Battery cells, batteries and power consuming devices

Abstract

A battery cell, a battery, and a power consuming device are provided. The battery cell includes an outer casing, an electrode assembly accommodated in the outer casing, and a buffer member accommodated in the outer casing and connected to the electrode assembly for buffering the expansion of the electrode assembly, where the buffer member includes a first closed hole, and the volume V1 of the first closed hole and the volume V of the buffer member satisfy V1 / V>10%. The technical solution of the present application can improve the performance of the battery.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims priority to Chinese Patent Application No. 202210396262.9, filed on April 15, 2022, for the invention entitled "Battery Cell, Battery and Power Consumption Device," the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the field of battery technology, and more particularly to battery cells, batteries, and power consuming devices. [Background technology]

[0003] Energy saving and emission reduction are the keys to the sustainable development of the automotive industry. In this context, electric vehicles have become an important part of the sustainable development of the automotive industry due to their energy saving and environmental protection advantages. For electric vehicles, battery technology is a key element in their development.

[0004] The space utilization rate, strength, and long-term charge / discharge performance of a battery cell are extremely important factors in determining battery performance, and so how to improve battery performance has become an urgent issue. Summary of the Invention

[0005] The embodiments of the present application provide a battery cell, a battery, and a power consuming device that can improve the performance of the battery.

[0006] In a first aspect, an embodiment of the present application provides a battery cell, the battery cell including: an outer casing; an electrode assembly housed in the outer casing; and a buffer member housed in the outer casing and connected to the electrode assembly for buffering expansion of the electrode assembly, wherein the buffer member includes a first closed hole, and a volume V1 of the first closed hole and a volume V of the buffer member satisfy V1 / V>10%.

[0007] In the embodiment of the present application, the battery cell includes an outer casing, an electrode assembly accommodated in the outer casing, and a buffer member. The buffer member is accommodated in the outer casing and connected to the electrode assembly, and the buffer member is for buffering the expansion of the electrode assembly. When the electrode assembly expands, pressure is applied to the buffer member, and after the buffer member is compressed, a reverse force is applied to the electrode assembly. Due to the action of the buffer member, the surface of the electrode assembly in contact with the buffer member receives a uniform force, and the force received by the surface changes uniformly throughout the entire process, so that the expansion force of the electrode assembly can be uniformly released, thereby reducing the accumulation of polarization of the electrode assembly. At the same time, since the buffer member is installed inside the battery cell, when the internal space of the battery is sufficient, the space of the buffer member between the battery cells originally installed in the battery can be transferred to the internal space of the battery cell, thereby improving the space utilization rate of the battery cell. The buffer member includes a first closed hole, and the volume V1 of the first closed hole and the volume V of the buffer member satisfy V1 / V>10%. Since the first closed hole does not contact the electrolyte in the battery cell, the absorption of the electrolyte by the buffer material can be reduced, and at the same time, the provision of the first closed hole is also advantageous to reduce the mass of the buffer material and improve the mass energy density of the battery. In this way, the occurrence of phenomena such as insufficient lithium absorption and lithium precipitation in a part of the negative electrode due to insufficient free electrolyte inside the battery cell can be avoided to a certain extent, while the increase in the weight of the battery cell due to the necessary addition of electrolyte due to insufficient free electrolyte can be avoided to a certain extent, and not only can the energy density of the battery be improved, but also the space for accommodating gas generated during the use of the battery cell can be saved. Furthermore, since the first closed hole does not contact the electrolyte, the reaction area between the buffer material and the electrolyte can be reduced, thereby reducing the occurrence of side reactions, avoiding damage to the buffer material to a certain extent, and improving the buffering effect of the buffer material. Therefore, the technical solution according to the embodiment of the present application can improve the performance of the battery.

[0008] In one possible embodiment, the volume V1 of the first closed pores and the volume V of the buffer member further satisfy V1 / V≧30%, thus further reducing the absorption of the electrolyte by the buffer member and reducing the weight of the buffer member, thereby improving the energy density of the battery.

[0009] In one possible embodiment, the volume V1 of the first closed pores and the volume V of the buffer material satisfy (V1+V2) / V≧50%, where V2 is the volume of the material of the buffer material. In this way, the ratio of the volume of the open pores in the buffer material to the volume of the buffer material is less than 50%, which can further reduce the absorption of electrolyte by the open pores.

[0010] In one possible embodiment, the buffer member includes a first layer and a second layer, the first layer is closer to the electrode assembly than the second layer, and the first density of the first layer is greater than the second density of the second layer. By providing buffer members with different densities, it is possible to balance the weight requirement of the buffer member with the demand for electrolyte of the electrode assembly.

[0011] In one possible embodiment, the first density ρ1 and the second density ρ2 satisfy ρ1 / ρ2≧1.05. Thus, the ratio of the first density ρ1 to the second density ρ2 is within a reasonable range, and there is an obvious density difference between the first layer and the second layer of the buffer member, which can better balance the weight requirement of the buffer member and the electrolyte requirement of the electrode assembly.

[0012] In one possible embodiment, the volume ratio of the first closed pores in the first layer to the first layer is greater than the volume ratio of the first closed pores in the second layer to the second layer, so that the content of electrolyte absorbed by the first layer is less than the content of electrolyte absorbed by the second layer, and after the second layer is compressed, the second layer can release more electrolyte to further meet the electrolyte demand of the electrode assembly.

[0013] In one possible embodiment, the second layer is placed between two of the first layers, in this way the force experienced by the entire buffer element is more uniform, which is favorable for uniform release of the electrolyte.

[0014] In one possible embodiment, a protective layer is provided on the surface of the cushioning member, thus reducing the risk of damage to the outer surface of the cushioning member.

[0015] In one possible embodiment, the protective layer is provided on a first surface and a second surface of the buffer member, the first surface and the second surface being opposite to each other along the thickness direction of the buffer member, the first surface and the second surface being the surface with the largest surface area of ​​the buffer member, and providing the protective layer on the first surface and the second surface is a simple process and easy to operate.

[0016] In one possible embodiment, the protective layer is installed on the third surface and the fourth surface of the buffer member, the third surface and the fourth surface are installed opposite to each other along a direction perpendicular to the thickness direction of the buffer member, and the third surface and the fourth surface are both connected to the first surface and the second surface, so that the buffer member can be protected all over, and the protective effect is better.

[0017] In one possible embodiment, the thickness of the protective layer is 1 μm to 5000 μm. In this way, it is possible to achieve both production costs and the utilization rate of the internal space of the battery cell.

[0018] In one possible embodiment, the thickness d1 of the protective layer and the thickness d2 of the buffer member satisfy d1 / (d1+d2)≦50%, thus reducing the risk of the buffer member's buffer effect being reduced due to the protective layer being too thick.

[0019] In one possible embodiment, the protective layer is a coating layer applied to the surface of the buffer member, which is advantageous in preventing gas from escaping from the inside of the buffer member and in blocking corrosion of the buffer member by the electrolyte.

[0020] In one possible embodiment, the wettability r1 between the surface of the buffer member where the coating layer is not provided and the electrolyte, and the wettability r2 between the coating layer and the electrolyte satisfy r1 / r2≧1.02, where r2=L2 / 2 and r1=L1 / 2, where L1 is the diffusion distance of the electrolyte on the surface of the buffer member where the coating layer is not provided within a predetermined time, and L2 is the diffusion distance of the electrolyte on the coating layer within the predetermined time. Thus, the poor wettability between the coating layer and the electrolyte reduces the absorption ability of the buffer member into the electrolyte, and can reduce the occurrence of phenomena such as insufficient lithium absorption and lithium precipitation in a portion of the negative electrode due to insufficient electrolyte.

[0021] In one possible embodiment, the protective layer is a protective case that surrounds the cushioning member.

[0022] In one possible embodiment, the thickness d3 of the protective case and the thickness d1 of the buffer member satisfy d3 / d1≦50%, thus reducing the risk of reducing the buffer effect of the buffer member and the risk of reducing the internal space utilization rate of the battery cell due to the protective case being too thick.

[0023] In one possible embodiment, the protective case includes a second closed hole, and the volume V3 of the second closed hole and the volume V4 of the protective case satisfy V3 / V4≧90%, thus favoring the formation of a closed space inside the protective case, which further reduces or even avoids the absorption of electrolyte by the buffer material.

[0024] In one possible embodiment, the buffer member is installed between the electrode assembly and the outer casing, and / or the buffer member is installed between adjacent electrode assemblies. In this way, the position and number of the buffer members can be flexibly set according to actual needs.

[0025] In a second aspect, an embodiment of the present application provides a battery, the battery including a battery cell of the first aspect or any possible implementation of the first aspect, and a housing for accommodating the battery cell.

[0026] In a third aspect, embodiments of the present application provide a power consumer device including a battery according to the second aspect or any possible implementation of the second aspect.

[0027] In a fourth aspect, an embodiment of the present application provides a method for manufacturing a battery cell, the method including: providing an outer casing; providing an electrode assembly housed in the outer casing; and providing a buffer member housed in the outer casing and connected to the electrode assembly for buffering expansion of the electrode assembly, wherein the buffer member includes a first closed hole, and a volume V1 of the first closed hole and a volume V of the buffer member satisfy V1 / V>10%.

[0028] In a fifth aspect, an embodiment of the present application provides an apparatus for manufacturing a battery, the apparatus including: a first providing module for providing an outer casing; a second providing module for providing an electrode assembly housed in the outer casing; and a third providing module for providing a buffer member housed in the outer casing and connected to the electrode assembly for buffering expansion of the electrode assembly, wherein the buffer member includes a first closed hole, and a volume V1 of the first closed hole and a volume V of the buffer member satisfy V1 / V>10%.

[0029] In the embodiment of the present application, the battery cell includes an outer casing, an electrode assembly accommodated in the outer casing, and a buffer member. The buffer member is accommodated in the outer casing and connected to the electrode assembly, and the buffer member is for buffering the expansion of the electrode assembly. When the electrode assembly expands, pressure is applied to the buffer member, and after the buffer member is compressed, a reverse force is applied to the electrode assembly. Due to the action of the buffer member, the surface of the electrode assembly in contact with the buffer member receives a uniform force, and the force received by the surface changes uniformly throughout the entire process, so that the expansion force of the electrode assembly can be uniformly released, thereby reducing the accumulation of polarization of the electrode assembly. At the same time, since the buffer member is installed inside the battery cell, when the internal space of the battery is sufficient, the space of the buffer member between the battery cells originally installed in the battery can be transferred to the internal space of the battery cell, thereby improving the space utilization rate of the battery cell. The buffer member includes a first closed hole, and the volume V1 of the first closed hole and the volume V of the buffer member satisfy V1 / V>10%. Since the first closed hole does not contact the electrolyte in the battery cell, the absorption of the electrolyte by the buffer material can be reduced, and at the same time, the provision of the first closed hole is also advantageous to reduce the mass of the buffer material and improve the mass energy density of the battery. In this way, the occurrence of phenomena such as insufficient lithium absorption and lithium precipitation in a part of the negative electrode due to insufficient free electrolyte inside the battery cell can be reduced to a certain extent, while the increase in the weight of the battery cell due to the necessary addition of electrolyte due to insufficient free electrolyte can be avoided to a certain extent, which is not only advantageous to guarantee the energy density of the battery, but also saves space for accommodating gas generated during the use of the battery cell, and furthermore, since the first closed hole does not contact the electrolyte, the reaction area between the buffer material and the electrolyte can be reduced, thereby reducing the occurrence of side reactions, avoiding damage to the buffer material to a certain extent, and ensuring the buffering effect of the buffer material. Therefore, the technical solution according to the embodiment of the present application can improve the performance of the battery.

[0030] In order to more clearly explain the technical solutions of the embodiments of the present application, the following briefly introduces drawings that may be used in the embodiments of the present application. It should be apparent that the drawings described below are only some embodiments of the present application, and those skilled in the art can also obtain other drawings based on the drawings without exerting creative efforts. [Brief description of the drawings]

[0031] [Figure 1] 1 is a schematic diagram of a vehicle according to one embodiment of the present application; [Diagram 2] FIG. 1 is a schematic diagram of a battery according to one embodiment of the present application. [Diagram 3] FIG. 1 is a schematic diagram of a battery cell according to one embodiment of the present application. [Figure 4] FIG. 1 is a schematic diagram of a battery cell according to one embodiment of the present application. [Diagram 5] FIG. 2 is a schematic diagram of a cushioning member according to an embodiment of the present application. [Figure 6] 2 is a schematic diagram of a cushioning member on which a protective layer is installed according to one embodiment of the present application; [Figure 7] 2 is a schematic diagram of a cushioning member on which a protective layer is installed according to one embodiment of the present application; [Figure 8] 2 is a schematic diagram of a cushioning member on which a protective case is installed according to one embodiment of the present application. [Figure 9] FIG. 1 is a schematic diagram of a battery cell according to one embodiment of the present application. [Figure 10] FIG. 1 is a schematic diagram of a battery cell according to one embodiment of the present application. [Figure 11] FIG. 1 is a schematic diagram of a battery cell according to one embodiment of the present application. [Figure 12] FIG. 1 is a schematic diagram of a battery cell according to one embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] In the drawing section, the drawings are not drawn to scale.

[0033] The technical solutions in the embodiments of the present application are described below in conjunction with the drawings. The detailed description of the embodiments and the drawings below are for illustrative purposes only and are not intended to limit the scope of the present application, i.e. the present application is not limited to the described embodiments.

[0034] In the description of this application, it should be pointed out that, unless otherwise specified, "multiple" means two or more, and the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "inner", and "outer" does not indicate or imply that the device or element shown must have a specific orientation or be configured and operated in a specific orientation, but is merely for the purpose of facilitating and simplifying the description of this application, and should not be understood as a limitation of this application. In addition, terms such as "first", "second", and "third" are used for the purpose of explanation only, and should not be understood as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but is within the margin of error. "Parallel" is not parallel in the strict sense, but is within the margin of error. All directional terms appearing in the following description are directions shown in the figures, and do not limit the specific structure of this application. In the description of this application, it should be further explained that unless expressly specified and limited, the terms "attached", "connected" and "connected" should be understood in a broad sense, for example, they may be fixedly connected, detachably connected, or integrally connected, and may be directly connected or indirectly connected via an intermediate medium. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific situation.

[0035] The term "and / or" in this application merely describes the relationship between related objects and indicates that three relationships may exist, for example, A and / or B can represent three cases: A alone, a combination of A and B, and B alone. In addition, the character " / " in this application generally indicates that the related objects before and after are in an "or" relationship.

[0036] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. Note that the thickness, length, width, and other dimensions of each member in the embodiments of the present application shown in the drawings, and the overall thickness, length, width, and other dimensions of the integrated device are merely illustrative and do not limit the present application. In the present application, "plurality" means two or more (including two).

[0037] In the present application, the battery cell may include a lithium ion secondary battery, a lithium ion primary battery, a lithium sulfur battery, a sodium lithium ion battery, a sodium ion battery, or a magnesium ion battery, etc., but is not limited thereto in the embodiments of the present application. The battery cell may be cylindrical, flat, rectangular, or have other shapes, etc., but is not limited thereto in the embodiments of the present application. Depending on the packaging form, the battery cell is generally divided into three types, namely, a prismatic battery cell, a rectangular battery cell, and a pouch battery cell, but is not limited thereto in the embodiments of the present application.

[0038] The battery referred to in the embodiments of the present application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in the present application may include a battery module or a battery pack. The battery generally includes a housing for packaging one or more battery cells. The housing can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.

[0039] The battery cell includes an electrode assembly and an electrolyte, and the electrode assembly is composed of a positive electrode plate, a negative electrode plate, and a separator. The battery cell is mainly operated by the movement of metal ions between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive electrode collector and a positive electrode active material layer, and the positive electrode active material layer is applied to the surface of the positive electrode collector, and the collector on which the positive electrode active material layer is not applied protrudes from the collector on which the positive electrode active material layer is applied, and the collector on which the positive electrode active material layer is not applied is called a positive electrode tab. Taking a lithium ion battery as an example, the material of the positive electrode collector may be aluminum, and the positive electrode active material may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, lithium manganate, etc. The negative electrode plate includes a negative electrode collector and a negative electrode active material layer, the negative electrode active material layer is applied to the surface of the negative electrode collector, the collector on which the negative electrode active material layer is not applied protrudes from the collector on which the negative electrode active material layer is applied, and the collector on which the negative electrode active material layer is not applied is called a negative electrode tab. The material of the negative electrode collector may be copper, and the negative electrode active material may be carbon or silicon, etc. In order to prevent melting even when a large current is passed through the positive electrode tabs, a plurality of positive electrode tabs are stacked, and a plurality of negative electrode tabs are stacked. The material of the separator may be polypropylene or polyethylene, etc. In addition, the electrode assembly may have a wound structure or a stacked structure, and the embodiment of the present application is not limited thereto.

[0040] In order to meet various power demands, a battery may include multiple battery cells, where the multiple battery cells may be connected in series, parallel, or series-parallel, and the series-parallel connection refers to a mixture of the series and parallel connections. Optionally, multiple battery cells may be connected in series, parallel, or series-parallel to form a battery module, and multiple battery modules may be connected in series, parallel, or series-parallel to form a battery. That is, multiple battery cells may directly form a battery, or a battery module may be first formed, and then the battery module may form a battery. The battery is further installed in a power consuming device to provide electrical energy for the power consuming device.

[0041] The development of battery technology requires consideration of a wide range of design factors, such as energy density, cycle life, discharge capacity, charge / discharge rate, safety, etc. at the same time. A buffer material in a battery is usually installed between battery cells to buffer the battery cells, but this installation method is complicated to assemble and disadvantageous to improving the internal space utilization rate of the battery. When a buffer material is installed inside a battery cell, the buffer material absorbs the electrolyte in the battery cell and reacts with the electrolyte, which causes various safety problems and reduces the energy density of the battery, thereby affecting the performance of the battery. As can be seen from the above, the installation of the battery cell is extremely important for the performance of the battery. Therefore, how to provide a battery cell to improve the performance of the battery is an issue that needs to be solved as soon as possible.

[0042] In view of this, an embodiment of the present application provides a battery cell, which includes an outer casing, an electrode assembly accommodated in the outer casing, and a buffer member. The buffer member is accommodated in the outer casing and connected to the electrode assembly, and the buffer member is for buffering the expansion of the electrode assembly. When the electrode assembly expands, pressure is applied to the buffer member, and after the buffer member is compressed, a reverse force is applied to the electrode assembly. Due to the action of the buffer member, the surface of the electrode assembly in contact with the buffer member receives a uniform force, and the force received by the surface changes uniformly during the entire process, so that the expansion force of the electrode assembly can be uniformly released, thereby reducing the accumulation of polarization of the electrode assembly. At the same time, since the buffer member is installed inside the battery cell, when the internal space of the battery is sufficient, the space of the buffer member originally installed between the battery cells in the battery can be transferred to the internal space of the battery cells, thereby improving the space utilization rate of the battery cell. The buffer member includes a first closed hole, and the volume V1 of the first closed hole and the volume V of the buffer member satisfy V1 / V>10%. Since the first closed hole does not contact the electrolyte in the battery cell, the absorption of the electrolyte by the buffer material can be reduced, and at the same time, the provision of the first closed hole is also advantageous to reduce the mass of the buffer material and improve the mass energy density of the battery. In this way, the occurrence of phenomena such as insufficient lithium absorption and lithium precipitation in a part of the negative electrode due to insufficient free electrolyte inside the battery cell can be avoided to a certain extent, while the increase in the weight of the battery cell due to the necessary addition of electrolyte due to insufficient free electrolyte can be avoided to a certain extent, which is not only advantageous to guarantee the energy density of the battery, but also saves space for accommodating gas generated during the use of the battery cell, and furthermore, since the first closed hole does not contact the electrolyte, the reaction area between the buffer material and the electrolyte can be reduced, thereby reducing the occurrence of side reactions, avoiding damage to the buffer material to a certain extent, and ensuring the buffering effect of the buffer material. Therefore, the technical solution according to the embodiment of the present application can improve the performance of the battery.

[0043] The technical solutions described in the embodiments of the present application can be applied to various battery-powered devices, such as mobile phones, handheld devices, laptops, electric scooters, electric toys, electric tools, electric vehicles, ships, and spacecraft, including, for example, airplanes, rockets, space shuttles, and spaceships.

[0044] It should be understood that the technical solutions described in the embodiments of the present application are not only applicable to the devices described above, but also to all devices that use batteries. For the sake of simplicity, however, the following embodiments will be described using an electric vehicle as an example.

[0045] For example, as shown in FIG. 1, a structural schematic diagram of a vehicle 1 according to an embodiment of the present application, the vehicle 1 may be a fuel oil vehicle, a gas vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, a range extender vehicle, etc. A motor 40, a controller 30, and a battery 10 may be installed inside the vehicle 1, and the controller 30 is for controlling the battery 10 to supply power to the motor 40. For example, the battery 10 can be installed 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 for the vehicle 1 for the electric circuit system of the vehicle 1, for example, for the operating power demand during starting, navigation, and running of the vehicle 1. In another embodiment of the present application, the battery 10 can not only be used as an operating power source for the vehicle 1, but also as a driving power source for the vehicle 1 to provide driving power to the vehicle 1 instead of gasoline or natural gas, or instead of a part thereof.

[0046] In order to meet various power consumption demands, the battery 10 may include multiple battery cells. For example, as shown in FIG. 2, which is a structural schematic diagram of the battery 10 according to an embodiment of the present application, the battery 10 may include multiple battery cells 20. The battery 10 may further include a housing 11, the inside of which is a hollow structure, and the multiple battery cells 20 are accommodated in the housing 11. For example, the multiple battery cells 20 are placed in the housing 11 after being combined by being connected in parallel, in series, or in series-parallel to each other.

[0047] Optionally, the battery 10 may further include other structures, but the description thereof will be omitted here. For example, the battery 10 may further include a busbar component for realizing electrical connection between the multiple battery cells 20, for example, parallel connection, series connection, or series-parallel connection. Specifically, the busbar member can be connected to the electrode terminals of the battery cells 20 to realize electrical connection between the battery cells 20. Furthermore, the busbar component can be fixed to the electrode terminals of the battery cells 20 by welding. The electrical energy of the multiple battery cells 20 can further be extracted through the housing by a conductive mechanism. Optionally, the conductive mechanism may belong to the busbar member.

[0048] According to various power demands, the number of battery cells 20 may be set to any value. Large capacity or power can be realized by connecting multiple battery cells 20 in series, parallel, or series-parallel. Each battery 10 may contain a large number of battery cells 20, and for ease of installation, the battery cells 20 may be installed in groups, and each group of battery cells 20 may constitute a battery module. The number of battery cells 20 included in a battery module is not limited and may be installed according to demand. A battery may include multiple battery modules, and these battery modules may be connected in series, parallel, or series-parallel.

[0049] As shown in FIG. 3, it is a structural schematic diagram of a battery cell 20 according to an embodiment of the present application, the battery cell 20 includes one or more electrode assemblies 22, a housing 211, and an end cap 212. The housing 211 and the end cap 212 form an outer casing or battery box 21. The walls of the housing 211 and the end cap 212 are both referred to as the walls of the battery cell 20, where for a rectangular battery cell 20, the walls of the housing 211 include a bottom wall and four side walls. The housing 211 is determined based on the shape after assembling one or more electrode assemblies 22, for example, the housing 211 may be a hollow rectangular prism, cube, or cylinder, and one surface of the housing 211 has an opening so that one or more electrode assemblies 22 can be placed in the housing 211. For example, when the housing 211 is a hollow rectangular parallelepiped or cube, one plane of the housing 211 is an open surface, i.e., the plane does not have a wall and communicates between the inside and outside of the housing 211. When the housing 211 is a hollow cylinder, an end surface of the housing 211 is an open surface, i.e., the end surface does not have a wall and communicates between the inside and outside of the housing 211. The end cap 212 covers the opening and is connected to the housing 211 to form a sealed cavity in which the electrode assembly 22 is disposed. The housing 211 is filled with an electrolyte, for example, an electrolyte solution.

[0050] The battery cell 20 may further include two electrode terminals 214, which may be installed on the end cap 212. The end cap 212 has a generally flat plate shape, and the two electrode terminals 214 are fixed on the flat surface of the end cap 212, and the two electrode terminals 214 are a positive electrode terminal 214a and a negative electrode terminal 214b, respectively. Each electrode terminal 214 is correspondingly installed with a connection part 23 (also called a current collecting part 23), which is located between the end cap 212 and the electrode assembly 22, and is for realizing an electrical connection between the electrode assembly 22 and the electrode terminal 214.

[0051] As shown in FIG. 3, each electrode assembly 22 has a first tab 221a and a second tab 222a. The first tab 221a and the second tab 222a have opposite polarities. For example, if the first tab 221a is a positive tab, the second tab 222a is a negative tab. The first tab 221a of one or more electrode assemblies 22 is connected to one electrode terminal via one connection part 23, and the second tab 222a of one or more electrode assemblies 22 is connected to another electrode terminal via another connection part 23. For example, the positive electrode terminal 214a is connected to the positive electrode tab via one connection part 23, and the negative electrode terminal 214b is connected to the negative electrode tab via another connection part 23.

[0052] In the battery cell 20, one or more electrode assemblies 22 may be installed according to actual usage needs, but as shown in FIG. 3, four independent electrode assemblies 22 are installed in the battery cell 20.

[0053] Fig. 4 is a schematic diagram of a battery cell according to an embodiment of the present application. Fig. 5 is a schematic diagram of a buffer member according to an embodiment of the present application. As shown in Figs. 4 and 5, the battery cell 20 includes an outer casing 21, an electrode assembly 22, and a buffer member 25, where the electrode assembly 22 is accommodated in the outer casing 21, the buffer member 25 is accommodated in the outer casing 21 and connected to the electrode assembly 22, the buffer member 25 is for buffering the expansion of the electrode assembly 22, the buffer member 25 includes a first closed hole 251, and the volume V1 of the first closed hole 251 and the volume V of the buffer member 25 satisfy V1 / V>10%.

[0054] The outer casing 21 is for housing the electrode assembly 22 and the electrolyte, and the electrode assembly 22 and the electrolyte can be enclosed within the battery cell 20 via the outer casing 21 .

[0055] The buffer member 25 is housed in the outer casing 21 and is connected to the electrode assembly 22. Here, the buffer member 25 may be directly connected to the electrode assembly 22 or indirectly connected to the electrode assembly 22. Since the buffer member 25 is installed inside the battery cell 20, if the internal space of the battery 10 is sufficient, the space of the buffer member originally installed between the battery cells 20 in the battery 10 can be given over to the internal space of the battery cell 20, thereby improving the space utilization rate of the battery cell 20.

[0056] The buffer member 25 is for buffering the expansion of the electrode assembly 22. When the electrode assembly 22 expands, pressure is applied to the buffer member 25, and after the buffer member 25 is compressed, a reverse acting force is applied to the electrode assembly 22. Due to the action of the buffer member 25, the force received by the surface of the electrode assembly 22 in contact with the buffer member 25 is uniform as a whole, and as the expansion of the electrode assembly 22 progresses, the force received by the surface changes or increases uniformly, thereby realizing a uniform release of the expansion force of the electrode assembly 22, and further reducing or even avoiding the accumulation of polarization of the electrode assembly 22. Therefore, the occurrence of phenomena such as lithium deposition due to the accumulation of polarization is avoided, thereby ensuring the safety performance, long-term charge / discharge performance, capacity, etc. of the battery.

[0057] The buffer member 25 includes a first closed hole 251, and the volume V1 of the first closed hole 251 and the volume V of the buffer member 25 satisfy V1 / V>10%. The volume of the buffer member 25 is the apparent volume of the buffer member 25. For example, when the buffer member 25 is a rectangular buffer member, the volume V of the buffer member 25 is a*b*h, where a is the length of the buffer member 25, b is the width of the buffer member 25, and h is the thickness of the buffer member 25. The volume of the buffer member 25 may further satisfy V=V1+V2+V5, where V1 is the volume of the first closed hole, V2 is the volume of the material of the buffer member 25, and V5 is the volume of the open hole in the buffer member 25.

[0058] The material of the buffer member 25 may be foam, silicone rubber, silicone rubber composite polyurethane, polypropylene, melamine, etc., and the embodiment of the present application is not specifically limited thereto.

[0059] The apertures may be cavities and tunnels communicating with the outside, for example, the electrolyte, and the surface area of ​​the apertures may be analyzed by gas adsorption method, and the volume V5 of the apertures may be measured by GB / T21650-2008 gas method. The apertures may absorb the electrolyte in the battery cell 20, and the larger the ratio of the volume V5 of the apertures to the volume V of the buffer member 25, the greater the weight and speed of the electrolyte absorption by the buffer member 25.

[0060] Because the first closed holes 251 do not communicate with the outer surface of the buffer member 25 and the electrolyte in the battery cell 20 cannot enter the first closed holes 251, the provision of the first closed holes 251 can reduce the absorption of the electrolyte by the buffer member 25 and can also reduce the weight of the buffer member 25. The volume V2 of the first closed holes 251 can be calculated from the volume V of the buffer member 25, the volume V5 of the open holes and the volume V2 of the material of the buffer member 25.

[0061] Compared with a buffer material that does not have the first closed pores 251 or has a volume ratio of the first closed pores 251 of 10% or less, the volume ratio of the first closed pores 251 of the buffer material 25 in the present application is greater than 10%, and the absorption speed of the buffer material 25 into the electrolyte and the weight of the absorbed electrolyte are both small, so that the content of the free electrolyte in the battery cell 20 can be guaranteed. In this way, the occurrence of phenomena such as insufficient lithium absorption and lithium precipitation in a part of the negative electrode during the formation or full charge process can be avoided, thereby ensuring the safety performance of the battery 10, while there is no need to add electrolyte, which can avoid an increase in the weight of the battery cell 20 due to an increase in electrolyte, not only ensuring the energy density of the battery 10 but also saving the space for accommodating gas generated during the use of the battery cell 20, and further, since the first closed pores 251 do not contact the electrolyte, the reaction area between the buffer material 25 and the electrolyte can be reduced, thereby reducing the occurrence of side reactions, avoiding damage to the buffer material 25, and ensuring the buffering effect of the buffer material 25.

[0062] Optionally, in one embodiment of the present application, the volume V1 of the first closed hole 251 and the volume V of the buffer member 25 further satisfy V1 / V≧30%. In this way, the absorption of the electrolyte by the buffer member 25 can be further reduced, and the weight of the buffer member 25 can also be reduced, thereby improving the energy density of the battery 10.

[0063] Optionally, in one embodiment of the present application, the volume V1 of the first closed hole 251 and the volume V of the buffer member 25 further satisfy (V1+V2) / V≧50%, where V2 is the volume of the material of the buffer member 25. The volume V2 of the material of the buffer member 25=m / ρ, where m is the weight of the buffer member 25 and ρ is the density of the material itself. In this way, the ratio of the volume V5 of the open holes in the buffer member 25 to the volume V of the buffer member 25 is less than 50%, which can further reduce the absorption of electrolyte by the open holes.

[0064] Optionally, in one embodiment of the present application, as shown in FIG. 5 , the buffer member 25 includes a first layer 261 and a second layer 262, the first layer 261 being closer to the electrode assembly 22 than the second layer 262, and the first density ρ1 of the first layer 261 being greater than the second density ρ2 of the second layer 262.

[0065] The first density ρ1=m4 / v4 and the second density ρ2=m5 / v5, where m4 and v4 are the weight and volume, respectively, of the first layer 261, and m5 and v5 are the weight and volume, respectively, of the second layer 262. The volume of the first layer 261 may be the apparent volume of the first layer 261, i.e., the product of the length, width, and height of the first layer 261. Analogously, the volume of the second layer 262 may be the apparent volume of the second layer 261.

[0066] The first density ρ1 of the first layer 261 is greater than the second density ρ2 of the second layer 262, the amount of electrolyte absorbed by the first layer 261 is less than the amount of electrolyte absorbed by the second layer 262, and the weight per unit volume of the second layer 262 is less than the weight per unit volume of the first layer 261. In this way, it can be ensured that the amount of electrolyte absorbed by the buffer material 25 and the weight of the buffer material 25 are both within a reasonable range, so as to avoid the loss of free electrolyte and also to improve the energy density of the battery.

[0067] The first layer 261 is closer to the electrode assembly 22 than the second layer 262, and the second layer 262 is compressed behind the first layer 261; thus, during the later expansion of the electrode assembly 22, the electrolyte in the second layer 262 is pushed out from the second layer and becomes free electrolyte, further satisfying the demand for electrolyte by the electrode assembly 22.

[0068] By providing the buffer member 25 having a density difference, it is possible to satisfy both the weight requirement of the buffer member 25 and the demand for the electrolyte of the electrode assembly 22 .

[0069] Optionally, in one embodiment of the present application, the first density ρ1 and the second density ρ2 satisfy ρ1 / ρ2≧1.05. Thus, the ratio of the first density ρ1 to the second density ρ2 is within a reasonable range, and there is an obvious density difference between the first layer and the second layer of the buffer member, which can better balance the weight requirement of the buffer member and the electrolyte requirement of the electrode assembly.

[0070] Optionally, in one embodiment of the present application, a volume ratio of the first closed pores 251 in the first layer 261 to the first layer 261 is greater than a volume ratio of the first closed pores 251 in the second layer 262 to the second layer 262. In this way, the second layer 262 can absorb more electrolyte than the first layer 261, and after the second layer 262 is compressed, the second layer 262 can release more electrolyte to further meet the electrolyte demand of the electrode assembly 22.

[0071] Optionally, in one embodiment of the present application, the second layer 262 is placed between the two first layers 261. In this way, the force experienced by the buffer member 25 as a whole is more uniform, which is favorable for uniform release of the electrolyte.

[0072] 6 is a schematic diagram of a buffer member provided with a protective layer according to an embodiment of the present application. Optionally, in an embodiment of the present application, a protective layer 200 is provided on the surface of the buffer member 25 as shown in FIG. 6. In this way, damage to the outer surface of the buffer member 25 can be prevented, and the outer surface of the buffer member 25 is the surface of the buffer member 25 that contacts the electrolyte.

[0073] Optionally, in one embodiment of the present application, as shown in FIG. 6, the protective layer 200 is installed on the first surface 201 and the second surface 202 of the buffer member 25, and the first surface 201 and the second surface 202 are surfaces that are installed opposite to each other along the thickness direction of the buffer member 25. The thickness direction of the buffer member 25 may be the x direction in the figure, and the first surface 201 and the second surface 202 are installed opposite to each other along the x direction. The first surface 201 and the second surface 202 are the surfaces with the largest surface area of ​​the buffer member 25, and installing the protective layer on the first surface 201 and the second surface 202 is a simple process and easy to operate. In other embodiments, the protective layer 200 may be installed on only one of the first surface 201 and the second surface 202, and may be specifically installed according to actual needs, and the embodiment of the present application is not specifically limited thereto.

[0074] 7 is a schematic diagram of a buffer member provided with a protective layer according to an embodiment of the present application. Optionally, in an embodiment of the present application, as shown in FIG. 7, the protective layer 200 is provided on the third surface 203 and the fourth surface 204 of the buffer member 25, and the third surface 203 and the fourth surface 204 are surfaces that are provided opposite each other along a direction perpendicular to the thickness direction of the buffer member 25, and the third surface 203 and the fourth surface 204 are both connected to the first surface 201 and the second surface 202. The third surface 203 and the fourth surface 204 may be surfaces that are provided opposite each other along the z direction. In this way, the first surface 201, the second surface 202, the third surface 203 and the fourth surface 204 of the buffer member 25 are all provided with a protective layer, so that the buffer member 25 can be protected more comprehensively.

[0075] Optionally, in one embodiment of the present application, the thickness of the protective layer 200 is 1 μm to 5000 μm. If the thickness of the protective layer 200 is less than 1 μm, high control precision is required for manufacturing the protective layer 200, which increases the production cost, and if the thickness of the protective layer 200 is greater than 5000 μm, it occupies more of the internal space of the battery cell 20, which is disadvantageous for improving the space utilization rate of the battery cell 20. By setting the thickness of the protective layer 20 to 1 μm to 5000 μm, it is possible to achieve both the production cost and the internal space utilization rate of the battery cell 20.

[0076] Optionally, in one embodiment of the present application, the thickness d1 of the protective layer 200 and the thickness d2 of the buffer member 25 satisfy d1 / (d1+d2)≦50%. In this way, it is possible to avoid a decrease in the buffer effect of the buffer member 25 caused by the protective layer 200 being too thick.

[0077] Optionally, in one embodiment of the present application, the protective layer 200 is a coating layer applied to the surface of the buffer member 25. The coating layer can prevent gas from escaping from the inside of the buffer member 25, and can also block corrosion of the buffer member 25 by the electrolyte.

[0078] Optionally, in one embodiment of the present application, the wetting force r1 between the electrolyte and a surface of the buffer member 25 on which no coating layer is provided, and the wetting force r2 between the electrolyte and the coating layer satisfy r1 / r2≧1.02, where r2=L2 / 2 and r1=L1 / 2, where L1 is the diffusion distance of the electrolyte on the surface of the buffer member 25 on which no coating layer is provided within a specified time, and L2 is the diffusion distance of the electrolyte in the coating layer within a specified time.

[0079] Since the wetting force between the coating layer and the electrolyte is poor, the ability of the buffer member 25 to absorb the electrolyte is reduced, and it is possible to avoid the occurrence of phenomena such as insufficient lithium absorption and lithium precipitation in some areas of the negative electrode due to insufficient electrolyte.

[0080] The test method for the wetting force is as follows: take a certain volume of electrolyte using a capillary, place the capillary perpendicular to the surface of the object to be measured, the vertical distance between the bottom of the capillary and the object to be measured is H, release the electrolyte inside the capillary to allow the electrolyte to penetrate for a certain time, and read the diffusion distance of the electrolyte on the surface of the object to be measured within a certain time from the soft ruler.

[0081] Optionally, the material of the protective layer 200 may include an inert material and an adhesive, where the inert material may be alumina, zirconia, silicon oxide, etc., and the adhesive may be styrene butadiene rubber (SBR), polyvinylidene fluoride (PVDF), resin, etc. The inert material may be mixed with the adhesive and applied to the surface of the buffer member 25, but may also be formed on the surface of the buffer member 25 by other methods, and the embodiments of the present application are not specifically limited thereto.

[0082] Optionally, the material of the protective layer 200 may include an inert material, where the inert material may be one or more of aminated phenolic polymers, cationic or anionic polymers, chitosan derivatives, reactions of polyester or acrylic polyols with isocyanates, bisphenol A, bisphenol F type epoxy resins, polyvinyl alcohol, and the like.

[0083] 8 is a schematic diagram of a cushioning member on which a protective case is installed according to an embodiment of the present application. Optionally, in an embodiment of the present application, as shown in FIG. 8, the protective layer 200 is a protective case 300 surrounding the cushioning member 25. The protective case 300 may include an aluminum plastic film, a polyethylene terephthalate (PET) film, etc.

[0084] Optionally, in one embodiment of the present application, the thickness d3 of the protective case 300 and the thickness d1 of the buffer member 25 satisfy d3 / d1≦50%, as shown in Fig. 8. In this way, it is possible to avoid a reduction in the buffer effect of the buffer member 25 and a reduction in the internal space utilization rate of the battery cell 20 due to the protective case 300 being too thick.

[0085] Optionally, in one embodiment of the present application, the protective case 300 includes a second closed pore, and the volume V3 of the second closed pore and the volume V4 of the protective case 300 satisfy V3 / V4≧90%. In this way, it is advantageous to form a closed space inside the protective case 300, which further reduces or even prevents the absorption of electrolyte by the buffer member 25. In some embodiments, a space with a closed porosity of 100% may be formed inside the protective case 300 to achieve zero absorption of electrolyte by the buffer member 25.

[0086] 9 to 11 are schematic diagrams of a battery cell according to an embodiment of the present application. Optionally, in an embodiment of the present application, as shown in FIGS. 9 to 11, a buffer member 25 is installed between the electrode assembly 22 and the outer casing 21, and / or a buffer member 25 is installed between adjacent electrode assemblies 22.

[0087] As shown in Figs. 9 and 10, the buffer member 25 is installed between the electrode assembly 22 and the outer casing 21, and the buffer member 25 may be arranged asymmetrically as in Fig. 9 or symmetrically as in Fig. 10. As shown in Fig. 11, the buffer member 25 is installed between adjacent electrode assemblies 22. Fig. 12 is a schematic diagram of a battery cell according to an embodiment of the present application. As shown in Fig. 12, a protective case 300 is further installed on the surface of the buffer member 25 between the adjacent electrode assemblies 22. The specific position of the buffer member 25 and the protective layer on the surface of the buffer member 25 may be specifically set according to actual needs, but the embodiment of the present application is not limited thereto.

[0088] The buffer member 25 in the embodiment of the present application was used to carry out the experiment, and the data is shown in Table 1. The external buffer member is a buffer member disposed outside the battery cell, and the built-in buffer member is a buffer member disposed inside the battery cell 20 in the embodiment of the present application. As can be seen from Comparative Example 1 and Example 1, and Comparative Example 2 and Example 7, disposing the buffer member inside the battery cell can significantly improve the capacity retention rate of the battery cell and significantly reduce the expansion force. As can be seen from Examples 1, 2, and 3, increasing the thickness of the buffer member is advantageous for improving the capacity retention rate of the battery cell and reducing the expansion force. As can be seen from Examples 1, 5, and 6, the larger r1 / r2 is, the more advantageous it is for improving the capacity retention rate of the battery cell and reducing the expansion force.

[0089] The relevant parts in each embodiment of the present application may be referred to each other, and for the sake of brevity, the description will be omitted here.

[0090] An embodiment of the present application further provides a battery 10 including the battery cell 20 in the above embodiment and a housing 11, where the housing 11 is used to accommodate the battery cell 20.

[0091] An embodiment of the present application further provides a power consumption device, which may include the battery 10 in the above embodiment for providing electricity to the power consumption device. Optionally, the power consumption device may be a vehicle 1, a ship, a spacecraft, etc., but the embodiment of the present application is not limited thereto.

[0092] The above describes the battery 10 and the power consuming device according to the embodiment of the present application. The following describes the method and device for manufacturing the battery according to the embodiment of the present application. Hereinafter, the parts not described in detail can be referred to the above embodiments.

[0093] [Table 1]

[0094] An embodiment of the present application further provides a method for manufacturing a battery cell 20, the method including: providing an outer casing 21; providing an electrode assembly 22 housed in the outer casing 21; and providing a buffer member 25 housed in the outer casing 21 and connected to the electrode assembly 22, for buffering expansion of the electrode assembly 22, where the buffer member 22 includes a first closed hole 251, and a volume V1 of the first closed hole 251 and a volume V of the buffer member 25 satisfy V1 / V>10%.

[0095] An embodiment of the present application further provides an apparatus for manufacturing a battery 10, the apparatus including: a first providing module for providing an outer casing 21; a second providing module for providing an electrode assembly 22 housed in the outer casing 21; and a third providing module for providing a buffer member 25 housed in the outer casing 21 and connected to the electrode assembly 22, for buffering the expansion of the electrode assembly 22, wherein the buffer member 22 includes a first closed hole 251, and a volume V1 of the first closed hole 251 and a volume V of the buffer member 25 satisfy V1 / V>10%.

[0096] Although the present application has been described with reference to preferred embodiments, various improvements may be made thereto and the elements therein may be replaced with equivalents without departing from the scope of the present application. In particular, the respective technical features mentioned in each embodiment may be combined in any manner, so long as there is no structural contradiction. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions included in the claims.

Claims

1. A battery cell, Outer case (21), an electrode assembly (22) housed in the outer casing (21); a buffer member (25) that is housed in the outer casing (21) and connected to the electrode assembly (22) and that buffers the expansion of the electrode assembly (22); A battery cell, wherein the buffer member (25) includes a first closed hole (251), and a volume V1 of the first closed hole (251) and a volume V of the buffer member (25) satisfy V1 / V>10%.

2. The battery cell according to claim 1 , wherein the volume V1 of the first closed hole (251) and the volume V of the buffer member (25) further satisfy V1 / V≧30%.

3. The battery cell according to claim 1 or 2, wherein the volume V1 of the first closed hole (251) and the volume V of the buffer member (25) further satisfy (V1 + V2) / V≧50%, and V2 is the volume of the material of the buffer member (25).

4. The battery cell of any one of claims 1 to 3, wherein the buffer member (25) includes a first layer (261) and a second layer (262), the first layer (261) is closer to the electrode assembly (22) than the second layer (262), and a first density of the first layer (261) is greater than a second density of the second layer (262).

5. The battery cell according to claim 4 , wherein the first density ρ1 and the second density ρ2 satisfy ρ1 / ρ2≧1.

05.

6. 6. The battery cell of claim 4 or 5, wherein a volume ratio of the first closed pores (251) in the first layer (261) to the first layer (261) is greater than a volume ratio of the first closed pores (251) in the second layer (262) to the second layer (262).

7. The battery cell of any one of claims 4 to 6, wherein the second layer (262) is disposed between two of the first layers (261).

8. The battery cell according to any one of claims 1 to 7, wherein a protective layer (200) is provided on a surface of the buffer member (25).

9. 9. The battery cell of claim 8, wherein the protective layer (200) is provided on a first surface (201) and a second surface (202) of the buffer member (25), and the first surface (201) and the second surface (202) are provided opposite each other along a thickness direction of the buffer member (25).

10. 10. The battery cell of claim 9, wherein the protective layer (200) is installed on a third surface (203) and a fourth surface (204) of the buffer member (25), the third surface (203) and the fourth surface (204) are installed opposite each other along a direction perpendicular to the thickness direction of the buffer member (25), and the third surface (203) and the fourth surface (204) are both connected to the first surface (201) and the second surface (202).

11. The battery cell according to any one of claims 8 to 10, wherein the protective layer (200) has a thickness of 1 μm to 5000 μm.

12. The battery cell according to any one of claims 8 to 11, wherein a thickness d1 of the protective layer (200) and a thickness d2 of the buffer member (25) satisfy d1 / (d1+d2)≦50%.

13. The battery cell according to any one of claims 8 to 12, wherein the protective layer (200) is a coating layer applied to a surface of the buffer member (25).

14. 14. The battery cell of claim 13, wherein a wetting force r1 between a surface of the buffer member (25) on which the coating layer is not formed and the electrolyte, and a wetting force r2 between the coating layer and the electrolyte satisfy r1 / r2≧1.02, where r2=L2 / 2 and r1=L1 / 2, where L1 is the diffusion distance of the electrolyte on the surface of the buffer member (25) on which the coating layer is not formed within a predetermined time, and L2 is the diffusion distance of the electrolyte in the coating layer within the predetermined time.

15. The battery cell according to claim 8 , wherein the protective layer (200) is a protective case (300) surrounding the buffer member (25).

16. The battery cell according to claim 15, wherein a thickness d3 of the protective case (300) and a thickness d1 of the buffer member (25) satisfy d3 / d1≦50%.

17. 17. The battery cell of claim 15 or 16, wherein the protective case (300) includes a second closed hole, and a volume V3 of the second closed hole and a volume V4 of the protective case (300) satisfy V3 / V4≧90%.

18. The battery cell according to any one of claims 1 to 17, wherein the buffer member (25) is provided between the electrode assembly (22) and the outer casing (21), and / or the buffer member (25) is provided between adjacent electrode assemblies (22).

19. A battery, A battery cell according to any one of claims 1 to 18; and a housing for housing the battery cell.

20. 20. A power consuming device comprising the battery of claim 19.

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