Battery pack

The present application discloses a battery pack including a first battery and a second battery arranged in a stack, the second battery being closer to a center of the battery pack than the first battery in a stacking direction of the first battery and the second battery, wherein the first battery includes a first thermally conductive component and a first electrode assembly, the second battery includes a second thermally conductive component and a second electrode assembly, and a thermal conductivity of the second thermally conductive component is not lower than that of the first thermally conductive component. The battery pack provided by the present application may achieve temperature uniformity while keeping the overall temperature of the battery pack low.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Chinese Patent Application No. 201920175872.X, filed on Jan. 31, 2019, the content of which is incorporated herein by reference in its entirety.

FIELD

The present application relates to the technical field of battery, in particular, to a battery pack.

BACKGROUND

A battery pack generally includes a plurality of electrode assemblies connected together, the temperatures of the electrode assemblies in different locations of the battery pack are different. This is because the electrode assembly at the edge position generates heat accumulation for the electrode assembly at the intermediate position, and the electrode assembly at the intermediate position has a longer heat transfer path than the electrode assembly at the edge position, so that the heat dissipation boundary condition is also worse. In liquid cooling, the accumulation of heat can be avoided by liquid flow control or piping arrangement at different locations. However, for the condition of natural heat dissipation, limited by the unity of the heat dissipation means, an effective method for the temperature uniformity of the battery pack has not been proposed yet.

At present, it is common practice to uniformly apply heat-dissipating aluminum sheets to all the surface of the electrode assemblies in the battery pack to transfer heat to a housing of the battery pack. However, the problem of this method is that the electrode assembly in the middle position of the battery pack also has a phenomenon of heat accumulation, so that the problem of large temperature difference of the electrode assemblies at different positions cannot be completely solved. For a battery pack having more than 10 electrode assemblies arranged side by side, when discharging at a high rate, the temperature difference between the electrode assemblies easily exceeds 5° C., which seriously affects the life of the battery pack.

Another way to solve the problem of large temperature difference between electrode assemblies in different positions is to use insulation measures to deteriorate the heat dissipation conditions of the electrode assemblies at the edge positions. However, this method will increase the overall temperature of the battery pack, and although the temperature uniformity is improved to some extent, it also brings about a problem that the temperature rise of the battery pack is large, which also causes a loss of the life of the battery pack.

SUMMARY

For the above problems in the related art, a battery pack is provided by the present application, which may achieve temperature uniformity while keeping the overall temperature.

According to one aspect of present application, a battery pack is provided, including a first battery and a second battery arranged in a stack, the second battery being closer to a center of the battery pack than the first battery in a stacking direction of the first battery and the second battery; wherein the first battery includes a first thermally conductive component and a first electrode assembly, the second battery includes a second thermally conductive component and a second electrode assembly, and a thermal conductivity of the second thermally conductive component is not lower than that of the first thermally conductive component.

By differential design for heat dissipation through a second battery near a center of the battery pack and a first battery away from the center, the above technical solution of the present application reduces the electrode assembly temperature at the center where heat is accumulated. Therefore, it is possible to achieve uniform temperature between the individual electrode assemblies in the battery pack while keeping the overall temperature of the battery pack low.

DETAILED DESCRIPTION

The technical schemes of the embodiments of the present disclosure will be clearly and completely described in the following with reference to the accompanying drawings. It is obvious that the embodiments to be described are only a part rather than all of the embodiments of the present disclosure. All other embodiments obtained by persons skilled in the art based on the embodiments of the present disclosure without creative efforts shall fall within the protection scope of the present disclosure. It should be understood that the respective exemplary embodiments in the following description and in the drawings may be combined with each other to form other embodiments not described below; and some of the components may be omitted in different embodiments. In other words, the following description does not limit the present application.

A battery pack according to an embodiment of the present application includes a first battery and a second battery, and the first battery and the second battery are stacked. In a stacking direction of the first battery and the second battery, the second battery is closer to a center of the battery pack than the first battery. The first battery includes a first thermally conductive component and a first electrode assembly, the second battery includes a second thermally conductive component and a second electrode assembly, and a thermal conductivity of the second thermally conductive component of the second battery is not lower than that of the first thermally conductive component of the first battery. By differential design for heat dissipation through a second battery near a center of the battery pack and a first battery away from the center, the above technical solution of the present application reduces the electrode assembly temperature at the center where heat is accumulated. Therefore, it is possible to achieve uniform temperature between the individual electrode assemblies in the battery pack while keeping the overall temperature of the battery pack low.

With reference toFIG. 1, an exploded view of the battery pack according to a first embodiment of the present application is shown. The battery pack100includes a first battery10and a second battery20, and the first battery10and the second battery20are stacked. In a stacking direction of the first battery10and the second battery20, the second battery20is closer to a center of the battery pack100than the first battery10. The first battery10includes a first thermally conductive component12and a first electrode assembly14, and the second battery20includes a second thermally conductive component22and a second electrode assembly24. The first thermally conductive component12includes a first heat sink122and the second thermally conductive component22includes a second heat sink222. Specifically, the first battery10includes a plurality of first heat sinks122and a plurality of first electrode assemblies14, and at least one surface of each of the first electrode assemblies14is provided with the first heat sink122. The second battery20includes a plurality of second heat sinks222and a plurality of second electrode assemblies24, and at least one surface of each of the second electrode assemblies24is provided with the second heat sink222. The structure and size of the first heat sink122and the second heat sink222may be the same. The number of the first battery10may be plural, and the number of the second battery20may be plural. It should be understood that the number of the first electrode assembly14and the second electrode assembly24shown inFIG. 1is merely exemplary, and the first electrode assembly14and the second electrode assembly24may be any other suitable number. The number of the first battery10and the second battery20shown inFIG. 1is merely exemplary, and the first battery10and the second battery20may also be any other suitable number. In an embodiment, the number of the first battery10may be different from the number of the second battery20. In another embodiment, the number of the first battery10may be the same as the number of the second battery20. Among them, the first electrode assembly14and the second electrode assembly24may be soft-pack batteries or square-shell batteries, which is not limited in this application.

In an embodiment, the thermal conductivity of the second thermally conductive component22of the second battery20is not lower than that of the first thermally conductive component12of the first battery10. The difference between the thermal conductivity of the second thermally conductive component22and the thermal conductivity of the first thermally conductive component12is not less than 90% of the thermal conductivity of the first thermally conductive component12.

It should be noted that the thermal conductivity of the first thermally conductive component and the second thermally conductive component may be tested according to the simulation data or the test data, so that the second electrode assembly near the center of the battery pack has the same heat dissipation efficiency as the first electrode assembly away from the center. Specifically, the heat dissipation efficiency11may be calculated by the following formula:
η=ΔT/q;

That is, the heat dissipation efficiency may be expressed as a ratio of the temperature rise of the heat source to the heat generation power of the heat source. Among them, ΔT represents the temperature rise of the heat source relative to the ambient temperature, in ° C.; q represents the heat production power of the heat source in W, which is used to characterize how much heat is generated by the heat source per unit time. When testing the heat dissipation efficiency of the first electrode assembly14and the second electrode assembly24, it is assumed that the consistency of the first electrode assembly14and the second electrode assembly24is good, that is, the heat generation powers of the first electrode assembly14and the second electrode assembly24are the same, and comparing the heat dissipation efficiencies of the first electrode assembly14and the second electrode assembly24is to compare the temperature rise values of the first electrode assembly14and the second electrode assembly24. When the temperature rise of the first electrode assembly14and the second electrode assembly24under the respective heat dissipation conditions is the same, it may be considered that the heat dissipation efficiency of the two is the same.

With continued reference toFIG. 1, the battery pack100further includes a buffer plate30, and the buffer plate30is located between the first battery10and the second battery20. In an embodiment, the buffer plate30may also be located between a plurality of first batteries10. The buffer plate30may be a material having a cushioning effect such as foam. By providing the buffer plate30, it is possible to reserve an expansion space for the first battery and the second battery while alleviating the problem of heat concentration of the second electrode assembly close to the center of the battery pack.

Further, with reference toFIG. 2, a thermally conductive plate40is also disposed between the adjacent two second electrode assemblies24. In an embodiment, the thermally conductive plate40may be a metal plate. Optionally, the metal plate may be an aluminum plate. In an embodiment, the thermally conductive plate40may be a solid phase change plate. The solid phase change plate is a phase change material which is in a solid state when a phase transition occurs and whose original form is a sheet shape. In an embodiment, the thermally conductive plate40may be a thermally conductive gasket. Optionally, the thermally conductive gasket may be a thermally conductive gasket containing silicone. By providing the thermally conductive plate40between the second electrode assemblies24, the heat dissipation efficiency of the second electrode assemblies24close to the center of the battery pack may be enhanced, so that the temperature of the second electrode assembly24in which heat is accumulated is lowered. Therefore, it is possible to achieve uniform temperature between the individual electrode assemblies in the battery pack while keeping the overall temperature of the battery pack low. A thickness of the thermally conductive plate may be based on simulation or test data such that the heat dissipation efficiency of the second electrode assembly24close to the center of the battery pack is about the same as the heat dissipation efficiency of the first electrode assembly14in the edge region.

In addition, the buffer plate30may also be located between the adjacent two second batteries20. It should be understood that any suitable configuration of the arrangement of the thermally conductive plate40between the plurality of second electrode assemblies20may be performed, or any arrangement of the buffer plate30between the plurality of first batteries and the plurality of second batteries may be randomly and appropriately configured, and the present application is not limited thereto.

Referring toFIG. 3, the thermally conductive plate40and the second heat sink222are respectively located on opposite sides of the second electrode assembly24. The second heat sink222may be bonded to a surface26of the second electrode assembly24. The thermally conductive plate40contacts a first surface28of the second electrode assembly24, and a contact area of the thermally conductive plate40and the second electrode assembly24may be greater than or equal to 90% of the area of the first surface28, so as to ensure a sufficient heat dissipating area of the thermally conductive plate.

The thermally conductive plate40and the second electrode assembly24may be bonded and fixed by a thermally conductive adhesive. That is to say, the second heat sink222may be bonded to a surface26of the second electrode assembly24by a thermally conductive adhesive. The thermally conductive adhesive may include a thermally conductive silica gel, one-component thermally conductive paste and two-component thermally conductive gel, and may be made of a silicone rubber-based material, and filled with a highly thermally conductive metal oxide or other highly thermally conductive particles in the silicone rubber to simultaneously obtain the elasticity of the silicone rubber and the thermal conductivity of the filled particles. A thickness profile of the thermally conductive adhesive may be suitably configured to achieve sufficient bond strength while minimizing the thermal resistance of the thermally conductive adhesive. In an embodiment, a thickness of the thermally conductive adhesive is greater than 20 μm and less than 60 μm, for example 40 μm.

As shown inFIG. 4, the second heat sink222is configured in a U shape such that the second heat sink222may be located on three surfaces of the second electrode assembly24. The structure of the second heat sink222may be designed such that the second heat sink222may be located on at least two surfaces of the second electrode assembly24, such as on two or three surfaces of the second electrode assembly24. In this way, a sufficient heat dissipation area of the second heat sink222may be ensured.

As shown inFIG. 5, the first heat sinks122are bonded to a surface16of the first electrode assembly14. The first heat sink122may be bonded to a surface16of the first electrode assembly14by a thermally conductive adhesive. Similar to the second heat sink222, in an embodiment, the first heat sink122may have a structure as shown inFIG. 4. In some embodiments, the first heat sink122may be located on at least two surfaces of the first electrode assembly14.

With reference toFIG. 6, an exploded view of the battery pack according to a second embodiment of the present application is shown. The battery pack200includes a first battery10and a second battery20, and the first battery10and the second battery20are stacked. In a stacking direction of the first battery10and the second battery20, the second battery20is closer to a center of the battery pack200than the first battery10. The first battery10includes a first thermally conductive component12and a first electrode assembly14, and the second battery20includes a second thermally conductive component22and a second electrode assembly24. The first thermally conductive component12includes a first heat sink122and the second thermally conductive component22includes a second heat sink222. The first battery10includes a plurality of first heat sinks122and a plurality of first electrode assemblies14, and at least one surface of each of the first electrode assemblies14is provided with the first heat sink122. The second battery20includes a plurality of second heat sinks222and a plurality of second electrode assemblies24, and at least one surface of each of the second electrode assemblies24is provided with the second heat sink222. The battery pack200further includes a buffer plate30, and the buffer plate30may be located between the first battery10and the second battery20. The buffer plate30may also be located between the adjacent two second batteries20.

A thermal conductivity of the second heat sink222is better than that of the first heat sink122. The second heat sink222may have a thermal conductivity superior to that of the first heat sink122by a variety of implementable methods. Thus, the heat dissipation efficiency of the second electrode assemblies24close to the center of the battery pack may be enhanced, so that the temperature of the second electrode assembly in which heat is accumulated is lowered. Therefore, it is possible to achieve uniform temperature between the individual electrode assemblies in the battery pack while keeping the overall temperature of the battery pack low.

As shown inFIGS. 7A and 7B, the second heat sink222may be the same material as the first heat sink122, and the second heat sink222has a thickness H2while the first heat sink122having a thickness H1, the thickness H2of the second heat sink222is greater than the thickness H1of the first heat sink122. The thickness H1of the first heat sink122may be 0.2 mm-0.5 mm, and the thickness H2of the second heat sink222may be 0.4 mm-1.0 mm. In an embodiment, the thickness H1of the first heat sink122is 0.2 mm, and the thickness H2of the second heat sink222is 0.5 mm. In another embodiment, the thickness H1of the first heat sink122is 0.4 mm, and the thickness H2of the second heat sink222is 0.8 mm. Other suitable designs may be made for the thickness H1of the first heat sink122and the thickness H2of the second heat sink222according to the temperature rise simulation data and the test data. By differentiated design for the thicknesses of the first heat sink122and the second heat sink222, the thickness H2of the second heat sink222is greater than the thickness H1of the first heat sink122, so that the heat dissipation effect of the second electrode assembly close to the center of the battery pack is enhanced, thereby achieving uniform temperature between the respective electrode assemblies in the battery pack.

Other aspects of the battery pack200of the second embodiment may be similar to the battery pack100of the first embodiment, and are not described herein again.

With reference toFIG. 8, a schematic structural view of the battery pack according to an embodiment of the present application is shown. A top of the plurality of first batteries10and second batteries20of the battery pack300are provided with an adapter plate50. A buffer layer60is disposed between the adapter plate50and a plurality of first battery10and the second battery20, and the buffer layer60may be a material such as foam, the buffer layer60serving as a support for the adapter plate50and acting as an insulator between a plurality of electrode assemblies.

In addition, the battery pack300may further include a housing connected to the first heat sink122and the second heat sink222, and the housing may be a metal housing. A pressure may be applied between the housing and the plurality of first batteries10and the second batteries20by screws, so that the first heat sink122may be contact with an inner surface of the housing tightly. In an embodiment, a thermally conductive material may be filled between the first heat sink122and the second heat sink222and the housing.

The foregoing is only preferred exemplary embodiments of the present application and is not intended to be limiting of the present application, and any modifications, equivalent substitutions, improvements and the like within the spirit and principles of the present application are intended to be embraced by the protection range of the present application.