KR20060073387A - Secondary battery module of improved stability - Google Patents

Abstract

The present invention is a high-output large-capacity module consisting of a plurality of unit cells, a plurality of unit cells, which is a secondary battery capable of charging and discharging, are arranged in the battery case so that their pole plates face each other and arranged in parallel. Provided is a secondary battery module in which a plate-shaped high strength safety member is mounted between an outermost unit cell of the unit cells and the battery case in parallel with the pole plate of the unit battery.

The battery module according to the present invention has a small size, light weight, compact structure, and provides high safety against external physical shocks.

Description

Secondary Battery Module of Improved Stability             

1 is a schematic perspective view of a battery module according to an embodiment of the present invention;

2 is a side view of FIG. 1;

3 is a perspective view illustrating a configuration relationship between an upper case and a safety member in the battery module of FIG. 1;

4 is a schematic diagram of a partial process of assembling the battery module of FIG. 1.

<Description of Major Symbols in Drawing>

100: battery module 200: upper case

300: lower case 400: unit cell

500: first circuit portion 600: second circuit portion

700: third circuit portion 800: safety member

900: insulation member 1000: fastener

1100: double sided adhesive tape

The present invention relates to a secondary battery module or a pack having improved safety, and a plurality of unit cells, which are rechargeable / dischargeable secondary batteries, are arranged inside the battery case so that their pole plates face each other and are arranged in parallel. A high output large capacity secondary battery providing high mechanical safety against external physical shocks by mounting a high-strength safety member in parallel to the pole plate of the unit battery between the outermost unit cell and the battery case among the unit cells. It is about a module.

Recently, secondary batteries capable of charging and discharging have been widely used as energy sources of wireless mobile devices. In addition, the secondary battery has attracted attention as an energy source of electric vehicles, hybrid electric vehicles, etc. which are proposed as a solution for air pollution of conventional gasoline and diesel vehicles using fossil fuel. Therefore, the type of applications using the secondary battery is very diversified due to the advantages of the secondary battery, and it is expected that the secondary battery will be applied to many fields and products in the future.

As the application fields and products of secondary batteries are diversified as described above, the types of batteries are also diversified to provide outputs and capacities suitable for them. In addition, batteries applied to the art and products are strongly required for small size and light weight.

For example, small mobile devices such as mobile phones, PDAs, digital cameras, notebook computers, etc., have correspondingly used one or three or four small light battery cells per device according to the small size of the products. On the other hand, medium and large devices such as electric bicycles, electric vehicles, hybrid electric vehicles, etc., due to the need for high output and large capacity, battery modules (or sometimes referred to as "battery packs") that electrically connect a plurality of battery cells are used. Since the size and weight of the battery module are directly related to the accommodation space and output of the medium and large devices, manufacturers are trying to manufacture a battery module that is as small and lightweight as possible.

The conventional medium-large secondary battery module is electrically connected to a plurality of unit cells mounted inside a case (housing) of a predetermined size, and the voltage, current, temperature, etc. of the unit cells on the outer surface of the case to operate the battery It comprises a circuit portion for controlling the.

As described above, in the field of medium and large devices, as a variety of products using secondary batteries are required, various types of electric modules are required to provide corresponding capacities and outputs. In other cases, the required capacitance and output also vary, so the design of the battery module must be changed.

On the other hand, one of the most problematic items in a secondary battery and a battery module including a plurality thereof is safety. In particular, the high-output large-capacity battery module is used in large devices such as electric bicycles, electric vehicles, etc., and thus receives various external forces such as shocks and vibrations from the outside. In addition, the lithium secondary battery, which has recently been the subject of much interest and research on the possibility of being used as a unit cell constituting a battery module, has a problem of low safety. Therefore, the safety problem of a battery module in which a plurality of unit cells are concentrated may be more serious.

The safety problem of the battery module is largely caused by internal short circuit of the module components due to overheating or the like due to overheating or external shock. In order to solve problems such as damage and overheating of the unit cell due to overcharge and overdischarge, generally, the battery module includes a battery management system (BMS) that senses and controls the current and voltage of the unit cell and the temperature of the battery system. It includes a circuit section. Therefore, it is possible to protect the unit cell and to ensure safety by cutting off the current in the event of overcurrent, overvoltage, overheating, and the like.

On the other hand, the problem of an internal short circuit caused by an external physical shock can vary greatly depending on the kind of such an external shock. For example, when a device equipped with a battery module is a transportation device such as an electric bicycle, an electric motorcycle, an electric vehicle, or the like, the battery module may be separated and dropped by an impact of such a device, or an external object may collide with the battery module. The situation may occur. A particularly serious situation is when the needle conductor applied to the battery module penetrates the unit cell, and the penetration of the needle conductor may cause an explosion of the battery.

A unit cell generally consists of a structure in which an electrode assembly in which a porous separator is interposed between a positive electrode and a negative electrode coated with an active material on a current collector, is sealed in a battery case. Therefore, when the positive electrode active material and the negative electrode active material contact by penetrating the needle conductor, a high resistance heat is caused by the current passing through the contact resistance portion. When the internal temperature of the battery rises above the threshold due to such high heat of resistance, the oxide structure of the positive electrode active material collapses, causing a thermal runaway phenomenon, and ultimately, the battery ignites or explodes.

One method of protecting the battery module from such a physical shock is a method of making the module case of a high strength material or structure. A material having a high strength may be representatively a metal, but when the battery case is manufactured from such a metal, the weight is greatly increased and moreover, there is a problem of causing a short circuit with various elements constituting the battery module. In addition, the structure of the battery module capable of exhibiting high strength is, for example, to make the thickness of the battery case thick or double or triple, but this method also increases the size and weight of the battery module, thereby counteracting the request for compact and lightweight. Done.

Accordingly, there is a high need for a battery module that can be manufactured in a small size and light weight while providing a high output capacity and, in particular, safety which is one of the most important tasks, in particular, safety against external physical shocks.

The present invention aims to solve the problems of the prior art as described above and the technical problems that have been requested from the past.                         

The inventors, after extensive and in-depth research, construct a high-density battery module by overlapping square or pouch-type unit cells. When installing a high-strength safety member, even when using a module case of a relatively weak strength, it was confirmed that it can provide a high safety against external physical impact and came to complete the present invention.

Accordingly, the secondary battery module according to the present invention is a high output large capacity module composed of a plurality of unit cells, and a plurality of unit cells, which are chargeable and dischargeable batteries, are overlapped in parallel so that their pole plates face each other. Arranged, and the plate-shaped high-strength safety member is mounted between the outermost unit cell of the overlapped unit cells and the battery case in parallel to the pole plate of the unit cell.

According to the present invention, in order to provide a battery module having a high output capacity with respect to size and weight, a plurality of unit cells are arranged in parallel so as to face each other and electrically connected to each other.

The unit cell is not particularly limited as long as it is a secondary battery capable of charging and discharging, and examples thereof include lithium secondary batteries, nickel-hydrogen (Ni-MH) batteries, nickel-cadmium (Ni-Cd) batteries, and the like. Among them, a lithium secondary battery providing high power to weight may be preferably used.

As the unit cell, a rectangular secondary battery or a pouch-type secondary battery, which can overlap with a high density, is used. The square secondary battery is a battery that can be charged and discharged in which an electrode assembly composed of a positive electrode, a separator, and a negative electrode is built in a rectangular case such as aluminum. Built-in battery capable of charging and discharging. The electrode assembly may be, for example, a jelly-roll electrode assembly and a full cell or bicell that are wound in a plate shape after being wound with a porous separator interposed between a positive electrode and a negative electrode each having an active material applied to a current collector. A stacked electrode assembly in which a plurality of unit cells are stacked may be used.

The electrode plate means the current collector itself of the electrode assembly or the electrode to which the current collector active material is applied, and thus, the unit cells overlap each other in parallel so that the electrode plates face each other. This means that the current collectors or electrodes of (b) are overlapped to face each other. Therefore, unit cells having a plate-like structure as a whole may be mounted in a module case with high density when overlapping in the above manner.

When the unit cells overlap, the direction of the electrode terminal may vary according to the circuit configuration of the battery module, and thus may be in the same direction, opposite direction, or vertical direction to each other.

The unit cells overlapped in such a configuration are mounted in the module case, and the module case has a structure corresponding to the shape of the overlapped unit cells.

The module case is not particularly limited as long as it is a structure in which the unit cells can be stacked, and may be a case structure in which an accommodating part corresponding to the size of the unit cell is formed so as to facilitate the installation of the unit cells. May be a separate structure covering the upper and lower portions of the stacked unit cells, respectively.

The module case also includes a circuit unit for controlling the operation of the unit cells, such operation control, the function of performing the charging and discharging of the battery, by measuring the voltage, current, temperature, etc. of the unit cells, overcharge, over-discharge, Functions to prevent overheating and the like are included. In order to design a battery module having a compact structure, the circuit part may be preferably attached to an inner surface or an outer surface of a battery case.

The most preferable structure for the manufacture of a small and lightweight battery module is a structure close to the total size and weight of the unit cells in which the size and weight of the entire module is overlapped while ensuring safety. In addition to the safety that can be secured by the circuit unit as described above, the mechanical safety against physical external shocks is highly dependent on the module case surrounding the unit cells. In order to achieve mechanical safety with a module case, it must be of sufficient strength to withstand physical external shocks or of a size sufficient to cushion such shocks. In general, metal may be used as a material capable of providing a high strength to size, but as described above, the metal is generally not preferable because it is heavy in weight and exhibits conductivity. Therefore, the configuration for achieving a compact and lightweight battery module may be a configuration that hinders the mechanical safety of the battery module.

On the other hand, in the battery module of the present invention, the module case need not be made of a material having a high strength corresponding to the metal. The module case may be a plastic resin which is preferably electrically insulating and lightweight, or a composite in which a reinforcing agent is added thereto. Such materials are lightweight and easy to form into various shapes by known techniques and exhibit electrical insulation. Examples of the plastic resin include, but are not limited to the following, preferably ABS (Acrylonitrile-Butadiene-Styrene), PC (polycarbonate), PBT (Polybutylene Terephthalate) and the like.

In the present invention, in order to provide a high mechanical strength, by providing a high-strength safety member between the outermost unit cell and the module case of the overlapping unit cells to provide the mechanical safety required for the battery module. The mechanical safety in question in the battery module is an internal short circuit of the unit cell due to falling of the module due to external impact, collision, penetration of the needle conductor, and the like as described above. The inventors have conducted various in-depth studies to confirm that the safety of the battery module may be seriously impaired when such an external shock is applied toward the pole plate of the unit cell. Therefore, it has been found that when a safety member having a high strength and a plate-like structure is installed inside the case in the direction of the pole plate of the unit cell, high mechanical safety can be provided despite a small weight increase.

The safety member is preferably made of a high strength metal material, more preferably made of stainless steel. The size of the safety member preferably has a surface area and an appropriate thickness corresponding to the unit cell. Too thin a thickness makes it difficult to provide the desired mechanical strength and, on the contrary, too thick causes a significant weight increase of the battery module, which is undesirable.

In one preferred embodiment, the battery module according to the present invention,

A rectangular lower case including a lower accommodating part to which the main board assembly is attached and an upper accommodating part to sequentially stack the unit cells;

A rectangular upper case including a lower accommodating part covering an upper end of unit cells stacked on the lower case;

A circuit unit electrically connected to the unit cells, controlling operation of the cell, and attached to the side of the module; And

A plate-shaped high strength safety member mounted between the upper case or the lower case, or between the upper case and the lower case and the unit cell, between the outermost unit cell of the overlapping unit cells and the case in parallel to the pole plate of the unit cell;

It is configured to include.

The battery module is separated from each other, the upper case and the lower case, when necessary to change the capacity and output, it is possible to design a fluid by adding or removing the unit cell between the upper case and the lower case.

The overall size of the upper case and the lower case is about the size of the unit cell. Therefore, the upper accommodating part of the lower case in which the unit cell is accommodated and the lower accommodating part of the upper case correspond to the body size of the unit cell.

In one preferred example, a double-sided adhesive member may be interposed between the unit cells to be stacked. This double-sided adhesive member allows the unit cells to be more stably stacked and fixed in the battery module. Examples of the double-sided adhesive member include a double-sided adhesive tape, but is not limited thereto. Preferably, two or more double-sided adhesive members spaced apart from each other may be interposed on one lamination surface. In this case, a predetermined space is secured by the double-sided adhesive members spaced apart between the stacked unit cells, and the separation space functions to buffer a volume change of the unit cell during charge and discharge, and simultaneously generates heat of the unit cell. Help

The unit cells are stacked so that their electrode terminals are oriented in the same direction. Preferably, the electrode cells of the unit cells can be firmly bonded to the unit cells and at the same time facilitate contact of the connection terminals for electrical connection. It may be formed in the through hole, the connecting member connecting the through hole may be a structure coupled to the upper case and the lower case.

In one preferred example, the circuit portion,

A first circuit unit including a sensing board assembly configured to electrically connect the stacked unit cells and sense a voltage, a current, a temperature, and the like of the unit cells, the first circuit unit being attached to the side of the module in an electrode terminal direction of the unit cells;

A second circuit part electrically connected to the first circuit part and including a main board assembly for overall control of the module and mounted to a lower housing of the lower substrate; And

A third circuit portion electrically connected to the second circuit portion, connected to an external output terminal while preventing overcurrent, and attached to opposite sides of the module opposite the first circuit portion;

Consists of

The first circuit portion is attached to the electrode terminal of the unit cell. The first circuit unit includes connection terminals for connecting unit cells in parallel or in series, and a sensing board assembly for receiving voltage and current signals from each unit cell and sensing a temperature of the cells. The temperature can be measured as the temperature of the entire cell in the sensing board assembly.

The configuration of the connection terminal is not particularly limited as long as it is a structure for connecting unit cells in parallel or in series. Preferably, the connection terminal may have a structure in which a safety device for blocking current when an overcurrent or overheating is connected. Examples of such safety devices include fuses, bimetals, PTC devices, and the like.

The sensing board assembly has a structure electrically connected to each unit cell.

The unit cells are electrically connected to the second circuit unit mounted on the lower housing of the lower case via the first circuit unit, and the operation of the battery is controlled in the main board assembly of the second circuit unit.

On the opposite side of the module side on which the first circuit portion is mounted, a third circuit portion electrically connected to the second circuit portion is mounted, and the third circuit portion controls an overcurrent during charging and discharging of a battery and is connected to an external device. The final device of the module. The overcurrent control during charging and discharging can preferably be executed by the FET element included in the third circuit section.

The sensing board assembly and the main board assembly are preferably made of a PCB, so that the sensing board assembly and the main board assembly have a constant strength as such, and thus the main board assembly of the second circuit unit may protect the unit cells against external shock. Therefore, preferably, the safety member may be installed only in the upper case.

The battery module is connected to a circuit part related to the operation of the battery wrapped in the module form is greatly reduced the overall size of the module.

The battery module according to the present invention can be preferably used in a medium-to-large battery system of high output large capacity, the range of the high output large capacity is not particularly limited.

For example, the battery according to the present invention may be used as a power source for various fields and products including a power source of a vehicle such as an electric bicycle, an electric motorcycle, an electric vehicle, a hybrid electric vehicle, and the like. The battery module according to the present invention is particularly preferable as a power source of an electric bicycle due to its compact structure and safety.

In the following, with reference to the drawings according to embodiments of the present invention in more detail, this is to help the understanding of the present invention, the scope of the present invention is not limited thereto.

1 and 2 schematically show a perspective view and a side view of a battery module according to an embodiment of the present invention.

1 and 2, the battery module 100 includes an upper case 200, a lower case 300, a plurality of unit cells 400, a first circuit unit 500, a second circuit unit 600, and the like. The third circuit portion 700 is included. The unit cells 400 are stacked between the upper case 200 and the lower case 300 which are separated from each other, the first circuit unit 500 is located in front of the battery module 100, the second circuit unit 600 ) Is located at the bottom, and the third circuit portion 700 is located at the back.

Since the upper case 200 and the lower case 300 are separated, the number of unit cells 400 that can be stacked is not limited thereto, and according to the number of stacked units of the unit cells 400, the first circuit unit 500 may be used. ) And only the third circuit unit 700 can be easily designed, the battery module 100 of the desired capacitance and output. In addition, since the unit cells 400 are exposed, heat dissipation of the unit cells 400 may be efficiently performed during charging and discharging.

3 is a perspective view of a lower surface of the upper case and the safety member mounted thereto in the battery module of FIG. 1.

Referring to FIG. 3, the upper case 200 has a lower accommodating portion 220 corresponding to its size so as to cover the upper end of the unit cell 400 of FIG. 1, and the electrode of the unit cell 400. The hole 210 is drilled at a position corresponding to the through hole of the terminal. This will be described later in detail with reference to FIG. 4.

The upper case 200 may be made of an insulating member that is the same as or different from the lower case, and is preferably made of plastic resin.

The lower housing portion 220 of the upper case 200 is provided with a plate-like safety member 800. The safety member 800 has a size substantially similar to that of a unit cell.

4 is a schematic view of a part of a process of manufacturing a battery module according to one embodiment of the present invention.

Referring to FIG. 4, a plurality of unit cells 400 and 401 are stacked between the lower case 300 and the upper case 200 separated from each other such that the electrode terminals 410 and 411 have the same orientation. . An insulating member 900 is interposed between the electrode terminals 410 and 411 for electrical insulation, and a protrusion 910 is formed on the insulating member 900 to be inserted into the through hole 420 of the electrode terminal 410. The through hole 920 having a small inner diameter is drilled in the center of the protrusion 910.

Holes 210 and 310 corresponding to the through hole 920 of the protrusion 910 are drilled in the upper case of the lower case 300 and the upper case 200, which can accommodate the unit cells 400 and 401. It is. The inner diameters of the holes 210 and 221 formed in the upper and lower cases 200 and 300, respectively, are approximately the same as the inner diameter of the through hole 920 formed in the insulating member 900. On the other hand, the inner diameter of the through hole 420 formed in the electrode terminal 410 is larger than the holes 210 and 310 and the through hole 920, and is approximately equal to the outer diameter of the protrusion 910.

Therefore, the unit cells 400 and 401 and the insulating member 900 interposed therebetween are stacked on the lower case 300 so that the holes are located on the same line, and the safety member (on the unit cell 401) is disposed. After covering the upper case 200 so that the 800 is installed, the fastener 1000 as a fastening member may be inserted into the holes to form the unit cells 400 and 401, and formed at the lower end of the fastener 1000. A nut (not shown) corresponding to the screw line 1010 may be fastened to the lower end of the lower case 300 to be fixed.

The safety member 800 mounted between the unit cell 401 and the upper case 200 prevents the unit cells 400 and 401 from being shorted by an external shock applied to the battery module. The external shock applied to the battery module causes a short circuit by deforming or penetrating the outer shape of the unit cells 400 and 410, and the safety member 800 protects the unit cells 400 and 401 from such deformation or penetration. . In particular, when a needle conductor (not shown) is applied to the battery module, the short circuit is mainly caused when applied to the pole plate direction of the unit cells 400 and 401, specifically, the upper or lower surface having a large surface area. Therefore, such a problem can be solved by arranging the plate-shaped safety member 800 in parallel with the pole plates of the unit cells 400 and 401.

In FIG. 4, a process of combining two unit cells 400 and 401 is schematically illustrated, but the number of unit cells may vary depending on the capacity and output of the battery module.

The electrode terminals 410 and 4111 may be connected in series or in parallel by a conductive connecting member (not shown) that is fastened to the insulating member 800, and the connecting member may be made in various structures. Since the conductive connecting member is directly fastened to the insulating member 900, electrical connection between the connecting member and the electrode terminals 410 and 411 can be easily achieved by physical contact, and in some cases, welding the contact portion. You can also increase the bonding strength.

Two double-sided adhesive tapes 110 are attached to the upper surface of the case of the unit cell 100 to further ensure stable coupling with the unit cells 401 stacked. In addition, since the stacked unit cells 400 and 401 are spaced apart by the thickness of the double-sided adhesive tape 110, such a spaced groove buffers a volume change of the unit cells 400 and 401 during charging and discharging. It effectively serves to dissipate heat generated by the batteries 400 and 401.

Although the present invention has been described above with reference to the drawings according to embodiments of the present invention, those skilled in the art to which the present invention pertains to various applications and modifications within the scope of the present invention based on the above contents. It will be possible.

As described above, according to the present invention, by compactly overlapping the unit cells in parallel so that the pole plates face, it is possible to manufacture a compact and lightweight battery module, the plate-shaped high strength in the direction of the pole plate of the unit cell between the outermost unit cell and the module case By installing a safety member, even when using a module case of relatively weak strength, it is possible to provide high safety against external physical impact.

Therefore, the battery module of the present invention may be variously applied to medium and large battery modules such as an electric bicycle, an electric vehicle, a hybrid electric vehicle, and the like.

Claims (11)

A high-output large-capacity module composed of a plurality of unit cells, wherein a plurality of unit cells, which are chargeable and dischargeable batteries, are arranged in a battery case in parallel with each other so that their pole plates face each other, and among the overlapped unit cells. A secondary battery module, wherein a plate-shaped high strength safety member is mounted between an outermost unit cell and the battery case in parallel with a pole plate of the unit cell. The secondary battery module of claim 1, wherein the unit battery is a lithium secondary battery. The secondary battery module according to claim 1, wherein the battery is a rectangular secondary battery or a pouch secondary battery. The secondary battery module according to claim 1, wherein the module case has a hexahedral structure as a whole, and a circuit portion for controlling the operation of the unit cells is included on an inner surface or an outer surface of the case. The secondary battery module according to claim 1, wherein the module case is made of a plastic resin or a composite in which a reinforcing agent is added thereto. The secondary battery module of claim 1, wherein the safety member is made of a high-strength metal material. The secondary battery module of claim 6, wherein the metal is stainless steel. The secondary battery module of claim 1, wherein the size of the safety member has a surface area corresponding to a unit cell. The method of claim 1, wherein the module, A rectangular lower case including a lower accommodating part to which the main board assembly is attached and an upper accommodating part to sequentially stack the unit cells; A rectangular upper case including a lower accommodating part covering an upper end of unit cells stacked on the lower case; A circuit unit electrically connected to the unit cells, controlling operation of the cell, and attached to the side of the module; And A plate-shaped high strength safety member mounted between the upper case or the lower case, or between the upper case and the lower case and the unit cell, between the outermost unit cell of the overlapping unit cells and the case in parallel to the pole plate of the unit cell; Secondary battery module, characterized in that consisting of. The method of claim 9, wherein the circuit portion, A first circuit unit including a sensing board assembly configured to electrically connect the stacked unit cells and sense a voltage, a current, a temperature, and the like of the unit cells, the first circuit unit being attached to the side of the module in an electrode terminal direction of the unit cells; A second circuit part electrically connected to the first circuit part and including a main board assembly for overall control of the module and mounted to a lower housing of the lower substrate; And A third circuit portion electrically connected to the second circuit portion, connected to an external output terminal while preventing overcurrent, and attached to opposite sides of the module opposite the first circuit portion; Secondary battery module, characterized in that consisting of. The secondary battery module of claim 9, wherein the safety member is installed only between the outermost unit cell and the upper case.

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