KR20180055341A - Battery Cell Having Reinforcement Sheet and Battery Pack Having the Same - Google Patents

Abstract

The present invention provides a battery cell in which a positive electrode, a negative electrode, and an electrode assembly of a separation film structure interposed between the positive electrode and the negative electrode are embedded in a battery case. A reinforcement sheet for reinforcing strength of the battery case and increasing a resistance to internal explosion is attached to at least a part of the outer surface of the battery case.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery cell including a reinforcing sheet,

The present invention relates to a battery cell including a reinforcing sheet and a battery pack including the same.

BACKGROUND ART [0002] In recent years, rechargeable secondary batteries have been widely used as energy sources for wireless mobile devices. The secondary battery is also attracting attention as a power source for an electric vehicle (EV) and a hybrid electric vehicle (HEV), which are proposed as solutions for the air pollution of existing gasoline vehicles and diesel vehicles using fossil fuels .

In the case of small mobile devices, one or two or more battery cells are used per device, while a middle- or large-sized battery module such as an automobile is used as a middle- or large-sized battery module in which a plurality of battery cells are electrically connected due to the necessity of a large-

Since the middle- or large-sized battery module is preferably manufactured in a small size and weight, a prismatic battery, a pouch-shaped battery, and the like, which can be charged with a high degree of integration and have a small weight to capacity ratio, are mainly used as the battery cells of the middle- or large-sized battery modules. In particular, a pouch-shaped battery using an aluminum laminate sheet or the like as an exterior member has attracted a great deal of attention recently due to its advantages such as small weight, low manufacturing cost, and easy shape deformation.

In order for the middle- or large-sized battery module to provide the output and capacity required by a predetermined device or device, a plurality of battery cells must be electrically connected in series and a stable structure with respect to external force must be maintained.

1 is a schematic cross-sectional view illustrating a battery pack including battery cells according to the related art.

Referring to FIG. 1, when the needle-shaped conductor 20 having electrical conductivity and having a pointed end like a nail penetrates the battery pack 10, the electrochemical energy inside the battery pack is converted into thermal energy, And the heat accompanying the chemical reaction of the positive electrode or the negative electrode material may cause safety problems such as ignition and explosion of the battery.

Specifically, the conventional battery pack 10 may include a battery cell stack 15 in which the battery cells 11, 12, and 13 are stacked in the pack case 12. However, when the sharp needle-shaped conductor 20 penetrates the battery module in such a battery pack 10, there is a case where short-circuiting occurs in the battery cell around the needle-shaped conductor 20 passing therethrough, The battery cells 11, 12 and 13 may be short-circuited to each other through the needle-shaped conductors passing through the plurality of battery cells 11, 12 and 13 at the same time.

Furthermore, the above-described safety problems are becoming more serious as lithium secondary batteries are increased in capacity and energy density is increased.

Further, in the conventional battery module, since the pad member for cooling or compression is applied between the battery cells of the battery cell stack body, there is a greater difficulty in ensuring safety against penetration of the needle-shaped conductive object.

In addition, in the prior art, methods for increasing the thickness or volume of the structures have been devised to solve the above-described safety problems. However, it has been difficult to apply such a method to practical applications when considering manufacturing costs and the like.

Accordingly, in order to secure safety against external physical shock, which is one of the most important problems in manufacturing a high-output large-capacity battery module, when a sharp needle-like conductor penetrates through a battery module, an internal short- It is necessary to develop a technology to prevent such a problem.

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

The inventors of the present application have conducted intensive research and various experiments. As described later, when the reinforcing sheet is attached to at least a part of the outer surface of the battery case for housing the electrode assembly, the strength of the battery case is reinforced It is possible to increase the resistance to internal explosion, and the present invention has been accomplished.

According to an aspect of the present invention, there is provided a battery cell comprising:

A battery cell in which an electrode assembly having a separator structure interposed between an anode and a cathode and between the anode and the cathode is embedded in a battery case,

And a reinforcing sheet is attached to at least a part of the outer surface of the battery case to reinforce the strength of the battery case and increase the resistance against internal explosion.

Therefore, the battery cell according to the present invention exerts the effect of reinforcing the strength of the battery case and increasing the resistance against internal explosion by attaching the reinforcing sheet to at least a part of the outer surface of the battery case accommodating the electrode assembly .

In one specific example, the battery case may be a pouch-shaped case that is a laminate sheet structure including a resin layer, a metal layer, and a sealant layer.

Also, the battery cells may have a plate-like structure.

In one specific example, the reinforcing sheet may be made of one or more materials selected from the group consisting of polycarbonate, polyimide, polyethylene terephthalate and polypropylene.

In one specific example, the outer surface of the reinforcing sheet, which is the opposite surface of the surface of the battery cell, which is attached to the outer surface of the battery cell, may further include a reinforcement film for preventing penetration by the outer needle-shaped conductor.

More specifically, the reinforcement film may be at least one of the group consisting of polyethylene, polyethylene terephthalate, polyurethane, and polyimide. When the reinforcement film is a composite material composed of two or more materials May be a structure composed of a single film or a multi-layer film mixed with various materials.

In one specific example, the reinforcing film may be fixed to the outer surface of the reinforcing sheet in a non-adhered state, and when the needle-shaped conductor penetrates from the outside in the direction passing through the battery cell, As shown in FIG.

In one specific example, the outer surface of the reinforcing sheet may be provided with at least two or more linear notches for fixing and fixing the outer circumferential edge of the reinforcing film, and more particularly, when the reinforcing sheet is rectangular in plan view, Four line-shaped notches can be formed adjacent to the four sides of the reinforcing sheet.

In one specific example, the line-shaped notches may be arch-shaped, with the bent direction pointing towards the center of the reinforcing sheet. Alternatively, the line-shaped notch may have a stepped structure formed toward the center of the reinforcing sheet.

Further, the pouch-shaped battery case is a laminate sheet comprising an outer resin layer made of a polymer resin having weather resistance, a metal layer having gas and liquid barrier properties, and an inner resin layer made of a polymer resin having heat sealability And the battery cell may be a plate-like structure having a generally rectangular parallelepiped structure having a small thickness as a whole.

The anode may be prepared, for example, by coating a mixture of a cathode active material, a conductive material and a binder on a cathode current collector, followed by drying. If necessary, a filler may be further added to the mixture.

The cathode active material is a material capable of causing an electrochemical reaction. Examples of the lithium transition metal oxide include lithium cobalt oxide (LiCoO ₂ ) containing two or more transition metals and substituted with one or more transition metals, lithium Layered compounds such as nickel oxide (LiNiO ₂ ); Lithium manganese oxide substituted with one or more transition metals; Formula _{LiNi 1-y M y O 2} ( where, M = Co, Mn, Al , Cu, Fe, Mg, B, Cr, Zn or Ga and Lim, 0.01≤y≤0.7 include one or more elements of the element) A lithium nickel-based oxide represented by the following formula: _{Li 1 + z Ni 1/3 Co 1/3} Mn 1/3 O 2, Li 1 + z Ni 0.4 Mn 0.4 Co 0.2 O 2 , such as _{Li 1 + z Ni b Mn c} Co 1- (b + c + d _{) M d O (2-e} ) A e ( where, -0.5≤z≤0.5, 0.1≤b≤0.8, 0.1≤c≤0.8, 0≤d≤0.2 , 0≤e≤0.2, b + c + d <1, M = Al, Mg, Cr, Ti, Si or Y, and A = F, P or Cl; lithium nickel cobalt manganese composite oxide; And the formula _{Li 1 + x M 1-y} M 'y PO 4-z X z ( wherein, M = a transition metal, preferably Fe, Mn, Co or Ni, M' = Al, Mg or Ti, X = F, S or N, and -0.5? X? +0.5, 0? Y? 0.5, and 0? Z? 0.1), but the present invention is not limited thereto.

The conductive material is usually added in an amount of 1 to 20 wt% based on the total weight of the mixture including the cathode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The filler is optionally used as a component for suppressing the expansion of the anode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

Further, the negative electrode is prepared, for example, by coating a negative electrode current collector with a mixture of a negative electrode active material, a conductive material and a binder, and drying the mixture. Optionally, a filler may be further added to the mixture. The negative electrode active material may be at least one selected from the group consisting of graphite carbon, coke carbon, and hard carbon.

The present invention also relates to a battery cell laminate having two or more battery cells stacked thereon; And a pack case in which the battery cell stack body is housed.

In one specific example, the first reinforcing sheet and the second reinforcing sheet are attached to the upper surface and the lower surface of the battery case on the outer surface of the battery case with respect to the stacking direction of the battery cells, A reinforcing film may be added to the outer surface of at least one of the outer conductor and the outer conductor to prevent the outer conductor from penetrating the outer conductor.

In one specific example, reinforcement films may be added to the upper surfaces of the uppermost battery cells and the outer surfaces of the respective reinforcing sheets attached to the lower surface of the lowermost battery cell with reference to the stacking direction in the battery cell stack.

Since the configurations of the battery cells described above are well known in the art, a detailed description thereof will be omitted herein.

INDUSTRIAL APPLICABILITY As described above, in the battery cell according to the present invention, when the reinforcing sheet is attached to at least a part of the outer surface of the battery case for housing the electrode assembly, it is possible to reinforce the strength of the battery case and increase the resistance to internal explosion Effect.

Further, in the battery cell according to the present invention, when the reinforcing film is further provided on the outer surface of the reinforcing sheet, which is the opposite surface to the surface of the battery cell, the penetration of the reinforcing sheet by the outer needle-shaped conductor can be effectively prevented .

1 is a schematic cross-sectional view showing a battery pack including battery cells according to the prior art;
2 is a schematic perspective view showing a battery cell according to one embodiment of the present invention;
3 is a schematic plan view showing a battery cell according to one embodiment of the present invention;
4 is a schematic plan view showing a battery cell according to another embodiment of the present invention;
5 is a schematic cross-sectional view along the N dashed line in Fig. 4;
6 is a schematic cross-sectional view illustrating a battery pack according to one embodiment of the present invention;
7 is a schematic cross-sectional view showing that the battery pack of Fig. 6 is penetrated by the needle-like conductor; Fig.
8 is a schematic cross-sectional view illustrating a battery pack according to another embodiment of the present invention;
9 is a schematic cross-sectional view showing that the battery pack of FIG. 8 is penetrated by the needle-shaped conductor.

Hereinafter, the contents of the present invention will be described in detail with reference to the drawings, but the scope of the present invention is not limited thereto.

2 is a schematic perspective view illustrating a battery cell according to an embodiment of the present invention.

Referring to FIG. 2, a battery cell 100 according to the present invention includes a battery case 140 having an anode assembly, a cathode assembly, and an electrode assembly (not shown) having a separator structure interposed between the anode assembly and the cathode assembly, Cell.

The battery cell 100 is a pouch-shaped battery cell 100, and has a plate-like structure. The battery cell 100 has a rectangular structure in which two electrode leads 110 and 120 protrude from the upper and lower ends of the battery main body 130, respectively.

The battery case 140 has a laminated structure. The battery case 140 is attached by applying heat and pressure to the opposite side surfaces 142, the upper and lower ends 141 and 143, and fusing the resin layers. Since the electrode leads 110 and 120 protrude from the upper end 141 and the lower end 143 of the battery case 140 in consideration of the thickness of the electrode leads 110 and 120 and the material of the battery case 140, And the electrode leads 110 and 120 are thermally fused with a film sealing member 155 interposed therebetween.

In addition, the reinforcing sheet 160 is attached to at least a part of the outer surface of the battery case 140 according to the present invention. Therefore, the battery cell 100 according to the present invention has a structure in which the reinforcing sheet 160 is attached to the outer surface of the battery case 140 housing the electrode assembly, thereby reinforcing the strength of the battery case 140, Can be increased.

At this time, the reinforcing sheet 160 is made of one or more materials selected from the group consisting of polycarbonate, polyimide, polyethylene terephthalate and polypropylene.

FIG. 3 is a schematic plan view showing a battery cell according to an embodiment of the present invention, and FIG. 4 is a schematic plan view showing a battery cell according to another embodiment of the present invention. A schematic cross-sectional view along the N dashed line in Fig. 4 is shown.

3 to 5, the outer surface 161 of the reinforcing sheet 160, which is the opposite surface to the surface of the battery cell 100 attached to the outer surface 149, is prevented from penetrating by the outer needle- A reinforcing film 170 is further added.

Wherein the reinforcing film 170 is polyethylene terephthalate or polyurethane.

Further, the reinforcing film 170 is fixed to the outer surface 164 of the reinforcing sheet 160 in an unbonded state.

The reinforcing sheet 160 is rectangular in plan view and four outer notches 163 and 165 for inserting and fixing the outer circumferential edge 171 of the reinforcing film 170 are formed on the outer surface of the reinforcing sheet 160 167 and 169 are formed on the upper surface of the reinforcing sheet 160 and four notched lines 163, 165, 167 and 169 are formed adjacent to the four sides of the reinforcing sheet 160.

These line-shaped notches 163, 165, 167, 169 are arch-shaped with their curved directions pointing towards the center of the reinforcing sheet 160.

6 is a schematic cross-sectional view illustrating a battery pack according to an embodiment of the present invention.

6, a battery pack 200A according to the present invention includes a battery cell stack body 210 in which three battery cells 100A, 100B, and 100C are stacked, and a battery cell stack body 210, And a pack case 220 which is formed of a metal plate.

The first reinforcing sheet 160 and the second reinforcing sheet 162 are attached to the outer surface of the battery case 140 on the upper and lower surfaces of the battery cells 100A, 100B, and 100C, respectively, The reinforcing film 170 is further provided on the outer surface of the first reinforcing sheet 160 of the battery cell 100A to prevent it from being penetrated by the outer conductor having a needle-like structure.

The reinforcing sheets 160 and 162 attached to the upper surface of the uppermost battery cell 100A and the lower surface of the lowermost battery cell 100C on the outer surface of the reinforcing sheets 160 and 162, (170, 172) are added.

On the other hand, only the reinforcing sheets 162, 163, 164, and 165 are attached to the upper surface of the uppermost battery cell 100A, the upper surface of the lowermost battery cell 100C, and the upper and lower surfaces of the middle battery cell 100B, have.

FIG. 7 is a schematic cross-sectional view showing that the battery pack of FIG. 6 is penetrated by the needle-shaped conductor.

7, the battery pack 200A is penetrated by the needle-shaped conductor 300. At this time, the reinforcing film 170 is inserted into the needle-shaped conductor 300 in the direction in which the needle- Respectively.

8 is a schematic cross-sectional view illustrating a battery pack according to another embodiment of the present invention, and FIG. 9 is a schematic cross-sectional view showing that the battery pack of FIG. 8 is penetrated by needle-like conductors .

8 and 9, the battery pack 200B is different from the battery pack 200A of FIG. 6 in that the reinforcing sheets 163 and 164 attached to the upper and lower surfaces of the middle cell 100B Reinforced films 172 and 174 are additionally provided on the outer surface to prevent penetration by the outer conductor of the needle-shaped structure.

Therefore, the battery pack 200B is penetrated by the needle-shaped conductor 300, and at this time, the reinforcing film 172 is varied in the advancing direction of the needle-shaped conductor 300 in the direction in which the needle-shaped conductor 300 penetrates.

As described above, when the reinforcing sheet is attached to at least a part of the outer surface of the battery case accommodating the electrode assembly, the battery cell according to the present invention can reinforce the strength of the battery case and increase resistance to internal explosion The battery cell according to the present invention can effectively prevent penetration of the reinforcement film by the outer needle-shaped conductor when the reinforcing film is further provided on the outer surface of the reinforcing sheet, which is the opposite surface of the battery cell, have.

Claims (12)

A battery cell in which an electrode assembly having a separator structure interposed between an anode and a cathode and between the anode and the cathode is embedded in a battery case,
Wherein at least a part of the outer surface of the battery case is provided with a reinforcing sheet to reinforce the strength of the battery case and increase the resistance against internal explosion. The battery cell according to claim 1, wherein the battery cell has a plate-like structure. The reinforcing sheet according to claim 1, wherein the reinforcing sheet is made of one or more materials selected from the group consisting of polycarbonate, polyimide, polyethylene terephthalate, and polypropylene Battery cell. The battery cell according to claim 1, further comprising a reinforcing film for preventing the outer surface of the reinforcing sheet, which is opposite to the surface of the battery cell, from being penetrated by the outer needle-shaped conductor. The battery cell according to claim 4, wherein the reinforcing film is at least one member selected from the group consisting of polyethylene, polyethylene terephthalate, polyurethane, and polyimide. The battery cell according to claim 4, wherein the reinforcing film is fixed to the outer surface of the reinforcing sheet in a non-adhered state. The battery cell according to claim 4, wherein the reinforcing film is varied in the direction of travel of the needle-like conductor when the needle-shaped conductor penetrates from the outside in the direction of penetrating the battery cell. The battery cell according to claim 4, wherein at least two or more linear notches are formed on an outer surface of the reinforcing sheet to insert and fix outer edges of the reinforcing film. The battery cell according to claim 8, wherein the line-shaped notch is an arch type in which the bent direction is directed toward the center of the reinforcing sheet. 10. A battery cell laminate comprising at least two battery cells according to any one of claims 1 to 9 deposited thereon; And
A pack case in which the battery cell stack is accommodated;
The battery pack comprising: 11. The battery pack according to claim 10, wherein a first reinforcing sheet and a second reinforcing sheet are attached to the upper surface and the lower surface of the battery case on the basis of the stacking direction of the battery cells, Wherein at least one outer surface of the battery pack is provided with a reinforcing film for preventing penetration by an external conductor of a needle-like structure. 11. The battery pack according to claim 10, wherein reinforcing sheets are attached to outer surfaces of the uppermost and lowermost battery cells of the uppermost battery cell with respect to the stacking direction of the battery cell stack, .

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