KR20090077135A - Slim-typed secondary battery - Google Patents

Abstract

A slim-typed secondary battery is provided to ensure smaller cross section than width of a protection circuit module, to mount a battery cell on the site spaced from an external input-output terminal, and to efficiently utilize an internal space of a device. A secondary battery(100) comprises a battery cell, wherein an electrode assembly of a positive electrode/separator/negative electrode structure is mounted on a sheet type case having an accommodation part; a sealing part is formed in the outer circumference in the accommodation part by hot fusion; side ceiling portions(301) are bent vertically and are close to the side wall of the accommodation part. The protection circuit module is vertically mounted on the upper end ceiling(302) in a longitudinal direction of the battery cell. The wire-type lead(510) which is electrically connected to external input and output terminals of the protection circuit module is drawn in a one side direction of the protection circuit module.

Description

Slim type secondary battery {Slim-Typed Secondary Battery}

The present invention relates to a slim type secondary battery, and more particularly, an electrode assembly is mounted on a sheet-shaped case in which an accommodating part is formed, a sealing part is formed on an outer circumferential surface of the accommodating part by thermal fusion, and an electrode terminal among the sealing parts. Each of the sealing parts, which are not positioned, is a secondary battery having a structure that is vertically bent and closely adhered to the side wall of the housing. A protection circuit module (PCM) is vertically mounted in the upper sealing part of the sealing parts in a longitudinal direction, and A wire type lead connected to the external input / output terminal of the PCM is drawn out in one side direction, and the wire type lead is not protruded to the top of the side sealing part in the side sealing part located at the portion where the wire type lead is drawn out. It provides a secondary battery characterized in that the cutout is formed in a size corresponding to the wire-like lead.

As the development and demand for mobile devices increases, the demand for secondary batteries as a source of energy is increasing rapidly. Among these secondary batteries, a lot of researches are being conducted on commercially available lithium secondary batteries with high energy density and high discharge voltage. It is used.

In particular, the lithium secondary battery is classified into a cylindrical battery, a square battery, a pouch type battery, and the like according to its appearance, and may be classified into a lithium ion battery and a lithium ion polymer battery according to the type of electrolyte. Due to the recent trend toward miniaturization of mobile devices, there is an increasing demand for thinner rectangular batteries and pouch-type batteries.

However, lithium secondary batteries contain a variety of combustible materials, and may be exposed to overcharging, overcurrent, high temperature, overcharging, external short circuit, nail penetration, local crush, or other physical external shocks within a short time. When a large current flows, there is a risk of heat generation, explosion, etc. while the battery is heated by IR heat, and has a big disadvantage in safety.

Therefore, the lithium secondary battery is composed of a field effect transistor (FET) as a switching element for controlling current, and passive elements such as a voltage detector, a resistor, and a capacitor. The battery is overcharged, overdischarged, and overcurrent. By preventing the short circuit, reverse voltage, etc., it prevents battery explosion, overheating or leakage and deterioration of charge / discharge characteristics, and suppresses deterioration of electrical performance and physical and chemical abnormal behavior, thereby eliminating risk factors and extending service life. The protection circuit module (PCM) is built in the state connected to the battery cell.

The PCM consists of various safety elements, a protection circuit board and a connection member electrically connecting the protection circuit board to the electrode terminals. The protection circuit board is in the form of a plate, and one side thereof is overcharged, overdischarged, and overcurrent of the battery. It is provided with a protection circuit for controlling the light, and a connection terminal to be electrically connected to the battery body, the other side of the external input and output terminals connected to an external device (for example, wireless terminal, notebook, electric vehicle, etc.) It consists of a structure that is provided.

In this regard, Figure 1 is a schematic diagram of a secondary battery according to the prior art equipped with a PCM.

Referring to FIG. 1, the secondary battery 10 includes a battery cell 20 in which an electrode assembly is embedded; PCM which is connected to terminals (not shown) derived from the battery cell 20 and has an external input / output terminal 31 formed thereon so as to protect the battery secondaryly and to be connected to a corresponding device (not shown). 30);

Looking at the process of connecting and mounting the PCM 30 to the battery cell 20 in the secondary battery of such a structure, first, in a state in which the PCM 30 in the vertical direction with respect to the top surface of the battery cell, the PCM (30) The positive and negative connection terminals of the battery cell 20 by electrically connecting the electrode terminals of the battery cell 20 using a conductive connection member such as a nickel plate, and bending the conductive connection member to connect the PCM 30 to the battery cell 20. Mount parallel to the top surface of).

However, the secondary battery of such a structure, due to the space occupied by various elements mounted on the PCM mounted parallel to the top surface of the battery cell, and the bent portion of the conductive connection member for electrical connection, Since dead space is generated, a problem arises in that the battery density and capacity are reduced in a battery of the same standard. Moreover, since the width of the battery cell is limited by the width of the PCM, there is also a problem that it is impossible to manufacture a slim battery having a thickness smaller than that of the PCM.

Therefore, in response to miniaturization and thinning of external devices, there is a high need for a slim secondary battery while being able to stably mount a PCM.

Accordingly, an object of the present invention is to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

After extensive research and various experiments, the inventors of the present application mount a protection circuit module (PCM) vertically in the longitudinal direction of a battery, draw a wire-type lead in one side direction of the PCM, and When the electrical connection is formed and a cutout portion having a size corresponding to the wire-type lead is formed in the side sealing portion located at the portion where the wire-type lead is drawn out, it can be confirmed that a secondary battery having a compact and slim structure can be manufactured. The present invention has been completed.

In the secondary battery according to the present invention, an electrode assembly having a cathode / separation membrane / cathode structure is mounted on a sheet-shaped case in which an accommodating part is formed, and a sealing part is formed on an outer circumferential surface of the accommodating part by thermal fusion, and an electrode terminal among the sealing parts. The sealing parts ('side sealing parts'), which are not positioned, are secondary batteries including battery cells having a structure in which each of the sealing parts ('side sealing parts') is vertically bent and closely adhered to sidewalls of the receiving part.

A protection circuit module (PCM) is vertically mounted on the upper sealing part of the sealing parts in the longitudinal direction, and a wire-type lead electrically connected to an external input / output terminal of the PCM is drawn out in one direction of the PCM.

The side sealing portion located at a portion where the wire lead is drawn out, has a cutout portion formed in a size corresponding to the wire lead so that the wire lead does not protrude to the upper end of the side sealing portion. It is.

Unlike the secondary battery of the prior art, in which the PCM is mounted in the width direction in parallel with the battery cell, the secondary battery according to the present invention has a PCM mounted vertically in the longitudinal direction of the battery, and thus substantially corresponds to or exceeds the thickness of the PCM. It is easy to implement a slim battery having a thin thickness of a slightly larger size.

In addition, in the prior art, the external input / output terminals of the PCM have a structure in which the external input / output terminals of the PCM are directly connected to the corresponding portions of the external device. However, in the present invention, the external input / output terminals of the PCM are limited by the position of the external input / output terminals of the PCM. Is connected to an external device through a wired lead, which has the advantage that the connection portion of the external device is not limited.

Furthermore, since the cutout is formed on the side sealing part from which the wire-shaped lead is drawn out, it is possible to manufacture an ultra-slim battery without causing an increase in thickness due to the wire-type lead.

Specifically, the wire-like lead is drawn out in one side direction of the PCM. In general, the wire-like lead protrudes to the top of the side sealing part due to interference of the side sealing part in the drawing direction, thereby causing unnecessary space wastage. On the other hand, in the present invention, a predetermined cutout is formed in the side sealing portion located at the portion where the wire lead is drawn out. By drawing the wire type lead through the cutout, the battery can maintain the left and right balance in terms of thickness, and minimize the space waste due to the protrusion of the wire type lead. Therefore, since the wire type lead can be stably positioned without affecting the volume density of the battery, the ultra-slim battery can be effectively implemented.

The PCM may have a rectangular shape of a predetermined length and width, and may have a structure in which a safety device or the like is mounted on a protective circuit board (PCB), which is a cube having a predetermined thickness. This PCM is mounted on the top sidewall of the enclosure in an upright position.

In one preferred example, the upper sealing portion to which the PCM is mounted is made in a non-bending state, the PCM may be mounted on the upper sealing portion in a form seated on the side wall of the receiving portion. At this time, for stable mounting of the PCM, it is preferable that the surface on which the various safety elements and the like are mounted facing the upper surface of the battery.

In such a mounting structure, for example, in the case of a battery protruding to the outside while the electrode terminal is located in the upper sealing portion, the electrode terminal may be bent in the PCM direction to achieve electrical connection between the battery cell and the PCM.

The electrode terminal is configured to be electrically connected to the upper or lower surface of the PCM. That is, the connection terminal of the PCM to which the electrode terminal is connected may be formed on its upper surface or may be formed on its lower surface. As an example, in order to prevent the possibility of energizing with safety elements mounted on the upper surface of the PCM during the electrical connection process, the connection terminal is formed on the lower surface of the PCM opposite to the surface on which the safety elements are mounted, and the electrode terminal It may be a structure that is bent again in the direction of the PCM and connected to the connection terminal.

As such, the electrode terminal of the battery cell is coupled to the connection terminal of the PCM to achieve electrical connection between the battery cell and the PCM, and the connection terminal and the external input / output terminal are connected through a predetermined circuit, and coupled to the external input / output terminal. It is electrically connected to an external device via a wired lead.

In the present invention, the cutout is formed in the side sealing portion located at the portion where the wire-shaped lead is drawn out. That is, since the wire-shaped lead is drawn out in the direction of one side of the PCM located on the top surface of the battery cell, the cutout is formed at the left or right sealing part located at the top of the battery cell.

The cutout has a size corresponding to or slightly larger than the cross-sectional area of the wired lead. However, by cutting a part of the side sealing part to form the cutout part, there is a fear that the sealing property of the battery is weak at the corresponding part. That is, since the sealability is approximately proportional to the width of the sealing portion, the formation of the cutout portion can lead to a decrease in the sealing performance of the sealing portion.

Therefore, in one preferred example for preventing such degradation in sealing, it may be a structure in which an excess sealing portion is formed inside the sealing portion corresponding to the cutout portion. Here, the inner side of the sealing portion corresponding to the cutout means the direction in which the electrode assembly is mounted in the side sealing portion at the top of the battery cell in which the cutout is formed, and thus the sealing portion at the position corresponding to the upper edge portion of the electrode assembly. Corresponding.

The excess sealing portion preferably has a sealing width or area capable of exhibiting a predetermined sealing property within a range of the spaced space at the top of the battery cell. That is, in general, a plurality of electrode tabs protrude from the upper end of the electrode assembly to be coupled to the electrode lead, and a predetermined space is formed between the upper end surface of the electrode assembly and the outer circumferential surface of the housing by bending the electrode tabs. Since the excess sealing portion can be formed in such a space, it is possible to prevent the degradation of the sealability that can be caused by the formation of the cutout. In addition, the separation space of the upper end of the electrode assembly is reduced by the excess sealing part to prevent the movement of the electrode assembly, it is possible to prevent the occurrence of a short circuit inside the battery due to the application of an external impact, the fall of the battery.

In one preferred example, the excess sealing portion may have a structure in which the side sealing portion is extended such that its inner side reaches the edge of the electrode assembly. Such a structure can be formed, for example, by round sealing in the shape of an arc corresponding to the end of each corner of the electrode assembly by thermal fusion when forming the side sealing part.

However, since the electrode assembly is repeatedly contracted and expanded by charging and discharging of the battery, when the excess sealing portion is in close contact with the electrode assembly, the inside of the excess sealing portion may be gradually opened due to the expansion force of the electrode assembly, which is not preferable. Therefore, in order to secure the expansion space of the electrode assembly, the inner side of the excess sealing portion formed by the round sealing is preferably formed to have a radius of curvature larger than the radius of curvature of the edge of the electrode assembly.

On the other hand, the sheet-shaped case may be preferably a laminate sheet including a resin layer and a metal layer, in particular, a pouch-type case of an aluminum laminate sheet. The laminate sheet may have a structure including an inner resin layer, a barrier metal layer, and an outer resin layer.

Since the outer resin layer should have excellent resistance from the external environment, it is necessary to have a tensile strength and weather resistance of a predetermined or more. In such aspect, polyethylene terephthalate (PET) and a stretched nylon film may be preferably used as the polymer resin of the outer resin layer.

Preferably, the barrier metal layer may use aluminum to exhibit a function of improving the strength of the battery case in addition to a function of preventing inflow or leakage of foreign substances such as gas and moisture, and thus, the sheet may be an aluminum laminate sheet. Can be.

As the polymer resin of the internal resin layer, a polyolefin-based resin having heat fusion (heat adhesion), low hygroscopicity to suppress the invasion of the electrolyte, and which is not expanded or eroded by the electrolyte is preferably used. More preferably unstretched polypropylene (CPP) may be used.

In addition, the shape and size of the battery case is not particularly limited and include, for example, (i) a structure in which the lower end of the upper body and the lower body are integrally formed and the receiving portion is formed only in the lower body; (ii) a structure in which the upper main body and the lower main body are separated and a housing is formed in the lower main body; (iii) a structure in which the upper main body and the lower main body are separated, and a receiving portion is formed in the upper main body and the lower main body, respectively; (iv) a structure in which lower ends of the upper body and the lower body are integrally formed and receiving portions are formed in the upper body and the lower body, respectively; Etc. can be mentioned.

The electrode assembly is not particularly limited as long as it is a structure consisting of a cathode and an anode, and a separator interposed therebetween, and examples thereof include a folding type, a stack type, or a stack / folding type structure. 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, which are described in the context of the present invention. Incorporated by reference.

The present invention also provides a battery pack having a structure in which the secondary battery as described above is mounted in a pack case. The battery pack using the secondary battery as the unit cell can significantly increase the volume density of the pack, easily connect to external devices, and ensure the stability of the unit battery even when the battery pack is used in a harsh environment. In addition, it can be manufactured with a slimmer and more compact structure.

Figure 2 is an exploded perspective view of a secondary battery according to an embodiment of the present invention is shown schematically, Figures 3 and 4 is a plan view and a perspective view of the secondary battery according to Figure 2 combined with PCM. It is.

First, referring to FIG. 2, the secondary battery 100 includes an electrode assembly 200, electrode tabs 210 and 211 extending from the electrode assembly 200, and electrode leads welded to the electrode tabs 210 and 211. 220, 221, a battery case 400 accommodating the electrode assembly 200, and a cutout part 600 formed on an upper side sealing part (exactly, a sealing plan part) of the battery case 400. It is.

The electrode assembly 200 is a power generator in which a positive electrode and a negative electrode are sequentially stacked in a state where a separator is interposed therebetween, and has a stack type or a stack / fold type structure. The electrode tabs 210, 211 extend from each pole plate of the electrode assembly 200, and the electrode leads 220, 221 are welded with a plurality of electrode tabs 210, 211 extending from each pole plate, for example, welding. Each is electrically connected to each other, and part of the battery case 400 is exposed to the outside. In addition, an insulating film 230 is attached to upper and lower portions of the electrode leads 220 and 221 in order to increase the sealing degree with the battery case 400 and to secure an electrical insulation state.

The battery case 400 is made of an aluminum laminate sheet, provides a space for accommodating the electrode assembly 200, and has a pouch shape as a whole.

The sealing parts 300, 301, and 302 are formed by thermally fusion bonding the outer peripheral surfaces of the battery case 400 with the electrode assembly 200 mounted on the accommodating portion of the battery case 400, and the electrode leads 220, respectively. The upper sealing part 302 in which the 221 is located and the side sealing parts 300 and 301 in which the electrode lead is not formed are comprised. In order to prevent space waste of the battery 100, the side sealing parts 300 and 301 are vertically bent to closely contact the sidewalls of the housing part.

As shown in FIGS. 3 and 4, the PCM 500 is mounted on the upper sealing part 302 in a state perpendicular to the longitudinal direction of the battery 100, and for stable mounting of the PCM 500. The surface on which the various safety elements 520 are mounted is mounted to face the upper surface of the battery. Therefore, the thickness t of the secondary battery 100 is not limited by the size of the width w of the PCM 500.

In addition, the wire type lead 510 is coupled to the external input / output terminal 530 of the PCM 500 in one side direction of the PCM 500, and the side sealing part 301 is a direction in which the wire type lead 510 is drawn out. Cutout 600 is formed at the upper edge of the).

The cutout 600 is formed to have a size corresponding to the wire-like leads 510, through which the wire-shaped lead 510 is drawn out. Accordingly, the secondary battery 100 may be easily electrically connected to an external device (not shown) through the wire type lead 510 coupled to the PCM 500, and the wire type lead coupled to the PCM 500. The secondary battery 100 having a compact and slim structure may be manufactured by removing the left and right positional deviations between the dead space and the side sealing parts 300 and 301 generated by the 510 protruding to the upper side of the side sealing part 301. can do.

The electrode terminal 220 of the battery cell is vertically bent and coupled to a connection terminal (not shown) formed on the upper surface of the PCM 500 by soldering or welding to electrically connect the battery cell and the PCM 500. do. In some cases, the connection terminal may be formed on the lower surface of the PCM 500, in which case the electrode terminal 220 is bent again to connect to the connection terminal.

On the outer surface of the battery case, as shown in Figure 4, in order to display the information of the product and to ensure the insulation with the outside, an insulating film type label 310 may be additionally added.

5 is a schematic perspective view of a secondary battery according to another embodiment of the present invention.

Referring to FIG. 5, in the secondary battery 101, an excess sealing part 700 is formed at an inner portion corresponding to the cutout part 600 formed in the side sealing part 301. Since the cutting force 600 is formed in the side sealing part 301, the sealing force may be weak, and thus, the excess sealing part 700 may be prevented.

The surplus sealing part 700 has a circular arc shape corresponding to an end portion of the edge 201 of the electrode assembly 200 in a size from which the inside thereof reaches the edge 201 of the electrode assembly 200. Therefore, movement of the electrode assembly 200 and a corresponding internal short circuit can be prevented. The inner side of the excess sealing part 700 has a radius of curvature that is larger than the radius of curvature of the edge of the electrode assembly 20, and thus is not excessively in close contact with the electrode assembly 200. 700 can ensure a stable sealability.

The excess sealing part 700, for example, when the heat sealing of the outer peripheral surface of the battery case for forming the upper and side sealing parts 301, 302, the side sealing part 301 is the direction in which the electrode assembly 200 is accommodated It can be formed by a simple process to expand to, not only to compensate for the width of the reduced sealing portion due to the cutout 600, but also to provide a constant sealing area to withstand the internal pressure of the battery.

Although described with reference to the drawings according to an embodiment of the present invention, those of ordinary skill in the art will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

As described above, the secondary battery according to the present invention may implement a slim battery cell having a cross-section smaller than the width of the PCM because the PCM is vertically mounted in the longitudinal direction of the battery cell and connected to an external device through a wire-type lead. In addition, since the battery cell can be easily mounted to a portion spaced apart from the external input / output terminal, the internal space of the device can be efficiently utilized. Furthermore, by forming a cutout partially removing the side sealing portion of the portion where the wire lead is drawn out, it is possible to prevent the wire lead from protruding to the top of the side sealing portion, thereby providing a secondary battery having a more compact and slim structure. have.

1 is a schematic diagram of a general structure of a conventional secondary battery equipped with a PCM;

2 is an exploded perspective view of a secondary battery according to one embodiment of the present invention;

3 and 4 are a plan view and a perspective view of a secondary battery according to FIG. 2 in which a protection circuit module PCM is coupled;

5 is a plan perspective view of a secondary battery according to another embodiment of the present invention.

Claims (9)

The electrode assembly of the anode / separation membrane / cathode structure is mounted on the sheet-shaped case in which the housing part is formed, and the sealing parts are formed on the outer circumferential surface of the housing part by thermal fusion, and the sealing parts in which the electrode terminals are not located among the sealing parts (' Side sealing parts') are secondary batteries each including a battery cell of a vertical bending and close contact with the side wall of the housing, A protection circuit module (PCM) is vertically mounted in the longitudinal direction of the battery cell, and a wire-type lead electrically connected to an external input / output terminal of the PCM is drawn out in one side direction of the PCM. A secondary battery, characterized in that the cutout portion is formed in a size corresponding to the wire-type lead so that the wire-shaped lead does not protrude to the upper side of the side-sealing portion located at the portion where the wire-shaped lead is drawn out. The secondary battery of claim 1, wherein the upper sealing part on which the PCM is mounted is formed in a non-bending state, and the PCM is mounted on the upper sealing part in a form of being seated on a side wall of the receiving part. The secondary battery according to claim 1, wherein in order to prevent a decrease in the sealing property of the battery due to the cutout portion, an excess sealing portion is formed inside the seal portion corresponding to the cutout portion. The secondary battery of claim 3, wherein the excess sealing part has a sealing part extended to a size such that an inner side of the excess sealing part reaches an edge of the electrode assembly. The secondary battery of claim 4, wherein an inner side of the excess sealing part is formed to have a radius of curvature greater than a radius of curvature of an edge of an electrode assembly. The secondary battery of claim 1, wherein the sheet case is made of a laminate sheet including a resin layer and a metal layer. The secondary battery of claim 1, wherein the sheet is an aluminum laminate sheet. The secondary battery of claim 1, wherein the electrode assembly has a folding structure, a stacked structure, or a stack / folding structure. A battery pack having a structure in which the secondary battery according to any one of claims 1 to 8 is mounted in a pack case.

Images