KR20140032623A - Process for preparation of secondary battery - Google Patents

Abstract

The present invention relates to a method of manufacturing a secondary battery, and more particularly, to a method of manufacturing a secondary battery having a structure in which an electrode assembly having a structure in which a separator is placed between a cathode and an anode is sealed along with electrolyte in a pouch-type battery casing, the method including (a) installing an electrode assembly in a storage unit of a pouch-type battery casing; (b) sealing the external surface of the battery casing including a gas collection pocket in a state in which the electrode assembly is installed; (c) performing charging and discharging operations for battery activation in a state in which the external surface of a sealed battery casing is pressed with a pressure member; (d) removing a gas by perforating the gas collection pocket filled with the gas that emits during the charging and discharging operations and by cutting a portion of the gas collection pocket; and (e) removing the gas collection pocket and sealing the external surface of a corresponding storage unit.

Description

Process for Preparation of Secondary Battery

The present invention relates to a method for manufacturing a secondary battery, and more particularly, to a method of manufacturing a secondary battery having a structure in which an electrode assembly is sealed in an inside of a pouch type battery case together with an electrolyte. Mounting the electrode assembly, sealing the outer circumferential surface of the battery case including the gas collection pocket in the state in which the electrode assembly is mounted, and activating the battery while pressing the outer surface of the sealed battery case using a pressing member Performing charging and discharging for the gas, puncturing the gas collecting pocket in which the gas generated in the charging and discharging process is collected or cutting a part of the gas collecting pocket to remove the gas, and removing the gas collecting pocket. It relates to a manufacturing method comprising the step of sealing the outer peripheral surface of the corresponding housing.

As technology development and demand for mobile devices are increasing, the demand for batteries as energy sources is rapidly increasing, and accordingly, a lot of researches on batteries capable of meeting various demands have been conducted.

Typically, in terms of the shape of a battery, there is a high demand for a prismatic secondary battery and a pouch-type secondary battery which can be applied to products such as mobile phones with a small thickness, and has advantages such as high energy density, discharge voltage, There is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries.

In addition, secondary batteries are classified according to the structure of the electrode assembly having a cathode / separation membrane / cathode structure. Representatively, a jelly having a structure in which long sheet-shaped anodes and cathodes are wound with a separator interposed therebetween -Roll (electrode) electrode assembly, a stack (stacked type) electrode assembly in which a plurality of positive and negative electrodes cut in units of a predetermined size are sequentially stacked with a separator, and the positive and negative electrodes of a predetermined unit are interposed through a separator And a stack / foldable electrode assembly having a structure in which bi-cell or full cells stacked in a state are wound with a separation film.

Recently, a pouch-type battery having a structure in which a stack type or a stack / fold type electrode assembly is incorporated into a pouch type battery case of an aluminum laminate sheet has attracted much attention due to its low manufacturing cost, small weight, and easy shape deformation. Its usage is also gradually increasing.

FIG. 1 schematically shows a general structure of a typical conventional pouch-type secondary battery as an exploded perspective view.

1, the pouch type secondary battery 10 includes an electrode assembly 30, electrode taps 40 and 50 extending from the electrode assembly 30, electrodes 40 and 50 welded to the electrode taps 40 and 50, Leads 60 and 70, and a battery case 20 for accommodating the electrode assembly 30. [

The electrode assembly 30 is a power generation element in which an anode and a cathode are sequentially stacked with a separation membrane interposed therebetween. The electrode assembly 30 has a stacked or stacked / folded structure. The electrode tabs 40 and 50 extend from each electrode plate 30 of the electrode assembly 30 and the electrode leads 60 and 70 are connected to a plurality of electrode tabs 40 and 50 extending from each electrode plate, Respectively, and a part of the battery case 20 is exposed to the outside. An insulating film 80 is attached to the upper and lower surfaces of the electrode leads 60 and 70 in order to increase the degree of sealing with the battery case 20 and at the same time to ensure an electrically insulated state.

The battery case 20 is made of an aluminum laminate sheet, provides a space for accommodating the electrode assembly 30, and has a pouch shape as a whole. 1, a plurality of positive electrode taps 40 and a plurality of negative electrode tabs 50 may be coupled to the electrode leads 60 and 70. In the stacked electrode assembly 30, The upper end is spaced from the electrode assembly 30.

Generally, a lithium secondary battery is activated during the manufacturing process of a battery, and the activation process includes applying a current to a predetermined voltage to an electrode assembly impregnated with an electrolyte. In the initial charging and discharging process for such activation, a protective film is formed on the surface of the electrode, and some electrolyte is decomposed to generate a large amount of gas. Therefore, the battery assembly is completed in the state where the generated gas is removed to produce a finished product.

Pouch-type battery as shown in Figure 1 is also subjected to the process of sealing after removing the gas during the activation of the initial charge and discharge, in general, by forming a surplus of a considerable size on one side of the pouch case to collect the gas and then remove it Sealing process

However, the conventional method as described above attempts to discharge the gas inside the battery cell by a natural movement due to the pressure difference between the gas pocket and the battery cell, which occupies a certain space inside the battery cell. There is a limit to the effective removal of gas. The remaining gas inside the battery cell causes a phenomenon in which the capacity of the battery rapidly decreases as the number of charge and discharge cycles increases.

Therefore, there is an urgent need to develop a technology for manufacturing a pouch type secondary battery that can efficiently remove the gas generated during the initial charge / discharge process to achieve uniform activation and improve battery performance, capacity and lifetime. .

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.

That is, an object of the present invention is to perform the charging and discharging process for the activation of the battery in the pressurized state using the pressure member to the outer surface of the battery case including the gas collection pocket for collecting the gas generated in the charging and discharging process By eliminating the pocket, it is possible to efficiently remove the gas generated in the charging and discharging process for battery activation to achieve uniform activation, and to provide a method for manufacturing a secondary battery that can improve the performance, capacity and life of the battery. .

Still another object of the present invention is to provide a method for manufacturing a secondary battery that is easy in a manufacturing process while improving yield and ensuring high yield.

Secondary battery manufacturing method according to the present invention for achieving this object,

A method of manufacturing a secondary battery having a structure in which an electrode assembly having a structure interposed between a positive electrode and a negative electrode is sealed together with an electrolyte in a pouch type battery case.

(A) mounting the electrode assembly to the housing of the pouch-type battery case;

(b) sealing the outer circumferential surface of the battery case including a gas collecting pocket in a state where the electrode assembly is mounted;

(c) performing charging and discharging for battery activation in a state in which the outer surface of the sealed battery case is pressurized using a pressing member;

(d) perforating the gas collecting pocket in which the gas generated in the charging and discharging process is collected or cutting a part of the gas collecting pocket to remove the gas; And

(e) removing the gas collecting pocket and sealing an outer circumferential surface of a corresponding accommodating part;

It consists of a structure that includes.

Therefore, in the secondary battery manufacturing method according to the present invention, the charging and discharging process for battery activation is performed in a state in which the outer surface of the battery case including the gas collecting pocket is pressurized using a pressing member, and the gas generated in the charging and discharging process is By removing the collected gas collection pocket, the gas generated in the charge and discharge process for the battery activation is efficiently removed to achieve uniform activation, and there is an effect of improving the performance, capacity and life of the battery.

The electrode assembly is not particularly limited as long as it is a structure that connects a plurality of electrode tabs to form an anode and a cathode, and preferably includes a wound structure, a stacked structure, and a stack / folding structure. Details of the stacked / folded structure of the electrode assembly are disclosed in Korean Patent Application Laid-Open Nos. 2001-0082058, 2001-0082059 and 2001-0082060, the contents of which are incorporated herein by reference. As a reference.

In particular, the secondary battery according to the present invention may be preferably applied to a laminate sheet including a metal layer and a resin layer, and in one specific example, to a pouch type secondary battery in which an electrode assembly is built in a housing part of a pouch type case of an aluminum laminate sheet. .

In general, a pouch type secondary battery has, for example, a structure in which an electrode assembly is incorporated in a housing portion of a pouch type battery case made of an aluminum laminate sheet. That is, the pouch-type secondary battery forms an accommodating part for mounting the electrode assembly on a laminate sheet, and heat-seals a separate sheet which is separated from the sheet or a sheet extending therefrom while the electrode assembly is mounted on the accommodating part. It is produced by sealing.

 Therefore, the laminate sheet may have a structure in which the electrode assembly accommodating portion is formed on one side or both sides of the upper and lower laminate sheets. That is, it is possible to use separate upper and lower laminate sheets separated from each other or to use one sheet to which one side of the upper and lower laminate sheets is connected. This pouch case forms an accommodating portion by partially compressing a laminate sheet tens to hundreds of micrometers thick in a drawing process using a die and punch.

In one specific example, the laminate sheet has a structure in which one end of the upper and lower laminate sheets are coupled to each other.

In addition, a sealing portion is formed on the outer circumferential surface of the battery case to seal the outer circumferential surface in a state where the electrode assembly is mounted in the accommodating portion, and a gas collecting pocket is formed to protrude outward on one of the outer circumferential surface sealing portions. It can be made of a structure.

Specifically, the gas collecting pocket has a structure in which the protruding width thereof is 30 to 100% of the width of the accommodating portion to sufficiently collect the gas generated during the charge / discharge process for battery activation.

Furthermore, since the gas collecting pocket for collecting the generated gas is not substantially positioned on the electrode assembly accommodating portion, it is not necessary to make the accommodating portion larger than necessary, so that the mounting process of the electrode assembly to the accommodating portion is easy.

The secondary battery according to the present invention may preferably be a lithium secondary battery, and in particular, may be preferably applied to a so-called lithium ion polymer battery in which a lithium-containing electrolyte is impregnated into the electrode assembly in the form of a gel.

Meanwhile, the secondary battery may include lithium titanium oxide as a positive electrode active material and lithium lithium titanium oxide as a negative electrode active material.

When the lithium titanium oxide is used as a positive electrode or a negative electrode, due to the high moisture content of lithium titanium oxide, a large amount of charge and discharge for battery activation is caused by a water reduction reaction on the surface and an electrolyte decomposition reaction due to the catalysis of lithium titanium oxide. Gas may be generated.

On the other hand, in the secondary battery manufacturing method according to the present invention, the charging and discharging process for the activation of the battery in the state of pressing the outer surface of the battery case including the gas collection pocket by using the pressure member and generated during the charging and discharging process By removing the gas collecting pocket in which the gas is collected, a large amount of gas generated during charging and discharging for battery activation can be effectively removed.

In one specific example, the pressing member in the step (c) may be made of a structure for pressing both sides of the battery case except the gas collection pocket.

The pressing member may include, for example, two or more plate members having a size corresponding to at least a storage portion of the battery case, and may be configured to mutually adjust a gap so as to press two or more plate battery cells simultaneously. It may include three or more plate-like members that are mounted.

Specifically, the plate-like members are drilled with openings communicating with each other, the plate-like members are connected to each other by a connecting shaft passing through the openings, and the plate-shaped members are mounted in a state where battery cells are mounted between the plate-like members. It consists of pressurizing structure.

In addition, in order to efficiently discharge a large amount of gas, the process may further include applying a reduced pressure to remove the gas in the step (d), the battery case from the pressing member before or after the step (e) Of course, it may include the process of removing the pressing force applied to the outer surface of the.

The present invention also provides a battery cell, characterized in that produced by the above production method.

The secondary battery as described above may not only be used in a battery cell used as a power source for a small device, but also includes a plurality of battery cells used as a power source for medium and large devices requiring high temperature stability, long cycle characteristics, and high rate characteristics. It can also be preferably used as a unit cell in the battery pack.

Preferred examples of the medium-to-large device include a power tool driven by a battery-based motor; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart, and the like, but the present invention is not limited thereto.

As described above, the secondary battery manufacturing method according to the present invention, the charging and discharging process to perform the charge and discharge process for the battery activation in the pressurized state using a pressure member the outer surface of the battery case including the gas collection pocket By removing the gas collection pocket in which the gas generated in the gas trapped, the gas generated in the charging and discharging process for battery activation can be efficiently removed to ensure uniform activation and improve the performance, capacity and life of the battery. .

1 is an exploded perspective view of a general structure of a conventional pouch type battery;
2 to 8 are schematic diagrams showing the procedure of the secondary battery manufacturing method according to an embodiment of the present invention;
9 is a schematic diagram of a pressing member according to an embodiment of the present invention;
10 is a schematic view of a pressing member according to another embodiment of the present invention.

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.

2 to 8 are schematic diagrams showing the procedure of the battery cell manufacturing method according to an embodiment of the present invention.

Referring to these drawings, a secondary battery manufacturing method is described. The process of attaching the electrode assembly 110 to the accommodating portion of the pouch-type battery case 130 and the gas collection pocket 150 with the electrode assembly 110 mounted therein The process of sealing the outer circumferential surface 162 of the battery case, including), the process of performing charging and discharging for battery activation in the state of pressing the outer surface of the sealed battery case 130 using the pressing members (171, 172) And removing the gas by puncturing the gas collecting pocket 150 in which the gas generated in the charging and discharging process is collected or cutting a part of the gas collecting pocket 150. And removing the gas collecting pocket 150 and sealing the outer circumferential surface 164 of the corresponding accommodating part.

First, referring to FIGS. 2 and 3, after mounting the electrode assembly 110 to the accommodating part 120 of the battery case 130, the battery case 130 is folded in half and the accommodating part 120 of the battery case 130. In the state that the electrode assembly 110 is mounted on the), the outer peripheral surface 162 of the battery case is sealed by heat sealing including the pocket 150 for gas collection.

Specifically, as shown in FIG. 3, an outer circumferential surface sealing portion is formed on the outer circumferential surface 162 of the battery case 130 to seal the outer circumferential surface 162 in a state where the electrode assembly 110 is mounted on the accommodating part 120. The gas collecting pocket 150 is formed to protrude outward in one of the sealing portions.

Next, referring to FIGS. 4 and 5, charging and discharging for battery activation are performed in a state in which the outer surface of the sealed battery case 130 is pressed using the pressing members 171 and 172 as shown in FIG. 4.

Specifically, as shown in FIG. 5, the pressing members 171 and 172 pressurize both sides of the battery case 130 except for the gas collecting pocket 150, and more specifically, the pressing members 171 and 171. 172 is composed of at least a plate-like member having a size corresponding to the receiving portion 120 of the battery case 130.

Next, the gas generated in the charging and discharging process is collected in the gas collecting pocket 150 in the pressurized state using the pressing members 171 and 172 as shown in FIG. 6, and communicates with the inside of the battery case 130. A portion of the gas collecting pocket 150 is cut to form the through part 163 to remove the gas generated during the activation process.

 Finally, as shown in FIGS. 7 and 8, the pressing force applied using the pressing members 171 and 172 on both surfaces of the battery case 130 is removed, and the inner side 164 of the unsealed portion adjacent to the electrode assembly 110 is removed. After sealing by heat fusion, the remaining outer portion is cut off to complete the battery cell 100.

On the other hand, Figure 9 and 10 is a schematic diagram of the pressing member according to an embodiment of the present invention.

9, in order to effectively remove the gas generated during the activation process, the pressing member 200 for maintaining or depressurizing the outer surface of the battery case 130 may include two or more plate-shaped battery cells 231. It consists of a structure including three plate-shaped members (271, 272, 273) that is mounted in a structure that can be adjusted to each other so as to press the 232 at the same time.

In addition, referring to FIG. 10, the plate-shaped members 371, 372, 373, 374, and 375 of the pressing member 300 are provided with openings communicating with each other, and are connected to each other by a connecting shaft 380 penetrating the openings. The plate members are connected to each other, the structure to press the plate members 371, 372, 373, 374, 375 in the state that the battery cells are mounted between the plate members 371, 372, 373, 374, 375 Consists of

9 and 10 are described as being composed of plate-like members to pressurize the plate-shaped battery cells, the size and shape of the pressing member is configured in a variety of sizes or shapes depending on the battery cell to be applied It is also possible.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (19)

A method of manufacturing a secondary battery having a structure in which an electrode assembly having a structure interposed between a positive electrode and a negative electrode is sealed together with an electrolyte in a pouch type battery case.
(A) mounting the electrode assembly to the housing of the pouch-type battery case;
(b) sealing the outer circumferential surface of the battery case including a gas collecting pocket in a state where the electrode assembly is mounted;
(c) performing charging and discharging for battery activation in a state in which the outer surface of the sealed battery case is pressurized using a pressing member;
(d) perforating the gas collecting pocket in which the gas generated in the charging and discharging process is collected or cutting a part of the gas collecting pocket to remove the gas; And
(e) removing the gas collecting pocket and sealing an outer circumferential surface of a corresponding accommodating part;
Secondary battery manufacturing method comprising a. The method of claim 1, wherein the electrode assembly has a winding type, a stack type, or a stack / fold type structure. The method of claim 1, wherein the battery case is a secondary battery manufacturing method comprising a laminate sheet comprising a resin layer and a metal layer. The method of claim 3, wherein the laminate sheet is a secondary battery manufacturing method, characterized in that the aluminum laminate sheet. The method of claim 1, wherein the laminate sheet has a structure in which one end of the upper and lower laminate sheets is coupled to each other. The method of claim 1, wherein a sealing portion (“outer surface sealing portion”) is formed on an outer circumferential surface of the battery case to seal the outer circumferential surface in a state where the electrode assembly is mounted on the receiving portion, and gas collection is performed on one of the outer circumferential surface sealing portions. A secondary battery manufacturing method characterized in that the pocket for protruding in the outward direction. The method of claim 1, wherein the gas collection pocket is a secondary battery manufacturing method, characterized in that the protruding width thereof is the size of 30 to 100% of the width of the receiving portion. The method of claim 1, wherein the positive electrode comprises lithium titanium oxide as a positive electrode active material. The method of claim 1, wherein the negative electrode includes lithium titanium oxide as a negative electrode active material. The method of claim 1, wherein the secondary battery is a lithium ion polymer secondary battery. The method of claim 6, wherein the sealing is a secondary battery manufacturing method, characterized in that achieved by thermal fusion. The method of claim 1, wherein the secondary battery is a plate-shaped battery cell, in the step (c) the pressing member is a secondary battery manufacturing method characterized in that to compress both sides of the battery case excluding the gas collection pocket. The method of claim 12, wherein the pressing member comprises at least two plate-like members having a size corresponding to at least the receiving portion of the battery case. 15. The method of claim 13, wherein the pressing member comprises at least three plate-like members mounted in a structure capable of mutually adjusting a space so as to press two or more plate-shaped battery cells at the same time. 15. The apparatus of claim 14, wherein the plate-shaped members are formed with apertures communicating with each other, the plate-shaped members are connected to each other by a connecting shaft passing through the openings, and the battery cells are mounted between the plate-shaped members. Secondary battery manufacturing method comprising a structure for pressing the plate member. The method of claim 1, wherein in the step (d), a secondary battery manufacturing method, characterized in that to apply a reduced pressure to remove the gas. The method of claim 1, wherein the pressing force applied to the outer surface of the battery case is removed from the pressing member before or after the step (e). A secondary battery manufactured by the method according to any one of claims 1 to 17. A battery module comprising the secondary battery according to claim 18 as a unit cell.

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