example, a sixth machine direction length (MDL6) and a sixth width direction length (TDL6). Referring to FIG. 5c, the machine direction is, for example, the x direction, the width direction is, for example, the y direction, and the thickness direction is, for example, the z direction. The longitudinal ends of the dry electrode films (300a, 300b, 300) may be spaced apart from, for example, the longitudinal ends of the electrode collector (100), respectively. The machine direction fifth length (MDL5) of the dry electrode films (300a, 300b, 300) may be, for example, 60% to 99%, 70% to 99%, 80% to 99%, or 90% to 99% of the machine direction sixth length (MDL6) of the electrode collector (100). The width direction both ends of the dry electrode films (300a, 300b, 300) may be in contact with, for example, the width direction both ends of the electrode collector (100). The fifth widthwise length (TDL5) of the dry electrode film (300a, 300b, 300) may be 99 % to 101 %, 99.5 % to 100.5 %, 99.8 % to 100.2 %, or 99.9 % to 100.1 % of the sixth widthwise length (TDL6) of the electrode current collector (100).

Referring to FIG. 5d, a dry electrode (500) manufactured by a method for manufacturing a dry electrode (500) according to an embodiment may include, for example, a plurality of dry electrode films (300a, 300b, 300) that are spaced apart from each other along the machine direction of the electrode current collector (100) on one side or both sides of the electrode current collector (100). The plurality of dry electrode films (300a, 300b, 300) may have a patterned arrangement. Each of the plurality of dry electrode films (300a, 300b, 300) may be arranged spaced apart from both machine direction ends and both width direction ends of the electrode current collector (100). Each of the plurality of dry electrode films (300a, 300b, 300) may have, for example, a machine direction seventh length (MDL7) and a width direction seventh length (TDL7). The electrode collector (100) may have, for example, an eighth machine direction length (MDL8) and an eighth width direction length (TDL8). Referring to FIG. 5d, the machine direction is, for example, the x direction, the width direction is, for example, the y direction, and the thickness direction is, for example, the z direction. A ratio (MDL7/TDL7) of the machine direction seventh length (MDL7) of the dry electrode film (300a, 300b, 300) to the seventh width direction length (TDL7) may be, for example, 5 or less, 4 or less, 3 or less, or 2 or less. The seventh widthwise length (TDL7) of the dry electrode film (300a, 300b, 300) may be 60% to 99%, 70% to 99%, 80% to 99%, or 90% to 99% of the eighth widthwise length (TDL8) of the electrode current collector (100).

Referring to FIG. 5e, a dry electrode (500) manufactured by a method for manufacturing a dry electrode (500) according to one embodiment may include, for example, a plurality of dry electrode films (300a, 300b, 300) that are spaced apart from each other along the machine direction of the electrode current collector (100) on one side or both sides of the electrode current collector (100). The plurality of dry electrode films (300a, 300b, 300) may have a patterned arrangement. Each of the plurality of dry electrode films (300a, 300b, 300) may be arranged spaced apart from each other from both machine direction ends of the electrode current collector (100). Each of the plurality of dry electrode films (300a, 300b, 300) may have, for example, a ninth length (MDL9) in the machine direction and a ninth length (TDL9) in the width direction. The electrode collector (100) may have, for example, a tenth machine direction length (MDL10) and a tenth width direction length (TDL10). Referring to FIG. 5d, the machine direction is, for example, the x direction, the width direction is, for example, the y direction, and the thickness direction is, for example, the z direction. A ratio (MDL9/TDL9) of the machine direction ninth length (MDL9) of the dry electrode film (300a, 300b, 300) to the ninth width direction length (TDL9) may be, for example, 5 or less, 4 or less, 3 or less, or 2 or less. The ninth widthwise length (TDL9) of the dry electrode film (300a, 300b, 300) may be 99 % to 101 %, 99.5 % to 100.5 %, 99.8 % to 100.2 %, or 99.9 % to 100.1 % of the ninth widthwise length (TDL9) of the electrode current collector (100).

Referring to FIGS. 5d and 5e, the dry electrode films (300a, 300b, 300) can have, for example, a patterned array, and the patterned array can include, for example, a box pattern array, an annular pattern array, a serpentine pattern array, or a combination thereof. The patterned array can have, for example, a shape of FIGS. 6a to 6q.

In a dry electrode (500) manufactured by a method for manufacturing a dry electrode (500) according to an embodiment of the present invention, when the dry electrode film (300a, 300b, 300) is measured by a surface and interfacial measuring analysis system (SAICAS), a change rate in a vertical relative binding force (F VR) according to a depth from a first point spaced 5% apart from the surface of the dry electrode film (300a, 300b, 300) in the direction of the electrode current collector (100) to a second point spaced 5% apart from the surface of the electrode current collector (100) with respect to the entire thickness of the dry electrode film ( _300a , 300b, 300) is 300% or less, 250% or less, 200% or less, 150% or less, or 140% or less.

The rate of change in vertical relative bonding force is calculated from the following mathematical expression 1. For the SAICAS measurement method, see Evaluation Example 1, for example.

<Mathematical formula 1>

Rate of change of vertical relative binding force (F _V ) = [(maximum vertical relative binding force - minimum vertical relative binding force) / minimum vertical relative binding force)] × 100

In the dry electrode (500), since the rate of change in the vertical relative adhesion of the dry electrode films (300a, 300b, 300) is 300% or less when measured by the surface and interfacial measuring analysis system (SAICAS), the uniformity of distribution of the components of the dry electrode films (300a, 300b, 300) within the dry electrode (500) is improved. In addition, since side reactions and increases in internal resistance due to uneven distribution of the components within the dry electrode films (300a, 300b, 300) are suppressed, the reversibility of the electrode reaction can be improved. Therefore, even in the case of the dry electrode (500) having a high loading, the cycle characteristics of the lithium battery are improved. The rate of change in the vertical relative bonding force of the dry electrode films (300a, 300b, 300) is, for example, 10 to 300 %, 20 to 250 %, 30 to 200 %, 40 to 160 %, 50 to 150 %, or 60 to 140 %.

In a dry electrode (500) manufactured by a method for manufacturing a dry electrode (500) according to an embodiment of the present invention, when the dry electrode film (300a, 300b, 300) is measured by SAICAS, a ratio of a horizontal binding force of a second horizontal binding force (F HA2, Horizontal binding Force) at a second point located 10% away from the surface of the electrode collector (100) to a first horizontal binding force (F _HA1 , Horizontal binding Force) at a first point located 10% away from the surface of the dry electrode film ( _300a , 300b, 300) in the direction of the electrode collector (100) is 50% or more.

The horizontal bonding force ratio is expressed, for example, by the following mathematical expression 2.

<Mathematical formula 2>

Horizontal bonding force ratio = [Second horizontal bonding force (F _H2 ) / First horizontal bonding force (F _H1 )] × 100

In the electrode, when the horizontal binding force ratio is 50% or more in the SAICAS measurement, the uniformity of the distribution of the components within the electrode is further improved. When the electrode has the horizontal binding force ratio in this range, the cycle characteristics of a lithium battery employing the electrode are further improved. The horizontal binding force ratio is, for example, 50 to 300%, 50 to 250%, 50 to 200%, 50 to 150%, or 50 to 100%.

Method for manufacturing dry electrode film

Dry electrode films (300a, 300b, 300) can be manufactured, for example, by the following method.

First, a mixture is prepared by dry mixing a dry electrode active material, a dry conductive agent, and a dry binder.

Dry mixing means mixing without a process solvent. The process solvent is, for example, a solvent used in the manufacture of an electrode slurry. The process solvent is, for example, water, NMP, etc., but is not limited thereto, and is not limited as long as it is a process solvent used in the manufacture of an electrode slurry. Dry mixing can be performed using a stirrer at a temperature of 25°C to 65°C and a rotation speed of 10 to 10,000 rpm, or 100 to 10,000 rpm. Dry mixing can be performed using a stirrer for 1 to 200 minutes, or 1 to 150 minutes.

The dry mixing can be performed, for example, more than once. First, a first mixture can be prepared by first dry mixing a dry electrode active material, a dry conductive material, and a dry binder. The first dry mixing can be performed, for example, at a temperature of 25 to 65° C., at a rotation speed of 2000 rpm or less, for 15 minutes or less. The first dry mixing can be performed, for example, at a temperature of 25 to 65° C., at a rotation speed of 500 to 2000 rpm, for 5 to 15 minutes. The dry electrode active material, the dry conductive material, and the dry binder can be uniformly mixed by the first dry mixing. Subsequently, a second mixture can be prepared by second dry mixing a dry electrode active material, a dry conductive material, and a dry binder. The secondary dry mixing can be performed, for example, at a temperature of 25 to 65° C., at a rotation speed of at least 3000 rpm, for a time of at least 10 minutes. The secondary dry mixing can be performed, for example, at a temperature of 25 to 65° C., at a rotation speed of at least 3000 to 9000 rpm, for a time of at least 10 minutes. The secondary dry mixing can result in a dry mixture comprising a fibrillated dry binder.

The stirrer is, for example, a kneader. The stirrer includes, for example, a chamber; one or more rotating shafts arranged inside the chamber and rotating; and blades rotatably coupled to the rotating shaft and arranged in the longitudinal direction of the rotating shaft. The blades may be, for example, one or more blades selected from a ribbon blade, a sigma blade, a jet (Z) blade, a dispersion blade, and a screw blade. By including the blades, an electrode active material, a dry conductive material, and a dry binder can be effectively mixed without a solvent to produce a dough-like mixture. The produced mixture can be fed into an extrusion device and extruded in a sheet form. The pressure during extrusion is, for example, 4 MPa to 100 MPa, or 10 MPa to 90 MPa. The obtained mixture can be in the form of a film. That is, the obtained mixture can be a dry electrode film (300a, 300b, 300).

As the dry conductive agent, carbon black, graphite particles, natural graphite, artificial graphite, acetylene black, Ketjen black, carbon fibers; carbon nanotubes; metal powders or metal fibers or metal tubes such as copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives, etc. are used, but are not limited thereto, and any conductive agent used in the relevant technical field may be used. The conductive agent is, for example, a carbon-based conductive agent.

Examples of dry binders include vinylidene fluoride/hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene (PTFE), mixtures of the above polymers, styrene butadiene rubber-based polymers, etc., and examples of solvents include, but are not limited to, N-methylpyrrolidone (NMP), acetone, water, etc., and any solvent used in the relevant technical field may be used.

It is also possible to form pores inside the electrode plate by further adding a plasticizer or a pore forming agent to the electrode active material composition.

The contents of electrode active material, dry conductive agent, and dry binder used in the electrode active material layer are at levels typically used in lithium batteries.

The positive electrode uses a positive electrode active material as an electrode active material. The positive electrode active material refers to the electrode part described above. The negative electrode uses a negative electrode active material as an electrode active material. The negative electrode active material refers to the electrode part described above.

Lithium battery

According to another embodiment, a lithium battery (1) includes a positive electrode; a negative electrode; and an electrolyte disposed between the positive electrode and the negative electrode, and at least one of the positive electrode and the negative electrode is a dry electrode (500) manufactured by the above-described dry electrode (500) manufacturing method.

Lithium batteries (1) include, for example, lithium ion batteries, lithium solid-state batteries, and lithium air batteries.

The lithium battery (1) is manufactured by, for example, the following exemplary method, but is not necessarily limited to this method and varies depending on required conditions.

First, one or both of the positive electrode and the negative electrode can be manufactured according to the above-described dry electrode (500) manufacturing method. Alternatively, when one of the positive electrode and the negative electrode is manufactured by the above-described electrode manufacturing method, the other electrode can be manufactured by a wet manufacturing method. For example, the other electrode can be manufactured by manufacturing an electrode slurry including an electrode active material, a conductive material, a binder, and a solvent, coating the manufactured electrode slurry on an electrode current collector (100), and drying it. The conductive material and binder included in the electrode manufactured by the wet manufacturing method can be selected from the conductive material and binder used in the manufacture of the above-described dry electrode (500).

Next, a separator to be inserted between the positive and negative electrodes is prepared.

Any separator that is commonly used in lithium batteries can be used. For example, a separator having low resistance to ion movement of the electrolyte and excellent electrolyte moisture retention ability is used. The separator is selected from, for example, glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or a combination thereof, and is in the form of a nonwoven fabric or a woven fabric. For lithium ion batteries, a windable separator such as polyethylene or polypropylene is used, and for lithium ion polymer batteries, a separator having excellent organic electrolyte moisture retention ability is used.

The separator is manufactured by the following exemplary methods, but is not necessarily limited to these methods and may be adjusted according to required conditions.

First, a separator composition is prepared by mixing a polymer resin, a filler, and a solvent. The separator composition is directly coated on the top of the electrode and dried to form a separator. Alternatively, the separator composition is cast on a support and dried, and then a separator film peeled from the support is laminated on the top of the electrode to form a separator.

The polymer used in the manufacture of the separator is not particularly limited, and any polymer used as a binder for the electrode plates may be used. For example, vinylidene fluoride/hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, or mixtures thereof may be used.

Next, the electrolyte is prepared.

The electrolyte is, for example, an organic electrolyte. An organic electrolyte is prepared by dissolving a lithium salt in an organic solvent, for example.

Any organic solvent used in the art may be used. Examples of the organic solvent include propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, or mixtures thereof.

Any lithium salt used in the relevant technical field is also possible. Lithium salts include, for example, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiAlO ₂ , LiAlCl ₄ , LiN(C _x F _2x+1 SO ₂ )(C _y F _2y+1 SO ₂ ) (where x and y are natural numbers), LiCl, LiI or mixtures thereof.

Alternatively, the electrolyte is a solid electrolyte. The solid electrolyte may be, for example, boron oxide, lithium oxynitride, or the like, but is not limited thereto, and any solid electrolyte used in the relevant technical field may be used. The solid electrolyte may be formed on the cathode by, for example, sputtering or a separate solid electrolyte sheet may be laminated on the cathode. The solid electrolyte may be, for example, an oxide-based solid electrolyte or a sulfide-based solid electrolyte.

Referring to FIG. 7, a lithium battery (1) according to an embodiment includes a positive electrode (3), a negative electrode (2), and a separator (4). The positive electrode (3), the negative electrode (2), and the separator (4) are wound or folded to form a battery structure (7). The formed battery structure (7) is accommodated in a battery case (5). An organic electrolyte is injected into the battery case (5) and sealed with a cap assembly (6), thereby completing the lithium battery (1). The battery case (5) is cylindrical, but is not necessarily limited to this shape, and may be, for example, square, thin-film, etc.

Referring to FIG. 8, a lithium battery (1a) according to an embodiment includes a positive electrode (3a), a negative electrode (2a), and a separator (4a). A separator (4a) is arranged between the positive electrode (3a) and the negative electrode (2a), and the positive electrode (3a), the negative electrode (2a), and the separator (4a) are wound or folded to form a battery structure (7a). The formed battery structure (7a) is accommodated in a battery case (5a). An electrode tab (8a) that acts as an electrical path for inducing current formed in the battery structure (7a) to the outside may be included. An organic electrolyte is injected into the battery case (5a) and sealed to complete the lithium battery (1a). The battery case (5a) is square, but is not necessarily limited to this shape, and may be, for example, cylindrical, thin-film, etc.

Referring to FIG. 9, a lithium battery (1b) according to an embodiment includes a positive electrode (3b), a negative electrode (2b), and a separator (4b). A separator (4b) is arranged between the positive electrode (3b) and the negative electrode (2b), thereby forming a battery structure. A battery structure (7b) is stacked in a bi-cell structure and then accommodated in a battery case (5b). An electrode tab (8b) that acts as an electrical path for guiding a current formed in the battery structure (7b) to the outside may be included. An organic electrolyte is injected into the battery case (5b) and sealed, thereby completing the lithium battery (1b). The battery case (5b) is square, but is not necessarily limited to this shape, and may be, for example, cylindrical, thin-film, etc.

The pouch-type lithium battery corresponds to each of the lithium batteries of FIGS. 7 to 9 in which a pouch is used as a battery case. The pouch-type lithium battery includes one or more battery structures. A separator is arranged between a positive electrode and a negative electrode to form a battery structure. The battery structures are laminated in a bi-cell structure, then impregnated with an organic electrolyte, and accommodated and sealed in a pouch to complete the pouch-type lithium battery. For example, although not shown in the drawings, the above-described positive electrode, negative electrode, and separator may be simply laminated and accommodated in a pouch in the form of an electrode assembly, or may be wound or folded into a jellyroll-type electrode assembly and then accommodated in a pouch. Subsequently, an organic electrolyte is injected into the pouch and sealed to complete the lithium battery.

Lithium batteries have excellent life characteristics and high-rate characteristics, so they are used in electric vehicles (EVs). For example, they are used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). They are also used in fields that require large amounts of power storage. For example, they are used in electric bicycles, power tools, etc.

A plurality of lithium batteries are stacked to form a battery module, and the plurality of battery modules form a battery pack. This battery pack can be used in all devices requiring high capacity and high output. For example, it can be used in laptops, smartphones, electric vehicles, etc. The battery module includes, for example, a plurality of batteries and a frame that holds them. The battery pack includes, for example, a plurality of battery modules and a bus bar that connects them. The battery module and/or the battery pack may further include a cooling device. The plurality of battery packs are controlled by a battery management system. The battery management system includes a battery pack and a battery control device connected to the battery pack.

The present invention is described in more detail through the following examples and comparative examples. However, the examples are intended to illustrate the present invention and the scope of the present invention is not limited to these examples.

(Manufacture of lithium batteries (half-cell))

Example 1: Outer region/middle region thickness ratio = 2, cross-sectional electrode

(dry electrode film)

LiNi _0.91 Co _0.05 Al _0.04 O ₂ (hereinafter referred to as NCA91) having an average particle size (D50) of 15 ㎛ as a dry cathode active material, carbon conductive material (Denka Black) as a dry conductive material, and polytetrafluoroethylene (PTFE) as a dry binder were placed in a blade mixer at a weight ratio of 96:1.8:2.2, and then primary dry mixing was performed at a speed of 1000 rpm at 25°C for 10 minutes to prepare a first mixture in which the cathode active material, conductive material, and binder were uniformly mixed.

Subsequently, in order to allow the fibrillization of the dry binder to proceed, the first mixture was additionally mixed at 25°C and a speed of 5000 rpm for 20 minutes to prepare a second mixture. No separate solvent was used in the preparation of the first mixture and the second mixture. The prepared second mixture was put into an extruder and extruded to prepare a sheet-shaped positive electrode active material layer. The pressure during extrusion was approximately 50 MPa. The extrusion direction corresponds to the machine direction.

The prepared cathode active material layer sheet was rolled to prepare a dry cathode film. The dry cathode film is a self-standing film. The pressure during rolling was approximately 3 ton/cm ² .

(Manufacture of the first layer)

A first laminate was prepared in which a carbon layer was arranged as an interlayer on one side of a 12 ㎛ thick aluminum thin film cathode current collector.

The length of the carbon layer was the same as the length in the machine direction of the positive electrode collector. The width of the carbon layer was 90% of the length in the width direction of the positive electrode collector. The carbon layer was placed at the center of the positive electrode collector at a distance of 5% from each end of the positive electrode collector in the width direction.

In addition, the carbon layer further included an outer peripheral region whose length was the same as the length in the machine direction of the positive electrode collector and was arranged in an area of up to 5% from each end of the carbon layer, and the ratio of the thickness of the outer peripheral region to the thickness of the central region excluding the outer peripheral region was 2.

The carbon layer was prepared by coating a composition including a carbon conductive material (Danka black) and polyvinylidene fluoride (PVDF) on an aluminum thin film and then drying it. The thickness of the carbon layer disposed on one side of the aluminum thin film was about 1 ㎛.

(Manufacture of the second layer and dry anode)

A second laminate was prepared by placing a dry cathode film on one side of the first laminate where the carbon layer was placed. The thickness of the dry cathode film was approximately 100 ㎛.

The area of the dry cathode film was the same as that of the cathode current collector. The dry cathode film included a first region disposed on a carbon layer and a second region disposed on the cathode current collector. The second region was disposed to extend from the first region beyond the outer periphery of the carbon layer.

A second region of the dry positive electrode film was folded 180 degrees from one longitudinal end of the dry positive electrode film, and then pulled longitudinally along the cut line of the dry positive electrode film.

The second region of the dry positive electrode film was completely removed by separating the first region from the second region of the dry positive electrode film from one longitudinal end of the dry positive electrode film to the other end, and the second region of the dry positive electrode film arranged on the positive electrode current collector was completely removed. A dry positive electrode was prepared in which the dry positive electrode active material layer was arranged only on the carbon layer and the dry positive electrode active material layer was absent (free) on the positive electrode current collector.

There was no damage to the cathode current collector during the process of removing the second region of the dry cathode film. There was no burr or depression adjacent to the outer periphery of the dry cathode active material layer.

After removing the second region of the dry cathode film, a scanning electron microscope image of the cross-section of the dry cathode active material layer is shown in Fig. 10. As shown in Fig. 10, it was confirmed that a fibrillized binder was arranged along the longitudinal direction (horizontal direction in the drawing, X direction) of the dry cathode active material layer.

(Manufacturing of coin cells)

Using the positive electrode manufactured as above, a coin cell was manufactured using lithium metal as a counter electrode, a PTFE separator, and a solution of 1.3 M LiPF ₆ dissolved in EC (ethylene carbonate) + EMC (ethyl methyl carbonate) + DMC (dimethyl carbonate) (volume ratio of 3:4:3) as an electrolyte.

Example 2: Outer region/middle region thickness ratio = 1.5, cross-sectional electrode

A dry positive electrode and a lithium battery were manufactured in the same manner as in Example 1, except that the ratio of the thickness of the outer region to the thickness of the middle region among the intermediate layers was changed to 1.5.

Example 3: Outer region/middle region thickness ratio = 1.2, cross-sectional electrode

A dry positive electrode and a lithium battery were manufactured in the same manner as in Example 1, except that the ratio of the thickness of the outer region to the thickness of the middle region among the intermediate layers was changed to 1.2.

Example 4: Outer region/middle region thickness ratio = 2.5, cross-sectional electrode

A dry positive electrode and a lithium battery were manufactured in the same manner as in Example 1, except that the ratio of the thickness of the outer region to the thickness of the middle region among the intermediate layers was changed to 1.2.

Example 5: Dry positive electrode film MDS/TDS=2, double-sided electrode

(Manufacture of dry electrode film)

A dry positive electrode film was prepared in the same manner as in Example 1.

(Manufacture of the first layer)

A first laminate was manufactured in the same manner as in Example 1, except that an interlayer including a middle region and an outer peripheral region was formed on each side of a 12 ㎛ thick aluminum thin film anode collector.

(Manufacture of the second layer and dry anode)

A second laminate was prepared by placing a dry positive electrode film on each side of the first laminate.

The machine direction length of the dry positive electrode film was the same as the machine direction length of the first laminate. The width direction length of the dry positive electrode film was 120% of the width direction length of the first laminate. The two dry positive electrode films were in direct contact with each other in a region exceeding both ends in the width direction of the first laminate. The dry positive electrode film included a first region disposed on the intermediate layer and a second region extending from the first region exceeding the outer periphery of the intermediate layer. The first region of the dry positive electrode film was in contact with the intermediate layer, and the second region of the dry positive electrode film was not in contact with the intermediate layer. The thickness of the dry positive electrode film disposed on one surface of the positive electrode current collector was about 100 ㎛.

In this case, a cut line was formed in the dry positive electrode film along the boundary between the first region and the second region at one end in the longitudinal direction of the dry positive electrode film by the outer region.

A second region of the dry positive electrode film was folded 180 degrees from one longitudinal end of the dry positive electrode film, and then pulled longitudinally along the cut line of the dry positive electrode film.

The second region of the dry positive electrode film was completely removed by separating the first region from the second region of the dry positive electrode film from one longitudinal end of the dry positive electrode film to the other end. A dry positive electrode was prepared in which a dry positive electrode active material layer was disposed only on the first laminate.

There was no damage to the cathode current collector during the process of removing the second region of the dry cathode film. There was no burr or depression adjacent to the outer periphery of the dry cathode active material layer.

(Manufacturing of coin cells)

Using the positive electrode manufactured as above, a coin cell was manufactured using lithium metal as a counter electrode, a PTFE separator, and a solution of 1.3 M LiPF ₆ dissolved in EC (ethylene carbonate) + EMC (ethyl methyl carbonate) + DMC (dimethyl carbonate) (volume ratio of 3:4:3) as an electrolyte.

Comparative Example 1: Wet Anode

(Manufacture of wet anode)

A mixture of LiNi _0.91 Co _0.05 Al _0.04 O ₂ (hereinafter referred to as NCA91) having an average particle size (D50) of 15 ㎛ as a cathode active material, a carbon conductive material (Denka Black) as a conductive material, and polytetrafluoroethylene (PTFE) as a binder was mixed in a weight ratio of 96:1.8:2.2 together with N-methylpyrrolidone (NMP) in an agate mortar to prepare a slurry for forming a cathode active material layer. The slurry was bar coated on one side of a 12 ㎛ thick aluminum foil cathode current collector, dried at room temperature, and then dried again under vacuum at 120° C. to introduce a cathode active material layer, thereby preparing a laminate. The prepared laminate was rolled to manufacture a cathode. The pressure during rolling was 3.0 ton/cm. The thickness of the cathode active material layer of the cathode of Comparative Example 1 was the same as the thickness of the cathode active material layer of the cathode of Example 1.

A cutting line was introduced into the wet cathode active material layer at the same position and shape as the dry cathode from the side of one longitudinal end of the wet cathode. With respect to the cutting line, the center of the width direction of the wet cathode was designated as the first region, and the end of the width direction of the wet cathode was designated as the second region. The second region of the wet cathode active material layer was bent by 180 degrees from one longitudinal end of the wet cathode and then pulled along the longitudinal direction of the wet cathode.

Since the positive electrode active material layer manufactured by the wet method was hard, cracks occurred in the positive electrode active material layer during the separation process of the second region, making it unusable as a positive electrode.

Therefore, for the charge-discharge experiment, a laser cutter was used to separate the second region from the first region of the cathode active material layer to prepare a cathode.

(Manufacturing of coin cells)

A lithium battery was manufactured in the same manner as in Example 1, except that the above-mentioned wet positive electrode was used instead of the dry positive electrode.

Comparative Example 2: Absence of intermediate and outer regions

A positive electrode was manufactured in the same manner as in Example 1, except that the first electrode body was prepared by forming a carbon layer of uniform thickness on a 12 ㎛ thick aluminum film.

A cutting line was introduced into the dry cathode active material layer at the same position and shape as the dry cathode of Example 1 from the side of one longitudinal end of the dry cathode. The center of the width direction of the dry cathode based on the cutting line was designated as the first region, and the end of the width direction of the dry cathode was designated as the second region. After the second region of the dry cathode active material layer was bent by 180 degrees at one longitudinal end of the dry cathode, it was pulled along the longitudinal direction of the dry cathode to remove the second region.

In this case, the number of dry electrodes that could be manufactured per unit time decreased compared to Example 1 as an additional procedure for introducing a cutting line was performed.

Comparative Example 3: Absence of middle region, outer region and cutting line

A positive electrode was manufactured in the same manner as in Example 1, except that the first electrode body was prepared by forming a carbon layer of uniform thickness on a 12 ㎛ thick aluminum film.

Thereafter, the width-wise central portion of the dry positive electrode was designated as the first region, and the width-wise end portion of the dry positive electrode was designated as the second region. The second region of the dry positive electrode active material layer was folded by 180 degrees at one length-wise end of the dry positive electrode, and then pulled along the length-wise direction of the dry positive electrode to remove the second region.

In this case, the number of dry electrodes that could be manufactured per unit time was similar to Example 1, but since there was no cutting line, some cracks occurred in the first region during the process of removing the second region.

Comparative Example 4: Laser Cutting

A dry electrode film and a cathode current collector/intermediate layer laminate were prepared in the same manner as in Example 1.

(dry electrode)

A dry positive electrode was manufactured in the same manner as in Example 1, except that a laser cutter was used to separate the second region from the first region of the positive electrode active material layer along the boundary between the first region and the second region at one longitudinal end of the dry positive electrode. During the process of removing the second region of the positive electrode active material layer, the positive electrode current collector was damaged by the laser.

A burr and/or depression is formed adjacent to the outer periphery of the dry cathode active material layer.

Comparative Example 4: Laser Cutting

A dry electrode film and a cathode current collector/intermediate layer laminate were prepared in the same manner as in Example 5.

(dry electrode)

A dry positive electrode was manufactured in the same manner as in Example 5, except that a laser cutter was used to separate the second region from the first region of the positive electrode active material layer along the boundary between the first region and the second region at one longitudinal end of the dry positive electrode. During the process of removing the second region of the positive electrode active material layer, the positive electrode current collector was damaged by the laser.

A burr and/or depression is formed adjacent to the outer periphery of the dry cathode active material layer.

Evaluation Example 1: Evaluation of room temperature charge/discharge characteristics

The lithium batteries manufactured in Examples 1 to 4 and Comparative Examples 1 and 3 were charged under constant current at 25°C at a current of 0.1 C rate until the voltage reached 4.4 V (vs. Li), and then cut-off was achieved at a current of 0.05 C rate while maintaining 4.4 V in constant voltage mode. Subsequently, the batteries were discharged under constant current at 0.1 C rate until the voltage reached 2.8 V (vs. Li) during discharge (formation cycle).

The lithium battery that had undergone the Mars cycle was charged at a constant current of 0.5C at 25℃ until the voltage reached 4.4 V (vs. Li). Then, it was discharged at a constant current of 0.5C until the voltage reached 2.8 V (vs. Li), and this cycle was repeated under the same conditions up to the ^100th cycle (repeated 100 times).

In all charge/discharge cycles, a pause of 10 minutes was allowed after one charge/discharge cycle. Some of the results of the room temperature charge/discharge experiments are shown in Table 1 below. The capacity retention at the ^100th cycle is defined by the following mathematical expression 3.

<Mathematical Formula 3>

Capacity retention ratio [%] = [discharge capacity at ^100th cycle / discharge capacity at ^1st cycle] Х 100

Electrode type Outer area thickness/Center area thickness Capacity retention rate [%] Example 1 deflation 2 96 Example 2 deflation 1.5 96.5 Example 3 deflation 1.2 95 Example 4 deflation 2.5 95 Comparative Example 1 Wet - 92 Comparative Example 3 deflation 1 90

As shown in Table 1, the lithium batteries of Examples 1 to 4 showed improved room temperature life characteristics compared to the lithium battery of Comparative Example 1.

The lithium battery equipped with the wet electrode of Comparative Example 1 had poor life characteristics compared to the lithium batteries equipped with the dry electrodes of Examples 1 to 4.

It was determined that the wet electrode of Comparative Example 1 had a reduced lifespan due to an increase in side reactions caused by burrs and/or depressions in the electrode current collector formed adjacent to the outer periphery of the positive electrode active material layer by laser cutting.

The dry electrode of Comparative Example 3 did not include an outer peripheral region, so the second region was removed without a cutting line, and it was determined that the life characteristics were deteriorated as some cracks were formed in the first region during the process.

1, 1a, 1b lithium battery 2, 2a, 2b cathode
3, 3a, 3b positive electrode 4, 4a, 4b separator
5, 5a, 5b battery case 6, 6a, 6b cap assembly
7, 7a, 7b battery structure 8a, 8b electrode tab
100 Electrode Collector
200, 200a, 200b middle layer 210 middle area
220 Outsourcing Area 260 Outsourcing Department
261 1st Outsourcing Department 262 2nd Outsourcing Department
300, 300a, 300b dry electrode film
500 electrode assembly

Claims (20)

Electrode current collector;
A dry electrode film disposed on one or both sides of the electrode collector; and
An intermediate layer disposed between the electrode current collector and the dry electrode film,
The intermediate layer includes an outer periphery region arranged along at least a portion of an outer periphery of the intermediate layer and an intermediate region excluding the outer periphery region,
A dry electrode wherein the thickness of the outer peripheral region is thicker than the thickness of the middle region. In the first paragraph,
The above outer circumference includes a first outer circumference parallel to the machine (X) direction and a second outer circumference parallel to the width (Y) direction,
The above outer peripheral region is a dry electrode arranged along the first outer peripheral portion. In the first paragraph,
The above outer peripheral region is a dry electrode arranged along the outer peripheral portion. In the first paragraph,
A dry electrode, wherein the ratio of the area of the outer peripheral region to the total area of the intermediate layer is 1 to 20%. In the first paragraph,
A dry electrode, wherein the ratio of the thickness of the outer peripheral region to the thickness of the middle region is greater than 1 and less than or equal to 5. In the first paragraph,
A dry electrode, wherein the intermediate layer comprises a binder, and the binder comprises at least one selected from a conductive binder and a non-conductive binder. In Article 6,
A dry electrode, wherein the intermediate layer further comprises a carbon-based conductive material. In the first paragraph,
A dry electrode, wherein the composition of the intermediate region among the intermediate layers is the same as the composition of the outer peripheral region. In the first paragraph,
A dry electrode, wherein the composition of the intermediate region among the intermediate layers is different from the composition of the outer peripheral region. In the first paragraph,
A dry electrode, wherein the thickness of the region disposed on the middle region among the above dry electrode films is thicker than the thickness of the region disposed on the outer region. In the first paragraph,
The above dry electrode film is a self-standing film, and the dry electrode film is free of residual processing solvent,
A dry electrode, wherein the dry electrode film comprises a dry electrode active material and a dry binder, the dry binder comprises a fibrillized binder, and the dry binder comprises a fluorine-based binder. In Article 11,
A dry electrode, wherein the dry electrode film further comprises a dry conductive material, and the dry conductive material comprises a carbon-based conductive material. A step of preparing a first laminate by arranging an intermediate layer on an electrode collector;
A step of preparing a second laminate by arranging a dry electrode film having a larger area than the area of the intermediate layer on the first laminate, the dry electrode film including a first region where the dry electrode film is arranged on the intermediate layer and a second region extending from the first region beyond the outer periphery of the intermediate layer; and
A step of pulling at least a portion of the second region of the dry electrode film to separate the second region from the first region to provide a dry electrode,
The intermediate layer includes an outer periphery region arranged along at least a portion of an outer periphery of the intermediate layer and an intermediate region excluding the outer periphery region,
A method for manufacturing a dry electrode, wherein the thickness of the outer region is thicker than the thickness of the middle region. In Article 13,
A method for manufacturing a dry electrode, wherein the dry electrode film further includes a cut line disposed along at least a portion of a boundary between the first region and the second region. In Article 14,
A method for manufacturing a dry electrode, wherein in the above dry electrode film, the cutting line is arranged along at least a part of the outer peripheral portion of the intermediate layer. In Article 14,
A method for manufacturing a dry electrode, wherein the length of the above-mentioned cutting line is 40% or less of the total length of the boundary between the first region and the second region. In Article 13,
A method for manufacturing a dry electrode, wherein the second region is separated from the first region along the machine direction (MD) of the dry electrode film. In Article 13,
A method for manufacturing a dry electrode, wherein the second region is separated from the first region along the outer periphery of the intermediate layer. A first electrode; a second electrode; and an electrolyte disposed between the first electrode and the second electrode,
A lithium battery, wherein the first electrode, the second electrode, or a combination thereof is a dry electrode according to claim 1. In Article 19,
A lithium battery, wherein the electrolyte comprises a liquid electrolyte, a solid electrolyte, or a combination thereof.

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