Battery cell, battery, and electric device

Abstract

The application discloses a battery monomer (1000), which comprises a shell (100), at least one electric core (200) and a buffer piece (300). The at least one electric core (200) is contained in the shell (100). The buffer piece (300) is arranged in correspondence with the side wall of the electric core (100). The buffer piece (300) has a containing cavity (305). The outer periphery of the containing cavity (305) comprises at least one packaging structure (3010). The packaging structure (3010) comprises at least one packaging area with a predetermined length. When the pressure in the containing cavity (305) exceeds the packaging strength of the packaging structure (3010), the packaging area is opened and a buffer space in communication with the containing cavity (305) is formed, so that the influence of the expansion of the electric core is reduced.

Description

Technical Field

[0001] This application relates to the field of batteries, specifically to a battery cell, a battery, and an electrical device. Background Technology

[0002] Energy conservation and emission reduction are key to the sustainable development of the automotive industry, and electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of this sustainable development. For electric vehicles, battery technology is a crucial factor in their development.

[0003] The inventors of this application discovered in their research that, during the charging and discharging process of existing batteries, as the cell temperature rises and the usage time increases, the cell will swell, which in turn squeezes the battery casing, posing a risk to the use of lithium batteries. Summary of the Invention

[0004] In view of the above problems, this application provides a battery cell, a battery, and an electrical device to solve the problems existing in the prior art.

[0005] In a first aspect, embodiments of this application provide a single battery cell, comprising:

[0006] A housing; at least one battery cell housed within the housing; and a buffer member housed within the housing and disposed corresponding to the sidewall of the battery cell, the buffer member having a receiving cavity, the outer periphery of the receiving cavity including at least one encapsulation structure, the encapsulation structure including at least one encapsulation region having a predetermined length, the encapsulation region opening and forming a buffer space communicating with the receiving cavity when the pressure inside the receiving cavity exceeds the encapsulation strength of the encapsulation structure.

[0007] By setting the buffer component corresponding to the side wall of the battery cell, the initial gap between the battery cell and the casing can be effectively filled, avoiding loosening of the battery cell winding structure and lithium plating. On the other hand, when the battery cell expands during use, the pressure caused by the expansion of the battery cell can be relieved, and the impact of the expansion of the battery cell on the electrode sheet can be reduced.

[0008] Optionally, the sidewall includes a middle sidewall portion located in the middle region between the two ends in the height direction of the cell, and the buffer is disposed correspondingly to the middle sidewall portion.

[0009] By setting the buffer and the middle sidewall of the battery cell to correspond, a buffer space can be provided for the part of the battery cell with the greatest expansion force, thus maximizing the relief of the pressure caused by the expansion of the battery cell.

[0010] Optionally, the buffer is disposed between the cell and the side wall of the housing, and / or the buffer is sandwiched between adjacent cells.

[0011] By placing buffer components at different locations within the battery cell, the problems caused by cell expansion can be mitigated to the greatest extent possible, taking into account the characteristics of the battery cell.

[0012] Optionally, the packaging structure is located at one or both ends of the buffer along the height direction of the battery cell.

[0013] This configuration allows the packaging structure to fully utilize the space in the height direction of the battery cell during the cracking process. On the one hand, it can fill the space in the height direction of the battery cell, and on the other hand, it facilitates the buffer component to crack in the height direction of the battery cell under the action of the battery cell expansion force.

[0014] Optionally, in the height direction of the battery cell, the height of the receiving cavity is 10% to 90% of the battery cell height.

[0015] By setting the height of the receiving cavity to be in proportion to the height of the battery cell, the packaging structure can be arranged in the space along the height of the battery cell, making the arrangement of the buffer more flexible.

[0016] Optionally, the encapsulation structure includes at least two levels of encapsulation regions with different encapsulation strengths, such that as the pressure inside the receiving cavity increases, the encapsulation regions open step by step, and form buffer spaces communicating with the receiving cavity step by step.

[0017] With this configuration, as the battery cell is used and its expansion force gradually increases, the encapsulation area is gradually opened, and the space of the receiving cavity can be gradually released as the expansion force of the battery cell increases.

[0018] Optionally, the at least two levels of the encapsulation regions are arranged continuously; and / or, the at least two levels of the encapsulation regions are arranged at intervals, with a buffer of a predetermined length between adjacent levels of the encapsulation regions.

[0019] By arranging the encapsulation areas continuously, the cavity gradually releases space as the cell expands, avoiding abrupt spatial changes. This makes the resistance from the buffer components on the cell more stable, significantly improving the lifespan of the individual battery cells. Spacing the encapsulation areas and setting buffer zones between them allows for flexible adjustment of the released space.

[0020] Optionally, the at least two levels of the encapsulation regions are arranged along the height direction of the cell, and the encapsulation regions farther from the receiving cavity have greater encapsulation strength.

[0021] The above configuration allows the buffer to expand gradually in the direction of cell height very easily, and as the cell expansion pressure increases, space can be gradually released.

[0022] Optionally, the pressure inside the receiving cavity is greater than or equal to the air pressure inside the battery cell.

[0023] Because the pressure inside the containment cavity is greater than the air pressure inside the battery cell, the containment cavity exerts a certain pressure on the battery cell, thereby enabling the battery cell to remain fully filled even when the cell margin is low, thus preventing lithium plating caused by electrode wrinkles.

[0024] Optionally, the encapsulation strength of the encapsulation structure is 0.1 to 50 MPa.

[0025] The setting of the encapsulation strength takes into account both the internal pressure of the cavity and the pressure caused by the expansion of the battery cell. On the one hand, it enables the internal pressure of the cavity to exert pressure on the battery cell in the initial state, thus preventing lithium plating. On the other hand, under the pressure of the battery cell expansion force, the internal pressure of the cavity can gradually open the encapsulation structure.

[0026] Optionally, the battery cell is a square battery cell, and the buffer is disposed at one or both ends of the battery cell in the thickness direction; and / or, the buffer is disposed at one or both ends of the battery cell in the width direction.

[0027] By flexibly placing buffers in various directions of the battery cell, the expansion force of the battery cell in various directions can be alleviated.

[0028] Optionally, when the buffer is disposed at one or both ends of the battery cell in the thickness direction, the width of the receiving cavity in the width direction of the battery cell is 50 to 100% of the width of the battery cell.

[0029] By setting the ratio between the width of the receiving cavity and the width of the battery cell, space can be flexibly reserved for the packaging structure according to the performance of the battery cell, thereby reducing the impact of battery cell expansion.

[0030] Optionally, the receiving cavity has an annular cross-section in the height direction of the battery cell, continuously surrounding the battery cell.

[0031] This design creates a buffer around the battery cell, preventing lithium plating caused by cell movement and providing space for expansion in all directions around the cell when it expands.

[0032] Optionally, the material of the buffer has an outer protective layer and an inner sealing layer, and the encapsulation area is formed by heat-sealing the inner sealing layer.

[0033] By employing a heat-sealing method for the two-layer structure, the manufacturing process is simple, the sealing effect is good, and it is easy to produce various buffer components that are suitable for the battery cell structure.

[0034] Optionally, the receiving cavity is filled with an inert fluid.

[0035] By filling the cavity with an inert material, the expansion of the cavity of the buffer component due to the material contained within it is avoided when the cell temperature rises, thus preventing the expansion of the buffer component itself from compressing the expansion space of the cell.

[0036] Secondly, this application provides a battery that includes the battery cell described in the above embodiments.

[0037] Thirdly, this application provides an electrical device that includes the battery described in the above embodiments, the battery being used to provide electrical energy.

[0038] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0039] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0040] Figure 1 This is a schematic diagram of the vehicle structure provided in an embodiment of this application;

[0041] Figure 2 This application provides an exploded view of the battery structure in an embodiment.

[0042] Figure 3 This is a cross-sectional view of a battery cell provided in an embodiment of this application;

[0043] Figure 4 A cross-sectional view of the buffer provided in an embodiment of this application;

[0044] Figure 5 Another cross-sectional view of a battery cell provided in an embodiment of this application;

[0045] Figure 6a A schematic diagram of another buffer provided in an embodiment of this application;

[0046] Figure 6b A schematic diagram of a second type of buffer provided in an embodiment of this application;

[0047] Figure 6c A schematic diagram of a third type of buffer provided in the embodiments of this application;

[0048] Figure 6d A schematic diagram of the fourth type of buffer provided in the embodiments of this application;

[0049] Figure 6e A schematic diagram of the fifth type of buffer provided in the embodiments of this application;

[0050] Figure 6f A schematic diagram of the sixth type of buffer provided in the embodiments of this application;

[0051] Figure 7 A diagram showing the usage state of the buffer provided in the embodiments of this application;

[0052] Figure 8 A cross-sectional view of another buffer provided in an embodiment of this application;

[0053] Figure 9 A usage state diagram of another buffer provided in an embodiment of this application;

[0054] Figure 10 An exploded view of a single battery cell provided in an embodiment of this application;

[0055] Figure 11 Another exploded view of a battery cell provided in an embodiment of this application;

[0056] Figure 12 A schematic diagram of a ring-shaped buffer provided in an embodiment of this application;

[0057] Figure 13 A schematic diagram of a rectangular buffer provided in an embodiment of this application.

[0058] Figure 14 A structural diagram of the buffer material provided in the embodiments of this application;

[0059] Figure 15 This is a schematic diagram of the molding process of the buffer element provided in an embodiment of this application;

[0060] Figure 16 This is a schematic diagram of a battery structure provided in an embodiment of this application;

[0061] Figure 17 A cross-sectional view of a battery cell provided in the embodiment of this application for test one;

[0062] Figure 18 A cross-sectional view of a battery cell for Test 2 provided in this application embodiment;

[0063] Figure 19 This is a cross-sectional view of a battery cell for Test 3 provided in an embodiment of this application.

[0064] The reference numerals in the detailed embodiments are as follows:

[0065] Battery cell 1000, casing 100, cell 200, first end 201, first sidewall 203, tab 205, first cell 210, second cell 220, first sidewall 2203 of the second cell, first corner 2205 of the second cell, buffer 300, aluminum-plastic film 301, encapsulation structure 3010, first buffer zone 3011, first encapsulation area 3012, second buffer zone 3013, second encapsulation area 3014, third... Buffer zone 3015, third encapsulation area 3016, receiving cavity 305, first buffer 310, first encapsulation structure 3110, second buffer 320, second encapsulation structure 3210, annular buffer 330, annular encapsulation structure 3310, end cap 400, vehicle 2000, battery 2100, busbar component 2101, controller 2200, motor 2300, housing 2110, upper housing 2111, lower housing 2112. Detailed Implementation

[0066] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0067] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0068] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0069] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0070] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0071] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0072] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0073] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0074] Currently, with technological advancements, the application of power batteries is becoming increasingly widespread. Power batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively applied in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. As the application areas of power batteries continue to expand, the market demand is also constantly increasing.

[0075] The inventors of this application have observed that as ions are inserted into or extracted from the positive and negative electrode active materials during charge-discharge cycles, the battery cell swells, meaning the positive and negative electrode plates expand outwards. This expansion is particularly pronounced in the middle region of the stacked or wound electrode layers. Electrode expansion negatively impacts battery performance and lifespan. For example, it may affect the wetting of the electrode by the electrolyte, altering ion transport pathways and leading to lithium plating problems. Furthermore, the electrode may break under prolonged high compressive stress, potentially causing internal short circuits. In addition, the electrolyte is continuously consumed during charge-discharge cycles, and after a certain period of use, localized electrolyte depletion may occur. Cell expansion further exacerbates this localized electrolyte deficiency.

[0076] To alleviate the problem of cell expansion, an elastic support plate can be installed inside the cell. The elastic contraction of this plate creates space for cell expansion, addressing the issue of loosening contact between the positive and negative electrodes and the separator after multiple charge-discharge cycles. However, our research has found that this method has several drawbacks. The elastic support plate is thick and heavy, occupying significant internal space and increasing the cell's mass, leading to substantial energy density loss. Furthermore, the presence of numerous metal components in the elastic support plate poses a risk of dissolution over prolonged use. Dissolved metal ions can precipitate on the electrode surface, potentially causing separator puncture. Additionally, the elastic support plate reduces the compressible space within the cell, resulting in a sharp increase in expansion force later in the cell's lifespan.

[0077] Based on the above considerations, in order to solve the problem of cell performance deterioration caused by expansion force during cell use, the inventors of this application have conducted in-depth research and designed a new type of battery cell. By setting a buffer inside the battery cell casing, the buffer gradually releases the expansion buffer space as the expansion force of the battery cell gradually increases, which effectively solves the problem of cell performance deterioration caused by cell expansion during cell use.

[0078] The battery cells disclosed in this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power system for such an electrical device can be constructed using battery cells and batteries disclosed in this application. This helps to mitigate and automatically regulate the deterioration of cell expansion forces, thereby improving the stability of battery performance and battery life.

[0079] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0080] For ease of explanation, the following embodiments will be described using a vehicle 2000 as an example of an electrical device according to an embodiment of this application.

[0081] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 2000 provided in an embodiment of this application. The vehicle 2000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery 2100 is installed inside the vehicle 2000, and the battery 2100 can be located at the bottom, front, or rear of the vehicle 2000. The battery 2100 can be used to supply power to the vehicle 2000; for example, the battery 2100 can serve as the operating power source for the vehicle 2000. The vehicle 2000 may also include a controller 2200 and a motor 2300. The controller 2200 is used to control the battery 2100 to supply power to the motor 2300, for example, to meet the power needs of the vehicle 2000 during startup, navigation, and driving.

[0082] In some embodiments of this application, the battery 2100 can not only serve as the operating power source for the vehicle 2000, but also as the driving power source for the vehicle 2000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 2000.

[0083] Please refer to Figure 2 , Figure 2This is an exploded view of a battery 2100 provided in an embodiment of this application. The battery 2100 includes a housing 2110 and a battery cell 1000, with the battery cell 1000 housed within the housing 2110. The housing 2110 provides a space for the battery cell 1000, and the housing 2110 can have various structures. In some embodiments, the housing 2110 may include an upper housing 2111 and a lower housing 2112, which overlap each other, and together define a space for accommodating the battery cell 1000. The lower box 2112 can be a hollow structure with one open end, and the upper box 2111 can be a plate-like structure. The upper box 2111 covers the open side of the lower box 2112, so that the upper box 2111 and the lower box 2112 together define the accommodating space. Alternatively, both the upper box 2111 and the lower box 2112 can be hollow structures with one open end, with the open side of the upper box 2111 covering the open side of the lower box 2112. Of course, the box 2110 formed by the upper box 2111 and the lower box 2112 can be of various shapes, such as a cylinder, a cuboid, etc.

[0084] The battery 2100 mentioned in this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery 2100 mentioned in this application may include a battery module or a battery pack. There may be multiple battery cells 1000, which can be connected in series, parallel, or a combination thereof. A combination thereof means that multiple battery cells 1000 are connected in both series and parallel. Multiple battery cells 1000 can be directly connected in series, parallel, or a combination thereof, and then the entire assembly of the multiple battery cells 1000 is housed within the housing 2110. Alternatively, multiple battery cells 1000 can first be connected in series, parallel, or a combination thereof to form a battery module 2100, and then the multiple battery modules can be connected in series, parallel, or a combination thereof to form a whole, which is then housed within the housing 2110. The battery 2100 may also include other structures; for example, the battery 2100 may also include a busbar component for realizing electrical connections between multiple battery cells 1000.

[0085] Each battery cell 1000 can be a lithium-ion secondary battery, a lithium-ion primary battery, a lithium-sulfur battery, a sodium-lithium-ion battery, or a magnesium-ion battery, but is not limited to these. The battery cell 1000 can be cylindrical, flat, cuboid, or other shapes.

[0086] To further illustrate the battery cell provided in the embodiments of this application, please refer to... Figure 3 For ease of explanation, in this embodiment, the height direction of the battery cell is defined as the Y-axis direction, the thickness of the battery cell is defined as the X-axis direction, and the width direction of the battery cell is defined as the Z-axis direction. Figure 3This is a cross-sectional view of a battery cell 1000 provided in some embodiments of this application along the Y-axis. The battery cell 1000 refers to the smallest independent unit that makes up a battery. Figure 3 The battery cell 1000 includes a casing 100, a cell 200, an end cap 400, and other functional components.

[0087] End cap 400 refers to a component that covers the opening of housing 100 to isolate the internal environment of the battery cell from the external environment. The shape of end cap 400 can be adapted to the shape of housing 100. Optionally, end cap 400 can be made of a material with certain hardness and strength (such as aluminum alloy), so that the end cap is less prone to deformation under pressure and impact, enabling the battery cell to have higher structural strength and improved safety performance. Functional components such as electrode terminals can be provided on the end cap. Electrode terminals can be used for electrical connection with the battery cell to output or input electrical energy to the battery cell. In some embodiments, the end cap can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of the battery cell reaches a threshold. The material of the end cap can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose any special limitations on this. In some embodiments, an insulating member can also be provided on the inner side of the end cap, which can be used to isolate the electrical connection components inside the housing from the end cap to reduce the risk of short circuits. For example, the insulating element can be made of plastic, rubber, etc.

[0088] The housing 100 is an assembly used to cooperate with the end cap 400 to form the internal environment of a battery cell, wherein the formed internal environment can accommodate the battery cell, electrolyte, and other components. The housing 100 and the end cap 400 can be independent components. An opening can be provided on the housing 100, and the end cap closes the opening to form the internal environment of the battery cell. Alternatively, the end cap and housing can be integrated. Specifically, the end cap and housing can form a common connecting surface before other components are inserted into the housing, and the end cap closes the housing when it is necessary to encapsulate the interior. The housing can have various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing can be determined according to the specific shape and size of the battery cell assembly. The housing material can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose any special limitations on this.

[0089] Cell 200 is the component in the battery cell 1000 where the electrochemical reaction takes place. The casing may contain one or more cells. Cells are mainly formed by winding or stacking positive and negative electrode plates, and a separator is usually provided between the positive and negative electrode plates.

[0090] The portions of the positive and negative electrode plates containing active material constitute the main body of the battery cell assembly, while the portions of the positive and negative electrode plates without active material each constitute a tab. The positive and negative tabs can be located together at one end of the main body or separately at both ends. During the charging and discharging process, the positive and negative active materials react with the electrolyte, and the tabs connect to the electrode terminals to form a current loop.

[0091] like Figure 3 and Figure 4 As shown, this application embodiment provides a battery cell 1000, including a housing 100 and at least one battery cell 200. The at least one battery cell 200 is housed within the housing 100. The battery cell 1000 also includes a buffer member 300. The buffer member 300 is housed within the housing 100 and is disposed corresponding to the sidewall of the battery cell 200. The buffer member 300 has a receiving cavity 305, and the outer periphery of the receiving cavity 305 includes at least one encapsulation structure 3010. The encapsulation structure 3010 includes at least one encapsulation region 3012 with a predetermined length. When the pressure within the receiving cavity 305 exceeds the encapsulation strength of the encapsulation structure 3010, the encapsulation region 3012 opens and forms a buffer space communicating with the receiving cavity 305.

[0092] The cushioning element 300 is housed within the housing 100 and is a cavity structure with an internal receiving cavity 305 and a closed outer periphery. The cushioning element 300 can be a bag-shaped structure, which can be formed by folding a piece of flexible material in half and sealing the edges, or by placing two pieces of flexible material opposite each other and sealing the edges.

[0093] The buffer 300 and the first sidewall 203 of the cell 200 are correspondingly disposed to fill the gap between the housing 100 and the first sidewall 203 of the cell 100. In this application, the housing 100 provides initial pores for the expansion of the cell 200 during use. However, the presence of these initial pores increases the movement space of the cell 200 within the housing 100, causing the winding structure of the cell 200 to become loose, leading to wrinkles in the positive and negative electrode sheets and resulting in lithium plating. In the battery cell 1000 structure of this embodiment, the buffer 300 is provided within the housing 100, which can effectively fill the gap and prevent lithium plating on the electrode sheets.

[0094] The outer periphery of the receiving cavity 305 of the buffer 300 includes at least one encapsulation structure 3010 for sealing the receiving cavity. One encapsulation structure 3010 can be provided on the outer periphery of the receiving cavity 305 so that the receiving cavity 305 can gradually increase in volume as the battery cell 200 expands with the increase in battery usage time. Multiple encapsulation structures 3010 can also be provided on the outer periphery of the receiving cavity 305, and the increased volume can be arranged according to the internal space layout of the battery cell housing 100 to fully utilize these internal gaps and alleviate the pressure of the battery cell 100 expansion.

[0095] The encapsulation region 3012 is a structural region where the encapsulation material of the outer periphery of the buffer 300 is pressed into a single layer. After the encapsulation material in this region is pressed into a single layer, it does not form a cavity. The encapsulation region 3012 can be formed with different thicknesses depending on the magnitude of the pressing force. When the pressing force is large, the thickness of the encapsulation region 3012 is small, and the force required to open the encapsulation region is relatively large; when the pressing force is small, the thickness of the encapsulation region is large, and the force required to open the encapsulation region is relatively small.

[0096] The package structure 3010 includes at least one package region having a predetermined length, such as... Figure 4 As shown, the encapsulation structure 3010 on the outer periphery of the buffer 300 has three-level encapsulation regions with lengths L2, L4, and L6. Each encapsulation region has a predetermined length. When the encapsulation region is opened, forming upper and lower layers of encapsulation material, the encapsulation region forms a buffer space with a certain volume. When the pressure of the receiving cavity due to the expansion of the battery cell 200 continues to increase and exceeds the pressure threshold of the first encapsulation region, the first-level encapsulation region opens and connects with the receiving cavity, increasing the volume of the receiving cavity and releasing the pressure in the receiving cavity. When the pressure of the receiving cavity due to the expansion of the battery cell 200 continues to increase and exceeds the pressure threshold of the second-level encapsulation region, the second-level encapsulation region opens, allowing the receiving cavity to continue to increase in volume and relieving the pressure in the receiving cavity. The length and number of the encapsulation regions can also be set according to actual needs. For example, within the casing 100 of the battery cell 1000, the buffer 300 includes a second-level encapsulation region, which can be opened separately when the pressure inside the receiving cavity continues to increase.

[0097] When the encapsulation area 3010 is opened and connected to the receiving cavity 305, the overall thickness of the buffer component becomes thinner, thereby providing space for the expansion of the battery cell. Due to the expansion of the battery cell 200, the receiving cavity is compressed. When the compressive force reaches a predetermined pressure value, the encapsulation area of ​​a predetermined length on the outer periphery of the receiving cavity is opened, increasing the volume of the receiving cavity and transferring the expansion pressure to the outer periphery of the receiving cavity. The encapsulation area of ​​the buffer component can be set according to the internal space of the housing 100, thus making full use of the space at both ends of the battery cell in the height direction where the expansion is less, and also making full use of the redundant space of the tab portion in the height direction of the battery cell. The buffer component 300 can be made of a flexible material. Due to the strong deformability of the receiving cavity brought by the flexible material, the encapsulation structure of the buffer component does not need to be strictly set to correspond to the gap space existing after the battery cell expands; these gaps can be filled by pressure and the deformation ability of the flexible material.

[0098] Therefore, in summary, by correspondingly configuring the buffer to the battery cell, this embodiment effectively fills the initial gap between the battery cell and the casing when the battery cell has not expanded, preventing the battery cell winding structure from becoming loose and avoiding lithium plating on the electrode sheets. Furthermore, when the battery cell expands during use, the buffer deforms under the pressure of the expanding battery cell. When the expansion pressure of the battery cell is low, the deformation of the buffer is small. However, as the expansion pressure gradually increases to a certain extent, the encapsulation area of ​​the buffer gradually opens, the accommodating cavity space gradually increases, and the deformation of the buffer gradually increases, thereby alleviating the pressure caused by the battery cell expansion. This ensures that the gap between the battery cell and the casing is filled by the buffer throughout the entire lifespan of the battery cell, reducing the impact of battery cell expansion on the electrode sheets and preventing lithium plating.

[0099] In some embodiments of this application, the buffer is disposed corresponding to the intermediate sidewall portion in the cell height direction. For example... Figure 3 The diagram shows a cross-sectional view of a battery cell along its height (Y-axis). The sidewall of the cell refers to the outer wall of the cell 200 parallel to the height direction (Y-axis), including the outer wall along the cell thickness direction (X-axis) and the outer wall along the cell width direction (Z-axis). A tab 205 is provided along the height direction (Y-axis) of the cell. In a battery cell, gaps exist between the cell sidewall and the casing sidewall, and between the cell tab and the casing. During use, the cell's expansion force is generated in various directions, including along the cell sidewall and along the cell tab. Therefore, the buffer can be provided at any part of the cell to fill the gaps and alleviate the expansion force caused by the cell's expansion.

[0100] During their research, the inventors of this application discovered that during the use of a battery cell, the expansion forces generated in its thickness and width directions are the most significant and have the greatest impact on the cell. In this embodiment, the buffer member 300 is correspondingly positioned with the middle sidewall portion of the cell 200. The middle sidewall portion is the area between the two ends of the cell in the height direction, including the sidewall in the thickness direction (X-axis direction) and the sidewall in the width direction (Z-axis direction). The corresponding positioning means that the buffer member 300 and the cell 200 are disposed within the housing 100, and at least a portion of the buffer member 300 is in contact with the middle sidewall of the cell 200. Figure 3 As shown, the buffer 300 is attached to the first sidewall 203 of the battery cell, and the buffer 300 is located in the middle sidewall portion of the battery cell 200. In this embodiment, by correspondingly arranging the buffer 300 with the middle sidewall portion of the battery cell 200, the expansion force of the battery cell 200 can be mitigated to the greatest extent.

[0101] According to some embodiments provided in this application, the buffer 300 may be disposed between the battery cell 200 and the side wall of the housing 100. (Continue to refer to...) Figure 3 The buffer 300 is disposed between the first sidewall 203 of the battery cell and the sidewall of the housing 100. In some embodiments, such as Figure 3 As shown, the battery cell includes two cells 200, and the buffer 300 is disposed between each cell 200 and the side wall of the housing 100. When there is only one cell, the buffer can be disposed at the position corresponding to one side wall of the cell, and the other side of the cell is against the side wall of the housing. Alternatively, buffers can be disposed between the two side walls of the cell 200 and the side wall of the housing 100 respectively.

[0102] According to some embodiments provided in this application, optionally, the buffer 300 may also be disposed between adjacent battery cells 200, such as... Figure 5 As shown, another battery cell 1000 structure is illustrated. The battery cell 1000 includes a housing 100, a battery cell 200, and a buffer member 300. The battery cell 200 and the buffer member 300 are disposed within the housing. The buffer member 300 is disposed between adjacent battery cells 200. One side of each battery cell 200 corresponds to the side wall of the housing 100, and the other side corresponds to the buffer member 300. Figure 5 The battery cell structure shown indicates that when the cell expands, it bulges out towards the buffer, thereby squeezing the buffer from both sides. The buffer provides buffer space for the cell expansion by gradually opening the encapsulation area. The battery cell occupies relatively little space, resulting in a high group margin for the battery cell.

[0103] According to some embodiments, optionally, the buffer 300 and the battery cell 200 can also be arranged in a mixed manner, that is, the buffer can be simultaneously arranged between the battery cell and the side wall of the housing and between adjacent battery cells, such as... Figure 3 The battery cell structure shown can have buffers between the cell sidewalls and the casing sidewalls, as well as between the cells themselves. Figure 3 In the structure of a single battery cell, there are two cells and three buffer components working together. When there are multiple cells in the single battery cell, the mixed arrangement provided in this embodiment can solve the problem of cell expansion to the greatest extent.

[0104] According to some embodiments proposed in this application, the encapsulation structure of the buffer 300 is located at one or both ends of the buffer 300 along the height direction of the battery cell. For example... Figure 3 As shown, tabs 205 are provided along the height direction (Y-axis direction) of the battery cell, and there is a gap between the tabs 205 and the housing 100. The encapsulation structure of the buffer 300 is disposed at one or both ends of the buffer 300 along the height direction of the battery cell. During battery cell use, this can alleviate the pressure caused by cell expansion and facilitate the expansion of the buffer encapsulation structure into the gap along the height direction of the battery cell, filling the gap and preventing lithium plating. Furthermore, an end cap 400 is provided on the housing 100 at a position corresponding to the tabs 205. To release internal pressure within the battery cell, in some battery cell structures, the end cap 400 is also provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of the battery cell reaches a threshold. By setting the encapsulation structure of the buffer 300 at one or both ends of the buffer 300 along the height direction of the battery cell, when the buffer is subjected to a sufficiently large expansion force from the battery cell, and all encapsulation structures are opened, the inert material in the accommodating cavity can be easily discharged through the pressure relief mechanism on the end cap, thereby reducing the impact of battery cell expansion.

[0105] Figure 6a and Figure 6b A schematic diagram showing the arrangement of the encapsulation structure on the buffer is shown. Figure 6aIn this configuration, the encapsulation structure 3210 is located at both ends of the buffer member 320 along its height direction. When the buffer member is adapted to the battery cell, and the height direction of the buffer member is consistent with the height direction of the battery cell, the encapsulation structure 3210 is located at both ends of the buffer member 320 along the height direction of the battery cell. During use, when the buffer member 320 is compressed by the expansion force of the battery cell, the receiving cavity will compress the encapsulation structure towards both ends of the buffer member along its height direction. This provides space for the expansion and release of the battery cell, and also expands into the gaps along the height direction of the battery cell, filling the gaps and preventing lithium plating from occurring in the battery cell. Figure 6b Another arrangement of the encapsulation structure on the buffer is shown; the encapsulation structure 3210 may also be disposed only at one end of the buffer 320 in the height direction, such as... Figure 6b As shown, one end of the buffer is provided with an encapsulation structure, and the other end is the outer wall of the receiving cavity. When the buffer 320 is squeezed by the expansion force of the battery cell, the receiving cavity will squeeze the encapsulation structure towards one end of the buffer in the height direction. The encapsulation structure gradually cracks at one end of the buffer in the height direction, which provides space for the expansion and release of the battery cell and gradually fills the gap at one end of the battery cell in the height direction.

[0106] The above embodiments, by placing the packaging structure at one or both ends in the height direction of the cell, can alleviate the pressure caused by cell expansion on the one hand, and facilitate the expansion of the packaging structure of the buffer component into the gap in the height direction of the cell on the other hand, filling the gap in the height direction of the cell and preventing lithium plating from occurring in the cell.

[0107] Optionally, to adapt to different battery cell structures, some embodiments of this application also propose that the encapsulation structure be disposed at one or both ends of the buffer in the width direction, such as... Figure 6c and Figure 6d As shown.

[0108] like Figure 6c As shown, the encapsulation structure 3210 is located at both ends of the buffer member in the width direction. When the buffer member 320 is adapted to the battery cell, and the height direction of the buffer member is consistent with the height direction of the battery cell, the encapsulation structure 3210 is located at both ends of the buffer member along the width direction of the battery cell. When the buffer member 320 is squeezed by the expansion force of the battery cell, the receiving cavity will squeeze the encapsulation structure towards both ends of the buffer member in the width direction, and the encapsulation structure is gradually opened, gradually releasing space. Of course, the encapsulation structure 3210 can also be only provided at one end of the buffer member 320 in the width direction, such as... Figure 6d As shown, the other end is the outer wall of the receiving cavity. When the buffer 320 is squeezed by the expansion force of the battery cell, the receiving cavity will squeeze the encapsulation structure towards one end of the buffer in the width direction and gradually release the space.

[0109] Optionally, to adapt to different battery cell structures, some embodiments of this application also propose to respectively arrange the encapsulation structure at one or both ends of the buffer in the height direction and the width direction, such as... Figure 6e and Figure 6f As shown.

[0110] like Figure 6e As shown, the encapsulation structures 3210 and 3211 are located at both ends of the buffer in the width direction and the height direction, respectively. When the buffer 320 is adapted to the battery cell, and the height direction of the buffer is consistent with the height direction of the battery cell, the encapsulation structure 3210 is located at both ends of the buffer along the width direction of the battery cell, and the encapsulation structure 3211 is located at both ends of the buffer along the height direction of the battery cell. When the buffer 320 is squeezed by the expansion force of the battery cell, the receiving cavity will simultaneously squeeze the encapsulation structure towards both ends of the buffer in the width and height directions. In this way, the encapsulation structure can release space in four directions simultaneously, and can quickly release space under the pressure of the battery cell's expansion force. Of course, the encapsulation structure 3210 can also be only located at one end of the buffer 320 in the width direction, and the encapsulation structure 3211 can also be only located at one end of the buffer 320 in the height direction, as shown. Figure 6f As shown, when the buffer 320 is squeezed by the expansion force of the battery cell, the receiving cavity will squeeze the packaging structure towards one end in the width direction and one end in the height direction of the buffer, and gradually release the space.

[0111] The above embodiments illustrate the arrangement of the encapsulation structure on the buffer, wherein the encapsulation structure is located at one end and / or both ends of the buffer in the height and / or width directions. In practical applications, the encapsulation structure can be arranged in various ways and in various combinations of positions, all of which cannot deviate from the scope of the content described in the above embodiments of this application.

[0112] According to some embodiments of this application, the height of the receiving cavity in the height direction of the battery cell is 10% to 90% of the battery cell height. The height of the receiving cavity can be flexibly set according to the performance of the battery cell. When the battery cell has a large coefficient of expansion, a smaller receiving cavity can be set, and more encapsulation structures can be arranged in the remaining height area. This allows the receiving cavity of the buffer to open the encapsulation structure and gradually release a larger space when squeezed by the expansion force of the battery cell. For example, when the battery cell expansion force is large, the height of the receiving cavity can be set to 10% of the battery cell height, and encapsulation structures can be arranged in the remaining height area. When the battery cell is squeezed by the expansion force, after the encapsulation area opens, the thickness of the buffer will be reduced by about 90%, greatly increasing the space for the battery cell expansion. When the battery cell expansion force is small, in order to better fill the initial gap between the battery cell and the casing, the height of the receiving cavity can be 90% of the battery cell height. Of course, other heights can also be set according to the performance of the battery cell, such as 50% to 85% or 60% to 80%. Such height ratios are relatively close, which better balances the need for space release and the need to fill the gap between the battery cell and the casing.

[0113] Therefore, by setting the height of the receiving cavity to be in a certain proportion to the height of the battery cell, the above-described embodiment allows for the arrangement of the encapsulation structure in the remaining height area when the height direction is not fully filled. The arrangement of the receiving cavity and the encapsulation structure can be flexibly arranged according to the performance of the specific battery cell, making the setting of the buffer more flexible.

[0114] According to some embodiments proposed in this application, the packaging structure includes at least two levels of packaging regions with different packaging strengths, such that as the pressure inside the receiving cavity increases, the packaging regions open step by step, and gradually form buffer spaces communicating with the receiving cavity. Figure 4 The diagram shown is a schematic of a buffer structure provided in an embodiment of this application. The buffer adopts a three-level encapsulation structure. Of course, the buffer can also adopt other forms of encapsulation structure such as two-level or four-level.

[0115] The buffer 300 includes an encapsulation structure 3010, which includes a first encapsulation region 3012, a second encapsulation region 3014, and a third encapsulation region 3016. The first encapsulation region 3012 is close to the receiving cavity 305. When the expansion force of the battery cell squeezes the buffer, the pressure inside the receiving cavity causes the first encapsulation region to crack first. Therefore, the sealing layer of the first encapsulation region is compressed the least and has the weakest strength. Compared with the first encapsulation region, the second encapsulation region has increased encapsulation strength, and so on, with the third encapsulation region having the highest encapsulation strength. This achieves an encapsulation structure with a gradient change in encapsulation strength. There is approximately a 1 N / mm difference in encapsulation strength between different encapsulation regions. For example, the encapsulation strength of the first encapsulation region is 1 N / mm, the encapsulation strength of the second encapsulation region is 3 N / mm, and the encapsulation strength of the third encapsulation region is 5 N / mm; or the encapsulation strength of the first encapsulation region is 1 N / mm, the encapsulation strength of the second encapsulation region is 5 N / mm, and the encapsulation strength of the third encapsulation region is 8 N / mm. It should be noted that the different encapsulation strengths reflect the tolerance to different cell expansion forces. Therefore, in actual use, the encapsulation strength needs to be set according to the characteristics of the cell and the specific usage environment.

[0116] Furthermore, such as Figure 4 As shown, in order to allow different spaces to be released when the sealed area cracks, the embodiments of this application set predetermined lengths for different encapsulation areas, such as... Figure 4 In this design, the encapsulation length of the first encapsulation region 3012 is L2, the encapsulation length of the second encapsulation region is L4, and the encapsulation length of the third encapsulation region is L6. The encapsulation lengths of the different encapsulation regions can be the same or different. When the encapsulation lengths are the same, each encapsulation region can release the same space when it cracks. When the encapsulation lengths are different, different spaces can be released at different stages, allowing for adjustment of the released space. In this application, there is no specific limitation on the encapsulation length. In actual use, the user can determine it independently based on the characteristics of the battery cell. For example, in the early stages of battery cell use, its expansion force is small, and the space occupied after the battery cell expands is small, so the encapsulation length of the first encapsulation region can be set smaller. As the battery cell is used, its expansion force gradually increases, and the space occupied during each expansion gradually increases, so the encapsulation lengths of the second and third encapsulation regions can be gradually increased to gradually release more space.

[0117] As the expansion force of the battery cell gradually increases, the pressure on the receiving cavity gradually increases. When the pressure exceeds the sealing strength of the first packaging area, the first packaging area cracks first. After the first packaging area cracks, the space inside the receiving cavity increases, and the thickness of the buffer component decreases. Similarly, when the second and third packaging areas crack, the space released by the buffer component gradually increases. When the third packaging area is expanded, the buffer component is in a state of maximum space release, that is, the buffer component is in a state of minimum space occupation. That is, the space occupied by the buffer component is only the thickness of the aluminum-plastic film, with an incompressible thickness of less than or equal to 1 mm and a mass density of less than or equal to 0.5 kg / m2. This has a very small impact on the volume and weight of the battery cell.

[0118] According to some embodiments proposed in this application, at least two levels of packaging regions are arranged continuously; and / or at least two levels of packaging regions are arranged at intervals, with a buffer of a predetermined length between adjacent two levels of packaging regions.

[0119] Further reference Figure 4 To increase the space that the buffer can release when compressed by the expansion force of the battery cell, embodiments of this application arrange at least two levels of the packaging regions at intervals, with a buffer of a predetermined length provided between adjacent two levels of packaging regions. Figure 4 As shown, a first buffer zone 3011 of a predetermined length is provided between the receiving cavity 305 and the first encapsulation area 3012. The first buffer zone 3011 is an unheat-sealed area. The unheat-sealed area means that the sealing layer of the buffer material is only attached together and is not heat-sealed. In this way, when the receiving cavity 305 is squeezed by the expansion force of the battery cell, the unheat-sealed aluminum-plastic film will be stretched open, thereby releasing more space.

[0120] like Figure 4As shown, a first buffer zone 3011 of length L1 is provided between the receiving cavity 305 and the first encapsulation region 3012; a second buffer zone 3013 of length L3 is provided between the first encapsulation region 3012 and the second encapsulation region 3014; and a third buffer zone 3015 of length L5 is provided between the third encapsulation region 3016 and the second encapsulation region 3014. These multiple buffer zones divide the encapsulation region 3010 into multiple encapsulation regions. On the one hand, this can block heat radiation between different encapsulation regions; on the other hand, it can provide more release space for the receiving cavity. The lengths of the different buffer zones can be set as needed; they can be the same or different. When the lengths of the buffer zones are the same, the same space can be released when each buffer zone breaks open; when the lengths of the buffer zones are different, different spaces can be released at different stages, allowing for adjustment of the release space. In this application, the length of the buffer zone is not specifically limited. In actual use, the user can determine it independently according to the characteristics of the battery cell. For example, in the early stage of battery cell use, its expansion force is small and the space occupied after the battery cell expands is small, so the length of the first buffer zone can be set to be smaller. As the battery cell is used, the expansion force of the battery cell gradually increases and the space occupied each time it expands gradually increases, so the length of the second buffer zone and the length of the third buffer zone can be gradually increased in order to gradually release more space.

[0121] To more accurately describe the changing state of the aforementioned buffer during the use of the battery cell, embodiments of this application... Figure 7 The document describes the state changes of a buffer component with spaced encapsulation areas during use. For example... Figure 7 The diagram illustrates the working state of the buffer component under the pressure of the battery cell's expansion force. State 1 represents the state of the buffer component when the expansion force from the battery cell is relatively small, with both the buffer area and the encapsulation area of ​​the buffer component in their initial states. When the receiving cavity of the buffer component is compressed by the expansion force of the battery cell, since the buffer zone is not heat-sealed, it can withstand the least pressure, so the first buffer zone is opened first. When the pressure generated in the receiving cavity on the first encapsulation area exceeds the encapsulation strength of the first encapsulation area, the first encapsulation area and the second buffer zone are opened, and the resulting buffer space communicates with the receiving cavity, as shown below. Figure 7 As shown in state 2, the thickness of the receiving cavity is significantly reduced, and its length is increased, thus freeing up more space for the expansion of the battery cell. When the buffer is subjected to a further increase in the expansion force of the battery cell, the receiving cavity further compresses the second packaging area. When the pressure on the second packaging area exceeds the packaging strength of the second packaging area, the second packaging area and the third buffer zone are opened, and the buffer space formed therein communicates with the receiving cavity, as shown in state 2. Figure 7As shown in state 3, the thickness of the cavity is further reduced and the length of the cavity is further increased, thereby freeing up more space for the expansion of the battery cell.

[0122] Normally, the sealing strength of the third encapsulation area is set relatively high, and it is usually not opened. However, in extreme cases, when the expansion force of the battery cell on the buffer exceeds the encapsulation strength of the third encapsulation area, the receiving cavity is completely opened, and the two sides of the receiving cavity are completely sealed together, occupying only the thickness of the aluminum-plastic film on both sides of the receiving cavity. This shows that by setting up multiple encapsulation areas, more buffer space is provided for the expansion of the battery cell, greatly mitigating the impact of the expansion force.

[0123] In this embodiment of the application, at least two levels of the encapsulation regions can also be arranged continuously, specifically as follows: Figure 8 As shown, the buffer 300 has a trapezoidal encapsulation structure 3010. The encapsulation areas of the encapsulation structure 3010 are continuously arranged. The sealing layer on the side of the encapsulation structure 3010 closer to the receiving cavity 305 has less compression and weaker strength, while the sealing layer on the encapsulation area farther from the receiving cavity 305 has greater compression and higher strength, resulting in greater encapsulation strength. For example, the strength of the long-side sealing layer can be 1 N / mm, and the strength of the short-side sealing layer can be 5 N / mm, with the encapsulation strength of the encapsulation structure gradually increasing from 1 N / mm to 5 N / mm. In practical use, the encapsulation strength needs to be set according to the characteristics of the battery cell and the specific usage environment. Preferably, the encapsulation strength can be set to 0.1–50 MPa. In this embodiment, the encapsulation strength of the continuously packaged trapezoidal encapsulation structure gradually changes, so that when the cavity is subjected to the expansion force of the battery cell, the encapsulation structure 3010 gradually cracks open. This makes the space released by the buffer 300 more continuous, avoiding the sudden spatial changes caused by the space release of the space in the space-spaced encapsulation structure. This makes the resistance of the buffer on the battery cell more stable, greatly improving the service life of the battery cell.

[0124] To more accurately describe the changing state of the aforementioned buffer during the use of the battery cell, embodiments of this application... Figure 9 The document provides details on the state changes of a buffer component with continuously arranged encapsulated areas during use. For example... Figure 9As shown, during battery cell use, the expansion force of the cell gradually increases. Under the pressure of the receiving cavity, the encapsulation area gradually cracks open. From state 1 to state 2, the thickness of the buffer gradually decreases, and the length of the receiving cavity gradually increases; from state 2 to state N, the receiving cavity gradually thins out. Because the encapsulation area cracks gradually, gaps between the cell and the buffer are avoided when too much buffer space is released at once, which could cause cell shaking. The trapezoidal encapsulation structure with continuously arranged encapsulation areas effectively avoids abrupt changes in the release space caused by the buffer. This not only provides space for the cell's expansion but also ensures that the pressure exerted on the cell by the buffer is more continuous, thus improving the battery cell's lifespan.

[0125] According to some embodiments proposed in this application, at least two levels of packaging regions are arranged along the height direction of the cell, and the packaging regions farther from the receiving cavity have greater packaging strength. For example... Figure 4 and Figure 8 As shown, when the receiving cavity 305 is compressed by the expansion force of the battery cell, the at least two-level packaging regions 3010, which are continuously arranged or spaced apart, need to be opened separately. To facilitate opening, the at least two-level packaging regions 3010 are arranged along the height direction of the battery cell, so that the packaging regions 3010 can be opened and expanded along the height direction of the battery cell. Furthermore, in order to allow the packaging structure to be opened gradually, as... Figure 4 and Figure 8 As shown, the sealing layer of the encapsulation structure 3010 near the receiving cavity 305 has less compression and weaker strength, while the sealing layer in the encapsulation area farther from the receiving cavity 305 has greater compression and stronger strength, resulting in greater encapsulation strength. By arranging at least two levels of encapsulation areas along the height direction of the battery cell and setting a greater encapsulation strength in the encapsulation area farther from the receiving cavity, the buffer can easily expand gradually towards the height direction of the battery cell, gradually releasing space as the battery cell expansion pressure increases.

[0126] According to some embodiments of this application, the pressure inside the containment cavity is greater than or equal to the gas pressure inside the battery cell. Since the casing provides an initial gap for the expansion of the battery cell during use, this gap increases the space for the battery cell to move within the casing, causing the winding structure of the battery cell to loosen, leading to wrinkles in the positive and negative electrode sheets and resulting in lithium plating. Therefore, embodiments of this application set the pressure inside the containment cavity to be greater than or equal to the gas pressure inside the battery cell. For example, if the initial gas pressure inside the battery cell is 0.1–0.2 MPa, the pressure inside the containment cavity can be set to 0.1–0.5 MPa. Because the pressure inside the containment cavity is greater than the gas pressure inside the battery cell, the containment cavity exerts a certain pressure on the battery cell, thereby ensuring that the battery cell remains fully filled even with low cell margins, thus preventing lithium plating caused by electrode wrinkles.

[0127] According to some embodiments of this application, the encapsulation strength of the buffer structure is 0.1–50 MPa. To seal the material within the cavity and to ensure the encapsulation structure can crack promptly after the battery cell expands to a certain extent, the buffer structure has strict requirements for encapsulation strength. On one hand, the encapsulation strength must be greater than the pressure of the material within the cavity; on the other hand, it must be able to crack quickly after the expansion force generated by the battery cell reaches a certain threshold. Since the pressure within the cavity is typically 0.1–0.2 MPa, and considering the pressure during battery cell expansion, the preferred range for encapsulation strength is 0.1–50 MPa. Furthermore, because the encapsulation area farther from the cavity has a higher encapsulation strength, the encapsulation strength varies between different areas. For example, the encapsulation strength of the area closest to the cavity is 0.1 MPa, while the encapsulation strength of the area farthest from the cavity is 50 MPa.

[0128] According to some embodiments proposed in this application, the battery cell is a square battery cell, and a buffer is disposed at one or both ends of the battery cell in the thickness direction; and / or a buffer is disposed at one or both ends of the battery cell in the width direction. Figure 10 As shown, for ease of explanation, the height direction of the battery cell is defined as the Y-axis direction, the thickness of the battery cell as the X-axis direction, and the width direction of the battery cell as the Z-axis direction. In the embodiments of this application, the buffer is disposed at one or both ends of the battery cell in the thickness direction. Figure 10 As shown, the battery cell 1000 includes a casing 100, a first cell 210, a second cell 220, a first buffer 310, a second buffer 320, and an end cap 400. The first cell 210 and the second cell 220 have the same structure; this embodiment uses the second cell 220 as an example for illustration. Figure 10As shown, the second battery cell 220 has a square structure, including a first sidewall 2203 and a first corner 2205. The first sidewall 2203 is one end of the battery cell 200 in the thickness direction (Z-axis direction), and the first corner 2205 is one end of the battery cell 200 in the width direction (X-axis direction). The first buffer 310 includes a first encapsulation structure 3110, and the second buffer 320 includes a second encapsulation structure 3210.

[0129] The second buffer 320 is disposed between the inner wall of the housing 100 and the first side wall 2203 of the second battery cell, and the first buffer 310 is also disposed between the side wall of the first battery cell 210 and the inner wall of the housing 100. Alternatively, another buffer can be disposed between the side walls of the first battery cell 210 and the second battery cell 220 to increase the expansion space of the battery cell. By disposing the buffer at one or both ends of the battery cell in the thickness direction, space can be provided on both sides of the battery cell for expansion during use.

[0130] like Figure 11 The diagram shown is a structural diagram of another battery cell proposed in this application embodiment. In this embodiment, the buffer is disposed at one or both ends of the cell in the width direction. Figure 10 In contrast, the second buffer 320 is disposed on one side of the first corner 2205 and the second corner 2105 of the second battery cell, and the width of the second buffer 320 is approximately equal to the sum of the thicknesses of the first battery cell 210 and the second battery cell 220. Similarly, a first buffer 310 may also be disposed on one side of the other corner of the first battery cell 210 and the second battery cell. The encapsulation areas of the first and second buffers may be located in the height direction (Y-axis direction) or the thickness direction (X-axis direction) of the battery cell.

[0131] Furthermore, regarding Figure 10 and Figure 11 The battery cell can also have buffers installed at one or both ends in the thickness direction and at one or both ends in the width direction. This is equivalent to having buffers installed on all four sides of the cell. In this way, the expansion force of the cell in all directions can be relieved.

[0132] According to some embodiments proposed in this application, when the buffer is disposed at one or both ends of the battery cell in the thickness direction, the width of the receiving cavity in the width direction of the battery cell is 50% to 100% of the width of the battery cell. For example... Figure 10As shown, the first buffer 310 is respectively disposed at one or both ends of the first battery cell 210 and the second battery cell 220 in the thickness direction. The width of the battery cell is K2, and the width of the buffer is K1. In order to better fit the buffer with the sidewall of the battery cell, generally, when the packaging structure of the buffer is located at one or both ends of the battery cell in the height direction, the width of the buffer is the same as the width of its receiving cavity. Preferably, the maximum width of the receiving cavity is 100% of the battery cell width. Alternatively, depending on the expansion of the battery cell, the width of the receiving cavity can be set to 80% of the battery cell width, leaving appropriate space on both sides of the battery cell. Similarly, when the expansion coefficient of the battery cell is small, the width of the receiving cavity can be set to 50% of the battery cell width. It should be noted that the ratio of the width of the receiving cavity to the width of the battery cell can be adjusted according to the expansion of the battery cell, and adjusted within the above range according to actual needs.

[0133] According to some embodiments of this application, the receiving cavity has an annular cross-section in the height direction of the battery cell, continuously surrounding the battery cell. In some embodiments of this application, various types of buffers are also provided to adapt to different battery cell structures, such as annular columnar buffers, rectangular buffers, and polygonal annular buffers, etc.

[0134] like Figure 12 The diagram shows a schematic of an annular buffer 330 provided in an embodiment of this application. The annular buffer 330 is an annular columnar structure adapted to a cylindrical battery cell. The annular buffer 330 includes an annular encapsulation structure 3310, which is located at one or both ends of the annular buffer 330 along the height direction of the battery cell. When the annular buffer 330 is disposed together with the cylindrical battery cell, the annular buffer continuously surrounds the battery cell, and the accommodating cavity of the annular buffer has an annular cross-section in the height direction of the battery cell.

[0135] like Figure 13 The rectangular buffer 340 shown is a rectangular ring structure adapted to a square battery cell. The rectangular buffer 340 includes an encapsulation structure 3410. The accommodating cavity of the rectangular buffer has a rectangular cross-section in the height direction of the battery cell, continuously surrounding the battery cell. The rectangular encapsulation structure is located at one or both ends of the rectangular buffer along the height direction of the battery cell. In use, the rectangular buffer 340 wraps around the battery cell.

[0136] The above embodiments, by setting the buffer in a variety of ring structures, can surround the battery cell and form a buffer around the battery cell. On the one hand, it can effectively fill the gaps between the battery cell and the casing at various positions at the beginning, avoiding lithium plating caused by battery cell shaking. On the other hand, it can also provide space for the expansion of the battery cell in various directions around the battery cell when the battery cell expands.

[0137] According to some embodiments proposed in this application, the material of the buffer 300 has an outer protective layer and an inner sealing layer, and the encapsulation area of ​​the buffer is formed by heat-sealing the inner sealing layer. For example... Figure 14 The diagram shows the structure of the buffer material. The protective layer, located on the outer layer of the buffer, primarily serves to prevent scratches and corrosion. It can be a single material or a combination of multiple materials such as polyester resin, polyamide resin, Teflon, and aluminum. The inner sealing layer primarily serves to tightly seal and isolate the internal material from external substances. It can be a single material or a combination of multiple materials such as polyolefin, resin, and silicone adhesive. The aluminum-plastic film has good elasticity, which can fully release the expansion force during charging and discharging, ensuring uniform expansion force in the central area, reducing polarization differences, and avoiding localized lithium plating or electrode breakage caused by polarization. Preferably, in this embodiment, aluminum-plastic film is used as the material for making the buffer. It should be noted that other materials can also be used instead of aluminum-plastic film to make the buffer, as long as the requirements of elasticity and sealing are met. This application does not limit the use of these materials.

[0138] In some embodiments of this application, Figure 15 The diagram illustrates the molding process of the buffer 300 and a cross-sectional view of the buffer 300. The buffer is formed by pressing an aluminum-plastic film 301. The aluminum-plastic film 301 undergoes a die-punching process to create a recess with a certain depth and area at its center. The punched aluminum-plastic film is then heat-sealed together. During heat sealing, the inner sealing layer melts and adheres to the film, forming an encapsulation area 3010. The encapsulation area 3010 seals the recess, forming a receiving cavity 305. The inner sealing layer seals the contents of the receiving cavity, while the outer protective layer protects the sealing layer. During molding, two pressed aluminum-plastic films can be sealed together vertically to form the buffer; alternatively, a punched aluminum-plastic film can be folded in half and directly sealed to form the buffer. After punching and sealing the aluminum-plastic film, at least one encapsulation structure and a receiving cavity are formed on the outer periphery of the buffer. Of course, it should be noted that the above embodiments use heat sealing as an example to illustrate the formation of the encapsulation area. Optionally, other processes can also be used to form the encapsulation area, such as adhesive bonding, etc., which are not limited here. By adopting the above process structure, the manufacturing process is simple, the sealing effect is good, and it is easy to manufacture various buffer components adapted to the battery cell structure.

[0139] According to some embodiments of this application, the receiving cavity of the buffer is filled with an inert fluid. In embodiments of this application, to enhance the effectiveness of the buffer, during encapsulation, the receiving cavity of the buffer can be filled with a deformable inert fluid substance, such as argon, nitrogen, paraffin, or silicone oil. In the case of non-pure liquid filling, the pressure of the receiving cavity is not lower than the pressure of the residual space inside the battery cell (typically, the pressure inside the battery cell is 0.1–0.2 MPa); when pure liquid is used for filling, the receiving cavity is completely filled. By filling the receiving cavity with an inert substance, this application avoids the expansion of the receiving cavity of the buffer due to the substances or materials it contains when the battery cell temperature rises, thereby preventing the expansion of the buffer itself from compressing the expansion space of the battery cell.

[0140] According to some embodiments proposed in this application, a battery 2100 is also proposed, such as... Figure 16 As shown, the battery may include one or more battery cells 1000 as described in the above embodiments, and a busbar component 2101.

[0141] The busbar component 2101 connects the one or more battery cells 1000 in series or in parallel.

[0142] The one or more battery cells 1000 include at least a cell 200 and a buffer 300. The buffer 300 adopts the encapsulation structure mentioned in the above embodiments and is disposed corresponding to the side wall of the cell 200. It is used to open the encapsulation structure when the cell 200 expands, so as to provide buffer space for the expansion of the cell.

[0143] According to some embodiments of this application, an electrical device is also provided, comprising the battery 2100 described in the above embodiments, the battery being used to provide electrical energy to the electrical device. The electrical device may be, but is not limited to, a mobile phone, tablet, laptop, electric toy, power tool, electric vehicle, electric car, ship, spacecraft, etc. Among them, electric toys may include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft may include airplanes, rockets, space shuttles, and spacecraft, etc.

[0144] In order to better demonstrate the technical effects of the technical solutions proposed in the embodiments of this application, the applicant has made the following improvements. Figures 17 to 19 The cell expansion force of the provided battery cells was tested. Figure 17 This is a commonly used battery cell structure. In this battery cell structure, no buffer is used to handle expansion forces. Figure 18The battery cell shown has a buffer component positioned between its sidewall and the casing. This buffer component is encapsulated using a spaced-out packaging structure. Figure 19 The battery cell has a buffer component located between its side wall and the casing. The buffer component is encapsulated using a continuously packaged trapezoidal packaging structure.

[0145] The applicant conducted the following tests on the battery cells using the above three structures:

[0146] Test 1:

[0147] Battery cell structure such as Figure 17 As shown, the battery includes cell 200 and casing 100, excluding buffer components. The LFP positive / negative electrode / separator is wound into a core, which is then cold-pressed. This is followed by tab welding, casing insertion, top cover welding, baking, and electrolyte injection until the finished battery cell is placed in the storage chamber. The finished battery cell dimensions are 40*200*100mm. The core full-charge group margin (core full-charge group margin = core thickness at 100% SOC / casing internal thickness) is 98%, and the cell full-charge group margin (cell full-charge group margin = (core thickness at 100% SOC + initial buffer cavity thickness) / casing internal thickness) is 98%, with a rated capacity of 100Ah. The battery cell is tested with a three-piece aluminum plate clamp and sensors, with an initial clamping force of 1000N. A constant temperature chamber is used at 25℃ to conduct 1C / 1C cycle retention rate tests, recording expansion force data in real time until the capacity decays to 90% SOH.

[0148] Test 2:

[0149] Figure 18 The battery cell, comprising cell 200, casing 100, and buffer 300, uses an aluminum-plastic film with a thickness of 150µm, including a 70µm protective layer and an 80µm sealing layer. Buffer 300 is a two-stage sealing layer design. The first encapsulation area is hot-pressed at 180℃, 100kgf, for 1s, with a width of 1mm and a strength of 3N / mm. The second encapsulation area is hot-pressed at 190℃, 150kgf, for 2s, with a width of 1mm and a strength of 8N / mm. The LFP positive electrode / negative electrode / separator is wound into a core, which is then cold-pressed. Subsequently, the electrode tabs are welded, the casing is inserted, the top cover is welded, baking is performed, electrolyte is injected, and formation is carried out until the finished battery cell is installed in the warehouse. The finished battery cell has dimensions of 40*200*100mm, a full charge group margin of 93% for the core, a full charge group margin of 98% for the cell, and a rated capacity of 95Ah. The battery cell was tested with a three-aluminum plate clamp and sensor, with an initial clamping force of 1000N. A constant temperature chamber was used to conduct a 1C / 1C cycle retention rate test at 25℃, and the expansion force data was recorded in real time until the capacity decayed to 90% SOH.

[0150] Test 3:

[0151] Figure 19 The battery cell, comprising cell 200, casing 100, and buffer 300, uses an aluminum-plastic film with a thickness of 150µm, including a 70µm protective layer and an 80µm sealing layer. The buffer adopts a trapezoidal encapsulation structure design, using a 180℃, 200kgf, 3s hot-pressing oblique edge sealing condition, with a long side strength of 3N / mm and a short side strength of 10N / mm. A cross-sectional view of the battery cell structure is shown below. Figure 19 As shown, the system includes battery cells, buffer components, and a casing. The LFP positive / negative electrode / separator is wound into a core, which is then cold-pressed. This is followed by tab welding, casing insertion, top cover welding, baking, and electrolyte injection until the finished battery cell is placed in the storage chamber. The finished battery cell dimensions are 40*200*100mm, with a core full-charge group margin of 93%, a cell full-charge group margin of 98%, and a rated capacity of 95Ah. The battery cell undergoes testing with a three-aluminum-plate clamp and sensors, with an initial clamping force of 1000N. A constant temperature chamber is used at 25℃ to conduct 1C / 1C cycle retention rate tests, recording expansion force data in real time until the capacity decays to 90% SOH.

[0152] The test results are shown in Table 1:

[0153] Table 1

[0154] No. Buffer settings Buffer structure Expansion force Test 1 none none 8000N Test 2 2 Secondary packaged buffer 5000N Test 3 2 Trapezoidal packaged buffer 5000N

[0155] By comparing the results of Test 2 and Test 3 with those of Test 1, it can be seen that after adding the buffer element proposed in this embodiment to the battery cell, the expansion force of the entire battery cell is significantly reduced, from 8000N to 5000N, a decrease of 37.5%. Therefore, the solution proposed in this embodiment, by adding a buffer element to the battery cell, greatly reduces the expansion force of the battery cell, effectively solving the problems existing in the prior art.

[0156] Therefore, in summary, by correspondingly configuring the buffer to the battery cell, this embodiment effectively fills the initial gap between the battery cell and the casing when the battery cell has not expanded, preventing the battery cell winding structure from becoming loose and avoiding lithium plating on the electrode sheets. Furthermore, when the battery cell expands during use, the buffer deforms under the pressure of the expanding battery cell. When the expansion pressure of the battery cell is low, the deformation of the buffer is small. However, as the expansion pressure gradually increases to a certain extent, the encapsulation area of ​​the buffer gradually opens, the accommodating cavity space gradually increases, and the deformation of the buffer gradually increases, thereby alleviating the pressure caused by the battery cell expansion. This ensures that the gap between the battery cell and the casing is filled by the buffer throughout the entire lifespan of the battery cell, reducing the impact of battery cell expansion on the electrode sheets and preventing lithium plating.

[0157] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, include: case; At least one battery cell is housed within the housing; as well as A buffer element is housed within the housing and is disposed corresponding to the sidewall of the battery cell. The buffer element has a receiving cavity, and the outer periphery of the receiving cavity includes at least one encapsulation structure. The encapsulation structure includes at least one encapsulation region with a predetermined length. When the pressure inside the receiving cavity exceeds the encapsulation strength of the encapsulation structure, the encapsulation region opens and forms a buffer space communicating with the receiving cavity. The buffer is disposed between the battery cell and the side wall of the housing, and / or the buffer is disposed between adjacent battery cells; The encapsulation structure includes at least two levels of encapsulation regions with different encapsulation strengths, such that as the pressure inside the cavity increases, the encapsulation regions open up step by step, and form buffer spaces communicating with the cavity step by step.

2. The battery cell as described in claim 1, characterized in that, The sidewall includes a middle sidewall portion located in the middle region between the two ends in the height direction of the cell, and the buffer is provided correspondingly to the middle sidewall portion.

3. The battery cell as described in claim 1, characterized in that, The packaging structure is located at one or both ends of the buffer along the height direction of the battery cell.

4. The battery cell as described in claim 3, characterized in that, In the height direction of the battery cell, the height of the receiving cavity is 10-90% of the height of the battery cell.

5. The battery cell as described in claim 1, characterized in that, At least two levels of the encapsulation regions are arranged continuously; and / or The packaging regions of at least two levels are arranged at intervals, and a buffer of a predetermined length is provided between adjacent packaging regions of two levels.

6. The battery cell as described in claim 1, characterized in that, At least two levels of the encapsulation regions are arranged along the height direction of the cell, and the encapsulation regions farther from the receiving cavity have greater encapsulation strength.

7. The battery cell as described in claim 1, characterized in that, The pressure inside the containment cavity is greater than or equal to the air pressure inside the battery cell.

8. The battery cell as described in claim 1, characterized in that, The encapsulation strength of the encapsulation structure is 0.1~50MPa.

9. The battery cell as described in claim 1, characterized in that, The battery cell is a square battery cell, and The buffer is disposed at one or both ends of the battery cell in the thickness direction; and / or The buffer is disposed at one or both ends of the battery cell in the width direction.

10. The battery cell as described in claim 9, characterized in that, When the buffer is disposed at one or both ends of the battery cell in the thickness direction, the width of the receiving cavity in the width direction of the battery cell is 50 to 100% of the width of the battery cell.

11. The battery cell as described in claim 1, characterized in that, The cavity is annular in cross-section along the height of the battery cell, continuously surrounding the battery cell.

12. The battery cell as described in claim 1, characterized in that, The buffer material has an outer protective layer and an inner sealing layer, and the encapsulation area is formed by heat sealing the inner sealing layer.

13. The battery cell according to any one of claims 1 to 12, characterized in that, The cavity is filled with an inert fluid.

14. A battery, characterized in that, include: The battery cell as described in any one of claims 1 to 13.

15. An electrical appliance, characterized in that, The electrical device includes the battery as described in claim 14, the battery being used to provide electrical energy.

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