KR101539584B1 - Battery Module with Improved Safety - Google Patents

Abstract

A battery module including at least two battery cells, the battery module comprising: a battery cell stack body in which chargeable and dischargeable battery cells are stacked; And a member in which water and an endothermic inorganic material are sealed in a case, the at least one heat shield member being mounted in contact with the surface of the battery cell in the battery cell stack; The battery module includes a battery module.
Such a battery module prevents a rise in temperature beyond a certain temperature when the battery module passes through the surface of the battery module, slows down the voltage, and solves a safety problem such as ignition or explosion of the battery due to chemical reaction of the anode or cathode material by heat There is an effect.

Description

A battery module with improved safety {Battery Module with Improved Safety}

The present invention relates to a battery module including at least two battery cells, and more particularly, to a battery module including a battery cell stack body in which chargeable and dischargeable battery cells are stacked; And a member in which water and an endothermic inorganic material are sealed in a case, the at least one heat shield member being mounted in contact with the surface of the battery cell in the battery cell stack; And a battery module including the battery module.

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 an energy source for electric vehicles and hybrid electric vehicles, which are proposed to solve air pollution of existing gasoline vehicles and diesel vehicles using fossil fuels. Therefore, the application of the secondary battery is 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 the secondary battery are diversified, the type of the battery is also diversified to provide an appropriate output and capacity. In addition, there is a strong demand for miniaturization and weight reduction of cells applied to the field and products.

For example, a small mobile device such as a mobile phone, a PDA, a digital camera, a smart pad, a notebook computer, and the like is one or three small and lightweight battery cells per device corresponding to the tendency to miniaturize the products. On the other hand, a middle- or large-sized device such as an electric bicycle, an electric vehicle, a hybrid electric vehicle, etc., uses a battery module (also referred to as a "battery pack") in which a large number of battery cells are electrically connected, Since the size and weight of the battery module are directly related to the accommodating space and output of the middle- or large-sized device, manufacturers try to manufacture a battery module as small and light as possible.

In the conventional middle- or large-sized secondary battery module, a plurality of unit cells are mounted in a case (housing) of a predetermined size and are electrically connected to each other, and the voltage, current, And a circuit section for controlling the display section.

As described above, various types of secondary modules are being used in the field of medium to large-sized devices. Accordingly, various types of electric modules capable of providing electric capacity and output corresponding thereto have been demanded. Furthermore, The required capacity and output are also changed accordingly, so the design of the battery module must be changed.

On the other hand, safety is one of the most important issues in a secondary battery and a battery module including a plurality of the secondary battery. Particularly, since the battery modules of high power and large capacity are used in large-sized devices such as electric bicycles and electric vehicles, they are subjected to a variety of large external forces such as shocks and vibrations from the outside. Furthermore, a lithium secondary battery, which has been recently subjected to a great deal of interest and research as to the possibility of its use as a unit cell constituting a battery module, has a problem of low safety. Therefore, the safety problem of the battery module in which a large number of unit cells are concentrated may be more serious.

The safety problem of the battery module is largely caused by heat due to overcharging, internal short-circuiting of the module components due to external impact, and the like. In order to solve the problems of damage and heat generation of a unit cell due to overcharging, over-discharge, etc., a battery module generally includes a BMS (Battery Management System) capable of sensing current and voltage of a unit cell and a temperature of the battery system, And a circuit part. Therefore, when the overcurrent, overvoltage, overheat, or the like occurs, the current is cut off, thereby protecting the unit cell and securing the safety.

On the other hand, the problem of internal shorting due to external physical impact can vary greatly depending on the type of such external impact. For example, when the device on which the battery module is mounted is a transportation device such as an electric bicycle, an electric motorcycle, or an electric vehicle, the battery module may be detached and fall due to the collision of such device, or an external object may collide with the battery module May occur. A particularly serious situation is that a sharp member applied to the battery module penetrates the unit cell, and penetration of the needle-shaped conductor may cause explosion of the battery.

In such a case, when an object having electrical conductivity such as a nail penetrates the battery, electrochemical energy inside the battery is converted into thermal energy, and rapid heat generation occurs. As a result, the positive or negative electrode material is chemically reacted Which may lead to safety problems such as ignition and explosion of the battery. Such a safety problem may also occur when the battery is pressed against a heavy object, subjected to strong impact, or exposed to a high temperature. Such safety problems are becoming more serious as the capacity of lithium secondary batteries is increased and the energy density is increased.

The unit cell generally has a structure in which an electrode assembly in which a porous separator is interposed between a positive electrode and a negative electrode, in which an active material is applied to a current collector, is sealed in a battery case. Therefore, when the positive electrode active material and the negative electrode active material come into contact with each other due to the penetration of the sharp member, a high resistance heat is caused by the electric current passing through the contact resistance portion. Such high resistance heat raises the internal temperature of the battery. Generally, the active material used in the secondary battery has an ignition temperature of 400 ° C. If the internal temperature rises above a critical value, the oxide structure of the cathode active material is collapsed, causing thermal runaway phenomenon. Eventually, Lt; / RTI >

Therefore, it can be manufactured in a small size and light weight while providing high power, large capacity, and it is possible to more effectively cool the internal heat in the case of penetrating the sharp member so as to secure the safety, There is a high need for a battery module including a heat blocking member that can be provided.

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.

That is, it is an object of the present invention to provide a heat block member for preventing heat from being generated in the form of a pouch and to be inserted between the battery cells to prevent a rise in temperature beyond a predetermined temperature when passing through the surface of the battery module, The present invention provides a battery module capable of solving safety problems such as ignition and explosion of a battery by a chemical reaction of a positive electrode or a negative electrode material by heat.

It is still another object of the present invention to provide a battery pack including the above battery modules.

According to an aspect of the present invention, there is provided a battery module including at least two battery cells,

A battery cell laminate in which chargeable and dischargeable battery cells are stacked; And

1. A member in which water and an endothermic inorganic material are sealed in a case, comprising: at least one heat shielding member mounted in contact with a surface of the battery cell in the battery cell stack;

As shown in FIG.

That is, in order to prevent heat generation, the battery module according to the present invention includes a heat shielding member in which water and an endothermic inorganic material are sealed in a case, in a state where the heat shielding member is in contact with the surface of the battery cell in the battery cell stack, The heat generated on the surface of the battery cell is absorbed by the heat absorbing inorganic material inside the heat shielding member when the positive active material and the negative electrode active material come into contact with each other due to the penetration of the heat shielding member, It is constructed to prevent the temperature rise above a certain temperature by vaporizing water.

In one specific example, the battery cell may be a plate-shaped battery cell, and the plate-shaped battery cell may be a prismatic secondary battery or a pouch-type secondary battery.

In another specific example, the battery cell may be a lithium secondary battery.

As a concrete example, the case of the heat shielding member may be composed of a laminate sheet including a resin layer and a metal layer.

In another specific example, the case of the heat shielding member may be a pouch-shaped case of an aluminum laminate sheet.

The inventors of the present application have experimentally found that, in the case of using heat shielding members in which water and an endothermic inorganic material are sealed in a film made of only PP and polypropylene, in the case of a surface penetration test using a sharp member, The PP film is melted and penetrated by the heat so that the circular shape of the heat shielding member around the penetrating portion is largely retained, thereby deteriorating the heat absorbing efficiency of the heat absorbing inorganic material inside the heat shielding members, As shown in FIG.

On the other hand, in the case of the heat shielding member sealed with the pouch-shaped case of the aluminum laminate sheet as described above, it was confirmed that a large amount of water, which is judged as the main reaction in the endothermic process, is vaporized during the penetration test by the sharp member. Therefore, such a heat shielding member can provide an excellent cooling effect.

The endothermic inorganic material may be contained in an amount of 10 to 50% by weight based on the total weight of the heat shield member, and the endothermic inorganic material may be composed of SiO2, but is not limited thereto.

In order to meet the above objects and effects, the heat shielding member may be mounted so as to abut the inner or outer surface of the case of the battery cell.

In one specific example, the heat shielding member may be interposed at the interface between the battery cells.

In another specific example, the battery cells are enclosed in a cell cover in two or more units, and the heat blocking member may be interposed between the cell cover and the battery cell.

When the heat shielding member is interposed in the battery module as described above, since the heat shielding member cools the contact surface of the battery cells when the surface member is penetrated by the sharp member, the temperature rise exceeding a predetermined temperature is prevented, It is possible to solve the safety problem such as ignition and explosion of the battery by the chemical reaction of the positive electrode or the negative electrode material by heat.

The present invention also provides a battery pack including at least two battery modules, wherein the battery pack has a heat blocking member additionally mounted on at least one of an inner surface of the battery pack case and an outer surface of the battery pack case do.

Further, there is provided a device including the battery pack as a power source.

The device may comprise, for example, a power tool; An electric vehicle selected from the group consisting of Electric Vehicle (EV), Hybrid Electric Vehicle (HEV) and Plug-in Hybrid Electric Vehicle (PHEV); E-bike; E-scooter; Electric golf cart; And a power storage device, but the scope of application is not limited thereto.

As described above, in the battery module according to the present invention, the heat shielding member for preventing heat generation is manufactured in the form of a pouch and inserted between the battery cells, thereby preventing a rise in temperature beyond a predetermined temperature during penetration of the battery module, It is possible to solve the safety problem such as ignition and explosion of the battery due to the chemical reaction of the anode or the cathode material by heat by slowing down the voltage drop rate and even when using the module case of relatively weak strength, It is possible to provide a high degree of safety.

Accordingly, the battery module of the present invention can be variously applied to middle- or large-sized battery modules such as electric bicycles, electric vehicles, hybrid electric vehicles, and the like.

1 is a schematic view of a battery module in which eight heat blocking members are interposed according to another embodiment of the present invention;
FIG. 2 is a graph showing changes in temperature of the battery cell over time after penetration by the conductive object in Example 1; FIG.
3 is a graph showing a change in temperature of the battery cell over time after penetration by a conductive object in Comparative Example 1. FIG.

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.

1 is a schematic view of a battery module having a heat shielding member according to an embodiment of the present invention.

Although FIG. 1 schematically shows battery modules in which two battery cells are wrapped in a cell cover for convenience of explanation, a battery cell stack structure in which two or more chargeable and dischargeable battery cells are stacked Of course.

Referring to FIG. 1, a battery module 100 according to the present invention includes a battery cell stack in which two battery cells 121 and 122, which can be charged and discharged, are stacked, Unit cell module in which two battery cells 123, 124 capable of charging and discharging are stacked is enclosed by a cell cover 142, and the unit cell modules are electrically connected in series.

The battery cells 121, 122, 123, and 124 are plate-shaped battery cells, specifically, a prismatic secondary battery or a pouch-type secondary battery.

The heat shielding members 131, 132, 133 and 134 in which the water and the endothermic inorganic material are sealed in the case contact the contact surfaces of the cell covers 141 and 142 and the battery cells 121, Respectively.

The case of the heat shielding members 131, 132, 133, and 134 is a pouch-shaped case of an aluminum laminate sheet including a resin layer and a metal layer.

When the sharp member 150 passes through the unit cell module 100, the positive and negative electrode active materials in the battery cells 121, 122, 123, and 124 are brought into contact with each other, A high resistance heat is generated and the heat absorbing property in the heat blocking members 131, 132, 133, and 134 interposed between the cell covers 141 and 142 and the contact surfaces of the battery cells 121, 122, The heat generated on the surface of the battery cell by the inorganic material is absorbed and vaporizes the water, thereby cooling the battery cells 121, 122, 123, and 124.

2 is a schematic view of a battery module having a heat shielding member according to another embodiment of the present invention.

Referring to FIG. 2, a plurality of heat shielding members 131, 132, 133, 134, 135, 136, 137, and 138, in which water and an endothermic inorganic material are sealed in a case, 3 except that the battery cells 121, 122, 123, 124, 125, 126, 127, 128 are disposed on the contact surfaces of the battery cells 144, 144 and the plurality of battery cells 121, 122, 123, 124, 125, 126, 127, 128, .

Hereinafter, the content of the present invention will be described in detail by way of examples, but the scope of the present invention is not limited thereto.

[Example 1]

As shown in FIG. 2, the battery module was manufactured by interposing the eight heat shielding members on the contact surfaces of the cell cover and the battery cells. The heat shielding member was manufactured by sealing the water and the heat absorbing inorganic material with a pouch-shaped case of an aluminum laminate sheet, and the endothermic inorganic material was manufactured to include SiO 2 as 20 wt% based on the total weight of the heat shielding member.

The fabricated battery module was subjected to a surface penetration test using a nail as a conductive sharp member and the temperature change of the battery cells was measured with passage of time after passing through the surface. The results are shown in FIG.

[Comparative Example 1]

Except that the heat shielding member prepared by sealing the water and the endothermic inorganic material with the PP film was interposed between the battery cells, and the penetration test was carried out. As shown in FIG.

[Experimental Example 1]

The battery modules of Example 1 and Comparative Example 1 were forced to induce an internal short circuit, and the temperature inside the battery was measured and the change process was observed. As a result, as shown in FIG. 3 and FIG. 4, it can be seen that the battery cells of the battery module of Example 1 proceeded at a significantly lower temperature than the battery cells of the battery module of Comparative Example 1. The low rate of temperature rise in the cell of Example 1 was attributed to the fact that the water and the endothermic inorganic material adhered to the surface of the battery cell in the battery cell laminate were bonded to the heat shielding member sealed in the pouch-shaped case of the aluminum laminate sheet This is because a considerable amount of heat generated during the internal short circuit is absorbed.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (17)

A battery module comprising at least two battery cells,
A battery cell laminate in which chargeable and dischargeable battery cells are stacked; And
1. A member in which water and an endothermic inorganic material are sealed in a case, comprising: at least one heat shielding member mounted in contact with a surface of the battery cell in the battery cell stack;
Lt; / RTI >
The battery cell is a plate-shaped battery cell,
The plate-shaped battery cell is a pouch type secondary battery,
Wherein the case of the heat shielding member is a pouch-shaped case of an aluminum laminate sheet. delete delete The battery module according to claim 1, wherein the battery cell is a lithium secondary battery. delete delete The battery module according to claim 1, wherein the endothermic inorganic material is contained in an amount of 10 to 50% by weight based on the total weight of the heat shielding member. The battery module according to claim 1, wherein the endothermic inorganic material is SiO2. The battery module according to claim 1, wherein the heat shield member is mounted so as to abut the inner or outer surface of the case of the battery cell. The battery module according to claim 1, wherein the heat shielding member is interposed between the battery cells. The battery module according to claim 1, wherein the battery cells are wrapped around a cell cover in two or more units. The battery module according to claim 11, wherein the heat shielding member is disposed on a contact surface between the cell cover and the battery cell. 12. A battery pack comprising the battery module according to any one of claims 1, 4, and 12. The battery pack according to claim 13, wherein a heat blocking member is additionally attached to at least one of an inner surface of the battery pack outer casing and an outer surface of the outer casing of the battery pack. 15. The battery pack according to claim 14, wherein the heat shielding member case comprises a laminate sheet including a resin layer and a metal layer. A device as claimed in claim 13 comprising a battery pack as a power source. 17. The apparatus of claim 16, wherein the device comprises: a power tool; An electric vehicle selected from the group consisting of Electric Vehicle (EV), Hybrid Electric Vehicle (HEV) and Plug-in Hybrid Electric Vehicle (PHEV); E-bike; E-scooter; Electric golf cart; And a power storage device.

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