WO2021075619A1 - Anode, secondary battery comprising same, and manufacturing method therefor - Google Patents

Abstract

An anode according to one embodiment of the present invention comprises a porous metal layer comprising a metal capable of absorbing and desorbing an alkali metal or alkaline earth metal ions by being alloyed and dealloyed with an alkali metal or an alkaline earth metal, wherein the porous metal layer has a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected.

Description

Anode, secondary battery including same, and manufacturing method thereof

The present invention is a negative electrode comprising a porous metal layer having a porous three-dimensional network structure in which micro active material particles including a metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with an alkali metal or alkaline earth metal are interconnected. , To a method for manufacturing the same, and a secondary battery including the same.

As various portable electronic devices and electric vehicles are researched and developed, the need for energy storage technology is further increasing, and accordingly, lithium secondary batteries having high energy density and voltage are widely used.

However, due to the high price and limited reserves of lithium, active research on sodium ion batteries using sodium having a relatively low price and high energy density as a next-generation battery is being conducted.

However, even if a graphite negative electrode used in a lithium ion battery is applied to a sodium ion battery, there is a problem that not only a high capacity as in the conventional lithium ion battery cannot be achieved, and a battery having high energy cannot be developed.

Accordingly, there is a need to develop a new anode capable of achieving high capacity even when applied to a sodium ion battery or the like.

The present invention has been devised to solve the above-described problems, a high-capacity negative electrode comprising a porous metal layer capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with an alkali metal or alkaline earth metal, a method of manufacturing the same, and It is intended to provide a secondary battery including this.

A negative electrode according to an embodiment of the present invention includes a porous metal layer including a metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with an alkali metal or alkaline earth metal.

The porous metal layer may have a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected.

The porous metal layer may have an average pore diameter of 0.1 to 200 μm.

The porous metal layer may have a porosity of 50 to 90% by volume.

The metal microparticles may have an average diameter of 0.1 to 5 μm.

The metal microparticles may have an average length of 0.5 to 20 μm.

The metal microparticles may have an average aspect ratio (length/diameter) of 1 to 10.

The porous metal layer may include at least 90% by weight of a metal selected from the group including Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi based on 100% by weight of the total porous metal layer.

The porous metal layer may include at least 90% by weight of the metal represented by Formula 1 below based on 100% by weight of the total porous metal layer.

[Formula 1]

Wherein A is Li, Na, Mg, K, or Ca, and B is selected from the group containing Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi, and x may be 0 to 6 days have.

More specifically, the porous metal layer may include at least 90% by weight of the metal represented by the following Chemical Formula 2 or 3, based on 100% by weight of the total porous metal layer.

[Formula 2]

[Formula 3]

Y may be 0 to 1, and z may be 0 to 3.

A method of manufacturing a secondary battery according to an embodiment of the present invention includes the steps of configuring a half-cell including a negative electrode including a metal layer and a metal electrode, and forming the half-cell. Charging and discharging two or more times to convert the metal layer into a porous metal layer, and a full-cell including a negative electrode including the porous metal layer, a positive electrode including a positive electrode active material, and an electrolyte. It includes the step of manufacturing.

The metal layer may include a metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with an alkali metal or alkaline earth metal.

The metal electrode may include an alkali metal or an alkaline earth metal.

The step of converting the metal layer into a porous metal layer may be performing a cycle in which the cathode and the metal electrode are electrically connected to be fully charged and completely discharged.

In the step of converting the metal layer into a porous metal layer, the metal layer may be converted into a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected.

Prior to the step of configuring the half-cell, the method may further include a step of manufacturing a negative electrode including a metal layer by rolling a metal foil.

The manufacturing of the negative electrode may include forming a metal layer to a thickness of 25 μm to 2 mm. Specifically, it may be 27 μm to 2 mm.

A secondary battery according to an embodiment of the present invention may include a positive electrode, an electrolyte, and a negative electrode according to an embodiment of the present invention.

The electrolyte may include a metal salt and an ether-based solvent.

The ether solvent is dimethoxyethane (DME), 1,3-dioxolane (1,3-dioxolane), tetraethylene glycol dimethyl ether (TEGDME), diethylene glycol dimethyl ether (Diethylene glycol). dimethyl ether, DEGDME), triethylene glycol dimethyl ether (TEGDME), polyethylene glycol dimethyl ether (PEGDME), polyethylene oxide (PEO), and a mixture thereof. Can be.

A separator may be further included between the anode and the cathode.

The separation membrane may be a nanoporous separation membrane having pores of 10 nm to 100 nm. Specifically, it may be 20nm to 100nm, 50nm to 100nm, or 80nm to 100nm.

The separation membrane may be a microporous separation membrane having pores of 1 μm to 50 μm. Specifically, it may be 3 μm to 50 μm, 5 μm to 50 μm, 10 μm to 50 μm, or 15 μm to 50 μm.

The thickness of the nanopore separation membrane may be 5 μm to 1 mm. Specifically, it may be 10 μm to 1 mm, 15 μm to 1 mm, 20 μm to 1 mm, and 25 μm to 1 mm.

The micropore separation membrane may have a pore size of 1 μm to 50 μm. Specifically, it may be 3 μm to 50 μm, 5 μm to 50 μm, 8 μm to 50 μm, or 10 μm to 50 μm.

The microporous separation membrane may have a thickness of 0.2mm to 2mm. Specifically, it may be 0.5mm to 2mm, 0.8mm to 2mm, or 1mm to 2mm.

The separation membrane may be a multiple separation membrane including a nanoporous separation membrane and a microporous separation membrane.

A negative electrode according to an embodiment of the present invention, and a secondary battery including the same, are porous three-dimensional metal microparticles that can absorb and release alkali metal or alkaline earth metal ions by alloying and dealloying with an alkali metal or alkaline earth metal. By including the porous metal layer having a network structure, cracking or pulverization due to volume change of the active material does not occur in the charging/discharging process, cycle characteristics can be improved, and high capacity and high energy can be obtained.

In addition, since the method of manufacturing an anode of the present invention does not include a conventional nano-ization process of an active material in manufacturing an active material layer composed of fine particles, it is possible to facilitate the manufacturing process and reduce manufacturing cost.

1 is a diagram showing a rod-shaped metal microparticle.

2 is a view showing the structure of a cathode porous metal layer according to an embodiment of the present invention.

3 is an actual photograph of the negative electrode porous metal layer in Example 1.

4 is a SEM photograph of the cathode Sn porous metal layer in Example 1.

5 shows the EDS spectrum of the negative electrode porous metal layer in Example 1.

6 is a SEM photograph of a state in which the cathode Sn porous metal layer of Example 1 completely reacted with Na electrochemically.

7 shows the EDS spectrum result of Example 1 in which the cathode porous metal layer was discharged with sodium to 1 mV (Na _{3.75 Sn).}

8 is a graph of charging and discharging of the negative electrode of Example 1.

9 is a SEM photograph of an active material layer of a negative electrode of Comparative Example 1.

10 is a graph of charging and discharging at 0.1 C-rate of Comparative Example 1.

11 is a cycle graph of the negative electrode of Example 1 and the negative electrode of Comparative Example 1.

12 is an actual photograph of the cathode of Example 2.

13 is a SEM photograph of the anode Bi porous metal layer in Example 2.

14 is an XRD pattern of the anode Bi porous metal layer in Example 2.

15 is a graph of charging and discharging of the negative electrode of Example 2.

16 is a graph of 1 to 100 cycles of the negative electrode of Example 2.

17 is a diagram showing a half-cell structure.

18 is a diagram showing the structure of a full-cell.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, and the present invention is not limited thereby, and the present invention is only defined by the scope of the claims to be described later.

In this specification, the terminology used is only for referring to specific embodiments and is not intended to limit the present invention. Singular forms as used herein also include plural forms unless the phrases clearly indicate the opposite. In the present specification, when a certain part "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

When a part of a layer, film, region, plate, etc. is said to be "on" or "on" another part, this includes not only the case where the other part is "directly above", but also the case where there is another part in the middle. In addition, throughout the specification, the term "on" means that it is located above or below the target part, and does not necessarily mean that it is located above or below the direction of gravity.

In the present specification, the metal layer is used to include a plate-like (plate-shaped) metal having a thickness and an area.

In the present specification, a network structure means that particles have a physically interconnected form. In this way, when the active material particles are physically interconnected, a connection between the active material particles may be formed electrically.

In the present specification, the alloying material absorbs sodium by electrochemically reacting and alloying with an alkali metal or alkaline earth metal such as sodium, and electrochemically absorbs sodium and the like by electrochemically releasing sodium and the like by dealloying, It means a material that can be released. These alloying materials (metal active materials) are gallium (Ga, gallium), germanium (Ge, germanium), indium (In, indium), tin (Sn, tin), antimony (Sb, antimony), thallium (Tl, thallium), It may be selected from the group including lead (Pb, lead), bismuth (Bi, bismuth), and alloys thereof. However, it is not limited to the metals listed above, and metals capable of reversibly absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with alkali metal or alkaline earth metal may be included therein.

Materials that can be absorbed and released through the alloying and dealloying reactions with the alloying material may be alkali metals and alkaline earth metals, and the alloying and dealloying reactions have the following chemical reaction formula.

xA+ M ↔ A _x M

In the above chemical reaction formula, A is an alkali metal or alkaline earth metal, and M is an alloying material.

At this time, most of the values of x exceed 1, so the alloying material shows a high theoretical capacity.

For example, when tin reacts with sodium _{to form the final product Na 15} Sn ₄ (x=3.75), it exhibits a high theoretical capacity of 847 mAh/g. Table 1 below shows sodiumation reaction products and theoretical capacity according to the type of alloying material.

Referring to Table 1 below, it can be seen that the ion capacity of the alloying material may vary depending on the type of the alloying material. In addition, the alloying material may have a different capacity depending on the degree of sodiumization.

However, the volume of the alloying material (M) expands when alloyed with an alkali metal or alkaline earth metal such as sodium (A _x M), and returns to the original alloying material (M) during dealloying and decreases in volume. Therefore, when the alloying material is applied as an electrode active material, when charging and discharging the battery, alloying and dealloying occurs in the electrode active material, causing an intrinsic problem of causing volume change of volume expansion and contraction in the alloying material. Let it. That is, the volume change due to charging and discharging causes internal stress in the alloyed material, which leads to the generation of cracks in the electrode active material (layer), and finally, the crack grows, and the electrode active material (layer) This splitting leads to a process in which the electrode active material is pulverized into smaller particles. Such pulverization of the electrode active material (layer) causes a problem that the electrode active material (layer) is disconnected from the current collector or the conductive material in the electrode. Thus, since electrons are not supplied from the current collector, it is placed in a state in which the electrochemical reaction can no longer be performed, and as the charging and discharging proceeds repeatedly, a rapid decrease in capacity occurs. As a result, an electrode having an alloying mechanism has a short charge/discharge cycle life. In order to solve the pulverization problem due to a large volume change rate during charging and discharging of the electrode active material, a method of making the active material into fine particles may be considered. However, in the case of a process of pulverizing an active material into fine particles, there is a problem of increasing the electrode price by entailing a complicated and expensive process cost. In addition, when the powder electrode active material is used, a polymer binder is used to fix the powder electrode active material to the current collector, and a conductive material for improving conductivity is further included. However, these polymeric binders and conductive materials are materials that do not react electrochemically, and since the content of the active material in the electrode decreases, the total capacity of the electrode is reduced.

In order to provide a space to accommodate the volume expansion of the electrode active material during charging and discharging, a porous structure may be designed using the electrode active material, the same material, and the dissimilar material. However, even if the porous structure is designed using the same material, there is a problem that a fine powdering technique is required, and the manufacturing process becomes complicated. In addition, when designing a porous structure using dissimilar materials, a material that does not react electrochemically is added to the electrode, thereby reducing the total capacity of the electrode.

In addition, since the electrode using powder has a low tap density, the compression process must be entered. Even if the electrode is compressed, the processing density of the electrode using powder must be lower than that of an electrode made of a single mass. It is also generally very difficult to increase the processing density of an electrode containing them. For the same reason, it is difficult to increase the thickness in order to improve the loading amount of electrodes per area.

Moreover, even if all of the above methods are used, it is not possible to fundamentally solve the problem of pulverization of the electrode active material layer due to volume change occurring during a charge/discharge cycle, a capacity reduction, and a decrease in cycle characteristics, which is an essential problem.

In the present application, by including an electrode active material having a high capacity, a high capacity electrode may be realized, and a negative electrode for a secondary battery having improved charge/discharge cycle characteristics due to a stable porous structure may be provided.

In addition, it is possible to form an electrode active material layer having a porous structure in which fine electrode active material particles are interconnected without using micronized electrode active material powder, so that a high-capacity negative electrode for secondary battery and a battery including the same can be manufactured by a simple method. You can provide a way to do it.

In addition, since it is possible to provide an electrode having a porous structure in which micro-sized electrode active material particles that do not necessarily contain a conductive material and/or a binder are interconnected, it is possible to improve battery capacity.

cathode

The negative electrode according to an embodiment of the present invention includes a porous metal layer including a metal capable of reversibly absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with an alkali metal or alkaline earth metal.

The porous metal layer has a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected.

The metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with the alkali metal or alkaline earth metal may be a metal including an alloying material.

2 is a view showing the structure of a porous metal layer of a negative electrode according to an embodiment of the present invention. As described above, it can be seen that the porous metal layer of the negative electrode according to the exemplary embodiment of the present invention has a porous three-dimensional network structure in which rod-shaped metal active material particles are three-dimensionally interconnected. Such a three-dimensional network structure may have a structure that is continuously connected not only in the thickness direction (longitudinal direction) but also in the area direction (transverse direction) of the porous metal layer. By having such a structure, there is an advantage of implementing a negative electrode in which a current collector in contact with only a part of the area of the porous metal layer is applied, as well as when a current collector in the form of a surface in contact with the entire area of the porous metal layer is applied. have.

In addition, by having such a structure, it is possible to easily configure a large-area electrode by connecting a plurality of cathodes in the area direction (transverse direction).

The porous metal layer includes a metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with an alkali metal or alkaline earth metal, and thus can implement a high capacity.

Specifically, the alkali metal or alkaline earth metal may be selected from the group including Li, Na, Mg, K, or Ca.

The metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with the alkali metal or alkaline earth metal may be an alloying material. Specifically, the alloying material may be Ga, Ge, In, Sn, Sb, Tl, Pb, or Bi. These metals have the advantage of realizing a high theoretical capacity by alloying with an alkali metal or an alkaline earth metal.

Since the porous metal layer has a porous structure in which micro metal particles are interconnected, the porous metal layer itself may serve as an active material layer and a current collector. Accordingly, the negative electrode including the porous metal layer may further include a current collector, but is not limited thereto. The current collector may be copper, stainless steel, aluminum, a metal coated with carbon, carbon fiber, or carbon paper. . However, the present invention is not limited thereto, and may include those that can be applied based on common technical knowledge in the relevant technical field.

The negative electrode according to an embodiment of the present invention may have a porous three-dimensional network structure in which a porous metal layer is connected to each other in a rod-shaped metal microparticle.

As described above, when the alloyed material is applied as an electrode active material, the active material layer may be pulverized and the active material may be separated from the current collector due to a large volume change during charging and discharging, and the electrical connection of the active material layer may be disconnected. That is, there is a problem that the electrode performance is remarkably deteriorated as the number of charging and discharging increases.

However, the porous metal layer of the present application may provide a space capable of accommodating a volume change during charging and discharging as described above. In addition, the active material layer having the porous structure of the present application increases the specific surface area of the active material layer, thereby increasing the contact area with the electrolyte, decreasing the current per unit area, decreasing the internal resistance, reducing the overvoltage, and improving the charging and discharging speed.

Even if the active material layer has a porous structure, the active material layer may be cracked due to a change in volume. However, the porous structure of the present application can significantly reduce the breakage of the active material particles and the active material layer structure due to the stability of the structure despite a change in volume during charging and discharging, and improve charge/discharge cycle characteristics.

Specifically, the porous metal layer of the negative electrode according to an embodiment of the present invention may have the following characteristics.

The porous metal layer may have an average pore diameter of 0.1 to 200 μm. Specifically, it may be 0.1 to 150 μm, 0.1 to 100 μm, 0.1 to 50 μm, 0.1 to 30 μm, 0.1 to 20 μm, 1 to 15 μm, 1 to 10 μm, or 1 to 5 μm.

The porous metal layer may have a porosity of 50 to 90% by volume. Specifically, it may be 60 to 90% by volume, 70 to 90% by volume, 70 to 85% by volume, or 72 to 81% by volume.

The metal microparticles may have an average diameter of 0.1 to 5 μm. Specifically, it may be 0.1 to 3 μm, 0.3 to 3 μm, 0.5 to 2 μm, or 0.5 to 1.5 μm.

The metal microparticles may have an average length of 0.5 to 20 μm. Specifically, it may be 0.5 to 15 μm, 0.5 to 10 μm, 0.5 to 5 μm, 0.5 to 3 μm, or 1 to 3 μm. If the length of the metal microparticles is too long, the possibility of occurrence of structural breakage may increase because the volume expansion rate in the longitudinal direction is large during alloying.

By satisfying the above range, it is possible to reduce the occurrence of cracking of particles and contact points according to a change in volume during charge/discharge, and a problem in which the active material (layer) is pulverized can be reduced.

The metal microparticles may have an average aspect ratio (length/diameter) of 1 to 10. Specifically, it may be 1 to 8, 1 to 7, 1 to 5, 1 to 3, 1.1 to 10, 1.1 to 9, 1.1 to 7, 1.1 to 4, or 1.1 to 3.

The rod-shaped microparticles are randomly connected, and the particles may have a structure having a bonding angle of more than 0° and less than 180° at most of the contact points. In this case, since the pressure applied to the contact point due to volume expansion (especially, expansion in the longitudinal direction of the rod-shaped particles) during alloying decreases compared to the case where the angle is 180°, the active material is reduced by reducing the breakage of the contact point and rod-shaped particles. The crushing of the (layer) can be suppressed, and the charge/discharge cycle characteristics can be improved. This structure may be due to the fact that most of the contact points having an angle of 180° between particles disappear in the step of repeatedly charging and discharging in a half-cell to be described later.

In the present specification, the angle between particles refers to an angle formed by two or more rod-shaped particles based on a contact point, and in the case of a contact point where two particles are connected, it refers to a numerical value of the smaller angle.

In addition, each rod-shaped microparticle has a structure in which 5 or less particles are mainly connected at a contact point where each rod-shaped microparticle is connected, and preferably, it may have a structure in which 2 to 3 particles are connected. As the number of rod-shaped microparticles connected at the contact point increases, the pressure applied to the contact point during volume expansion may increase, and the contact point forming an angle of 180° between particles increases. The occurrence of cracking and cracking of the porous structure may increase.

The active material layer of the negative electrode manufactured according to an embodiment of the present invention forms a half-cell using a negative electrode including a metal layer, and repeatedly charges and discharges the same, thereby converting the metal layer into a porous metal layer. By repeatedly charging and discharging the half-cell, the metal layer repeatedly contracts and expands, and the metal layer is caused by factors such as heat of reaction generated during alloying and dealloying, and resistance at the contact point generated during charging and discharging of the half-cell. In, a sintering reaction occurs, forming a tight bond between the particles. In addition, during the repetitive contraction and expansion process, unstable contacts and particles are broken and adhered to other particles, and the process of maintaining stable contacts and particles is repeated. Accordingly, it is expected that the finally obtained porous metal layer will have a very stable three-dimensional network porous structure of the present invention having solid contact points between the particles in the form of rods.

4 is a tin porous metal layer (Example 1) manufactured according to an exemplary embodiment of the present disclosure, and it can be seen that rod-shaped particles have a porous three-dimensional network structure connected to each other.

6 is a state in which the porous tin metal layer of Example 1 of FIG. 4 was alloyed with sodium, and the rod-shaped particles increased and the pore volume decreased due to the expansion of the active material, but it can be seen that the structure is maintained without cracking. That is, it can be seen that the negative electrode porous metal layer of the present application has a stable structure in which no structural breakage occurs even when the active material layer is expanded by alloying. Even if the number of charge/discharge increases in the negative electrode including the porous metal layer having such a stable structure, pulverization and separation of the electrode active material (layer), and electrical disconnection of the active material layer may be significantly reduced, resulting in improved charge/discharge cycle characteristics. Can contribute to

In the rod-shaped metal microparticles, fine metal particles having a diameter smaller than the length of the metal microparticles are attached to the surface, or fine metal particles having a diameter smaller than the length of the metal microparticles protrude from the surface of the metal microparticles. It may have a surface. Specifically, the average particle diameter of the fine metal particles may be 0.1 to 5 μm. As described above, this may be formed in the process of repeatedly charging and discharging the half-cells, whereby unstable contacts and particles are broken and adhered to other particles during repetitive contraction and expansion of the metal layer.

Referring to FIG. 13, it can be seen that the rod-shaped Bi micro metal particles having an average diameter of 1.4 μm and an average length of 2.3 μm have fine particles with an average particle diameter of 0.5 μm protruding from the surface.

The porous metal layer may include at least 90% by weight of a metal selected from the group including Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi based on 100% by weight of the total porous metal layer. Specifically, it may be 90 to 100% by weight, 92 to 100% by weight, 95 to 100% by weight, 97 to 100% by weight, 99 to 100% by weight, or 99.5 to 100% by weight. In this case, since the content of the active material in the electrode is high, the electrode capacity can be improved.

The shape of the porous metal layer may be formed by the manufacturing method according to an exemplary embodiment of the present invention, but may not be limited thereto.

The porous metal layer of the present invention does not have a three-dimensional porous structure in which microparticles are mutually aggregated, or an active material is finely powdered and applied as a composition by controlling the shape of the particles or compressed to form a metal active material layer. , According to the manufacturing method of the present invention, a porous metal layer composed of micro-sized active material particles having the above shape may be formed from the metal layer. Therefore, since the process for fine powdering is not included, manufacturing cost can be reduced, and an active material layer and an electrode that do not contain a material that does not react electrochemically such as a binder can be formed, thus contributing to capacity improvement. I can.

In a specific embodiment of the present invention described later, a negative electrode including a porous metal layer having a three-dimensional network structure was prepared by combining Sn microparticles with each other. Looking at the SEM photograph of the surface of the porous metal layer according to the embodiment of the present invention, the porous metal layer of the embodiment provides a space capable of sufficiently accommodating changes in the volume of the active material when Na ions are absorbed by the porous three-dimensional network structure in which metal microparticles are interconnected. It was confirmed that the structure of the porous metal layer did not collapse even when alloyed. In addition, it was confirmed that the charge/discharge cycle characteristics can be maintained even though Sn having a large volume change during alloying was applied as the active material.

The porous metal layer may include at least 90% by weight of a metal selected from the group including Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi based on 100% by weight of the total porous metal layer. Specifically, one or two or more metals selected from the group including Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi may be included.

As the balance, other metals or unavoidable impurities may be included.

The content of the metal selected from the group containing Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi is 97 to 100% by weight, 99 to 100% by weight, or 99.5 to 100% by weight based on 100% by weight of the total porous metal layer. It may contain 100% by weight.

In the case of a porous metal layer manufactured according to an embodiment of the present invention and a negative electrode including the same, unlike the active material layer manufactured using fine powder active material particles in the related art, it does not contain a conductive material and/or a binder that does not contribute to electrode capacity. I can. Therefore, it is possible to improve the electrode capacity.

The porous metal layer may include at least 90% by weight of the metal represented by the following Formula 1 based on 100% by weight of the total porous metal layer.

[Formula 1]

The x may be 0 to 6. Specifically, it may be greater than 0 and less than or equal to 6.

Specifically, the porous metal layer may include 90% by weight or more of the metal represented by the following Formula 2 or 3 based on 100% by weight of the total porous metal layer.

[Formula 2]

[Formula 3]

The A may be an alkali metal and an alkaline earth metal.

B may be selected from the group including Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi.

The y may be 0 to 1. Specifically, it may be greater than 0 and less than or equal to 1.

The z may be 0 to 3. Specifically, it may be greater than 0 and 3 or less.

One specific embodiment of the present invention to be described later discloses a negative electrode in which the porous porous metal layer contains 100% by weight of Bi. Another embodiment of the negative electrode of the present invention discloses that the porous metal layer contains 92% by weight of Sn and Na as the balance.

The negative electrode according to the exemplary embodiment of the present invention may have a capacity retention rate of 95% or more after 80 charging and discharging times. Specifically, it may be 95 to 100%, 95% or more and less than 100%, 99.3% or more and less than 100%, 99% to 99.9%, or 99.3% to 99.9%. The negative electrode according to the exemplary embodiment of the present invention may have a capacity retention rate of 95% or more after 80 charging and discharging times. Specifically, it may be 95 to 100%, 95% or more and less than 100%, 99.3% or more and less than 100%, 99% to 99.9%, or 99.3% to 99.9%.

The negative electrode according to the exemplary embodiment of the present invention may have a capacity of 80% or more of the theoretical capacity. Specifically, it may be 80% to 100%, 80% or more, and less than 100%, 80% to 99.9%, or 85% to 99.9%.

Secondary battery manufacturing method

A method of manufacturing a secondary battery according to an embodiment of the present invention includes the steps of configuring a negative electrode including a porous metal layer and a half-cell including a metal electrode; Converting the metal layer into a porous metal layer by charging and discharging the half-cell two or more times; And preparing a full-cell including the negative electrode converted into the porous type, a positive electrode including a positive electrode active material, and an electrolyte. The porous metal layer includes a metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with an alkali metal or alkaline earth metal, and the metal electrode includes an alkali metal or alkaline earth metal.

The metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with the alkali metal or alkaline earth metal may be selected from the group including Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi. have.

The alkali metal or alkaline earth metal may include those selected from the group containing Li, Na, and Mg.

In this case, the negative electrode according to the exemplary embodiment of the present invention may realize a high capacity by alloying and dealloying with an alkali metal or alkaline earth metal.

In the step of configuring the half-cell, the half-cell may have a structure as shown in FIG. 17.

In the step of manufacturing the full-cell, the full-cell may have a structure as shown in FIG. 18.

In the step of converting the metal layer into a porous metal layer, the number of times of charging and discharging and the porous structure of the formed porous metal layer may vary according to the type of metal included in the metal layer and the type of metal electrode.

In the step of converting the metal layer into a porous metal layer, the porous metal layer may be converted into a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected. In this case, there is an advantage in that an active material layer composed of micro-sized active material particles can be manufactured without using an expensive and complicated process of finely powdering the active material and manufacturing an electrode active material layer by using it.

The step of converting the metal layer into a porous metal layer may be performing a cycle in which the cathode and the metal electrode are electrically connected to be fully charged and completely discharged.

In this case, in the half-cell, a cathode including the metal layer may be disposed on an anode, and the metal electrode may be disposed on a cathode to constitute a half-cell.

The volume expansion amount of the metal layer varies depending on the amount of alkali metal ions or alkaline earth metal ions absorbed and released during charging and discharging.

Therefore, when the amount of filling is too small, the volume change of the metal layer is too small to cause cracks in the metal layer, or the amount of cracking is small, so that conversion to the porous metal layer may not be performed, or conversion efficiency may be significantly lowered.

In the case of performing full charge and full discharge, micro-sized particles are interconnected even with a short period of time and a small number of charge and discharge times, thereby manufacturing a porous metal layer having a three-dimensional network structure.

In addition, in the case of an exemplary embodiment of the present invention, even if charging/discharging is repeatedly performed with full charge and full discharge, horizontal complete breakage of the metal layer may not occur. This is because even if the porous metal layer having a high surface energy and diffusion coefficient is cracked or crushed, room temperature sintering may occur in a limited space between the current collector and the separator. In addition, since the negative electrode including the metal layer includes a separator between the metal electrode as the counter electrode and constitutes a half-cell to perform charging and discharging, the current collector and the fine size of the current collector and the fine-sized The limited space of the separator having pores prevents the separation of the metal layer and the metal active material particles, and supports the shape of the metal layer.

Configuring the half-cell; It may be to further include the step of preparing a negative electrode including a metal layer previously.

The method of forming the metal layer may be by rolling, plating, sputtering, or aerosol.

The step of preparing the negative electrode including the porous metal layer may include manufacturing a negative electrode including the metal layer by rolling a metal foil. In this case, a metal layer can be simply formed on the current collector, a metal layer having a desired thickness and area can be easily formed, metal fragments can be easily recycled by pressure welding, and electrode capacity can be easily designed. have.

In addition, the capacity and energy of the battery are determined by the electrode, and since the thickness of the electrode means the specific gravity of the electrode in the battery, the capacity and energy of the battery may increase as the thickness of the electrode increases.

However, in the case of forming a thick metal layer by the plating method, since the concentration of the dissolved metal ions decreases in the process of reducing the dissolved metal ions in the solution, additional control is required to increase the thickness, homogeneity and density. There are drawbacks. On the other hand, when the metal layer is formed by rolling, it is easy to control the thickness of the metal layer, and there is an advantage in that a thick metal layer can be easily formed.

The manufacturing of the negative electrode may include forming a metal layer to a thickness of 25 μm to 2 mm. After the step of manufacturing the anode, the shape and thickness of the metal layer may be changed through the step of assembling the half-cell to convert the metal layer into a porous metal layer, so the thickness of the metal layer formed in the step of manufacturing the cathode may be determined by the following steps. It needs to be set in consideration.

If the thickness of the metal layer is too thin, the electrode may be easily torn, and the electrode may be completely broken due to pores. If the thickness is too thick, it is difficult to expand the inside of the metal active material, and since ion transfer may be very slow, an electrochemical reaction, that is, a charge/discharge rate may be significantly reduced.

Secondary battery

A secondary battery according to an embodiment of the present invention includes a positive electrode; Electrolytes; And a negative electrode according to an embodiment of the present invention.

Specifically, the negative electrode includes a current collector and a porous metal layer including a metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with an alkali metal or alkaline earth metal.

The porous metal layer has a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected.

The electrolyte may include a metal salt and an ether-based solvent. Specifically, the metal salt may be selected from the group including _{NaPF 6} , NaClO ₄ , NaCF ₃ SO ₃ , NaBF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiBF _{4, and LiTFSI.}

The ether solvent may be selected from the group including DME, TEGDME, DEGDME, PEGDME, and PEO.

Specifically, dimethoxyethane (DME), 1,3-dioxolane (1,3-dioxolane), tetraethylene glycol dimethyl ether (TEGDME), Diethylene glycol dimethyl ether , DEGDME), triethylene glycol dimethyl ether (TEGDME), polyethylene glycol dimethyl ether (PEGDME), polyethylene oxide (PEO), and mixtures thereof. have. When the solvent is included, it is possible to suppress the formation of SEI on the metal surface, improve ionic conductivity, and improve stability with respect to an electrode made of an alkali metal and an alkaline earth metal.

The anode is CuS. It may include those selected from the group including _{Cu 2} S, NiS, Ni ₃ S ₂ , NiS ₂ , TiS ₂ , and MoS _3.

The secondary battery according to the exemplary embodiment of the present invention may further include a separator between the positive electrode and the negative electrode.

The separation membrane may be a nanoporous separation membrane.

The nanopore separation membrane may have a pore size of 10 nm to 100 nm.

If the above range is satisfied, it may serve as a physical barrier so that the pulverized metal layer particles are not separated from the negative electrode according to battery charging and discharging. Accordingly, the pulverized metal layer particles may be attached to the metal layer to continuously serve as an active material, and a charge/discharge cycle life may be improved. If the pores of the separator are too large, the pulverized metal layer particles may be separated or separated from the negative electrode and the cycle characteristics may be deteriorated.If the pores of the separator are too small, impregnation of the electrolyte is difficult and the contact area between the electrolyte and the electrode decreases. Ion transfer may not be smooth, and consequently, ion conduction required for driving the battery may not be satisfied.

The thickness of the nanopore separation membrane may be 5 μm to 1 mm. When the above range is satisfied, it serves as a sufficient physical barrier to prevent separation from the pulverized metal layer, thereby contributing to improvement of cycle characteristics.

In an embodiment of the present invention to be described later, Celgard 2400 (thickness 25 µm, pores 100 nm or less) was used as a nanopore separation membrane.

The separation membrane may be a microporous separation membrane.

The micropore separation membrane may have a pore size of 1 μm to 50 μm.

The microporous separation membrane may have a thickness of 0.2mm to 2mm.

When the above numerical range is satisfied, the microporous separator may prevent a short circuit inside the battery due to the formation of dendrite generated on the electrode surface during the charging and discharging process.

In an embodiment of the present invention to be described later, a glass fiber filter (about 1 mm in thickness, 10 µm or more pores) was used as a microporous separation membrane.

According to one embodiment of the present invention, a plurality of microporous separation membranes and/or microporous separation membranes may be included.

In an embodiment of the present invention to be described later, a triple separation membrane (Celgard 2400 / glass fiber filter / Celgard 2400) in which nanoporous separation membranes are positioned on both sides of one microporous separation membrane, respectively, was used. Specifically, the nanoporous separation membrane may be in contact with each electrode, and a microporous separation membrane may be positioned between the two nanoporous separation membranes.

In this case, the role of the glass fiber filter may delay the time of internal short circuit due to sodium metal or dendritic phase of the anode.

In addition, Celgard 2400 in contact with the anode can suppress the formation of dendritic phase of the anode.

Celgard 2400 in contact with the cathode prevents the metal layer particles pulverized with nano pores from separating from the cathode and can delay the internal short circuit due to the formation of dendritic phase of the anode.

As a result, it is possible to improve the charge/discharge cycle characteristics of the electrode.

Hereinafter, in order to aid the understanding of the present invention, preferred examples and comparative examples of the present invention will be described. However, the following examples are only preferred examples of the present invention, and the present invention is not limited to the following examples.

Example 1: Cathode including Sn porous metal layer

In a specific embodiment of the present invention, a Sn foil metal layer having a thickness of 27 μm was formed by rolling Sn metal, and then a negative electrode having a diameter of 6 mm including the Sn foil metal layer was manufactured by punching the Sn metal layer.

A half-cell was constructed using the negative electrode. Specifically, by connecting the cathode including the Sn foil metal layer and the Na metal electrode, applying a current of 0.1 C-rate to perform charging and discharging 100 times, thereby repeatedly absorbing and discharging Na to the Sn foil metal layer to obtain Sn The foil metal layer was converted to a porous Sn porous metal layer.

The principle of conversion of the Sn foil metal layer to the porous Sn porous metal layer is as follows.

During discharge, Na is absorbed into the Sn foil metal layer, and the volume expands. After filling, Na is released from the Sn foil metal layer, and the volume shrinks again, resulting in cracks in the Sn foil metal layer and pulverized into small particles. The pulverized particles can recombine again to reduce the surface energy. It is believed that the reason why recombination is possible is because sintering occurs at the contact points between small particles. During this process, the pulverized particles form a connected structure.

By repeatedly performing such charge (desodiation, causing volume contraction) and discharge (discharge: sodiation, causing volume expansion), the Sn foil metal layer contracts and expands repeatedly, and in this process, crushing and recombination are repeated. It happens. Parts with mechanically unstable structures in contraction or expansion become small particles by cracking or crushing again, and these small particles recombine to form a new shape. On the other hand, when contracting or expanding, the part that is joined in a stable structure does not cause cracks or crushing even after repeated expansion and contraction, and maintains its original shape. After sufficiently repeated charging and discharging, the porous metal layer has a structure that is stable against volume expansion and contraction. That is, even if the volume of the porous metal layer of the negative electrode according to an embodiment of the present invention reacts with sodium to expand (discharge) or decreases the volume due to the release of sodium (charge), the occurrence of cracking or crushing is significantly reduced. In addition, even in repeated charging and discharging, a decrease in discharge capacity is suppressed, and charging/discharging cycle characteristics may be improved. As such, the structure that is stable against volume expansion and contraction appears as a porous three-dimensional network structure in which rod-shaped Sn metal microparticles are interconnected in a unique way.

In the present specification, a network structure means that particles have a physically interconnected form. In this way, when the active material particles are physically interconnected, a connection between the active material particles may be formed electrically.

The shape, particle size, or porosity of the porous metal layer may vary according to the number of times of charging and discharging and the type of metal of the metal layer.

3 is a real photograph of the porous metal layer of the negative electrode of Example 1. It can be seen that it is a porous metal layer having a three-dimensional network structure interconnected in the area direction and thickness direction of the electrode without visible cracks.

4 is a low magnification SEM photograph of the Sn porous metal layer of Example 1 negative electrode. The average pore diameter is 2 μm, and the porosity of the active material layer is 81% by volume. The rod-shaped Sn micro-metal particles have an average diameter of 0.8 μm, an average length of 1.2 μm, and the aspect ratio (length/diameter) of the rod-shaped micro particles is 1.3. In order to help understand the structure of the porous metal layer, the bonding direction of the rod-shaped metal particles at the contact point is indicated by a red arrow. It can be seen that the rod-shaped Sn micro-metal particles have a porous three-dimensional network structure by being interconnected in a random direction rather than a straight line in which the angle between the particles is 180 degrees. In particular, 1 to 5 rod-shaped particles are connected at each contact point (connection site) to form a three-dimensional porous structure. As described above, this porous structure and porosity not only provide a space to accommodate the increased volume when the porous metal layer reacts with an alkali metal or alkaline earth metal to expand the volume, but also provides a structure that is stable against volume expansion. By having it, it is possible to reduce cracking or pulverization of active material particles or structures due to charging and discharging, and suppressing capacity reduction during charging/discharging cycles.

Figure 5 shows the EDS spectrum of the porous metal layer of Example 1 negative electrode.

Example 1 The composition of the porous metal layer of the negative electrode is represented by Na _0.08 Sn. That is, 92% by weight of Sn and the balance Na are included with respect to 100% by weight of the porous metal layer.

The Cu peak shown in FIG. 5 is a peak due to the SEM holder, and the C peak and the O peak correspond to peaks independent of the porous metal layer as a result of electrolyte or oxidation.

However, Figure 5 is a measurement of the EDS spectrum of the porous metal layer in a state in which the negative electrode of Example 1 was not washed. Na is considered to be due to an electrolyte, or to remain in the active material layer without being released after being absorbed by the active material layer in the step of converting to the porous porous metal layer. That is, it is found that the Sn content in the porous metal layer substantially exceeds 92% by weight with respect to 100% by weight of the porous metal layer.

6 is a SEM photograph of a state in which the Sn porous metal layer of the negative electrode of Example 1 was completely electrochemically reacted with Na to 1 mV (full discharge, Na _{3.75 Sn).} It can be seen that the size and number of pores in the porous metal layer were reduced by the maximum expansion of the Sn metal microparticles by reaction with Na, but the pores were still secured. In particular, even though the volume has expanded, no cracks or crushed small particles can be observed. That is, it can be seen that the porous active material layer of the negative electrode of the present invention maintains a very stable structure without breaking or collapsing the structure even with volume expansion. Specifically, the _{average pore diameter of the Na 3.75} Sn active material layer of Example 1 was 0.5 μm, and the porosity was 10% by volume. Accordingly, the porous metal layer of Example 1 provides a sufficient space to accommodate volume expansion due to reaction with an alkali metal or alkaline earth metal, and at the same time, an inherent stable internal stress that occurs during volume expansion and contraction can be dispersed. It can be seen that it has a structure.

7 shows the EDS spectrum result of the state in which the porous metal layer of the negative electrode of Example 1 was discharged with sodium to 1 mV (Na _{3.75 Sn).}

When the porous metal layer of the negative electrode of the present invention reacts with sodium, the composition is Na _x Sn, and the range of x can be up to 3.75.

The Cu peaks shown in FIG. 7 are peaks due to the SEM holder, and the C peaks, O peaks, P peaks, and F peaks are peaks independent of the porous metal layer as a result of electrolyte or oxidation.

8 is a graph of charging and discharging of the negative electrode of Example 1.

The configuration of the battery is a sodium metal counter electrode, a separator layer impregnated with an electrolyte, and a negative electrode of Example 1 are sequentially stacked to show a charging/discharging curve at a current of 0.1 C-rate in the first cycle. Example 1 It can be seen that the negative electrode has a charge capacity and a discharge capacity of 692 mAh/g, and it can be seen that it has a very reversible charge and discharge capacity.

This has a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected, so that interference between particles can be reduced during volume expansion, and pores inside the electrode active material layer can accommodate volume expansion, and access to the electrolyte is difficult. It can be seen that it is due to its easy structure.

9 shows an SEM photograph of the negative electrode of Comparative Example 1.

Example 1 In order to compare and confirm the effect of the structure of the porous metal layer of the negative electrode, a porous tin negative electrode including the tin active material of Comparative Example 1 was prepared using tin powder. Specifically, a mixture of tin powder and NaCl powder having 150 nm particles was prepared in the form of pellets compressed at 15 ton in a 50 mm x 1.5 mm frame. Then, by removing NaCl with distilled water, a porous electrode composed of only the tin active material of Comparative Example 1 was prepared.

Referring to FIG. 9, it can be seen that tin particles having an average diameter of 150 nm and the particles are aggregated with each other to form a porous tin negative electrode having a structure in which 500 to 1 μm secondary particles and 200 to 1 μm pores coexist. .

10 is a graph showing charge and discharge characteristics at 0.1 C-rate of Comparative Example 1.

After the same battery as in FIG. 8 of Example 1 was constructed using the electrode of Comparative Example 1, a charge/discharge test was performed at 0.1 C-rate. The discharge capacity was shown to be a maximum of 1.3 mAh/g, and charging was not performed. In addition, it can be seen that this discharge capacity is remarkably low compared to the charge/discharge capacity of 692 mAh/g shown in FIG. 8.

11 is a graph showing the cycle characteristics of the negative electrode of Example 1 and the negative electrode of Comparative Example 1. Example 1 The negative electrode had an initial capacity of 692 mAh/g during 80 cycles, a maximum capacity of 757 mAh/g, and a minimum capacity of 601 mAh/g during the cycle. That is, in the case of Example 1, a capacity of 600 mAh/g or more was shown for 80 cycles, which corresponds to about 1.6 to 2 times the theoretical capacity of 372 mAh/g of a conventional graphite negative electrode for a lithium ion battery. Example 1 In the case of the negative electrode, it can be seen that the capacity retention rate after 80 charging and discharging was 99.3%, which has excellent cycle characteristics.

On the other hand, it can be seen that the negative electrode of Comparative Example 1 is discharged at about 1 mAh/g for 6 cycles, and charging does not occur. It can be seen that this is because the electrode of Comparative Example 1 includes the Sn active material layer having a porous structure, but the structure of the active material layer is not maintained due to volume change due to charging and discharging, and cracking and crushing occur.

That is, in the case of the active material layer of the negative electrode of Example 1 according to the exemplary embodiment of the present disclosure, as described above, it can be seen that the active material layer has a stable porous structure with a tight bond, and thus, is a high-capacity negative electrode with improved charge/discharge cycle characteristics. Specifically, in the case of Example 1, since 4 or less columnar tin particles are bonded in a random direction at each contact point between the columnar particles, it can be confirmed that stress can be effectively dispersed during volume expansion. However, the negative electrode of Comparative Example 1 has a structure that is difficult to disperse stress because a plurality of particles are bonded in various directions so that the bonding site of the metal particles is not distinguished, and more than four particles are bonded to the bonding site. That is, it can be seen that even if the electrode has a simple porous structure, it is difficult to maintain a stable structure by effectively distributing the stress upon expansion.

Example 2: Anode including Bi porous metal layer

Bi metal was rolled to a thickness of 2 mm to form a Bi metal foil layer, which was punched to prepare a 5 X 5 mm square cathode including the Bi foil metal layer.

A half-cell was constructed using the negative electrode. Specifically, the cathode including the Bi foil metal layer and the Na metal electrode were connected. By applying a current of 0.01 C-rate and performing charging and discharging four times, the Bi foil metal layer was converted into a Bi porous metal layer.

12 is an actual photograph of the Bi porous metal layer of the negative electrode of Example 2. It can be seen that no visible cracks were found in the porous metal layer.

13 is a SEM photograph of the Bi porous metal layer of Example 2 negative electrode. The average pore diameter is 2 μm, and the porosity of the active material layer is 72% by volume. The rod-shaped Bi micro metal particles have an average diameter of 1.4 μm, an average length of 2.3 μm, and the aspect ratio (length/diameter) of the rod-shaped micro particles is 1.6. In addition, it can be seen that the rod-shaped Bi micro metal particles are interconnected in random directions to have a porous three-dimensional network structure. At each contact point (connection site), 1 to 5 rod-shaped particles are connected to form a three-dimensional porous structure. As described above, such a porous structure and porosity may contribute to improvement of electrode cycle characteristics by providing a space capable of accommodating an increased volume when the porous metal layer reacts with an alkali metal or alkaline earth metal to expand the volume. More specifically, it can be seen that the rod-shaped Bi micro metal particles have a protruding shape of fine particles having an average particle diameter of 0.5 μm on the surface.

14 is an XRD pattern of the porous Bi porous metal layer of the negative electrode of Example 2. It agrees very well with the bismuth crystal peak of JCPDS #85-1329 used for XRD analysis, and no other additional peaks are observed. Accordingly, it can be seen that the Bi porous metal layer is composed of only Bi.

15 is a graph of charging and discharging of the negative electrode of Example 2.

The configuration of the battery is a sodium metal counter electrode, a separator layer impregnated with an electrolyte, and a negative electrode of Example 2 are sequentially stacked to show a charging/discharging curve at a current of 0.1 C-rate in the first cycle. It shows the charge/discharge graph at 0.01 C-rate of the 1st cycle. Example 2 It can be seen that the negative electrode has a charge capacity of 366 mAh/g and a discharge capacity of 352 mAh/g, and it can be seen that it has a very reversible charge and discharge capacity.

This has a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected, so that interference between particles can be reduced during volume expansion, and pores inside the electrode active material layer can accommodate volume expansion, and access to the electrolyte is difficult. It can be seen that it is due to its easy structure.

16 is a graph showing the cycle characteristics of 1 to 100 cycles of the negative electrode of Example 2. Charging and discharging proceeded at a current of 0.1 C-rate, and the initial capacity was 330 mAh/g, even after 100 cycles, 330 mAh/g, and the average capacity was 340 mAh/g, indicating a capacity of 85% of the theoretical capacity. In addition, it can be seen that the discharge capacity is maintained even after 100 cycles, and the capacity retention rate is 99.8%.

The present invention is not limited to the above embodiments, but may be manufactured in a variety of different forms, and those of ordinary skill in the art to which the present invention pertains, other specific forms without changing the technical spirit or essential features of the present invention. It will be appreciated that it can be implemented with. Therefore, it should be understood that the embodiments described above are illustrative in all respects and are not limiting.

Claims (17)

1. Including; a porous metal layer comprising a metal capable of reversibly absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with an alkali metal or alkaline earth metal,

   The porous metal layer is a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected, the negative electrode.
2. The method of claim 1,

   The porous metal layer has an average pore diameter of 0.1 to 200 μm, the negative electrode.
3. The method of claim 1,

   The porous metal layer has a porosity of 50 to 90% by volume, the negative electrode.
4. The method of claim 1,

   The metal microparticles have an average diameter of 0.1 to 5 μm, the negative electrode.
5. The method of claim 1,

   The metal microparticles have an average length of 0.5 to 20 μm, the negative electrode.
6. The method of claim 1,

   The metal microparticles have an average aspect ratio (length/diameter) of 1 to 10, the negative electrode.
7. The method of claim 1,

   The porous metal layer is a negative electrode comprising at least 90% by weight of a metal selected from the group including Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi based on 100% by weight of the total porous metal layer.
8. The method of claim 1,

   The porous metal layer is a negative electrode comprising at least 90% by weight of the metal represented by the following formula (1) based on 100% by weight of the total porous metal layer:

   [Formula 1]

   

   A is Li, Na, Mg, K, or Ca,

   B is selected from the group containing Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi,

   X is 0 to 6.
9. The method of claim 1,

   The porous metal layer is a negative electrode comprising at least 90% by weight of the metal represented by the following formula (2) or (3) based on 100% by weight of the total porous metal layer:

   [Formula 2]

   

   [Formula 3]

   

   Y is 0 to 1,

   Z is 0 to 3.
10. Configuring a cathode including a metal layer and a half-cell including a metal electrode;

    Converting the metal layer into a porous metal layer by charging and discharging the half-cell two or more times; And

    Including the step of preparing a full-cell including a negative electrode including the porous metal layer, a positive electrode including a positive electrode active material, and an electrolyte,

    The metal layer includes a metal capable of reversibly absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with an alkali metal or alkaline earth metal,

    The metal electrode comprises an alkali metal or an alkaline earth metal,

    Method of manufacturing a secondary battery.
11. The method of claim 10,

    Converting the metal layer to a porous metal layer,

    The cathode and the metal electrode are electrically connected to perform a cycle with full charge and complete discharge,

    Method of manufacturing a secondary battery.
12. The method of claim 10,

    In the step of converting the metal layer into a porous metal layer,

    The metal layer is converted into a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected,

    Method of manufacturing a secondary battery.
13. The method of claim 10,

    Before the step of configuring the half-cell

    To further comprising the step of manufacturing a negative electrode including a metal layer by rolling the metal foil,

    Method of manufacturing a secondary battery.
14. The method of claim 13,

    The step of preparing the negative electrode

    To form a metal layer to a thickness of 25 μm to 2 mm,

    Method of manufacturing a secondary battery.
15. anode;

    Electrolytes; And

    It comprises the negative electrode of any one of claims 1 to 9,

    Secondary battery.
16. The method of claim 15,

    The electrolyte will contain a metal salt, and an ether-based solvent.

    Secondary battery.
17. The method of claim 16,

    The ether solvent is dimethoxyethane (DME), 1,3-dioxolane (1,3-dioxolane), tetraethylene glycol dimethyl ether (TEGDME), diethylene glycol dimethyl ether (Diethylene glycol). dimethyl ether, DEGDME), triethylene glycol dimethyl ether (TEGDME), polyethylene glycol dimethyl ether (PEGDME), polyethylene oxide (PEO), and a mixture thereof. That,

    Secondary battery.

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