WO2024021248A1

WO2024021248A1 - Battery cell, battery and electric device

Info

Publication number: WO2024021248A1
Application number: PCT/CN2022/118501
Authority: WO
Inventors: 范国凌; 杜鑫鑫; 任莹莹; 薛凯元
Original assignee: 宁德时代新能源科技股份有限公司
Priority date: 2022-07-27
Filing date: 2022-09-13
Publication date: 2024-02-01
Also published as: CN117941126A; CN217562707U

Abstract

Disclosed in the embodiments of the present application are a battery cell, a battery and an electric device. The battery cell comprises: a shell; an electrolyte; an electrode assembly, the electrode assembly and the electrolyte being accommodated in the shell; and a buffer member, which is accommodated in the shell and is connected to the electrode assembly, a cavity being provided inside the buffer member and being isolated from the electrolyte, and the buffer member being configured to buffer the swelling of the electrode assembly. By means of the technical solution of the present application, the performance of the battery can be improved.

Description

Battery cells, batteries and electrical equipment

Cross-references to related applications

This application claims priority to Chinese patent application 202221954778.2 titled "Battery Cells, Batteries and Electrical Equipment" submitted on July 27, 2022. The entire content of this application is incorporated herein by reference.

Technical field

The present application relates to the field of battery technology, and more specifically, to a battery cell, a battery and electrical equipment.

Background technique

Energy conservation and emission reduction are the key to the sustainable development of the automobile industry. In this case, electric vehicles have become an important part of the sustainable development of the automobile industry due to their energy-saving and environmentally friendly advantages. For electric vehicles, battery technology is an important factor related to their development.

The space utilization, safety performance, strength, and long-term charge and discharge performance of the battery cells are crucial to the performance of the battery. Therefore, how to improve battery performance is an urgent problem that needs to be solved.

Contents of the invention

Embodiments of the present application provide a battery cell, a battery and electrical equipment, which can improve the performance of the battery.

In a first aspect, embodiments of the present application provide a battery cell, including: a casing; an electrolyte; an electrode assembly, the electrode assembly and the electrolyte are accommodated in the casing; and a buffer member, the buffer member is accommodated in the The outer casing is connected to the electrode assembly. A cavity is provided inside the buffer member. The cavity is isolated from the electrolyte. The buffer member is used to buffer the expansion of the electrode assembly.

In the embodiment of the present application, the battery cell includes a casing, an electrode assembly accommodated in the casing, an electrolyte and a buffer. The buffer member is accommodated in the housing and connected to the electrode assembly. The buffer member is used to buffer the expansion of the electrode assembly. Since the buffer members are arranged inside the battery cells, when the internal space of the battery is constant, the space of the buffer members originally provided between the battery cells in the battery can be transferred to the internal space of the battery cells, thereby improving the efficiency of the battery cells. Battery space utilization. A cavity is provided inside the buffer, and the cavity is isolated from the electrolyte. In this way, the cavity in the buffer can provide a space for the electrode assembly to deform, improve the weight energy density of the battery cell, and reduce the distance between the cavity and the electrode assembly or casing. temperature difference between. Therefore, the technical solutions of the embodiments of the present application can improve battery performance.

In one possible implementation, the cavity communicates with the outside of the housing. In this way, the cavity can conduct heat exchange with the outside of the shell, which is beneficial to reducing the temperature difference between the cavity and the outside of the shell.

In a possible implementation, the cavity is used to accommodate fluid to adjust the temperature of the battery cell. In this way, the fluid in the cavity can heat or cool the battery cells to reduce the temperature difference between the cavity and the exterior of the casing or the electrode assembly.

In a possible implementation, the buffer member is configured to adjust the thickness through pressure changes of the fluid in the cavity. In this implementation, on the one hand, the thickness of the cavity can be increased by increasing the pressure of the fluid, which is beneficial to reducing the gap between the electrode assembly and the housing or can make the electrode assembly contact the housing, thereby reducing the thermal resistance, Improve the heat dissipation efficiency of the battery cell; on the other hand, by adjusting the thickness of the cavity, the force exerted by the buffer member on the electrode assembly can be adjusted, so that the electrode assembly can be evenly stressed on both sides along the thickness direction of the buffer member. The expansion force of the electrode assembly can be released evenly, thereby reducing the accumulation of polarization of the electrode assembly, which is beneficial to improving the cycle life and safety performance of the battery cell.

In a possible implementation, an elastic support structure is provided in the cavity, and the elastic support structure is used to buffer the expansion of the electrode assembly. During the use of the battery cell, the arrangement of the elastic support structure is conducive to further improving the deformation ability of the buffer member and is conducive to providing more expansion space for the electrode assembly.

In a possible implementation, the elastic support structure is parallel to the thickness direction of the buffer member. In this way, the installation of the elastic support structure is facilitated.

In a possible implementation, the elastic support structure includes elastic support columns or elastic support plates. In this way, the elastic support structure has a simple structure and is easy to process.

In a possible implementation, the elastic support structure is a metal elastic support structure or a polymer elastic support structure. In this way, it is convenient to flexibly select the type of elastic support structure according to actual needs.

In a possible implementation, the housing includes a housing and an end cover, the housing has an opening and is used to accommodate the electrode assembly, and the end cover is used to cover the opening; wherein the buffer The surface of the component facing the end cap is provided with an inlet and outlet, and the cavity communicates with the outside of the housing through the inlet and outlet. In this way, the communication between the cavity of the buffer member and the outside of the housing is achieved through the arrangement of the inlet and outlet of the buffer member.

In a possible implementation, the end cover is provided with a connection port corresponding to the inlet and outlet, and the inlet and outlet communicates with the outside of the housing through the connection port. In this way, by arranging the connection port corresponding to the inlet and outlet on the end cover, there is no need to set up additional pipes to connect the inlet and outlet and the connection port. The battery cell has a simple structure and is easy to produce and assemble.

In a possible implementation, the inlet and outlet includes an inlet and an outlet. Fluid enters the cavity through the inlet and flows out of the cavity through the outlet. In this way, the arrangement of the inlet and outlet facilitates the circulation of fluid in the cavity and improves the efficiency of heat exchange.

In a possible implementation, along the thickness direction of the buffer member, the ratio of the size of the buffer member to the size of the battery cell is 1% to 20%. In this way, it is easy to balance the buffering effect of the buffer member and the space utilization of the battery cells.

In a possible implementation, the battery cell includes a plurality of electrode assemblies, and the buffer member is disposed between adjacent electrode assemblies. In this way, it is convenient to cool down or heat up the electrode assembly, and is beneficial to the temperature difference between the electrode assembly and the shell.

In a possible implementation, the buffer member is an aluminum buffer member, an aluminum alloy buffer member or a polymer buffer member. In this way, it is convenient to flexibly select the type of buffer according to actual needs.

In a possible implementation, the side surface of the electrode assembly includes a planar portion, and the buffer member is connected to the planar portion. In this way, the connection between the buffer member and the electrode assembly is facilitated.

In a possible implementation, the planar portion is a surface with the largest area of the electrode assembly. In this way, it is beneficial to realize the uniform release of the expansion force of the electrode assembly, and at the same time, it is beneficial to improve the heat exchange efficiency between the fluid in the cavity and the electrode assembly, and to improve the heat dissipation efficiency.

In a second aspect, embodiments of the present application provide a battery, including: the battery cell according to any one of the first aspect and its implementation; and a box, the box being used to accommodate the battery. monomer.

In a third aspect, embodiments of the present application provide an electrical device, including: the battery described in the second aspect, where the battery is used to provide electrical energy to the electrical device.

Description of drawings

In order to explain the technical solutions of the embodiments of the present application more clearly, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. Those of ordinary skill in the art can also obtain other drawings based on the drawings without exerting creative efforts.

Figure 1 is a schematic diagram of a vehicle according to an embodiment of the present application;

Figure 2 is a schematic diagram of a battery according to an embodiment of the present application;

Figure 3 is a schematic structural diagram of a battery cell according to an embodiment of the present application;

Figure 4 is a cross-sectional view of the battery cell in Figure 3 along the A-A direction;

Figure 5 is a schematic structural diagram of a buffer member according to an embodiment of the present application;

Figure 6 is a cross-sectional view of the buffer member in Figure 5 along the B-B direction;

Figure 7 is a cross-sectional view of the buffer member in Figure 5 along the C-C direction;

Figure 8 is a schematic structural diagram of an electrode assembly according to an embodiment of the present application.

Detailed ways

The embodiments of the present application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

In the description of this application, it should be noted that, unless otherwise stated, "plurality" means more than two; the terms "upper", "lower", "left", "right", "inside", " The orientation or positional relationship indicated such as "outside" is only for the convenience of describing the present application and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. Application restrictions. Furthermore, the terms "first," "second," "third," etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable error range. "Parallel" is not parallel in the strict sense, but within the allowable error range.

The directional words appearing in the following description are the directions shown in the figures and do not limit the specific structure of the present application. In the description of this application, it should also be noted that, unless otherwise clearly stated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection or a removable connection. Detachable connection, or integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in this application may be understood based on specific circumstances.

The term "and/or" in this application is just an association relationship describing related objects, indicating that there can be three relationships, for example, A and/or B, which can mean: A exists alone, A and B exist simultaneously, alone There are three situations B. In addition, the character "/" in this application generally indicates that the related objects are an "or" relationship.

In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of simplicity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length and width of the integrated device, are only illustrative illustrations and should not constitute any limitation to the present application. .

"Plural" appearing in this application means two or more (including two).

In this application, the battery cells may include lithium ion secondary batteries, lithium ion primary batteries, lithium-sulfur batteries, sodium lithium ion batteries, sodium ion batteries or magnesium ion batteries, etc., which are not limited in the embodiments of this application. The battery cells may be in the shape of a round body, a flat body, a rectangular parallelepiped or other shapes, and the embodiments of the present application are not limited to this. Battery cells are generally divided into three types according to packaging methods: cylindrical battery cells, square battery cells and soft-pack battery cells, and the embodiments of the present application are not limited to this.

The battery mentioned in the embodiments of this application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application may include a battery module or a battery pack. Batteries generally include a box for packaging one or more battery cells. The box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.

In order to meet different power requirements, the battery may include multiple battery cells, wherein the multiple battery cells may be connected in series, in parallel, or in mixed connection. Hybrid connection refers to a mixture of series and parallel connection. Alternatively, multiple battery cells can be connected in series, parallel, or mixed to form a battery module, and then multiple battery modules can be connected in series, parallel, or mixed to form a battery. In other words, multiple battery cells can directly form a battery, or they can first form a battery module, and then the battery module can form a battery. The battery is further installed in the electrical equipment to provide electrical energy to the electrical equipment.

The development of battery technology must consider multiple design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate, safety, etc. Buffers in batteries are usually arranged between battery cells to buffer the battery cells, but this arrangement is complicated to assemble and is not conducive to improving the internal space utilization of the battery. Placing buffers inside the battery cells can improve the above problems to a certain extent. However, during the use of the battery cells, more heat accumulates inside the battery cells. Conventional buffers have large thermal resistance and cannot be used. It is beneficial to the heat dissipation of the battery cell, resulting in a large temperature difference between the interior of the battery cell and the outer surface of the battery cell. On the one hand, the heat accumulated inside causes the temperature of the battery cell to rise, which is not conducive to improving the safety of the battery cell; on the other hand, the temperature difference between the inside of the battery cell and the outer surface of the battery cell is not conducive to the improvement of the battery cell. The choice of charging strategy affects charge and discharge performance. It can be seen that the internal settings of the battery cells are crucial to the performance of the battery. Therefore, how to provide a battery cell to improve battery performance is an urgent problem to be solved.

In view of this, embodiments of the present application provide a battery cell, which includes a casing, an electrode assembly accommodated in the casing, an electrolyte and a buffer. The buffer member is accommodated in the housing and connected to the electrode assembly. The buffer member is used to buffer the expansion of the electrode assembly. Since the buffer members are arranged inside the battery cells, when the internal space of the battery is constant, the space of the buffer members originally provided between the battery cells in the battery can be transferred to the internal space of the battery cells, thereby improving the efficiency of the battery cells. Battery space utilization. A cavity is provided inside the buffer, and the cavity is isolated from the electrolyte. In this way, the cavity in the buffer can provide a space for the electrode assembly to deform, which is beneficial to improving the weight energy density of the battery cell and reducing the distance between the cavity and the electrode assembly. or the temperature difference between enclosures. Therefore, the technical solutions of the embodiments of the present application can improve battery performance.

The technical solutions described in the embodiments of this application are applicable to various devices using batteries, such as mobile phones, portable devices, laptops, battery cars, electric toys, electric tools, electric vehicles, ships and spacecraft, etc., for example, spacecraft include Airplanes, rockets, space shuttles and spacecraft, etc.

It should be understood that the technical solutions described in the embodiments of the present application are not limited to the devices described above, but can also be applied to all devices using batteries. However, for the sake of simplicity, the following embodiments take electric vehicles as examples for description.

For example, as shown in Figure 1, it is a schematic structural diagram of a vehicle 1 according to an embodiment of the present application. The vehicle 1 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or a new energy vehicle. Extended range vehicles, etc. A motor 40 , a controller 30 and a battery 10 may be disposed inside the vehicle 1 . The controller 30 is used to control the battery 10 to provide power to the motor 40 . For example, the battery 10 may be disposed at the bottom, front or rear of the vehicle 1 . The battery 10 can be used to supply power to the vehicle 1 . For example, the battery 10 can be used as an operating power source of the vehicle 1 and used in the circuit system of the vehicle 1 , for example, to meet the power requirements for starting, navigation, and operation of the vehicle 1 . In another embodiment of the present application, the battery 10 can not only be used as an operating power source of the vehicle 1 , but also can be used as a driving power source of the vehicle 1 , replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1 .

In order to meet different power usage requirements, the battery 10 may include multiple battery cells. For example, as shown in FIG. 2 , it is a schematic structural diagram of a battery 10 according to an embodiment of the present application. The battery 10 may include a plurality of battery cells 20 . The battery 10 may also include a box 11. The inside of the box 11 is a hollow structure, and a plurality of battery cells 20 are accommodated in the box 11. For example, a plurality of battery cells 20 are connected in parallel or in series or in a mixed combination and then placed in the box 11 .

Optionally, the battery 10 may also include other structures, which will not be described in detail here. For example, the battery 10 may further include a bus component, which is used to realize electrical connection between multiple battery cells 20 , such as parallel connection, series connection, or mixed connection. Specifically, the bus component can realize electrical connection between the battery cells 20 by connecting the electrode terminals of the battery cells 20 . Furthermore, the bus part may be fixed to the electrode terminal of the battery cell 20 by welding. The electric energy of the plurality of battery cells 20 can be further drawn out through the box through the conductive mechanism. Alternatively, the electrically conductive means can also be part of the busbar.

According to different power requirements, the number of battery cells 20 can be set to any value. Multiple battery cells 20 can be connected in series, parallel or mixed connection to achieve larger capacity or power. Since the number of battery cells 20 included in each battery 10 may be large, in order to facilitate installation, the battery cells 20 may be arranged in groups, and each group of battery cells 20 forms a battery module. The number of battery cells 20 included in the battery module is not limited and can be set according to requirements. The battery may include multiple battery modules, which may be connected in series, parallel or mixed connection.

FIG. 3 is a schematic structural diagram of a battery cell according to an embodiment of the present application, and FIG. 4 is a cross-sectional view of the battery cell in FIG. 3 along the direction A-A. As shown in FIG. 3 and FIG. 4 , in an embodiment of the present application, the battery cell 20 includes a casing 21 , an electrolyte, an electrode assembly 22 and a buffer 25 .

In the battery cell 20, the casing 21 is used to accommodate the electrolyte, the electrode assembly 22 and the buffer member 25. The shell 21 is determined according to the combined shape of one or more electrode assemblies 22. For example, the shell 21 can be a hollow rectangular parallelepiped, a cube, or a cylinder.

The electrode assembly 22 may be composed of a positive electrode sheet, a negative electrode sheet and a separation film. The battery cell 20 mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. Among them, the separator is used to isolate the positive electrode sheet and the negative electrode sheet, and the material of the separator can be polypropylene or polyethylene.

The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode current collector. The current collector that is not coated with the positive electrode active material layer protrudes from the current collector that is coated with the positive electrode active material layer. The current collector coated with the positive electrode active material layer serves as the positive electrode tab. Taking lithium-ion batteries as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganate, etc.

The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode current collector. The current collector that is not coated with the negative electrode active material layer protrudes from the current collector that is coated with the negative electrode active material layer. The current collector coated with the negative active material layer serves as the negative electrode tab. The material of the negative electrode current collector can be copper, and the negative electrode active material can be carbon or silicon. In order to ensure that large currents can pass through without melting, the number of positive electrode tabs is multiple and stacked together, and the number of negative electrode tabs is multiple and stacked together.

The electrode assembly 22 may have a wound structure or a laminated structure, which is not specifically limited in the embodiment of the present application.

In the battery cell 20 , the electrode assembly 22 may be provided as a single or multiple electrode components according to actual usage requirements. As shown in FIG. 3 , the battery cell 20 is provided with two independent electrode assemblies 22 .

The electrolyte is disposed inside the casing 21 and plays a role in transmitting ions between the positive electrode sheet and the negative electrode sheet. The electrolyte can be liquid, gel or solid. This application does not specifically limit the type of electrolyte, and can be selected according to needs.

The buffer member 25 is accommodated in the housing 21 and connected to the electrode assembly 22 . The buffer member 25 can be directly connected to the electrode assembly 22 or indirectly connected to the electrode assembly 22 . Since the buffer member 25 is disposed inside the battery cell 20 , when the internal space of the battery 10 is constant, the space of the buffer member 25 originally provided between the battery cells 20 in the battery 10 can be transferred to the battery cells 20 internal space, thereby improving the space utilization of the battery 10.

A cavity 251 is provided inside the buffer member 25, and the cavity 251 is isolated from the electrolyte. The cavity 251 in the buffer member 25 can be elastically deformed when acted upon by an external force. For example, the cavity 251 can be compressed after being subjected to pressure. On the one hand, the cavity 251 in the buffer member 25 can provide space for the expansion of the electrode assembly 22; on the other hand, the arrangement of the cavity 251 is conducive to reducing the weight of the buffer member 25, thereby helping to increase the weight of the battery cell 20. Energy density; on the other hand, the arrangement of the cavity 251 is beneficial to reducing the thermal resistance of the buffer member 25, thereby reducing the temperature difference between the cavity 251 and the electrode assembly 22 or the shell 21.

The buffer member 25 is used to buffer the expansion of the electrode assembly 22 . When the electrode assembly 22 expands, it will exert pressure on the buffering member 25 , and after being compressed, the buffering member 25 will exert a reverse pressure on the electrode assembly 22 . Due to the function of the buffer member 25, the overall force on the surface of the electrode assembly 22 that is in contact with or connected to the buffer member 25 can be in an appropriate range, which is beneficial to achieving a uniform release of the expansion force of the electrode assembly 22.

The shape of the buffer member 25 may be a rectangular parallelepiped or a shape adapted to the electrode assembly 22 , which is not specifically limited in the embodiment of the present application.

The embodiment of the present application provides a battery cell 20. The battery cell 20 includes a casing 21, an electrode assembly 22 accommodated in the casing 21, an electrolyte and a buffer 25. The buffer member 25 is accommodated in the housing 21 and connected to the electrode assembly 22 . The buffer member 25 is used to buffer the expansion of the electrode assembly 22 . Since the buffer member 25 is disposed inside the battery cell 20 , when the internal space of the battery 10 is constant, the space of the buffer member 25 originally provided between the battery cells 20 in the battery 10 can be transferred to the battery cells 20 internal space, thereby improving the space utilization of the battery 10. A cavity 251 is provided inside the buffer member 25, and the cavity 251 is isolated from the electrolyte. In this way, the cavity 251 in the buffer member 25 can provide a deformation space for the electrode assembly 22, thereby increasing the weight energy density of the battery cell 20 and reducing the energy density of the battery cell 20. The temperature difference between the cavity 251 and the electrode assembly 22 or the housing 21. Therefore, the technical solutions of the embodiments of the present application can improve the performance of the battery 10 .

In an embodiment of the present application, the cavity 251 is connected with the outside of the housing 21 .

The outside of the casing 21 may also refer to the outside of the battery cell 20 , that is to say, the cavity 251 is connected to the external environment outside the casing 21 .

In this embodiment, the cavity 251 can exchange heat with the external environment. For example, when the temperature of the cavity 251 is relatively high, the cavity 251 can dissipate heat to the external environment to reduce the temperature of the cavity 251 , thereby further reducing the temperature of the cavity 251 . The temperature difference between the cavity 251, the electrode assembly 22 and the housing 21.

Temperature differences will affect the charge and discharge performance of the battery. For example, the temperature difference leads to the existence of a low-temperature region and a high-temperature region (relative to the low-temperature region). For the low-temperature region, the dynamic characteristics of the low-temperature region are poor, so the low-temperature region requires a smaller charging current, and a smaller charging current Current affects how quickly the battery charges.

In an embodiment of the present application, the cavity 251 is used to accommodate fluid to adjust the temperature of the battery cell 20 .

Optionally, the fluid can be circulated to achieve better temperature regulation effect. Alternatively, the fluid may be a gas or a liquid, such as water, a mixture of water and ethanol, refrigerant, or air.

In this embodiment, the fluid in the cavity 251 can further cool down or heat up the cavity 251 and the area around the cavity 251 inside the battery cell 20 to adjust the temperature of the cavity 251 and its surrounding area. . In this way, during the process of using the thermal management component to cool down or heat up the battery cell 20 , the temperature difference between the housing 21 and the electrode assembly 22 and the cavity 251 can be reduced.

In an embodiment of the present application, the buffer member 25 is configured to adjust the thickness through pressure changes of the fluid in the cavity 251 .

The thickness of the buffer member 25 may refer to the size of the buffer member 25 along the thickness direction of the buffer member 25, such as the x direction.

In this embodiment, the thickness of the cushioning member 25 can be adjusted by pressurizing the fluid. For example, when the fluid pressure increases, the size of the buffer member 25 along the thickness direction becomes larger, so that the space occupied by the buffer member 25 becomes larger, the gap between the electrode assembly 22 and the housing 21 becomes smaller, and even the gap between the electrode assembly 22 and the housing 21 becomes smaller. 21 contacts. In this way, it is beneficial to reduce the thermal resistance between the electrode assembly 22 and the housing 21, improve the heat dissipation efficiency, and effectively reduce the temperature of the electrode assembly 22.

In this embodiment, the thickness of the buffer member 25 can also be adjusted by reducing the pressure of the fluid. As the battery cell 20 is used, the size of the electrode assembly 22 becomes larger compared to the early use stage of the battery cell 20 , and the gap between the electrode assembly 22 and the housing 21 becomes smaller. At this time, the size of the buffer member 25 can be changed by adjusting the pressure of the fluid, for example, reducing the pressure of the fluid so that the electrode assembly 22 and the housing 21 are in a state of mutual extrusion to a state where the electrode assembly 22 and the housing 21 are in perfect contact.

In this embodiment, the thickness of the buffer 25 can be adjusted through changes in the pressure of the fluid within the cavity 251 . On the one hand, adjusting the thickness of the buffer member 25 can help reduce the thermal resistance between the electrode assembly 22 and the housing 21 and improve the heat dissipation efficiency. On the other hand, the force on the first surface and the second surface of the electrode assembly 22 can be made uniform and constant, that is, the force on the first surface and the second surface of the electrode assembly 22 can be relatively consistent, where the first surface can be the electrode assembly. 22 is the surface in contact with the buffer member 25, and the second surface is the surface in contact between the electrode assembly 22 and the housing 21; thus, the polarization accumulation of the electrode assembly 22 caused by one of the first surface and the second surface being suspended can be avoided, so that the electrode assembly 22 can be avoided. Avoiding the occurrence of lithium precipitation and other phenomena caused by polarization accumulation can ensure the safety performance, long-term charge and discharge performance, capacity, etc. of the battery. The suspension of the first surface may mean that the first surface is not in contact with the buffer member 25 and the second surface is in contact with the housing 21; the suspension of the second surface may be that the second surface is not in contact with the housing 21 and the first surface is in contact with the buffer. Piece 25 contacts.

FIG. 5 is a schematic structural diagram of a buffer member according to an embodiment of the present application. FIG. 6 is a cross-sectional view of the buffer member in FIG. 5 along the B-B direction. FIG. 7 is a cross-sectional view of the buffer member in FIG. 5 along the C-C direction. In one embodiment, as shown in Figures 5 to 7, an elastic support structure 252 is provided in the cavity 251, and the elastic support structure 252 is used to buffer the expansion of the electrode assembly 22. During the use of the battery cell 20 , the provision of the elastic support structure 252 is conducive to further improving the deformation ability of the buffer member 25 and is conducive to providing more expansion space for the electrode assembly 22 .

In one embodiment, the elastic support structure 252 is parallel to the thickness direction of the buffer member 25 .

The elastic support structure 252 is parallel to the thickness direction of the buffer member 25 . It can also be said that the elastic support structure 252 extends along the thickness direction of the buffer member 25 . In this way, the installation of the elastic support structure 252 is facilitated.

Optionally, multiple elastic support structures 252 are provided in the cavity 251 . The plurality of elastic support structures 252 may be distributed at certain intervals along the height direction of the battery cell 20 , such as the z direction in the figure.

Optionally, multiple elastic support structures 252 are arranged parallel to each other. Optionally, multiple elastic support structures 252 may also be connected to each other at a certain angle. The arrangement of the elastic support structure 252 can be specifically set according to actual needs, and this application does not impose specific restrictions on this.

In one embodiment, the elastic support structure 252 includes elastic support columns or elastic support plates. In this way, the elastic support structure 252 has a simple structure and is easy to process.

In one embodiment, the elastic support structure 252 is a metal elastic support structure or a polymer elastic support structure. In this way, it is convenient to flexibly select the type of elastic support structure according to actual needs.

The material of the polymer elastic support structure is a polymer, which can also be called a polymer compound, such as polypropylene. In the embodiment of the present application, the elastic support structure 252 can also be made of other elastically deformable polymer compounds, and is not specifically limited here.

Optionally, the elastic support structure 252 can also be made of other elastic materials, as long as the elastic deformation of the elastic support structure 252 can be achieved.

In one embodiment, the housing 21 includes a housing 211 and an end cover 212. The housing 211 has an opening and is used to accommodate the electrode assembly 22. The end cover 212 is used to cover the opening; wherein, the surface of the buffer member 25 facing the end cover 212 An inlet and outlet 253 is provided, through which the cavity 251 communicates with the outside of the housing 21 .

One face of the housing 211 has an opening so that one or more electrode assemblies 22 can be placed within the housing 211 . For example, when the housing 211 is a hollow rectangular parallelepiped or a cube, one of the planes of the housing 211 is an opening surface, that is, the plane does not have a wall so that the inside and outside of the housing 211 are connected. When the housing 211 can be a hollow cylinder, the end surface of the housing 211 is an open surface, that is, the end surface does not have a wall so that the inside and outside of the housing 211 are connected. The end cap 212 covers the opening and is connected with the housing 211 to form a closed cavity in which the electrode assembly 22 is placed.

Optionally, two of the faces of the housing 211 have openings. For example, the housing 211 has two opposite openings, and two end caps are respectively used to cover the two openings.

The end cap 212 may be provided with electrode terminals 214, which are respectively a positive electrode terminal 214a and a negative electrode terminal 214b. The end cap 212 is generally in the shape of a flat plate, and the two electrode terminals 214 are fixed on the flat surface of the end cap 212 . Each electrode terminal 214 may be provided with a corresponding connecting member. The connecting member is located between the end cover 212 and the electrode assembly 22 and is used to electrically connect the electrode assembly 22 and the electrode terminal 214 .

In this embodiment, the surface of the buffer member 25 facing the end cover 212 is provided with an inlet and outlet 253, and the cavity 251 communicates with the outside of the housing 21 through the inlet and outlet 253. In this way, the communication between the cavity 251 of the buffer member 25 and the outside of the housing 21 is achieved through the arrangement of the inlet and outlet 253 of the buffer member 25 .

In one embodiment, the end cover 212 is provided with a connection port 2121 corresponding to the inlet and outlet 253, and the inlet and outlet 253 communicates with the outside of the housing 21 through the connection port 2121. In this way, by providing the connection port 2121 corresponding to the inlet and outlet 253 on the end cover 212, there is no need to provide additional pipes to connect the inlet and outlet 253 and the connection port 2121. The battery cell 20 has a simple structure and is easy to produce and assemble.

In one embodiment, the inlet and outlet 253 includes an inlet 2531 and an outlet 2532. The fluid enters the cavity 251 of the buffer member 25 through the inlet 2531, and flows out of the cavity 251 of the buffer member 25 through the outlet 2532. In this way, the arrangement of the inlet 2531 and the outlet 2532 facilitates the circulation of fluid in the cavity 251 and helps improve the efficiency of heat exchange.

Optionally, the shape and size of the inlet 2531 and the outlet 2532 can be specifically set according to actual needs, and the embodiment of the present application does not impose specific restrictions on this.

In one embodiment, along the thickness direction of the buffer member 25 , the ratio of the size of the buffer member 25 to the size of the battery cells 20 is 1% to 20%.

Along the thickness direction of the buffer member 25, the size of the buffer member 25 may be L1, and the size of the battery cell 20 may be L2. When the ratio of L1 to L2 is less than 1%, the thickness of the buffer 25 is too small and it is difficult to realize the buffering effect of the buffer 25; when the ratio of L1 to L2 is greater than 20%, the thickness of the buffer 25 is too large and occupies more space. space, which is not conducive to improving the space utilization of the battery cell 20 and increasing the volumetric energy density.

In this embodiment, along the thickness direction of the buffer member 25 , the ratio of the size of the buffer member 25 to the size of the battery cell 20 is 1% to 20%, which facilitates balancing the buffering effect of the buffer member 25 and the space of the battery cell 20 Utilization.

Optionally, the ratio of the size L1 of the buffer member 25 to the size L2 of the battery cell 20 is 5% to 10%.

Optionally, the ratio of L1 to L2 can be specifically set according to the actual situation.

In one embodiment, the battery cell 20 includes a plurality of electrode assemblies 22 , and the buffer members 25 are disposed between adjacent electrode assemblies 22 . In this way, it is convenient to cool down or heat up the electrode assembly 22, and it is beneficial to reduce the temperature difference between the electrode assembly 22 and the housing 21.

Optionally, a buffer member 25 is also provided between the electrode assembly 22 and the housing 21 , which is beneficial to further reducing the temperature difference between the electrode assembly 22 and the housing 21 and increasing the heating or cooling rate of the battery cell 20 .

In one embodiment, the buffer member 25 is an aluminum buffer member, an aluminum alloy buffer member or a polymer buffer member. In this way, it is convenient to flexibly select the type of buffer member 25 according to actual needs.

The buffer member 25 is a polymer buffer member, which may mean that the material of the buffer member 25 is a polymer (or polymer compound), such as polypropylene, polyethylene, etc. The embodiments of the present application do not place specific restrictions on the specific type of polymer, as long as the buffering member 25 can achieve the buffering function and the function of isolating the electrolyte.

Optionally, the buffer member 25 is an aluminum buffer member, so that the buffer member 25 can have better thermal conductivity. Alternatively, the buffer member 25 can also be made of other materials that have excellent thermal conductivity and do not absorb electrolyte.

Figure 8 is a schematic structural diagram of an electrode assembly according to an embodiment of the present application. In one embodiment, as shown in FIG. 8 , the side surface of the electrode assembly 22 includes a planar portion 27 , and the buffer member 25 is connected to the planar portion 27 .

Electrode assembly 22 includes side surfaces and end surfaces. For example, the electrode assembly 22 includes two end surfaces that are opposite to each other and parallel to the end cover 212 , and the side surfaces of the electrode assembly 22 are respectively connected to the two end surfaces.

Figure 8 shows a schematic cross-sectional view of an electrode assembly 22. The electrode assembly 22 may include a planar portion 27 and a curved portion 28. The planar portion 27 and the curved portion 28 are connected to each other to form the electrode assembly 22. The electrode assembly 22 may be rolled. structure.

Alternatively, the electrode assembly 22 may not include a curved portion, but only a planar portion, which is not specifically limited in the embodiment of the present application.

In this embodiment, the flat portion 27 is connected to the electrode assembly 22 to facilitate the connection between the buffer member 25 and the electrode assembly 22 .

In one embodiment, the planar portion 27 is the largest surface of the electrode assembly 22 . In this way, it is beneficial to realize the uniform release of the expansion force of the electrode assembly 22, and at the same time, it is beneficial to increase the heat exchange area between the electrode assembly 22 and the buffer member 25, and can improve the heat exchange between the fluid in the cavity 251 and the electrode assembly 22. Efficiency, for example, can improve the heat dissipation efficiency inside the battery cell 20 .

The embodiment of the present application provides a battery cell 20 , which includes a casing 21 , an electrode assembly 22 accommodated in the casing 21 , an electrolyte and a buffer 25 . The buffer member 25 is accommodated in the housing 21 and connected to the electrode assembly 22. The buffer member 25 is used to buffer the expansion of the electrode assembly 22. A cavity 251 is provided inside the buffer member 25. The cavity 251 is isolated from the electrolyte and is separated from the shell 21. Connected to the outside, the cavity 251 is used to contain fluid to adjust the temperature of the battery cell 20 . The cavity 251 in the buffer member 25 can provide space for the electrode assembly 22 to deform, improve the weight energy density of the battery cell 20 , and reduce the temperature difference between the cavity 251 and the electrode assembly 22 or the housing 21 . Therefore, the technical solutions of the embodiments of the present application can improve the performance of the battery 10 .

It should be understood that relevant parts in the various embodiments of the present application may be referred to each other and will not be described again for the sake of brevity.

The embodiment of the present application provides a battery 10, including: the battery cell 20 of any one of the above embodiments; and a box 11, the box 11 is used to accommodate the battery cell 20.

The embodiment of the present application provides an electrical device, including: the battery 10 in the embodiment of the present application. The battery 10 is used to provide electric energy to the electrical device.

While the present application has been described with reference to preferred embodiments, various modifications may be made and equivalents may be substituted for components thereof without departing from the scope of the application. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any way. The application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

A battery cell (20), characterized by including:

Shell(21);

electrolytes;

An electrode assembly (22), the electrode assembly (22) and the electrolyte are contained in the housing (21);

Buffering member (25). The buffering member (25) is accommodated in the housing (21) and connected to the electrode assembly (22). A cavity (251) is provided inside the buffering member (25), so The cavity (251) is isolated from the electrolyte, and the buffer member (25) is used to buffer the expansion of the electrode assembly (22).
The battery cell (20) according to claim 1, characterized in that the cavity (251) is connected to the outside of the housing (21).
The battery cell (20) according to claim 1, characterized in that the cavity (251) is used to accommodate fluid to adjust the temperature of the battery cell (20).
The battery cell (20) according to claim 3, characterized in that the buffer (25) is configured to adjust the thickness by pressure changes of the fluid in the cavity (251).
The battery cell (20) according to claim 1, characterized in that an elastic support structure (252) is provided in the cavity (251), and the elastic support structure (252) is used to buffer the electrode assembly. expansion of (22).
The battery cell (20) according to claim 5, characterized in that the elastic support structure (252) is parallel to the thickness direction of the buffer member (25).
The battery cell (20) according to claim 5, characterized in that the elastic support structure (252) includes an elastic support column or an elastic support plate.
The battery cell (20) according to claim 5, characterized in that the elastic support structure (252) is a metal elastic support structure or a polymer elastic support structure.
The battery cell (20) according to any one of claims 1 to 8, characterized in that the outer casing (21) includes a housing (211) and an end cover (212), and the housing (211) It has an opening and is used to accommodate the electrode assembly (22), and the end cover (212) is used to cover the opening;

Wherein, the surface of the buffer member (25) facing the end cover (212) is provided with an inlet and outlet (253), and the cavity (251) communicates with the shell (21) through the inlet and outlet (253). external connectivity.
The battery cell (20) according to claim 9, characterized in that the end cover (212) is provided with a connection port (2121) corresponding to the inlet and outlet (253), and the inlet and outlet (253) It communicates with the outside of the housing (21) through the connection port (2121).
The battery cell (20) according to claim 9, wherein the inlet and outlet (253) includes an inlet (2531) and an outlet (2532), and fluid enters the cavity (2531) through the inlet (2531). 251), out of the cavity (251) through the outlet (2532).
The battery cell (20) according to any one of claims 1 to 8, characterized in that, along the thickness direction of the buffer member (25), the size of the buffer member (25) is consistent with the size of the battery cell. The size ratio of the body (20) is 1% to 20%.
The battery cell (20) according to any one of claims 1 to 8, characterized in that the battery cell (20) includes a plurality of the electrode assemblies (22), and the buffer member (25) Disposed between adjacent electrode assemblies (22).
The battery cell (20) according to any one of claims 1 to 8, characterized in that the buffer member (25) is an aluminum buffer member, an aluminum alloy buffer member or a polymer buffer member.
The battery cell (20) according to any one of claims 1 to 8, characterized in that the side surface of the electrode assembly (22) includes a planar portion (27), and the buffer member (25) and the The flat part (27) is connected.
The battery cell (20) according to claim 15, wherein the planar portion (27) is the largest surface of the electrode assembly (22).
A battery (10), characterized by including:

The battery cell (20) according to any one of claims 1 to 16;

A box (11) is used to accommodate the battery cell (20).
An electric device, characterized by comprising: the battery (10) according to claim 17, the battery (10) being used to provide electric energy to the electric device.