KR101123059B1 - Hybrid-typed Stack and Folding Electrode Assembly and Secondary Battery Containing the Same - Google Patents

Abstract

The present invention is an electrode assembly having a structure in which a plurality of unit cells of a stacked structure is wound on a long sheet-type separation film, wherein the unit cells are composed of two or more kinds according to the composition of the electrode mixture. Provide an assembly.

Therefore, the electrode assembly according to the present invention, by making the electrode mixture configuration in the unit cell, such as bi-cell, full cell, and the like, by enabling the optimum battery configuration, by allowing the combination as needed according to the desired battery performance There is an effect that can improve the manufacturing processability of the battery.

Description

Hybrid-typed Stacking and Folding Electrode Assembly and Secondary Battery Containing the Same}

1 and 2 are perspective views showing a process of assembling and before assembling the electrode assembly according to an embodiment of the present invention;

The present invention relates to a hybrid stack and a folding electrode assembly and a secondary battery including the same. More specifically, the electrode of the structure wound in a state in which a plurality of unit cells of a stacked structure is placed on a long sheet separator film As an assembly, the unit cell relates to an electrode assembly, characterized in that consisting of two or more kinds depending on the composition of the electrode mixture.

BACKGROUND ART [0002] In recent years, rechargeable secondary batteries have been widely used as energy sources for wireless mobile devices. In addition, the secondary battery is an electric vehicle (EV), a hybrid electric vehicle (HEV), a parallel hybrid electric vehicle, which is proposed as a solution for air pollution of conventional gasoline vehicles and diesel vehicles that use fossil fuels. It is attracting attention as a power source such as (PHEV).

One or two or four battery cells are used for small mobile devices, whereas medium and large battery modules, which are electrically connected to a plurality of battery cells, are used for medium and large devices such as automobiles due to the need for high output and large capacity.

Since the medium-large battery module is preferably manufactured in a small size and weight, the rectangular battery, the pouch-type battery, etc., which can be charged with high integration and have a small weight to capacity, are mainly used as battery cells of the medium-large battery module. In particular, a pouch-type battery using an aluminum laminate sheet or the like as an exterior member has attracted much attention in recent years due to its advantages such as low weight, low manufacturing cost, and easy deformation.

In order for the medium-large battery module to provide the output and capacity required in a predetermined device or device, it is necessary to electrically connect a plurality of battery cells in series and in parallel and maintain a stable structure against external force.

Therefore, in the case of constructing a medium-large battery module using a plurality of battery cells, since a large number of members are generally required for their mechanical fastening and electrical connection, the process of assembling these members is very complicated. Moreover, space is required for joining, welding, soldering, etc. a plurality of members for mechanical fastening and electrical connection, thereby increasing the size of the entire system. This increase in size is not desirable in view of the space limitation of the device or device in which the medium-large battery module is mounted. Furthermore, in order to be efficiently mounted in a limited interior space such as a vehicle, a medium to large battery module having a more compact structure is required.

On the other hand, since the required characteristics are different depending on the type of device in which the medium-large battery module is used, the secondary battery constituting the battery module is also required to be different in terms of output and capacity. For example, a high capacity battery is preferable for a battery module for an electric vehicle (EV), a high output battery is preferable for a battery module for a hybrid electric vehicle (HEV), and a high capacity for a battery module for a hybrid hybrid electric vehicle (PHEV). And high power batteries are preferred.

However, manufacturing batteries having different outputs and capacities is not practically easy given the limitations of manufacturing facilities and productivity. For example, the general secondary battery is composed of the same type of electrode mixture (electrode active material, conductive material, binder, etc.) applied to the current collector, and when the performance of the battery is to be changed to a predetermined condition, the electrode manufacturing process Since needs to be changed, a problem that the manufacturing processability and productivity of the battery is greatly reduced. In other words, the frequent changes in specifications are causing a significant decrease in the efficiency of existing manufacturing processes.

In order to solve this problem, some prior arts suggest a configuration in which the type of electrode mixture applied to both surfaces of the current collector is different, but the manufacturing of such an electrode has a disadvantage in that the efficiency of the process is greatly reduced in the actual mass production process. .

Therefore, there is a high need for a technology for a secondary battery that enables battery combination according to required battery performance and can improve manufacturing processability of the battery.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems of the prior art and the technical problems required from the past.

The inventors of the present application, after in-depth study and various experiments, change the electrode mixture composition in a unit cell composed of a bicell, a full cell, and the like, thereby enabling the optimum battery combination required according to desired battery performance, and manufacturing a battery. It was confirmed that the processability according to the work can be improved and came to complete the present invention.

Accordingly, the electrode assembly according to the present invention is an electrode assembly having a structure in which a plurality of unit cells in a stacked structure are placed on a long sheet-type separation film, wherein the unit cells are two or more depending on the composition of the electrode mixture. It consists of more than one kind.

That is, the electrode assembly of the present invention has a structure in which a plurality of unit cells having at least two or more types are wound on a long sheet type separation film according to the composition of an electrode mixture composed of an electrode active material, a conductive material, a binder, and the like. Therefore, when batteries with different performances are required as needed, secondary batteries having desired properties such as output, capacity, and lifetime characteristics can be easily manufactured by changing the combination of unit cells without changing the electrode manufacturing process. There are features that can be.

The electrode assemblies capable of charging and discharging are largely classified into cylindrical and plate shapes according to the form (outer structure) built into the case, and are also jelly-roll type and stack type according to the stack type (internal structure) of the electrode assembly. Are classified.

The jelly-roll type electrode assembly may be formed by stacking a long sheet-shaped anode and a cathode with a separator interposed therebetween and winding them round to form a cross-sectional circular structure, or after winding in such a circular structure, compresses in one direction to roughly cross-section. It can be made into a plate-like structure. On the other hand, the stacked electrode assembly may be formed in a plate-like structure by cutting the positive electrode and the negative electrode in units of a predetermined size and sequentially stacking them through a separator.

On the other hand, the electrode assembly according to the present invention, such a wound and stacked composite structure (stack / folding structure), a bi-cell or full cell as a unit cell of a small unit in a stacked manner and make them long separation film After placing a large number on the (separation membrane sheet), it is wound up sequentially to make an overall plate-like structure.

The 'full cell' is a unit cell composed of a unit structure of an anode, a separator, and a cathode, and is a cell in which an anode and a cathode are located at both sides of the cell, respectively. Such a full cell may include an anode / separator / cathode cell and an anode / separator / cathode / separator / anode / separator / cathode cell having the most basic structure. In order to configure an electrochemical cell such as a secondary battery using such a full cell, a plurality of full cells should be stacked such that the positive electrode and the negative electrode face each other with the separation film interposed therebetween.

The 'bicell' is a unit cell in which the same electrode is positioned at both sides of the cell, such as a unit structure of an anode / separator / cathode / separator / anode and a unit structure of a cathode / separator / anode / separator / cathode. . In order to construct an electrochemical cell including a secondary battery using such a bicell, a bicell and a cathode, a separator, an anode, a separator, and a cathode structure of the anode / separator / cathode / separator / anode structure with the separator film interposed therebetween. A plurality of bicells should be stacked so that the bicells face each other.

Further details of the electrode assembly of the stack / foldable structure are disclosed in Korean Patent Application Publication Nos. 2001-0082058, 2001-0082059, and 2001-0082060 to the present applicants. Is incorporated by reference.

Although some prior arts suggest a structure in which a structure of an electrode active material is different in a stacked electrode assembly, a process of stacking by a predetermined structure by varying the composition of an active material in a plurality of electrodes is very complicated. There is a limit to the application in the manufacturing process.

On the other hand, since the stack / foldable electrode assembly of the present invention is a form of winding unit cells of a predetermined unit, the formation process of the stacked stack is relatively simple, and some unit cells are selectively changed to manufacture a desired battery. Therefore, the change to the conventional process is not large in the process of manufacturing the battery according to the predetermined structure.

In the electrode assembly according to the present invention, the configuration of the electrode mixture may be determined by the kind, thickness, or kind and thickness of the electrode mixture which is preferably applied on the current collector. Specific structural examples of such an electrode mixture will be described below.

First, in order to manufacture an electrode assembly having high capacity and long life characteristics and high rate charge / discharge characteristics, for example, first unit cells having high capacity and long life characteristics, and a second unit having high rate charge and discharge characteristics. The electrode assembly may be composed of unit cells formed of cells.

In general, the capacity, lifespan characteristics, and high rate charge / discharge characteristics of a secondary battery tend to depend on the kind of the positive electrode active material or the negative electrode active material and its thickness.

Therefore, in one preferred example, when the electrode mixture having different configurations is the positive electrode mixture, the first unit cell includes one or more positive electrode active materials selected from the group consisting of lithium cobalt oxide, lithium manganese oxide, and lithium nickel oxide. The second unit cell is composed of one or more positive electrode active materials selected from the group consisting of lithium manganese-cobalt oxide, lithium manganese-nickel oxide, lithium nickel-cobalt oxide and lithium manganese-nickel-cobalt oxide Can be.

In the above example, since the two-component or three-component positive electrode active material constituting the second unit cell has better life characteristics and high temperature safety than the single-component positive electrode active material of the first unit cell, An electrode assembly in which the long life characteristics of the second unit cell are harmonized can be manufactured.

The electrode assembly manufactured by the combination of these unit cells has been found to have an unexpected effect in the electrode assembly using the positive electrode mixture prepared by mixing the two kinds of the positive electrode active material. That is, compared to the electrode assembly based on the mixture of the positive electrode active material, it has a synergistic effect.

In another preferred example, the thickness of the second unit cell, that is, the coating amount of the electrode mixture constituting the second unit cell may be made thinner than that of the first unit cell, thereby increasing the rate characteristic of the second unit cell. When the coating amount of the electrode assembly decreases, the migration path of the lithium ions is shortened and the rate characteristic is improved accordingly, so that excellent high rate charge and discharge characteristics can be obtained.

The capacity and output characteristics of the secondary battery are also greatly influenced by the negative electrode mixture. When the electrode mixture having a different composition is the negative electrode mixture, in one preferred example, the first unit cell is a negative electrode active material of a crystalline carbonaceous material. It includes, and the second unit cell may be configured to include a negative electrode active material of an amorphous carbon-based material. While the crystalline carbonaceous material is excellent in conductivity, the amorphous carbonaceous material is excellent in rate characteristics, and the combination thereof can improve the high output characteristics.

The capacity of the secondary battery is particularly influenced by the kind of the negative electrode active material. Generally, graphite, which is a crystalline carbon-based material, is mainly used as the negative electrode active material. However, the negative electrode made of the graphite-based material has a theoretical maximum capacity of 372 mAh / g (844 mAh / cc), which is limited in capacity increase. Recently, many studies have been conducted on the fact that silicon, tin, or alloys thereof can reversibly occlude and release a large amount of lithium through a compound formation reaction with lithium. It is becoming. For example, silicon is promising as a high capacity negative electrode active material because its theoretical maximum capacity is about 4020 mAh / g (9800 mAh / cc, specific gravity 2.23), which is much larger than graphite-based materials.

However, since silicon, tin, and alloys thereof have a large volume change of 200 to 300% due to reaction with lithium during charging and discharging, the negative electrode active material is detached from the current collector or continuously contacts the negative electrode active material during continuous charge and discharge. Due to the increase in resistance due to a large change in the interface, as the charge and discharge cycle proceeds, there is a problem that the capacity is drastically lowered and the cycle life is shortened.

Due to these problems, when a conventional binder for a graphite negative electrode active material, that is, polyvinylidene fluoride or the like is used as it is for a silicon-based or tin-based negative electrode active material, a desired effect cannot be obtained. In addition, when an excessive polymer is used as a binder to reduce the volume change during charging and discharging, the detachment of the active material from the current collector can be reduced to some extent, but the electrical resistance of the negative electrode is increased by the electrically insulating polymer as a binder. As the amount of the active material decreases, problems such as a decrease in capacity arise.

That is, when using different negative electrode active materials, the optimum binder type and content may be determined according to the type of the negative electrode active material. Therefore, in the present invention, when the electrode mixture having a different configuration is a negative electrode mixture, the first unit cell includes a negative electrode active material of carbon-based material and a binder of fluorinated hydrocarbon, and the second unit cell is a tin-based material or a silicon-based material. It may be configured to include a binder of the negative electrode active material and the latex-based polymer resin of the material or carbon-silicon-based composite material.

As described above, the electrode assembly according to the present invention can change the type and content of the components constituting the other electrode mixture in a preferred range according to the type of active material, it is possible to manufacture the electrode assembly of the optimum combination.

The present invention also provides an electrochemical cell comprising the electrode assembly, and representative examples of such an electrochemical cell include secondary batteries and capacitors.

The secondary battery has a structure in which the electrode assembly capable of charging and discharging is embedded in the battery case in the state of being impregnated with an ion-containing electrolyte solution, and among these, the electrode assembly according to the present invention is preferably used for a secondary battery using a plate-shaped battery case. Can be applied.

The secondary battery is preferably a lithium secondary battery having a high energy density, a discharge voltage, and an output stability, and among these, a lithium ion polymer which is less likely to leak electrolyte, has a low weight and manufacturing cost, and is easily manufactured in various forms. Secondary batteries are more preferred. Other components and a manufacturing method of the lithium secondary battery are well known in the art, and a detailed description thereof will be omitted herein.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

1 and 2 are perspective views showing before and during the assembly of the electrode assembly according to an embodiment of the present invention, respectively.

Referring to FIG. 1, first, a plurality of bicells 10 having a stacked structure of an anode (cathode) / separator / cathode (anode) / separator / anode (cathode) are formed in a continuous separation film 30 having a long length. Position on. The bicells 10 properly arrange the positive electrode and the negative electrode bicells in the winding process so that the positive electrode and the negative electrode face each other at their lamination interface during winding. At this time, one unit cell at the end of the winding is composed of the first unit cell 21 having high rate charge / discharge characteristics based on the winding direction, and the other unit cells are constituted of the second unit cell 22 having high capacity and long life characteristics. do.

In FIG. 2, an electrode assembly in a state in which a winding process is almost finished is illustrated. In the wound state, the positive electrode terminal 11 and the negative electrode terminal 12 are stacked in the same one direction. Meanwhile, as shown in FIG. 1, the first unit cell 21 having the high rate charging / discharging characteristics positioned at the end of the winding based on the winding direction is positioned at the top of the electrode assembly during the last winding process, and the second unit cell having the remaining high capacity and long life characteristics. Reference numeral 22 is located below the first unit cell 21. Therefore, the assembly process of the electrode assembly itself is facilitated, and the battery of the performance required by the customer can be easily manufactured according to the combination of the unit cells.

Although the drawings according to the embodiments of the present invention have been described by way of example, those of ordinary skill in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention.

As described above, the electrode assembly according to the present invention, by making the electrode mixture configuration in the unit cell, such as bi-cell, full cell, and the like, enables an optimal battery configuration, and combination as needed according to the desired battery performance Since this is possible, there exists an effect which can improve the manufacturing processability of a battery.

Claims (14)

An electrode assembly having a structure in which a plurality of unit cells in a stacked structure is wound on a long sheet-type separation film, wherein the unit cells are composed of two or more kinds depending on the composition of the electrode mixture. An electrode comprising first unit cells having a high capacity and a long lifespan for the second unit cells and second unit cells having a high rate charge / discharge characteristic for the first unit cells Assembly. The electrode assembly of claim 1, wherein the unit cell is a bicell or a full cell. The method of claim 1, wherein the composition of the electrode mixture is determined by (i) the type of electrode mixture, or (ii) the thickness of the electrode mixture, or (iii) the type and thickness of the electrode mixture applied on the current collector. Electrode assembly characterized in that. delete The method of claim 1, wherein when the electrode mixture having a different configuration is a positive electrode mixture, the first unit cell includes one or more positive electrode active material selected from the group consisting of lithium cobalt oxide, lithium manganese oxide and lithium nickel oxide. The second unit cell includes one or more positive electrode active materials selected from the group consisting of lithium manganese-cobalt oxide, lithium manganese-nickel oxide, lithium nickel-cobalt oxide, and lithium manganese-nickel-cobalt oxide. Electrode assembly, characterized in that configured. The electrode assembly according to claim 1, wherein the thickness of the second unit cell is made thinner than that of the first unit cell. 2. The method of claim 1, wherein when the electrode mixture having a different configuration is a negative electrode mixture, the first unit cell includes a negative electrode active material of a crystalline carbon material, and the second unit cell is a negative electrode of an amorphous carbon material. An electrode assembly comprising an active material. The method of claim 1, wherein when the electrode mixture having a different configuration is a negative electrode mixture, the first unit cell includes a negative electrode active material of a carbon-based material and a binder of a fluorinated hydrocarbon, and the second unit cell is a tin-based material And an anode active material of a silicon-based material or a carbon-silicon-based composite material and a binder of a latex-based polymer resin. A secondary battery comprising the electrode assembly according to claim 1. The secondary battery of claim 9, wherein the battery is a lithium secondary battery. An electrode assembly having a structure in which a plurality of unit cells in a stacked structure is wound on a long sheet-type separation film, wherein the unit cells are composed of two or more kinds depending on the composition of the electrode mixture. When the electrode mixture having a different configuration is a positive electrode mixture, the first unit cell includes one or two or more positive electrode active materials selected from the group consisting of lithium cobalt oxide, lithium manganese oxide, and lithium nickel oxide, and the second unit cell Silver electrode assembly comprising one or more positive electrode active material selected from the group consisting of lithium manganese-cobalt oxide, lithium manganese-nickel oxide, lithium nickel-cobalt oxide and lithium manganese- nickel-cobalt oxide . An electrode assembly having a structure in which a plurality of unit cells in a stacked structure is wound on a long sheet-type separation film, wherein the unit cells are composed of two or more kinds depending on the composition of the electrode mixture. An electrode assembly, wherein the thickness of the second unit cell is made thinner than that of the first unit cell. An electrode assembly having a structure in which a plurality of unit cells in a stacked structure is wound on a long sheet-type separation film, wherein the unit cells are composed of two or more kinds depending on the composition of the electrode mixture. When the electrode mixture having a different structure is a negative electrode mixture, the first unit cell includes a negative electrode active material of crystalline carbon-based material, and the second unit cell is configured to include a negative electrode active material of amorphous carbon-based material. Electrode assembly characterized in that. An electrode assembly having a structure in which a plurality of unit cells in a stacked structure is wound on a long sheet-type separation film, wherein the unit cells are composed of two or more kinds depending on the composition of the electrode mixture. When the electrode mixture having a different configuration is a negative electrode mixture, the first unit cell includes a negative electrode active material of a carbon-based material and a binder of a fluorinated hydrocarbon, and the second unit cell includes a tin-based material, a silicon-based material, or a carbon-silicon An electrode assembly comprising a binder of a negative electrode active material and a latex-based polymer resin of a sub-system composite material.

Images