Patent Description:
The present invention relates to a battery module including a thermal insulation member having a composite structure capable of, even when thermal runaway occurs in a battery cell, preventing heat transfer to an adjacent battery cell.

With technological development of mobile devices, such as smartphones, laptop computers, and digital cameras, and an increase in demand therefor, research on secondary batteries, which are capable of being charged and discharged, has been actively conducted. In addition, secondary batteries, which are energy sources substituting for fossil fuels causing air pollution, have been applied to an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (P-HEV), and an energy storage system (ESS).

There are a lithium ion battery, a lithium polymer battery, a nickel-cadmium battery, a nickel-hydride battery, and a nickel-zinc battery as secondary batteries that are widely used at present. The operating voltage of a unit secondary battery cell, i.e. a unit battery cell, is about <NUM>. 0V to <NUM>. In the case in which output voltage higher than the above operating voltage is required, therefore, a plurality of battery cells may be connected to each other in series to constitute a battery cell assembly. In addition, battery cell assemblies may be connected to each other in series or in parallel to constitute a battery module depending on required output voltage or charge and discharge capacities. In general, a battery pack is manufactured using at least one battery module by adding an additional component.

The battery module is manufactured so as to have a structure in which the battery cells are disposed densely in the case in order to increase energy density thereof. When thermal runaway occurs in a specific battery cell, therefore, heat may be transferred to battery cells adjacent thereto.

Meanwhile, conventionally, a thermal insulation material is provided between battery cells in order to prevent heat transfer between the battery cells and to prevent direct contact between the battery cells.

In the case in which the conventional thermal insulation material performs, for example, the function of a heat absorbing material having physical properties changed by heat generated when thermal runaway occurs in a battery cell, however, it is not possible to support battery cells and to interrupt heat transfer between the battery cells after thermal runaway occurs.

In addition, a conventional thermal insulation material having a shape remaining unchanged after thermal runaway occurs is disposed in tight contact with a battery cell in which thermal runaway occurs. As a result, it is difficult to discharge heat generated from the battery cell, whereby the battery cell is maintained in a high temperature state, and therefore heat may be transferred to battery cells adjacent thereto at a specific point in time.

Further examples and embodiments of prior art may be found in <CIT>, <CIT>, <CIT>, and <CIT>.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a battery module including a thermal insulation member having a composite structure capable of, even when thermal runaway occurs in a battery cell, preventing heat transfer to an adjacent battery cell and cooling the battery cell in which thermal runaway occurs.

In order to accomplish the above object, a battery module according to the present invention includes a plurality of battery cells, each battery cell of the plurality of battery cells having electrode leads, a case configured to receive the plurality of battery cells, and a thermal insulation member located between the plurality of battery cells, the thermal insulation member being configured to interrupt heat transfer between adjacent ones of the plurality of battery cells, wherein the thermal insulation member has a composite structure including an outer portion made of plastic having a lower melting point than temperature when thermal runaway occurs, in such a way that the plastic melts when thermal runaway occurs, and a support member provided in an inner portion of the thermal insulation member, the support member being made of a heat-resistant material having a higher melting point than the temperature when the thermal runaway occurs, wherein a shape of the support member is maintained even when the thermal runaway occurs to form an air layer between the plurality of battery cells, wherein the support member is made of high heat-resistant polyamide-based plastic.

Also, in the battery module according to the present invention, each of the plurality of battery cells may be a pouch-shaped battery cell having a structure in which two electrode leads, i.e. a positive electrode lead and a negative electrode lead, protrude in opposite directions.

Also, in the battery module according to the present invention, the case may include a lower case configured to receive the plurality of battery cells and the thermal insulation member and a cover located at the upper part of the lower case.

Also, the battery module according to the present invention may further include a busbar configured to electrically connect the electrode leads to each other.

Also, in the battery module according to the present invention, the thermal insulation member may be further provided between one of the plurality of battery cells and the case.

Also, in the battery module according to the present invention, the support member may have a plurality of protrusions formed on opposite surfaces of a thin plate.

Also, in the battery module according to the present invention, the support member may have rings which are joined to each other.

In addition, a battery pack according to the present invention includes a battery module according to the present invention.

In addition, a device according to the present invention includes a battery pack according to the present invention.

A battery module according to the present invention has an advantage in that the battery module includes a thermal insulation member having a composite structure in which, when thermal runaway occurs in a battery cell, only a support member provided in the thermal insulation member remains unchanged to form an air layer between battery cells, whereby it is possible to maximize heat insulation and cooling effects while maintaining the distance between the battery cell in which thermal runaway occurs and battery cells adjacent thereto.

Hereinafter, a battery module according to the present invention will be described with reference to the accompanying drawings.

<FIG> is an exploded perspective view of a battery module according to an embodiment of the present invention.

When describing the battery module <NUM> according to the present invention in detail with reference to <FIG>, the battery module <NUM> includes a plurality of battery cells <NUM>, each of which has electrode leads, a case <NUM> configured to receive the battery cells <NUM>, and a thermal insulation member <NUM> located between the battery cells <NUM>.

Here, each of the battery cells <NUM> may be a cylindrical battery cell, a prismatic battery cell, or a pouch-shaped battery cell. Hereinafter, the battery module <NUM> according to the present invention will be described with the focus on that the battery cell is a pouch-shaped battery cell <NUM>.

The pouch-shaped battery cell <NUM> includes a battery case having an electrode assembly received therein and a pair of electrode leads.

Here, the electrode assembly may be a jelly-roll type assembly, which is configured to have a structure in which a long sheet type positive electrode and a long sheet type negative electrode are wound in the state in which a separator is interposed therebetween, a stacked type electrode assembly, which is configured to have a structure in which a rectangular positive electrode and a rectangular negative electrode are stacked in the state in which a separator is interposed therebetween, a stacked and folded type assembly, which is configured to have a structure in which unit cells are wound using a long separation film, or a laminated and stacked type assembly, which is configured to have a structure in which unit cells are stacked in the state in which a separator is interposed therebetween and are then attached to each other. However, the present invention is not limited thereto.

In addition, a solid electrolyte or a quasi-solid electrolyte manufactured by adding an additive to the solid electrolyte, i.e. a gel-type electrolyte having an intermediate form between liquid and solid, may be used as an electrolyte, in addition to a liquid electrolyte, which is commonly used.

The electrode assembly is received in the battery case, and the battery case is generally configured to have a laminate sheet structure including an inner layer, a metal layer, and an outer layer. The inner layer is disposed in direct contact with the electrode assembly, and therefore the inner layer must exhibit high insulation properties and high resistance to an electrolytic solution. In addition, the inner layer must exhibit high sealability in order to hermetically seal the battery case from the outside, i.e. a thermally-bonded sealed portion between inner layers must exhibit excellent thermal bonding strength.

The inner layer may be made of a material selected from among a polyolefin-based resin, such as polypropylene, polyethylene, polyethylene acrylate, or polybutylene, a polyurethane resin, and a polyimide resin, which exhibit excellent chemical resistance and high sealability. However, the present invention is not limited thereto, and polypropylene, which exhibits excellent mechanical-physical properties, such as tensile strength, rigidity, surface hardness, and impact resistance strength, and excellent chemical resistance, is the most preferably used.

The metal layer, which is disposed so as to abut the inner layer, corresponds to a barrier layer configured to prevent moisture or various kinds of gas from permeating into the battery from the outside. An aluminum thin film, which is light and easily shapeable, may be used as a preferred material for the metal layer.

The outer layer is provided on the other surface of the metal layer. The outer layer may be made of a heat-resistant polymer that exhibits excellent tensile strength, resistance to moisture permeation, and resistance to air permeation such that the outer layer exhibits high heat resistance and chemical resistance while protecting the electrode assembly. As an example, the outer layer may be made of nylon or polyethylene terephthalate. However, the present invention is not limited thereto.

Meanwhile, the pair of electrode leads <NUM> is constituted by a positive electrode lead and a negative electrode lead, which may be exposed from the battery case in a state of being electrically connected respectively to positive electrode tabs and negative electrode tabs of the electrode assembly or may be directly connected to the electrode assembly in the state in which tabs are omitted.

In addition, the pouch-shaped battery cell <NUM> may be a unidirectional lead cell having a structure in which the electrode leads <NUM>, i.e., the positive electrode lead and the negative electrode lead, protrude in the same direction or a bidirectional lead cell having a structure in which the positive electrode lead and the negative electrode lead protrude in opposite directions.

In particular, the following description will be given with the focus on that the battery cell <NUM> according to the present invention is a pouch-shaped battery cell <NUM> having the structure of a bidirectional lead cell <NUM>.

The bidirectional lead cell <NUM> is generally longer in a direction in which the leads protrude than the unidirectional lead cell, and a member configured to support the battery cell <NUM> when the battery cell is received in the module is necessary due to the increased length thereof.

The case <NUM> includes a lower case <NUM> configured to receive the battery cells <NUM> and the thermal insulation member <NUM> and a cover <NUM> located at the upper part of the lower case <NUM>, the cover being configured to cover the upper part of the lower case after the battery cells <NUM> and the thermal insulation member <NUM> are received in the lower case.

In addition, the battery module <NUM> according to the present invention may further include various other components, such as a busbar configured to electrically connect the electrode leads to each other and a sensing board configured to sense voltage information of the battery cells.

Meanwhile, <FIG> is a plan view showing a thermal insulation member located between the battery cells in the battery module according to the embodiment of the present invention, and <FIG> is a plan view showing a thermal insulation member located between the battery cell and the case in the battery module according to the embodiment of the present invention.

When describing the position at which the thermal insulation member <NUM> is provided in the battery module <NUM> with reference to <FIG> and <FIG>, the thermal insulation member <NUM> may be located between one of the battery cells <NUM> and another battery cell <NUM>, or may be located between one of the battery cells <NUM> and another battery cell <NUM> and between each of the outermost battery cells <NUM> and a corresponding one of the side surfaces of the lower case <NUM>, in which the battery cells are received.

Since the thermal insulation member is located as described above, the thermal insulation member <NUM> may serve to insulate the battery cells <NUM> from each other while supporting the battery cells at a normal temperature, and may serve to prevent heat transfer between the battery cells <NUM> when thermal runaway occurs in any one of the battery cells.

Meanwhile, although the shape of the thermal insulation member <NUM> is not particularly restricted, it is preferable for the thermal insulation member <NUM> to be formed so as to be disposed in tight contact with the side surface of the battery cell <NUM> that abut the thermal insulation member in consideration of energy density of the battery module <NUM>.

Also, in the present invention, the area of the side surface of the thermal insulation member <NUM> is shown as being equal to the area of the side surface of the portion of the battery cell <NUM> in which the electrode is received. However, the area of the side surface of the thermal insulation member <NUM> is not limited thereto and may be variously selected within a range in which the thermal insulation member <NUM> is capable of performing the function described in the present invention and the thermal insulation member does not interfere with other components of the battery module <NUM>.

<FIG> is a front view showing shapes of a thermal insulation member according to an embodiment of the present invention before and after thermal runaway, and <FIG> is a perspective view showing various shapes of a support member according to an embodiment of the present invention.

When describing the structure of the thermal insulation member <NUM> according to the present invention and the behavior of the thermal insulation member when thermal runaway occurs in detail with reference to <FIG>, the thermal insulation member <NUM> is configured to have a composite structure including an outer portion made of plastic having a lower melting point than temperature when thermal runaway occurs and a support member <NUM> provided in an inner portion of the thermal insulation member, the support member being made of a heat-resistant material having a higher melting point than temperature when thermal runaway occurs.

Meanwhile, although <FIG> shows a structure in which protrusions are formed on a thin plate, a structure in which thin bands each having a predetermined width are connected to each other in ring shapes, or a structure in which thin bands each having a predetermined width are connected to each other in quadrangular shapes as an example of the shape of the support member <NUM>, the support member <NUM> may be formed so as to have various shapes as long as the area of contact between the support member and the battery cell <NUM> is as small as possible within a range capable of supporting the battery cells <NUM>.

When the area of contact between the support member <NUM> and the battery cell <NUM> is increased, a possibility of heat transfer to an adjacent battery cell <NUM> via the support member <NUM> is increased. Consequently, the structure in which the area of contact between the support member <NUM> and the battery cell <NUM> is as small as possible is advantageous in the aspect of thermal insulation.

According to the invention the support member is made of high heat-resistant plastic, as a heat-resistant material having a higher melting point than temperature when thermal runaway occurs. In consideration of ease and cost in manufacture of the support member <NUM> and the thermal insulation member <NUM> including the support member <NUM>, the support member is made, according to the invention, of high heat-resistant polyamide-based plastic.

When the temperature of the battery cell <NUM> is normal, plastic constituting the outer portion of the thermal insulation member <NUM> having the support member <NUM> therein remains unchanged, whereby the thermal insulation member is disposed in tight contact with the battery cell <NUM> adjacent thereto over a large area. When thermal runaway occurs, however, plastic constituting the outer portion of the thermal insulation member melts, whereby only the support member <NUM> provided in the thermal insulation member is left to support the battery cell <NUM> adjacent thereto over the minimum area.

As a result, an air layer is formed between the battery cells <NUM> or between the battery cell <NUM> and the case <NUM>, whereby thermal insulation performance may be improved. In addition, heat generated as the result of thermal runaway is discharged to the outside through convection in the air layer, whereby the function of cooling the battery cell <NUM> in which thermal runaway occurs may also be performed at the same time.

Claim 1:
A battery module (<NUM>) capable of, when thermal runaway occurs in a battery cell (<NUM>), preventing heat transfer to an adjacent battery cell (<NUM>), the battery module (<NUM>) comprising:
a plurality of battery cells (<NUM>), each battery cell of the plurality of battery cells having electrode leads (<NUM>) ;
a case (<NUM>) configured to receive the plurality of battery cells (<NUM>); and
a thermal insulation member (<NUM>) located between the plurality of battery cells (<NUM>), the thermal insulation member being configured to interrupt heat transfer between adjacent ones of the plurality of battery cells (<NUM>),
wherein the thermal insulation member (<NUM>) has a composite structure comprising an outer portion made of plastic having a lower melting point than a temperature when the thermal runaway occurs, in such a way that the plastic melts when thermal runaway occurs, and a support member (<NUM>) provided in an inner portion of the thermal insulation member, the support member being made of a heat-resistant material having a higher melting point than the temperature when the thermal runaway occurs,
wherein a shape of the support member (<NUM>) is maintained even when the thermal runaway occurs to form an air layer between the plurality of battery cells (<NUM>),
characterized in that the support member (<NUM>) is made of heat-resistant polyamide-based plastic.