Battery cell, battery device and electric device

Abstract

A battery cell (20), a battery device, and an electric device. The battery cell (20) comprises a casing (22), an electrode assembly (30), and a buffer member (40). The electrode assembly (30) comprises a positive electrode sheet, a negative electrode sheet, and a separator arranged between the positive electrode sheet and the negative electrode sheet. The negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer arranged on at least one side of the negative electrode current collector. In the negative electrode active material layer, the mass fraction m of silicon satisfies: 0.5%≤m≤80%. The buffer member and at least part of the negative electrode active material layer are stacked.

Description

Battery cells, battery packs and electrical devices

[0001] Cross-reference to related applications

[0002] This disclosure is based on and claims priority to Chinese Patent Application No. 202510192528.1, filed on February 20, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of battery technology, and in particular to a battery cell, battery device, and power supply device. Background Technology

[0004] With increasingly severe environmental problems, growing public awareness of environmental protection, and rising oil prices, more and more people are focusing on new energy vehicles when purchasing vehicles. The range and power performance of these vehicles significantly influence consumer choices. Currently, most new energy vehicles use power batteries as energy storage and power sources, and they are also found in other types of vehicles. The energy density of the power battery has a significant impact on the vehicle's range and power performance; therefore, improving battery energy density is a continuous research focus in the ongoing improvement and innovation of batteries.

[0005] Currently, high-energy-density batteries are usually accompanied by high expansion changes, which makes the electrode components subject to greater expansion forces during charging and discharging, which can easily affect the cycle performance of the electrode components and also make the battery reliability worse. Summary of the Invention

[0006] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one object of the present invention is to provide a battery cell, and a battery device and an electrical device comprising the battery cell.

[0007] In a first aspect, embodiments of this disclosure provide a battery cell, the battery cell comprising: a housing, an electrode assembly, and a buffer, wherein the electrode assembly is located within the housing, the electrode assembly comprising a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, wherein the negative electrode comprises a negative current collector and a negative active material layer disposed on at least one side of the negative current collector, wherein the mass percentage m of silicon element in the negative active material layer satisfies: 0.5% ≤ m ≤ 80%; the buffer is stacked with at least a portion of the negative active material layer.

[0008] In the above technical solution, by controlling the mass ratio of silicon in the negative electrode active material layer, the energy density of the battery cell can be increased, which is beneficial to improving the driving range of new energy vehicles and meeting people's demand for long driving range. By setting a buffer on the side of the electrode assembly, the expansion force on the electrode assembly during the charging and discharging of the battery cell can be effectively relieved, which can better protect the electrode assembly, thereby improving the cycle performance of the electrode assembly and extending the battery's service life. Moreover, it can also enhance the reliability of the battery cell, reduce the risk of battery cell failure during use, improve the safety and stability of battery cell operation, and reduce safety hazards caused by battery failure.

[0009] In some embodiments, the mass percentage m of silicon in the negative electrode active material layer satisfies: 15% ≤ m ≤ 60%.

[0010] In the above technical solution, by controlling the mass ratio of silicon element in the negative electrode active material layer (1.5%≤m≤60%), the energy density of the battery cell can be increased more effectively, which is conducive to further improving the driving range of new energy vehicles, meeting people's demand for long driving range, and enabling the vehicle to travel a longer distance after a single charge, reducing the charging frequency and providing users with a more convenient and efficient travel experience.

[0011] In some embodiments, the areal density p of the negative electrode active material layer satisfies: 2.6 mg / cm³ 2 ≤p≤10mg / cm 2 .

[0012] In the above technical solutions, meeting the aforementioned conditions allows the negative electrode active material layer to participate effectively in electrochemical reactions, facilitating the storage of more charge in the electrode assembly and thus effectively improving the energy density of the battery cell. Meeting these conditions also ensures a more uniform distribution of active material in the negative electrode active material layer. During repeated charge-discharge cycles of the electrode assembly, this reduces the shedding and pulverization of active material caused by stress concentration and uneven volume changes, significantly improving the battery's cycle life and enhancing the structural stability of the negative electrode active material layer during charge-discharge. Furthermore, meeting these conditions effectively controls the heat generation and distribution of the battery cell during operation, preventing excessively high local current density and heat accumulation due to excessive areal density, which could lead to thermal runaway and other safety hazards. Conversely, it also prevents overpotential rise and lithium plating during high-rate charge-discharge cycles due to excessively low areal density. Therefore, meeting these conditions allows the battery cell to maintain good thermal stability and safety while ensuring performance.

[0013] In some embodiments, the areal density p of the negative electrode active material layer satisfies: 3 mg / cm³ 2≤p≤6.5mg / cm 2 .

[0014] In the above technical solution, when the density p of the negative electrode active material layer is 3 mg / cm³ 2 ≤p≤6.5mg / cm 2 On the one hand, it can improve the energy density of battery cells, increase the driving range of new energy vehicles and improve the driving range of mobile devices; on the other hand, it can extend the cycle life of battery cells, reduce the cost of use, improve stability, and be suitable for various charging and discharging scenarios; at the same time, it ensures the safety of battery cells and avoids the risks of thermal runaway and lithium plating.

[0015] In some embodiments, the compaction density d1 of the negative electrode active material layer satisfies: 0.8 g / cm³ 3 ≤d1≤1.7g / cm 3 .

[0016] In the above technical solutions, meeting the aforementioned conditions results in a tighter contact between the negative electrode active material particles, effectively reducing gaps between particles and allowing more active material to participate in electrochemical reactions, thereby improving the battery's energy storage capacity and increasing energy density. During battery charge-discharge cycles, it reduces displacement and pulverization of the active material due to volume expansion and contraction, maintaining electrode integrity and good contact between the active material and the current collector, thus improving battery cycle life. The tightly compacted negative electrode active material layer shortens the electron transport path and improves electronic conductivity. When the battery cell is working, electrons can be conducted more quickly and efficiently between the active material and the current collector, reducing the battery's internal resistance, reducing energy loss during charge-discharge, and improving the battery's charge-discharge efficiency and power performance. The compaction density meeting the above conditions optimizes the internal thermal conductivity of the battery cell, allowing heat generated during charge-discharge to be distributed and dissipated more evenly, avoiding safety issues such as thermal runaway caused by localized overheating. Simultaneously, the stable structure also helps prevent internal short-circuit risks caused by active material shedding, improving the safety and reliability of the battery cell.

[0017] In some embodiments, the compaction density d1 of the negative electrode active material layer satisfies: 0.9 g / cm³ 3 ≤d1≤1.2g / cm 3 .

[0018] The above-mentioned technical solutions, by meeting the aforementioned conditions, can, on the one hand, improve battery energy density, increase the driving range of new energy vehicles and the usage time of electronic devices; on the other hand, they can enhance cycle stability, reduce battery loss, lower usage costs and resource consumption, and improve economic efficiency. Simultaneously, they improve electron conduction efficiency, meet the demands of high-rate charging and discharging, broaden the application range, and ensure battery safety, reducing the risk of thermal runaway and short circuits.

[0019] In some embodiments, when the negative electrode active material layer is fully charged, the compaction density d2 of the negative electrode active material layer satisfies: 0.5 g / cm³. 3 ≤d2≤1.6g / cm 3 .

[0020] In the above technical solution, if the above conditions are met, the negative electrode active material layer under full charge is conducive to the close arrangement of negative electrode active materials, and more active materials can be accommodated per unit volume to participate in electrochemical reactions, thereby increasing the energy storage capacity of the battery cell and improving the energy density. The compaction density of the negative electrode active material layer that meets the above conditions helps to maintain the structural stability of the negative electrode active material layer under full charge. During multiple charge and discharge cycles of the battery cell, it can reduce stress concentration caused by changes in the volume of active materials, reduce the risk of active material cracking and falling off, and thus extend the cycle life of the battery.

[0021] In some embodiments, the mass percentage m of silicon in the negative electrode active material layer satisfies: 15% ≤ m ≤ 60%, and the compaction density d2 of the negative electrode active material layer when fully filled satisfies: 0.6 g / cm³. 3 ≤d2≤0.9g / cm 3 .

[0022] In the above technical solution, meeting the above conditions can significantly improve energy density. The high specific capacity of silicon combined with appropriate compaction can effectively increase the energy storage and range of battery cells. On the other hand, it can effectively optimize the cycle performance of the negative electrode active material layer, alleviate silicon volume expansion, extend the life of battery cells, reduce costs, and enhance the safety performance of battery cells.

[0023] In some embodiments, the battery cell is a hard-shell battery cell, and the energy density u of the battery cell satisfies: 300Wh / kg≤u≤500Wh / kg, and / or, the energy density of the battery cell satisfies: 700Wh / L≤u≤1200Wh / L.

[0024] In the above technical solution, by ensuring that the energy density of the hard-shell battery cell meets the above conditions, the energy storage capacity of the battery cell can be improved, the range of new energy vehicles can be increased, and the power performance of new energy vehicles can also be improved.

[0025] In some embodiments, the energy density u of the battery cell satisfies: 330Wh / kg≤u≤450Wh / kg, and / or, the energy density u of the battery cell satisfies: 800Wh / L≤u≤1000Wh / L.

[0026] In the above technical solution, by ensuring that the energy density of the hard-shell battery cell meets the above conditions, the energy storage capacity of the battery cell can be improved, the range of new energy vehicles can be increased, and the power performance of new energy vehicles can also be improved.

[0027] In some embodiments, the battery cell is a pouch cell, and the energy density u of the battery cell satisfies: 350Wh / kg≤u≤550Wh / kg.

[0028] In the above technical solutions, the lightweight soft-pack battery cells can reduce the overall weight of the equipment carrying them, such as drones that can fly longer and farther; and the energy density of the battery cells meets the above conditions, which can improve the energy storage capacity of the battery cells, reduce the number of charging times, improve the user experience, and optimize the internal reaction process of the battery cells, reduce energy loss, improve charging and discharging efficiency, and reduce usage costs.

[0029] In some embodiments, the energy density u of the battery cell satisfies: 380Wh / kg≤u≤500Wh / kg.

[0030] In the above technical solution, the energy density of the battery cell meets the above conditions, which can effectively improve the energy storage capacity of the battery cell, reduce the number of charging cycles, improve the user experience, and optimize the internal reaction process of the battery cell, reduce energy loss, improve charging and discharging efficiency, and reduce usage costs.

[0031] In some embodiments, the mass percentage m of silicon in the negative electrode active material layer satisfies: 0.5% ≤ m ≤ 20%, and the thickness H of the buffer in the first direction satisfies: 0.5 mm ≤ H ≤ 4 mm; or, the mass percentage m of silicon in the negative electrode active material layer satisfies: 20% < m ≤ 40%, and the thickness H of the buffer in the first direction satisfies: 1 mm ≤ H ≤ 8 mm; or, the mass percentage m of silicon in the negative electrode active material layer satisfies: 40% < m ≤ 60%, and the thickness H of the buffer in the first direction satisfies: 2 mm ≤ H ≤ 12 mm; or, the mass percentage m of silicon in the negative electrode active material layer satisfies: 60% < m ≤ 80%, and the thickness H of the buffer in the first direction satisfies: 3 mm ≤ H ≤ 16 mm.

[0032] In the above technical solution, by ensuring that the mass ratio of silicon in the negative electrode active material layer and the thickness of the buffer meet the aforementioned conditions, the corresponding thickness of the buffer can effectively alleviate the expansion force experienced by the electrode assembly during the charging and discharging process of the electrode assembly, thus protecting the electrode assembly and improving its cycle performance and extending battery life. Furthermore, it enhances the reliability of the battery assembly, reduces the risk of failure during use, improves the safety and stability of battery operation, and reduces safety hazards caused by battery failure. In addition, matching different silicon mass ratios with different buffer thicknesses can increase the filling density of the electrode assembly in the battery assembly. This improves the battery assembly's energy storage capacity and effectively alleviates the expansion force experienced by the electrode assembly during charging and discharging. Moreover, after the electrode assembly and buffer are installed in the casing, the buffer can effectively restrain the electrode assembly, preventing deformation and wrinkling during charging and discharging, thereby ensuring the cycle performance and reliability of the electrode assembly.

[0033] In some embodiments, the electrode assembly is provided with one element, and the buffer is provided on at least one side of the electrode assembly in a first direction.

[0034] In the above technical solution, the battery cell is equipped with an electrode assembly, which has a simple structure and can effectively reduce the manufacturing process of the battery cell. In addition, the internal structure of the battery cell is relatively simple, making the electrochemical reaction and ion transport path inside the battery relatively clear and stable. This helps to reduce energy loss caused by complex structure, improve the charging and discharging efficiency of the battery, ensure the consistency of battery performance, and make subsequent maintenance and testing more convenient. It can more quickly and accurately locate potential problems, facilitate fault diagnosis and repair, and thus extend the overall service life of the battery cell. The arrangement of buffer components can better protect the electrode assembly, enhance the cycle performance of the electrode assembly, and make the battery cell more stable during long-term repeated charging and discharging.

[0035] In some embodiments, multiple electrode assemblies are provided, and the multiple electrode assemblies are arranged sequentially along a first direction, with the buffer disposed between two adjacent electrode assemblies.

[0036] In the above technical solution, by setting a buffer between the two electrode components, stress impact can be effectively blocked during battery charging and discharging, reducing the risk of local deformation of the electrode components and improving the reliability of the battery components.

[0037] In some embodiments, the electrode assembly is provided in multiple ways, and among the multiple electrode assemblies, the two electrode assemblies located at both ends of the first direction are respectively the first electrode assembly and the second electrode assembly, and the buffer is arranged between the first electrode assembly and the housing, and / or the buffer is arranged between the second electrode assembly and the housing.

[0038] In the above technical solution, by setting buffers at different locations, stress impacts can be effectively blocked during battery charging and discharging, reducing the risk of local deformation of the electrode assembly and improving the reliability of the battery assembly.

[0039] In some embodiments, the electrode assembly is a wound electrode assembly, or the electrode assembly is a stacked electrode assembly.

[0040] In the above technical solution, the arrangement of buffer components can effectively protect the wound electrode assembly and the stacked electrode assembly. During the battery charging and discharging process, it can effectively block stress impacts, reduce the risk of local deformation of the electrode assembly, and improve the reliability of the battery assembly.

[0041] In some embodiments, the electrode assembly is a wound electrode assembly, which includes a straight section and a corner section. The corner section includes two corner sections, which are respectively connected to both sides of the straight section in a second direction. The first direction and the second direction are perpendicular to each other. The buffer includes a connected straight portion and at least one corner portion. The straight portion is stacked with the straight section, and the corner portion is stacked with the corner section.

[0042] In the above technical solution, by arranging the coverage area of ​​the buffer, the electrode assembly can be effectively protected. During the charging and discharging process of the battery, it can effectively block stress impacts, reduce the risk of local deformation of the electrode assembly, and improve the reliability of the battery assembly.

[0043] In some embodiments, the connection between the straight section and the corner section is a corner connection, the end of the corner section away from the straight section is a corner tip, and in the winding direction of the electrode assembly, the dimension from the corner connection to the corner tip is c1, and the dimension c2 of the corner portion satisfies: 0 < c2 ≤ c1.

[0044] In the above technical solution, by arranging the coverage area of ​​the buffer, the electrode assembly can be effectively protected. During the charging and discharging process of the battery, it can effectively block stress impacts, reduce the risk of local deformation of the electrode assembly, and improve the reliability of the battery assembly.

[0045] In some embodiments, the electrode assembly is a stacked electrode assembly with sheets stacked along the first direction. In a projection plane perpendicular to the first direction, the projected area of ​​the positive electrode is smaller than the projected area of ​​the buffer, and the projection of the positive electrode is located within the projection of the buffer.

[0046] In the above technical solution, by arranging the coverage area of ​​the buffer, the electrode assembly can be effectively protected. During the charging and discharging process of the battery, it can effectively block stress impacts, reduce the risk of local deformation of the electrode assembly, and improve the reliability of the battery assembly.

[0047] In some embodiments, the silicon material containing the silicon element in the negative electrode active material layer includes silicon, silicon-carbon, or silicon-oxygen.

[0048] In the aforementioned technical solutions, silicon possesses a high theoretical specific capacity, which can improve battery energy density and enhance battery life. Silicon-carbon and silicon-oxygen compounds mitigate the volume expansion problem of silicon, improve cycle life and stability, and enable the battery to exhibit superior performance during charging and discharging. This allows the battery to meet the performance requirements of various application scenarios and demonstrates strong practicality.

[0049] In some embodiments, the cushioning element is composed of one of the following: foamed material, porous foam, aerogel, silicone rubber, polyethylene, polypropylene, and polyethylene terephthalate.

[0050] In the above technical solutions, there are various materials available for the buffer components, and the materials can be selected according to the actual situation, making them highly practical.

[0051] In one embodiment of this disclosure, the buffer is a porous buffer with a porosity design range of 10% to 95%.

[0052] In the above technical solution, the design of the buffer can achieve different compression effects of the buffer, and it is also beneficial to improve the liquid absorption and retention effect of the buffer, which can improve the problem of poor electrolyte extrusion and backflow wetting during the expansion and contraction of the silicon anode during charging and discharging.

[0053] In some embodiments, the quotient of the compressible thickness of the buffer divided by the thickness of the buffer before compression is Δh, satisfying: Δh = 0.4 * x + 0.5, where x is the mass percentage of silicon in the negative electrode active material layer.

[0054] In the above technical solution, by meeting the above conditions, the buffer can be designed according to the mass ratio of silicon, so that the buffer can better meet the buffering requirements of electrode components with different mass ratios of silicon during the charging and discharging process.

[0055] In some embodiments, in the first direction, the size of the receiving cavity of the housing is D1, the electrode assembly is a bare cell, and the sum of the thicknesses of the electrode assembly and the buffer before compression is D2, satisfying: 90% ≤ D2 / D1 ≤ 97%; when the electrode assembly is in a fully charged state, the sum of the thicknesses of the electrode assembly and the buffer after compression is D3, satisfying: 100% ≤ D2 / D1 ≤ 102%.

[0056] In the above technical solution, by meeting the above conditions, the safety and stability of the battery cell under different operating conditions can be improved, and the battery cell can be guaranteed to provide power to the electrical equipment efficiently and stably.

[0057] In some embodiments, the buffer is bonded to the electrode assembly, or the battery cell further includes an insulating film, in which the electrode assembly and the buffer are enclosed.

[0058] In the above technical solutions, when the buffer is bonded to the electrode assembly, this tight connection effectively prevents displacement of the buffer during use, ensuring it always protects the electrode assembly. During battery charging and discharging, the electrode assembly undergoes volume changes; the bonded buffer can effectively absorb and disperse stress, reducing damage to the electrode assembly caused by stress concentration, thereby improving the cycle life and stability of the battery cell. If the battery cell adopts a structure where the electrode assembly and buffer are encased in an insulating film, the insulating film provides additional protection, preventing the electrode assembly from contacting the external environment and short-circuiting, thus enhancing battery safety. Simultaneously, the insulating film also helps maintain the relative position of the electrode assembly and buffer, further optimizing stress distribution and ensuring the battery's performance reliability during long-term use.

[0059] Secondly, embodiments of this disclosure provide a battery device, which includes a housing and battery cells according to the first aspect of this disclosure. A plurality of battery cells are provided, and the plurality of battery cells are arranged sequentially in the housing along a first direction.

[0060] In the above technical solution, by setting the battery cells of the above embodiments, the energy density of the battery cells can be increased, and the safety and stability of the battery cell operation can be improved.

[0061] In some embodiments, the battery device further includes a heat insulation element disposed between two adjacent battery cells, and / or, the heat insulation element disposed between the battery cells and the housing.

[0062] In the above technical solution, the heat insulation component is arranged between two adjacent battery cells. This component effectively prevents heat transfer between battery cells, preventing thermal runaway caused by overheating of one battery cell from spreading to surrounding cells, reducing the risk of heat propagation, and improving the safety of the battery system. The heat insulation component, located between the battery cell and the casing, reduces heat transfer from the battery to the casing, preventing damage to the casing due to high temperatures. It also isolates the battery from external heat, keeping it in a relatively stable thermal environment. This helps maintain consistent battery performance, improves battery life and efficiency, and ensures safe and stable operation of the battery system under various operating conditions.

[0063] Thirdly, embodiments of this disclosure provide an electrical device, which includes the battery device of the second aspect of this disclosure.

[0064] In the above technical solution, by setting the battery device of the example above, the power device of this disclosure can have better battery life, as well as better safety and stability.

[0065] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0066] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0067] Figure 1 is a structural schematic diagram of a vehicle according to an embodiment.

[0068] Figure 2 is an exploded structural diagram of a battery according to one embodiment.

[0069] Figure 3 is an exploded structural diagram of a battery cell according to an embodiment (the electrode assembly is a wound electrode assembly).

[0070] Figure 4 is a cross-sectional view of a battery cell according to an embodiment (the electrode assembly is a stacked electrode assembly).

[0071] Figure 5 is a cross-sectional view of a battery cell according to an embodiment (the electrode assembly is a stacked electrode assembly).

[0072] Figure 6 is a cross-sectional view of a battery cell according to an embodiment (the electrode assembly is a stacked electrode assembly).

[0073] Figure 7 is a cross-sectional view of a battery cell according to an embodiment (the electrode assembly is a wound electrode assembly).

[0074] Figure 8 is a cross-sectional view of a battery cell according to an embodiment (the electrode assembly is a wound electrode assembly).

[0075] Figure 9 is a cross-sectional view of a battery cell according to an embodiment (the electrode assembly is a wound electrode assembly).

[0076] Figure 10 is a cross-sectional view of a wound electrode assembly according to an embodiment.

[0077] Figure 11 is a cross-sectional view of a wound electrode assembly and a buffer according to an embodiment.

[0078] Reference numerals: 1000, vehicle; 100, battery unit; 200, controller; 300, motor; 10, housing; 11, first housing; 12, second housing; 20, battery cell; 21, top cover; 22, casing; 30, electrode assembly; 31, straight section; 32, corner section; 33, corner connection; 34, corner tip; 40, buffer; 41, straight section; 42, corner section; X, first direction; Y, second direction; Z, third direction. Detailed Implementation

[0079] The embodiments of the technical solutions disclosed herein will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solutions disclosed herein and are therefore intended to limit the scope of protection of this disclosure.

[0080] 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 disclosure belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure; the terms “comprising” and “having”, and any variations thereof, in the specification, claims and foregoing description of the drawings of this disclosure are intended to cover non-exclusive inclusion.

[0081] In the description of the embodiments of this disclosure, 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 or secondary relationship of the indicated technical features. In the description of the embodiments of this disclosure, "a plurality of" means two or more, unless otherwise explicitly defined.

[0082] 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 disclosure. 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.

[0083] In the description of the embodiments of this disclosure, 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, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0084] In the description of embodiments of this disclosure, the term "a plurality of" refers to two or more (including two).

[0085] In the description of the embodiments of this disclosure, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "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 disclosure 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 disclosure.

[0086] In the description of the embodiments of this disclosure, 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. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0087] The battery apparatus mentioned in the embodiments of this disclosure may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include one or more battery cells, and when there are multiple battery cells, the multiple battery cells are connected in series, parallel, or mixed connection via a busbar.

[0088] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form a single module. As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0089] The battery cells mentioned in the embodiments of this disclosure may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and this disclosure does not limit the types. The battery cells may be cylindrical, flat, cuboid, or other shapes, and this disclosure does not limit the shapes either.

[0090] For example, a battery cell typically includes a housing, an electrode assembly, and an electrolyte. The housing is used to contain the electrode assembly and the electrolyte, and the housing has at least one positive electrode post and at least one negative electrode post. The electrode assembly includes one or more electrode assemblies, which are formed by stacking or winding positive electrode plates, negative electrode plates, and separators.

[0091] The positive electrode generally includes a positive current collector and a positive active material layer. The positive active material layer is directly or indirectly coated on the positive current collector. The positive current collector without the positive active material layer protrudes from the positive current collector with the positive active material layer. The positive current collector without the positive active material layer serves as a positive electrode tab. Multiple positive electrode tabs are stacked together and form an electrical connection with the positive electrode post. For example, the multiple stacked positive electrode tabs can be directly welded to the positive electrode post to form an electrical connection; or, the electrode assembly can also include a positive electrode adapter piece. The multiple stacked positive electrode tabs are welded to one end of the positive electrode adapter piece, and the other end of the positive electrode adapter piece is welded to the positive electrode post, so that the positive electrode tabs and the positive electrode post form an electrical connection.

[0092] The negative electrode generally includes a negative current collector and a negative active material layer. The negative active material layer is directly or indirectly coated on the negative current collector. The negative current collector without the negative active material layer protrudes from the negative current collector with the negative active material layer. The negative current collector without the negative active material layer serves as a negative electrode tab. Multiple negative electrode tabs are stacked together and form an electrical connection with the negative electrode post. For example, the stacked negative electrode tabs can be directly welded to the negative electrode post to form an electrical connection; alternatively, the electrode assembly may also include a negative electrode adapter piece. The stacked negative electrode tabs are welded to one end of the negative electrode adapter piece, and the other end of the negative electrode adapter piece is welded to the negative electrode post, so that the negative electrode tabs and the negative electrode post form an electrical connection. The material of the separator is not limited; for example, it can be polypropylene or polyethylene.

[0093] The technical solutions described in this disclosure are applicable to various electrical devices that use battery cells and battery devices, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0094] With increasingly severe environmental problems, growing public awareness of environmental protection, and rising oil prices, more and more people are focusing on new energy vehicles when purchasing vehicles. The range and power performance of these vehicles significantly influence consumer choices. Currently, most new energy vehicles use power batteries as energy storage and power sources, and they are also found in other types of vehicles. The energy density of the power battery has a significant impact on the vehicle's range and power performance; therefore, improving battery energy density is a continuous research focus in the ongoing improvement and innovation of batteries.

[0095] Currently, high-energy-density batteries are usually accompanied by high expansion changes, which makes the electrode components subject to greater expansion forces during charging and discharging, which can easily affect the cycle performance of the electrode components and also make the battery reliability worse.

[0096] Based on the above considerations, in order to improve the energy density, reliability, and stability of battery cells, the applicant, through in-depth research, designed a battery cell that can significantly increase the energy density of the battery cell by controlling the mass ratio of silicon in the negative electrode active material layer. This is beneficial for improving the driving range of new energy vehicles and meeting people's demand for longer driving range. By setting buffers on the sides of the electrode assembly, the expansion force on the electrode assembly during the charging and discharging process of the battery cell can be effectively alleviated, which can better protect the electrode assembly, thereby improving the cycle performance of the electrode assembly and extending the battery's lifespan. Moreover, it can also enhance the reliability of the battery cell, reduce the risk of battery cell failure during use, improve the safety and stability of battery cell operation, and reduce safety hazards caused by battery failure.

[0097] In this embodiment of the disclosure, the battery cell 20 can be a secondary battery, which refers to a battery cell 20 that can be used again after being discharged by recharging to activate the active materials.

[0098] The battery cell 20 can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and this embodiment does not limit it.

[0099] This disclosure provides an electrical device that uses a single battery cell 20 as a power source. The electrical device can be, but is not limited to, a mobile phone, tablet, laptop, electric toy, power tool, electric vehicle, electric car, ship, 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.

[0100] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this disclosure.

[0101] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of this disclosure. The vehicle 1000 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 cell 20 is disposed inside the vehicle 1000, and the battery cell 20 can be located at the bottom, front, or rear of the vehicle 1000. The battery cell 20 can be used to power the vehicle 1000; for example, the battery cell 20 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery cell 20 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0102] In some embodiments of this disclosure, the battery cell 20 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0103] Please refer to Figure 2, which is an exploded view of a battery device 100 provided in some embodiments of this disclosure. The battery device 100 mentioned in the embodiments of this disclosure may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include multiple battery cells 20, which are connected in series, parallel, or mixed connection via a busbar.

[0104] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells 20.

[0105] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells 20 together. As an example, a battery module can also be formed by bundling multiple battery cells 20 together with cable ties.

[0106] In some embodiments, the battery device 100 may be a battery pack, which includes a housing 10 and one or more individual battery cells housed within the housing 10.

[0107] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be housed in the housing 10 by fixing the battery module in the housing 10.

[0108] As an example, the battery cell assembly can also be housed in the housing 10 by directly fixing multiple battery cells 20 to the housing 10.

[0109] As an example, the housing 10 may include a first housing 11 and a second housing 12. The first housing 11 and the second housing 12 are fastened together to form a closed space inside the housing 10 to house the battery cell assembly. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first housing 11 may be a top cover 21 or a bottom plate.

[0110] As an example, the housing 10 may include a top cover 21, a frame, and a bottom plate. The top cover 21 and the bottom plate are respectively connected to the frame, so that the interior of the housing 10 forms an enclosed space to accommodate the battery cell assembly.

[0111] In some embodiments, the housing 10 may be part of the chassis structure of the vehicle 1000. For example, a portion of the housing 10 may be at least a portion of the floor of the vehicle 1000, or a portion of the housing 10 may be at least a portion of the crossbeams and longitudinal beams of the vehicle 1000.

[0112] The technical solutions described in this disclosure are applicable to various electrical devices that use battery cells 20, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles 1000, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0113] Please refer to Figure 3, which is an exploded structural diagram of a battery cell 20 provided in some embodiments of this disclosure. A battery cell 20 refers to the smallest unit constituting a battery device 100. The battery cell 20 includes a housing 22 and an electrode assembly 30.

[0114] For example, as shown in FIG3, the battery cell 20 includes a top cover 21, a housing 22, an electrode assembly 30, and other functional components.

[0115] The housing 22 is an assembly used to cooperate with the top cover 21 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 30, electrolyte and other components.

[0116] Electrode assembly 30 is the component in the battery cell 20 where electrochemical reactions occur. The housing 22 may contain one or more electrode assemblies 30. The electrode assembly 30 is mainly formed by winding or stacking positive and negative electrode plates, and a separator is usually provided between the positive and negative electrode plates.

[0117] Referring to Figure 4, which is a cross-sectional view of a battery cell according to one embodiment.

[0118] In one embodiment of this disclosure, the battery cell 20 includes: a housing 22, an electrode assembly 30, and a buffer 40. The electrode assembly 30 is located inside the housing 22 and includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. The negative electrode includes a negative current collector and a negative active material layer disposed on at least one side of the negative current collector. In the negative active material layer, the mass percentage m of silicon element satisfies: 0.5% ≤ m ≤ 80%. The buffer 40 is stacked with at least a portion of the negative active material layer.

[0119] For example, the buffer 40 is stacked with a portion of the negative electrode active material layer;

[0120] For example, the buffer 40 is stacked with the entire area of ​​the negative electrode active material layer.

[0121] For example, the negative electrode active material layer is disposed on one side of the negative electrode current collector.

[0122] For example, the negative electrode active material layer is disposed on both sides of the negative electrode current collector. In this example, the buffer 40 can be disposed on one side of the negative electrode current collector or on both sides of the negative electrode current collector.

[0123] For example, the mass percentage m of silicon can be 0.5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 75%, or 80%.

[0124] Increasing the proportion of silicon in the negative electrode active material layer can theoretically improve the energy storage capacity of the battery cell 20, thereby increasing its energy density. For example, as the mass proportion of silicon gradually increases within a reasonable range, the battery can store more charge and release more electrical energy with the same volume or mass. By controlling the mass proportion of silicon in the negative electrode active material layer (0.5% ≤ m ≤ 80%), the energy density of the battery cell 20 can be significantly increased, which is beneficial for improving the driving range of the new energy vehicle 1000, meeting people's demand for long driving range. Furthermore, the vehicle 1000 can travel a longer distance on a single charge, reducing the frequency of charging and providing users with a more convenient and efficient travel experience.

[0125] The buffer element 40 is stacked with at least a portion of the negative electrode active material layer. For example, the buffer element 40 is disposed on the side of the electrode assembly 30 in the first direction X, effectively mitigating the expansion force experienced by the electrode assembly 30 during the charging and discharging of the high-energy-density battery system. This effectively protects the electrode assembly 30, reducing problems such as electrode material detachment and separator damage caused by expansion force, thereby improving the cycle performance of the electrode assembly 30 and extending the battery's lifespan. Furthermore, it enhances the reliability of the battery cell 20, reduces the risk of failure during use, improves the safety and stability of the battery cell 20's operation, and reduces safety hazards caused by battery failure.

[0126] By providing a buffer 40 on the side of the electrode assembly 30, the buffer 40 can effectively restrain the electrode assembly 30 during the charging and discharging process, reducing the risk of deformation and wrinkling of the electrode assembly 30, thereby better ensuring the cycle performance and reliability of the electrode assembly 30.

[0127] In the above technical solution, by controlling the mass ratio of silicon in the negative electrode active material layer, the energy density of the battery cell 20 can be increased, which is beneficial to improving the driving range of the new energy vehicle 1000 and meeting people's demand for long driving range. By stacking the buffer 40 with at least part of the negative electrode active material layer, the expansion force on the electrode assembly 30 during the charging and discharging process of the battery cell 20 can be effectively alleviated, which can better protect the electrode assembly 30, thereby improving the cycle performance of the electrode assembly 30 and extending the service life of the battery. Moreover, it can also enhance the reliability of the battery cell 20, reduce the risk of failure of the battery cell 20 during use, improve the safety and stability of the operation of the battery cell 20, and reduce safety hazards caused by battery failure.

[0128] Furthermore, please refer to the following table:

[0129] In the table above, "the thickness of the buffer 40 is not compressed" can mean that the buffer 40 is not assembled or that the buffer 40 is assembled but the electrode assembly 30 has not expanded. "The thickness of the buffer 40 after compression" can mean that the thickness of the buffer 40 after the electrode assembly 30 has expanded and been compressed.

[0130] As can be seen from the table above:

[0131] In Comparative Examples 1 and 2, due to the presence of a buffer 40, the electrode assembly 30 experienced wrinkling as the silicon content increased.

[0132] In Comparative Examples 3, 4, and 5, with the silicon content remaining constant, the compressibility of the buffer 40 is the same. A thickness of 2 mm or more in the uncompressed state, or a thickness of 0.4 mm or more after compression, both contribute to reducing the likelihood of wrinkling in the electrode assembly 30. Furthermore, the maximum expansion surface pressure gradually increases as the thickness of the buffer 40 increases in either the uncompressed or compressed state.

[0133] In Comparative Examples 6 and 7, with the silicon content remaining constant, the thickness of the buffer 40 in the uncompressed state is the same. As the compressibility of the buffer 40 increases or the thickness of the buffer 40 after compression decreases, the maximum expansion surface pressure decreases.

[0134] In Comparative Examples 3, 8, 9, 10 and 11, under different silicon content transition states, by setting the buffer 40, the problem of wrinkling of the electrode assembly 30 can be effectively reduced, or even the problem of wrinkling of the electrode assembly 30 can be prevented.

[0135] In one embodiment of this disclosure, the mass percentage m of silicon in the negative electrode active material layer satisfies: 15% ≤ m ≤ 60%.

[0136] For example, the mass percentage m of silicon can be 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, or 60%.

[0137] In the above technical solution, by controlling the mass ratio of silicon elements in the negative electrode active material layer (1.5% ≤ m ≤ 60%), the energy density of the battery cell 20 can be increased more effectively, which is conducive to further improving the driving range of the new energy vehicle 1000, meeting people's demand for long driving range, and enabling the vehicle 1000 to travel a longer distance after a single charge, reducing the charging frequency and providing users with a more convenient and efficient travel experience.

[0138] In one embodiment of this disclosure, the areal density p of the negative electrode active material layer satisfies: 2.6 mg / cm³ 2 ≤p≤10mg / cm 2 .

[0139] For example, the areal density p of the negative electrode active material layer can be 2.6 mg / cm³. 2 3.4 mg / cm 2 4.2 mg / cm 2 5.0 mg / cm 2 5.8 mg / cm 2 6.6 mg / cm 27.4 mg / cm 2 8.2 mg / cm 2 9.0 mg / cm 2 9.8 mg / cm 2 .

[0140] In the above technical solution, meeting the aforementioned conditions allows the negative electrode active material layer to participate effectively in electrochemical reactions, which is beneficial for the electrode assembly 30 to store more electrical energy, thereby effectively improving the energy density of the battery cell 20. Meeting these conditions also ensures a more uniform distribution of active material in the negative electrode active material layer. During repeated charge-discharge cycles of the electrode assembly 30, this reduces the shedding and pulverization of active material caused by stress concentration and uneven volume changes, significantly improving the battery's cycle life and enhancing the structural stability of the negative electrode active material layer during charge-discharge. Meeting these conditions also effectively controls the heat generation and distribution of the battery cell 20 during operation, preventing excessively high local current density and heat accumulation due to excessive areal density, thus avoiding safety hazards such as thermal runaway. Simultaneously, it also prevents unsafe phenomena such as overpotential rise and lithium plating during high-rate charge-discharge of the battery cell 20 due to excessively low areal density. Therefore, meeting these conditions allows the battery cell 20 to maintain good thermal stability and safety while ensuring performance.

[0141] For example, the method for measuring the areal density of the negative electrode active material layer may include: disassembling the battery cell 20, removing two negative electrode sheets, namely a first negative electrode sheet and a second negative electrode sheet, both sides of which have a negative electrode active material layer; erasing the negative electrode active material layer on both sides of the second negative electrode sheet; then, punching out a first small disc from the first negative electrode sheet, and punching out a second small disc from the second negative electrode sheet, the areas of the first and second small discs being equal, S; weighing the first small disc, the weight is M; weighing the second small disc, the weight is M0; then the areal density of the negative electrode active material layer on one side is p = (M - M0) / 2 / S. In the above formula, "2" represents the negative electrode active material layer on both sides of the second negative electrode sheet. If the second negative electrode sheet has a negative electrode active material layer on only one side, then the areal density of the negative electrode active material layer is p = (M - M0) / S.

[0142] For example, the area S of the first or second small circular piece is 1540.25 mm². 2 .

[0143] Disassemble the battery, remove the electrode plates, and punch them into pieces with an area of ​​S = 1540.25 mm². 2 Take a small circular sheet, measure its weight M, and take another electrode sheet. Remove the negative electrode active material layer from the surface of the remaining empty current collector foil, and similarly punch it into a piece with S = 1540.25 mm. 2For a small round disc, the weight of the empty aluminum foil is M0. Then the areal density of the single-sided active material is (M-M0) / 2 / S, mg / cm³. 2

[0144] In one embodiment of this disclosure, the areal density p of the negative electrode active material layer satisfies: 3 mg / cm³ 2 ≤p≤6.5mg / cm 2 .

[0145] For example, the areal density p of the negative electrode active material layer can be 3 mg / cm³. 2 3.5 mg / cm 2 4mg / cm 2 4.5 mg / cm 2 5mg / cm 2 5.5 mg / cm 2 6mg / cm 2 6.2 mg / cm 2 6.4 mg / cm 2 6.5 mg / cm 2 .

[0146] In the above technical solution, when the density p of the negative electrode active material layer is 3 mg / cm³ 2 ≤p≤6.5mg / cm 2 On the one hand, it can improve the energy density of the battery cell 20, increase the driving range of new energy vehicles and improve the driving range of mobile devices; on the other hand, it can extend the cycle life of the battery cell 20, reduce the cost of use, improve stability, and be suitable for various charging and discharging scenarios; at the same time, it ensures the safety of the battery cell 20 and avoids the risks of thermal runaway and lithium plating.

[0147] In one embodiment of this disclosure, the compaction density d1 of the negative electrode active material layer satisfies: 0.8 g / cm³ 3 ≤d1≤1.7g / cm 3 .

[0148] For example, 0.8 g / cm 3 0.9g / cm 3 1.0g / cm 3 1.1g / cm 3 1.2g / cm 3 1.3g / cm 3 1.4g / cm 3 1.5g / cm 3 1.6g / cm 3 1.7g / cm 3 .

[0149] In the above technical solution, meeting the aforementioned conditions results in a tighter contact between the negative electrode active material particles, effectively reducing gaps between particles and allowing more active material to participate in the electrochemical reaction, thereby improving the battery's energy storage capacity and increasing energy density. During battery charge-discharge cycles, it reduces displacement and pulverization of the active material due to volume expansion and contraction, maintaining electrode integrity and good contact between the active material and the current collector, thus improving the battery's cycle life. The tightly compacted negative electrode active material layer shortens the electron transport path and improves electronic conductivity. When the battery cell 20 is working, electrons can be conducted more quickly and efficiently between the active material and the current collector, reducing the battery's internal resistance, reducing energy loss during charge-discharge, and improving the battery's charge-discharge efficiency and power performance. The compaction density meeting the above conditions optimizes the internal thermal conductivity of the battery cell 20, allowing the heat generated during charge-discharge to be distributed and dissipated more evenly, avoiding safety issues such as thermal runaway caused by localized overheating. Simultaneously, the stable structure also helps prevent internal short-circuit risks caused by active material shedding, improving the safety and reliability of the battery cell 20.

[0150] For example, the method for measuring the compaction density of the negative electrode active material layer may include: disassembling the battery cell 20, taking out two negative electrode sheets, namely a first negative electrode sheet and a second negative electrode sheet, both sides of the first negative electrode sheet and the second negative electrode sheet have a negative electrode active material layer, wiping away the negative electrode active material layer on both sides of the second negative electrode sheet, then punching out a first small disc from the first negative electrode sheet, punching out a second small disc from the second negative electrode sheet, the areas of the first small disc and the second small disc are equal and S, weighing the first small disc, the weight is M, the thickness of the first small disc is L, weighing the second small disc, the weight is M0, the thickness of the second small disc is L0, then the compaction density of the negative electrode active material layer d1=(M-M0) / S / (L-L0).

[0151] For example, the area S of the first or second small circular piece is 1540.25 mm². 2 The compaction density of the electrode (positive or negative electrode) is tested using the following method: Disassemble the battery, remove the electrode, and punch it into pieces with an area S = 1540.25 mm². 2 Take a small circular electrode, measure its weight M and thickness L, and then take another electrode. Remove the active material layer from the surface of the remaining current collector foil and punch it into a piece with a diameter S = 1540.25 mm. 2 The small round piece is weighed, and the weight M0 and thickness L0 of the empty aluminum foil are measured. Then the compaction density PD = (M-M0) / 1.54025 / (L-L0), where L0 is the thickness of the current collector foil.

[0152] In one embodiment of this disclosure, the compaction density d1 of the negative electrode active material layer satisfies: 0.9 g / cm³.3 ≤d1≤1.2g / cm 3 .

[0153] For example, 0.9 g / cm 3 0.95g / cm 3 1.0g / cm 3 1.05g / cm 3 1.1g / cm 3 1.12 g / cm 3 1.15g / cm 3 1.18 g / cm 3 1.2g / cm 3 .

[0154] The above-mentioned technical solutions, by meeting the aforementioned conditions, can, on the one hand, improve battery energy density, increase the driving range of new energy vehicles and the usage time of electronic devices; on the other hand, they can enhance cycle stability, reduce battery loss, lower usage costs and resource consumption, and improve economic efficiency. Simultaneously, they improve electron conduction efficiency, meet the demands of high-rate charging and discharging, broaden the application range, and ensure battery safety, reducing the risk of thermal runaway and short circuits.

[0155] In one embodiment of this disclosure, when the negative electrode active material layer is fully charged, the compaction density d2 of the negative electrode active material layer satisfies: 0.5 g / cm³. 3 ≤d2≤1.6g / cm 3 .

[0156] For example, 0.5 g / cm 3 0.7g / cm 3 0.9g / cm 3 1.1g / cm 3 1.2g / cm 3 1.3g / cm 3 1.4g / cm 3 1.45g / cm 3 1.5g / cm 3 1.6g / cm 3 .

[0157] In the above technical solution, if the above conditions are met, the negative electrode active material layer under full charge is conducive to the close arrangement of negative electrode active materials, and more active materials can be accommodated per unit volume to participate in electrochemical reactions, thereby increasing the energy storage capacity of the battery cell 20 and improving the energy density; if the compaction density of the negative electrode active material layer meets the above conditions, it helps to maintain the structural stability of the negative electrode active material layer under full charge, and can reduce the stress concentration caused by the volume change of active materials during multiple charge and discharge cycles of the battery cell 20, reduce the risk of active material cracking and falling off, thereby extending the cycle life of the battery.

[0158] For example, the above full charge can be referenced as follows: at 25°C, charge at a constant current of 1 / 3C rate to 4.25V, switch to constant voltage charging, and stop charging when the current drops to 0.05C rate; disassemble to obtain the full-charged positive and negative electrode plates.

[0159] At this point, the method for measuring the compaction density of the negative electrode active material layer may include: disassembling the battery cell 20, taking out two negative electrode sheets, the two negative electrode sheets being the first negative electrode sheet and the second negative electrode sheet, both sides of the first negative electrode sheet and the second negative electrode sheet having a negative electrode active material layer, wiping away the negative electrode active material layer on both sides of the second negative electrode sheet, then punching out a first small disc from the first negative electrode sheet, punching out a second small disc from the second negative electrode sheet, the areas of the first small disc and the second small disc being equal and S, weighing the first small disc, the weight being M, the thickness of the first small disc being L, weighing the second small disc, the weight being M0, the thickness of the second small disc being L0, then the compaction density of the negative electrode active material layer d1=(M-M0) / S / (L-L0).

[0160] In one embodiment of this disclosure, the mass percentage m of silicon in the negative electrode active material layer satisfies: 15% ≤ m ≤ 60%, and when the negative electrode active material layer is fully filled, the compaction density d2 of the negative electrode active material layer satisfies: 0.6 g / cm3 ≤ d2 ≤ 0.9 g / cm3.

[0161] For example, the mass percentage m of silicon is: 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%;

[0162] For example, the compaction density d2 of the negative electrode active material layer is 0.6 g / cm³. 3 0.65g / cm 3 0.7g / cm 3 0.75g / cm 3 0.8g / cm 3 0.82g / cm 3 0.85g / cm 3 0.88g / cm 3 0.9g / cm3 .

[0163] In the above technical solution, meeting the above conditions can significantly improve energy density. The high specific capacity of silicon combined with appropriate compaction density can effectively increase the energy storage and range of the battery cell 20. On the other hand, it can effectively optimize the cycle performance of the negative electrode active material layer, alleviate silicon volume expansion, extend the life of the battery cell 20, reduce costs, and enhance the safety performance of the battery cell 20.

[0164] In one embodiment of this disclosure, the battery cell 20 is a rigid-shell battery cell, and the energy density u of the battery cell 20 satisfies: 300Wh / kg≤u≤500Wh / kg, and / or, the energy density u of the battery cell 20 satisfies: 700Wh / L≤u≤1200Wh / L.

[0165] For example, the energy density u of the battery cell 20 is: 300Wh / kg, 330Wh / kg, 360Wh / kg, 390Wh / kg, 420Wh / kg, 450Wh / kg, 470Wh / kg, 480Wh / kg, 490Wh / kg, 500Wh / kg.

[0166] For example, the energy density u of the battery cell 20 is: 700Wh / L, 800Wh / L, 900Wh / L, 1000Wh / L, 1050Wh / L, 1100Wh / L, 1150Wh / L, 1180Wh / L, 1200Wh / L.

[0167] For example, the hard-shell battery cell can be encapsulated in a shell made of metal or high-strength engineering plastic. During the cyclic charging of the battery cell 20, the shell can provide stable support for the internal components and reduce structural damage caused by the expansion or contraction of the electrode assembly 30.

[0168] In the above technical solution, by making the energy density of the battery cell 20 meet the above conditions, the energy storage capacity of the battery cell 20 can be improved, the range of the new energy vehicle 1000 can be increased, and the power performance of the new energy vehicle 1000 can also be improved.

[0169] The method for measuring the energy density of the battery cell 20 may include: weighing the electrode assembly 30 by means of a balance (excluding the test connection plate, etc.), and measuring the length L, width W, and shoulder height H of the electrode assembly by means of a ruler.

[0170] At 25℃, the battery is charged at a constant current of 1 / 3C to 4.25V, then switched to constant voltage charging at 4.25V. Charging is stopped when the current drops to a constant current of 0.05C. After standing for 30 minutes, the battery is discharged at a constant current of 0.33C to 2.5V to obtain the discharge energy ED of the battery cell.

[0171] From the above, we can calculate: the gravimetric energy density of battery cell 20, GED = ED / M; the volumetric energy density of battery cell 20, VED = ED / (L*W*H).

[0172] In one embodiment of this disclosure, the energy density u of the battery cell 20 satisfies: 330Wh / kg≤u≤450Wh / kg, and / or, the energy density u of the battery cell 20 satisfies: 800Wh / L≤u≤1000Wh / L.

[0173] For example, the energy density u of the battery cell 20 is: 330Wh / kg, 350Wh / kg, 370Wh / kg, 390Wh / kg, 410Wh / kg, 420Wh / kg, 430Wh / kg, 440Wh / kg, 450Wh / kg.

[0174] For example, the energy density u of the battery cell 20 is: 800Wh / L, 830Wh / L, 860Wh / L, 890Wh / L, 920Wh / L, 950Wh / L, 970Wh / L, 980Wh / L, 1000Wh / L.

[0175] In the above technical solution, by making the energy density of the battery cell 20 meet the above conditions, the energy storage capacity of the battery cell 20 can be improved, the range of the new energy vehicle 1000 can be increased, and the power performance of the new energy vehicle 1000 can also be improved.

[0176] In one embodiment of this disclosure, the battery cell 20 is a pouch cell 20, and the energy density u of the battery cell 20 satisfies: 350Wh / kg≤u≤550Wh / kg.

[0177] For example, the soft-pack battery cell 20 is a battery cell 20 with a flexible material such as an aluminum-plastic composite film as its outer packaging.

[0178] For example, the energy density u of the battery cell 20 is 350Wh / kg, 370Wh / kg, 390Wh / kg, 410Wh / kg, 420Wh / kg, 430Wh / kg, 440Wh / kg, 450Wh / kg, 470Wh / kg, 480Wh / kg, 490Wh / kg, 500Wh / kg, and 550Wh / kg.

[0179] In the above technical solution, the lightweight soft-pack battery cell 20 can reduce the overall weight of the device equipped with it, such as a drone that can fly longer and farther; and the energy density of the battery cell 20 meets the above conditions, which can improve the energy storage capacity of the battery cell 20, reduce the number of charging times, improve the user experience, and optimize the internal reaction process of the battery cell 20, reduce energy loss, improve charging and discharging efficiency, and reduce the cost of use.

[0180] In one embodiment of this disclosure, the energy density u of the battery cell 20 satisfies: 380Wh / kg≤u≤500Wh / kg.

[0181] For example, the energy density u of the battery cell 20 is: 80Wh / kg, 390Wh / kg, 400Wh / kg, 410Wh / kg, 420Wh / kg, 430Wh / kg, 440Wh / kg, 450Wh / kg, 470Wh / kg, 500Wh / kg.

[0182] In the above technical solution, the energy density of the battery cell 20 meets the above conditions, which can improve the energy storage capacity of the battery cell 20, reduce the number of charging cycles, improve the user experience, and optimize the internal reaction process of the battery cell 20, reduce energy loss, improve charging and discharging efficiency, and reduce usage costs.

[0183] In one embodiment of this disclosure, the mass percentage m of silicon in the negative electrode active material layer satisfies: 0.5% ≤ m ≤ 20%, and the thickness H of the buffer 40 in the first direction X satisfies: 0.5 mm ≤ H ≤ 4 mm. It should be noted that the thickness H of the buffer 40 in the first direction X refers to the thickness of the buffer 40 in its uncompressed state, which will not be elaborated further in the following examples.

[0184] For example, the mass percentage m of silicon element in the negative electrode active material layer is: 0.5%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 20%.

[0185] For example, the thickness H of the buffer 40 in the first direction X is 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, or 4mm.

[0186] In one embodiment of this disclosure, the mass percentage m of silicon in the negative electrode active material layer satisfies: 20% < m ≤ 40%, and the thickness H of the buffer 40 in the first direction X satisfies: 1 mm ≤ H ≤ 8 mm.

[0187] For example, the mass percentage m of silicon element in the negative electrode active material layer is: 21%, 23%, 25%, 27%, 30%, 32%, 35%, 37%, 39%, 40%.

[0188] For example, the thickness H of the buffer 40 in the first direction X is 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, or 8 mm.

[0189] In one embodiment of this disclosure, the mass percentage m of silicon in the negative electrode active material layer satisfies: 40% < m ≤ 60%, and the thickness H of the buffer 40 in the first direction X satisfies: 2 mm ≤ H ≤ 12 mm.

[0190] For example, the mass percentage m of silicon element in the negative electrode active material layer is 41%, 43%, 45%, 47%, 50%, 52%, 55%, 57%, 59%, and 60%.

[0191] For example, the thickness H of the buffer 40 in the first direction X is 2mm, 4mm, 6mm, 8mm, 9mm, 10mm, 11mm, or 12mm.

[0192] In one embodiment of this disclosure, the mass percentage m of silicon in the negative electrode active material layer satisfies: 60% < m ≤ 80%, and the thickness H of the buffer 40 in the first direction X satisfies: 3 mm ≤ H ≤ 16 mm.

[0193] For example, the mass percentage m of silicon element in the negative electrode active material layer is 62%, 65%, 68%, 70%, 72%, 74%, 76%, 78%, and 80%.

[0194] For example, the thickness H of the buffer 40 in the first direction X is 3mm, 5mm, 7mm, 9mm, 11mm, 13mm, 15mm, or 16mm.

[0195] In the above technical solution, the thickness of the buffer 40 in the first direction X can be the sum of the thicknesses of the buffer 40. For example, if there is one buffer 40, the thickness of the buffer 40 is the thickness of this one buffer 40. Or, if there are multiple buffer 40s, the thickness of the buffer 40 in the first direction X can be the sum of the thicknesses of the multiple buffer 40s.

[0196] In the above technical solution, by ensuring that the mass ratio of silicon in the negative electrode active material layer and the thickness of the buffer 40 meet the above conditions, when the volume of the electrode assembly 30 changes during charging and discharging, the thickness of the corresponding buffer 40 can not only effectively alleviate the expansion force on the electrode assembly 30 during the charging and discharging of the battery cell 20, thus better protecting the electrode assembly 30 and improving the cycle performance of the electrode assembly 30 and extending the battery's service life, but also enhance the reliability of the battery cell 20, reduce the risk of failure during use, improve the safety and stability of the battery cell 20 operation, and reduce safety hazards caused by battery failure.

[0197] In addition, matching different mass ratios of silicon elements with different thicknesses of buffer components 40 can improve the filling degree of electrode components 30 in battery cells 20. This not only improves the energy storage capacity of battery cells 20, but also helps to alleviate the expansion force on electrode components 30 during charging and discharging when the battery cells 20 expand. Furthermore, after the electrode components 30 and buffer components 40 are installed in the housing 22, the buffer components 40 can also effectively restrain the electrode components 30, making it less prone to deformation and wrinkling during charging and discharging. This can better ensure the cycle performance and reliability of the electrode components 30.

[0198] Referring to Figures 4 and 5, Figure 4 is a cross-sectional view of a battery cell according to an embodiment (the electrode assembly is a stacked electrode assembly). Figure 5 is a cross-sectional view of a battery cell according to an embodiment (the electrode assembly is a stacked electrode assembly).

[0199] In one embodiment of this disclosure, an electrode assembly 30 is provided, and a buffer 40 is provided on at least one side of the electrode assembly 30 in a first direction X.

[0200] For example, the buffer 40 is disposed on one side of the electrode assembly 30, and the buffer 40 can protect one side of the electrode assembly 30 to a certain extent. During the charging and discharging process of the battery, it can effectively block stress impact, reduce the risk of local deformation of the electrode assembly 30, improve the reliability of the battery assembly, and since there is only one buffer 40, the arrangement cost of the buffer 40 can be reduced.

[0201] For example, two buffers 40 are provided, one on each side of the electrode assembly 30. These two buffers 40 can effectively balance the stress caused by the volume change of the negative electrode active material layer of the battery cell 20 during charging and discharging. By optimizing the stress distribution, problems such as wrinkling and cracking of the electrode layer can be effectively prevented, improving the charging and discharging efficiency of the battery. It can also significantly enhance the cycle performance of the electrode assembly 30, making the battery cell 20 more stable during long-term repeated charging and discharging.

[0202] In the above technical solution, the battery cell 20 is equipped with an electrode assembly 30, which has a simple structure and can effectively reduce the manufacturing process of the battery cell 20. In addition, the internal structure of the battery cell 20 is relatively simple, making the electrochemical reaction and ion transport path inside the battery relatively clear and stable. This helps to reduce energy loss caused by complex structure, improve the charging and discharging efficiency of the battery, ensure the consistency of battery performance, and make subsequent maintenance and testing more convenient. It can more quickly and accurately locate potential problems, facilitate fault diagnosis and repair, and thus extend the overall service life of the battery cell 20. The arrangement of the buffer 40 can better protect the electrode assembly 30, enhance the cycle performance of the electrode assembly 30, and make the battery cell 20 more stable during long-term repeated charging and discharging.

[0203] Please refer to Figures 6 and 7. Figure 6 is a cross-sectional view of a battery cell according to an embodiment (the electrode assembly is a stacked electrode assembly). Figure 7 is a cross-sectional view of a battery cell according to an embodiment (the electrode assembly is a wound electrode assembly).

[0204] In one embodiment of this disclosure, multiple electrode assemblies 30 are provided, and the multiple electrode assemblies 30 are arranged sequentially along a first direction X, with a buffer 40 disposed between two adjacent electrode assemblies 30.

[0205] For example, two or more electrode assemblies 30 may be provided, but this disclosure does not impose any limitation.

[0206] For example, two electrode assemblies 30 are provided, and a buffer 40 may be provided between the two electrode assemblies 30.

[0207] For example, three electrode assemblies 30 are provided, and two buffer members 40 can be provided, with the two buffer members 40 respectively disposed between two adjacent electrode assemblies 30.

[0208] In the above technical solution, by setting a buffer 40 between the two electrode assemblies 30, stress impact can be effectively blocked during battery charging and discharging, reducing the risk of local deformation of the electrode assembly 30 and improving the reliability of the battery assembly.

[0209] Please refer to Figures 8 and 9. Figure 8 is a cross-sectional view of a battery cell according to an embodiment (the electrode assembly is a wound electrode assembly). Figure 9 is a cross-sectional view of a battery cell according to an embodiment (the electrode assembly is a wound electrode assembly).

[0210] In one embodiment of this disclosure, multiple electrode assemblies 30 are provided. Among the multiple electrode assemblies 30, the two electrode assemblies 30 located at both ends of the first direction X are respectively the first electrode assembly and the second electrode assembly. The buffer 40 is arranged between the first electrode assembly and the housing 22, and / or the buffer 40 is arranged between the second electrode assembly and the housing 22.

[0211] For example, two electrode assemblies 30 are provided, namely a first electrode assembly and a second electrode assembly. For instance, one buffer 40 can be provided, which can be disposed between the first electrode assembly and the housing 22, or the buffer 40 can be disposed between the second electrode assembly and the housing 22; or two buffers 40 can be provided, that is, one buffer 40 can be disposed between the first electrode assembly and the housing 22, and the other buffer 40 can be disposed between the second electrode assembly and the housing 22. Furthermore, three buffers 40 can also be provided, that is, the first buffer 40 can be disposed between the first electrode assembly and the housing 22, the second buffer can be disposed between the second electrode assembly and the housing 22, and the third buffer 40 can be disposed between the first electrode assembly and the second electrode assembly.

[0212] For example, three electrode assemblies 30 are provided, arranged sequentially along the first direction X. The three electrode assemblies 30 are respectively a first electrode assembly, a second electrode assembly, and a third electrode assembly, with the third electrode assembly located between the first and second electrode assemblies. For example, one buffer member 40 can be provided, which can be located between the first electrode assembly and the housing 22, or between the second electrode assembly and the housing 22. Alternatively, two buffer members 40 can be provided, that is, one buffer member 40 can be located between the first electrode assembly and the housing 22, and the other buffer member 40 can be located between the second electrode assembly and the housing 22. Furthermore, four buffer members 40 can also be provided, that is, the first buffer member 40 can be located between the first electrode assembly and the housing 22, the second buffer member 40 can be located between the second electrode assembly and the housing 22, the third buffer member 40 can be located between the first and third electrode assemblies, and the fourth buffer member 40 can be located between the second and third electrode assemblies.

[0213] In the above technical solution, by setting buffers 40 at different locations, stress impacts can be effectively blocked during battery charging and discharging, reducing the risk of local deformation of the electrode assembly 30 and improving the reliability of the battery assembly.

[0214] In one embodiment of this disclosure, as shown in Figures 6 and 7, the electrode assembly 30 is a wound electrode assembly, or the electrode assembly 30 is a stacked electrode assembly.

[0215] When the electrode assembly 30 is a wound electrode assembly, the tightly wound structure can accommodate a larger amount of active material within a limited space, which helps to improve the energy density of the battery. Moreover, this structure has good stability and can resist external impacts to a certain extent, ensuring the safety and reliability of the battery.

[0216] If the electrode assembly 30 is a stacked electrode assembly, the connection between the electrodes is tighter, the electron transport path is shorter and more uniform, which can reduce the internal resistance of the battery and improve charge / discharge performance and rate performance. The stacked structure can better adapt to the expansion and contraction of the battery, reduce electrode damage caused by stress concentration, and extend battery life, making it suitable for scenarios with high requirements for battery performance and lifespan.

[0217] In the above technical solution, the arrangement of the buffer 40 can effectively protect the wound electrode assembly and the stacked electrode assembly. During the battery charging and discharging process, it can effectively block stress impact, reduce the risk of local deformation of the electrode assembly 30, and improve the reliability of the battery assembly.

[0218] Please refer to Figures 10 and 11. Figure 10 is a cross-sectional view of a wound electrode assembly according to an embodiment. Figure 11 is a cross-sectional view of a wound electrode assembly and a buffer member 40 according to an embodiment.

[0219] In one embodiment of this disclosure, the electrode assembly 30 is a wound electrode assembly. The electrode assembly 30 includes a straight section 31 and a corner section 32. There are two corner sections 32, which are respectively connected to the two sides of the straight section 31 in the second direction Y. The first direction X and the second direction Y are perpendicular to each other. The buffer member 40 includes a straight part 41 and at least one corner part 42 connected to each other. The straight part 41 is stacked with the straight section 31, and the corner part 42 is stacked with the corner section 32.

[0220] Here, the straight section 31 and the corner section 32 are explained with reference to Figures 10 and 11. After the electrode assembly 30 is wound, the straight section 31 is the part that extends along the second direction Y. In the straight section 31, both the positive electrode and the negative electrode are straight sheets, while the corner section 32 is the part where the positive electrode and the negative electrode are bent.

[0221] For example, the buffer 40 completely covers the straight section 31, thereby providing better protection for the straight section 31 of the electrode assembly 30. Furthermore, two corner sections 42 are constructed so that the corner sections 32 can also be better protected, and the connection between the straight section 31 and the corner sections 32 can also be better protected.

[0222] In the above technical solution, by arranging the coverage area of ​​the buffer 40, the electrode assembly 30 can be effectively protected. During the charging and discharging process of the battery, it can effectively block stress impacts, reduce the risk of local deformation of the electrode assembly 30, and improve the reliability of the battery assembly.

[0223] In one embodiment of this disclosure, as shown in Figures 10 and 11, the connection between the straight section 31 and the corner section 32 is a corner connection 33, and the end of the corner section 32 away from the straight section 31 is a corner tip 34. In the winding direction of the electrode assembly 30, the dimension from the corner connection 33 to the corner tip 34 is c1, and the dimension c2 of the corner portion 42 satisfies: 0 < c2 ≤ c1.

[0224] In other words, when the buffer 40 covers the outside of the electrode assembly 30, the buffer 40 can extend from the straight section 31 toward the corner section 32, and the corner connection 33 is covered on the inside of the buffer 40, so that the corner connection 33 can also be well protected. Furthermore, by arranging the coverage area of ​​the corner portion 42 in this disclosure, not only can the electrode assembly 30 be well protected, but the material used in the buffer 40 at the corner portion 42 can also be saved, thereby saving costs.

[0225] For example, the corner portion 42 can cover the corner connection 33.

[0226] For example, the corner portion 42 may extend from the corner connection 33 to the corner tip 34.

[0227] For example, one end of the corner portion 42 covers the corner connection 33, and the other end covers the corner tip 34, but does not cover the corner tip 34.

[0228] In the above technical solution, by arranging the coverage area of ​​the buffer 40, the electrode assembly 30 can be effectively protected. During the charging and discharging process of the battery, it can effectively block stress impacts, reduce the risk of local deformation of the electrode assembly 30, and improve the reliability of the battery assembly.

[0229] In one embodiment of this disclosure, the electrode assembly 30 is a stacked electrode assembly with sheets stacked along the first direction X. In the projection plane perpendicular to the first direction X, the projected area of ​​the positive electrode sheet is smaller than the projected area of ​​the buffer 40, and the projection of the positive electrode sheet is located within the projection of the buffer 40.

[0230] For example, the size of the buffer 40 is larger than the size of the positive electrode in both the second direction Y and the third direction Z, wherein the second direction Y and the third direction Z are perpendicular to each other.

[0231] For example, in both the second direction Y and the third direction Z, the size of the buffer 40 can be smaller than the size of the negative electrode.

[0232] For example, in both the second direction Y and the third direction Z, the size of the buffer 40 can be larger than the size of the negative electrode.

[0233] In the above technical solution, by arranging the coverage area of ​​the buffer 40, the electrode assembly 30 can be effectively protected. During the charging and discharging process of the battery, it can effectively block stress impacts, reduce the risk of local deformation of the electrode assembly 30, and improve the reliability of the battery assembly.

[0234] In one embodiment of this disclosure, the silicon material containing silicon in the negative electrode active material layer includes silicon, silicon-carbon, or silicon-oxygen.

[0235] In the aforementioned technical solutions, silicon possesses a high theoretical specific capacity, which can improve battery energy density and enhance battery life. Silicon-carbon and silicon-oxygen compounds mitigate the volume expansion problem of silicon, improve cycle life and stability, and enable the battery to exhibit superior performance during charging and discharging. This allows the battery to meet the performance requirements of various application scenarios and demonstrates strong practicality.

[0236] In one embodiment of this disclosure, the buffer 40 is composed of one of a foam material, porous foam, aerogel, silicone rubber, polyethylene, polypropylene, and polyethylene terephthalate.

[0237] In the above technical solution, the buffer 40 can be made of a variety of materials, and the material of the buffer 40 can be selected according to the actual situation, which makes it highly practical.

[0238] In one embodiment of this disclosure, the buffer 40 is a porous buffer with a porosity design range of 10% to 95%.

[0239] For example, the buffer 40 is a porous buffer made of the above-mentioned material. By combining the above-mentioned material with different porosity designs, the buffer 40 can achieve different degrees of compressibility.

[0240] For example, the porosity design range can be 10% to 95%. By designing the porosity of the buffer 40, the liquid absorption and retention effect of the buffer 40 can be improved, which can improve the problem of poor electrolyte extrusion and backflow wetting during the expansion and contraction of the silicon anode during charging and discharging.

[0241] In the above technical solution, by designing the buffer 40, different compression effects of the buffer 40 can be achieved better. In addition, it is also beneficial to improve the liquid absorption and retention effect of the buffer 40, which can improve the problem of poor electrolyte extrusion and backflow wetting during the expansion and contraction of the silicon negative electrode during charging and discharging.

[0242] In one embodiment of this disclosure, the quotient of the compressible thickness of the buffer 40 divided by the thickness of the buffer 40 before compression is Δh, which satisfies: Δh = 0.4*x + 0.5, where x is the mass percentage of silicon in the negative electrode active material layer.

[0243] In the above technical solution, by satisfying the above conditions, the buffer 40 can be designed according to the mass ratio of silicon element, so that the buffer 40 can better meet the buffering requirements of electrode assembly 30 with different mass ratios of silicon element during the charging and discharging process.

[0244] In one embodiment of this disclosure, in the first direction X, the size of the receiving cavity of the housing 22 is D1. When the electrode assembly 30 is a bare cell, the sum of the thicknesses of the electrode assembly 30 and the buffer 40 before compression is D2, satisfying: 90% ≤ D2 / D1 ≤ 97%; and / or, when the electrode assembly 30 is in a fully charged state, the sum of the thicknesses of the electrode assembly 30 and the buffer 40 after compression is D3, satisfying: 100% ≤ D2 / D1 ≤ 102%.

[0245] In other words, in the initial state, the design of 90%≤D2 / D1≤97% allows the electrode assembly 30 and the buffer 40 to be placed more tightly inside the housing 22, avoiding unnecessary shaking or displacement due to excessive looseness. This ensures the stability of the internal structure of the battery cell 20, reduces damage to the electrodes and separator caused by physical friction, collision and other factors, helps maintain the consistency and reliability of battery performance, reduces the risk of short circuit, and improves production assembly efficiency and battery yield.

[0246] When the electrode assembly 30 is fully charged, the ratio of 100% ≤ D3 / D1 ≤ 102% ensures that the expansion of the battery cell 20 during operation has adequate buffer space. This prevents the electrode assembly 30 from being damaged due to excessively small space inhibiting its normal expansion, and also prevents it from moving excessively within the casing 22 due to excessive space. This ensures that the battery maintains good electrical contact and structural integrity during charge-discharge cycles, extending its cycle life, improving the safety and stability of the battery cell 20 under different operating conditions, and guaranteeing its efficient and stable provision of power to electrical equipment.

[0247] In the above technical solution, by meeting the above conditions, the safety and stability of the battery cell 20 under different operating conditions can be improved, and the battery cell 20 can be better guaranteed to provide power to the electrical equipment efficiently and stably.

[0248] In one embodiment of this disclosure, the buffer 40 is bonded to the electrode assembly 30, and / or the battery cell 20 further includes an insulating film, in which the electrode assembly 30 and the buffer 40 are covered.

[0249] For example, the buffer 40 is bonded to the electrode assembly 30.

[0250] For example, the battery cell 20 also includes an insulating film, and the electrode assembly 30 and the buffer 40 are covered within the insulating film.

[0251] For example, after the buffer 40 is bonded to the electrode assembly 30, it is also covered by an insulating film.

[0252] In the above technical solution, when the buffer 40 is bonded to the electrode assembly 30, this tight connection effectively prevents the buffer 40 from shifting during use, ensuring that it always protects the electrode assembly 30. During battery charging and discharging, the electrode assembly 30 undergoes volume changes. The bonded buffer 40 can effectively absorb and disperse stress, reducing damage to the electrode assembly 30 caused by stress concentration, thereby improving the cycle life and stability of the battery cell 20. If the battery cell 20 adopts a structure in which the electrode assembly 30 and the buffer 40 are encased in an insulating film, the insulating film provides additional protection, preventing the electrode assembly 30 from short-circuiting due to contact with the external environment, thus enhancing battery safety. At the same time, the insulating film also helps maintain the relative position of the electrode assembly 30 and the buffer 40, further optimizing stress distribution and ensuring the performance reliability of the battery during long-term use.

[0253] This disclosure also proposes a battery device 100 having the battery cell 20 described in the above embodiments.

[0254] As shown in Figure 2, in some embodiments of this disclosure, the battery device 100 includes a housing 10 and battery cells 20. Multiple battery cells 20 are provided, and the multiple battery cells 20 are arranged sequentially in the housing 10 along the first direction X.

[0255] According to the battery device 100 of the present disclosure, by providing the battery cell 20 of the above embodiment, the energy density of the battery cell 20 can be increased, and the safety and stability of the operation of the battery cell 20 can also be improved.

[0256] The aforementioned battery device 100 can be applied to, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among these, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., while spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0257] Since the battery device 100 of this disclosure adopts all the technical solutions of all the above embodiments, it also has all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0258] In some embodiments of this disclosure, the battery device 100 further includes a heat insulation element disposed between two adjacent battery cells 20, and / or, the heat insulation element disposed between the battery cell 20 and the housing 10.

[0259] In the above technical solution, the heat insulation component is arranged between two adjacent battery cells 20. This component effectively prevents heat transfer between the battery cells 20, preventing thermal runaway caused by overheating of one battery cell 20 from affecting surrounding cells, reducing the risk of heat propagation, and improving the safety of the battery device 100. The heat insulation component, located between the battery cell 20 and the housing 10, reduces heat transfer from the battery to the housing 10, preventing damage to the housing 10 due to high temperatures. It also isolates the battery from external heat, keeping it in a relatively stable thermal environment. This helps maintain consistent battery performance, improves battery life and efficiency, and ensures safe and stable operation of the battery system under various operating conditions.

[0260] This disclosure also proposes an electrical device.

[0261] According to embodiments of the present disclosure, the power-consuming device may include a battery device 100 for storing or providing electrical energy.

[0262] In the above technical solution, by providing the battery device 100 of the above example, the power device of this disclosure can have better battery life, as well as better safety and stability.

[0263] Other configurations and operations of the battery cell 20, battery device 100, and electrical device according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0264] In the description of this specification, references to terms such as "some embodiments," "optionally," "furthermore," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0265] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A battery cell (20), wherein, include: Shell (22); An electrode assembly (30) is located inside the housing (22). The electrode assembly (30) includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. The negative electrode includes a negative current collector and a negative active material layer disposed on at least one side of the negative current collector. In the negative active material layer, the mass percentage m of silicon element satisfies: 0.5% ≤ m ≤ 80%. A buffer (40) is stacked with at least a portion of the negative electrode active material layer.

2. The battery cell (20) according to claim 1, wherein, In the negative electrode active material layer, the mass percentage m of silicon element satisfies: 15% ≤ m ≤ 60%.

3. The battery cell (20) according to claim 1 or 2, wherein, The areal density p of the negative electrode active material layer satisfies: 2.6 mg / cm³ 2 ≤p≤10mg / cm 2 .

4. The battery cell (20) according to claim 3, wherein, The areal density ρ of the negative electrode active material layer satisfies: 3 mg / cm³ 2 ≤p≤6.5mg / cm 2 .

5. The battery cell (20) according to any one of claims 1-4, wherein, The compaction density d1 of the negative electrode active material layer satisfies: 0.8 g / cm³ 3 ≤d1≤1.7g / cm 3 .

6. The battery cell (20) according to claim 5, wherein, The compaction density d1 of the negative electrode active material layer satisfies: 0.9 g / cm³ 3 ≤d1≤1.2g / cm 3 .

7. The battery cell (20) according to any one of claims 1-6, wherein, When the negative electrode active material layer is fully charged, the compaction density d2 of the negative electrode active material layer satisfies: 0.5 g / cm³. 3 ≤d2≤1.6g / cm 3 .

8. The battery cell (20) according to claim 7, wherein, In the negative electrode active material layer, the mass percentage m of silicon element satisfies: 15% ≤ m ≤ 60%, and when the negative electrode active material layer is fully filled, the compaction density d2 of the negative electrode active material layer satisfies: 0.6 g / cm³. 3 ≤d2≤0.9g / cm 3 .

9. The battery cell (20) according to any one of claims 1-8, wherein, The battery cell (20) is a hard-shell battery cell (20), and the energy density u of the battery cell satisfies: 300Wh / kg≤u≤500Wh / kg, and / or, the energy density u of the battery cell satisfies: 700Wh / L≤u≤1200Wh / L.

10. The battery cell (20) according to claim 9, wherein, The energy density u of the battery cell satisfies: 330Wh / kg≤u≤450Wh / kg, and / or, the energy density u of the battery cell satisfies: 800Wh / L≤u≤1000Wh / L.

11. The battery cell (20) according to any one of claims 1-10, wherein, The battery cell (20) is a soft-pack battery cell (20), and the energy density u of the battery cell satisfies: 350Wh / kg≤u≤550Wh / kg.

12. The battery cell (20) according to claim 11, wherein, The energy density u of the battery cell satisfies: 380Wh / kg≤u≤500Wh / kg.

13. The battery cell (20) according to any one of claims 1-12, wherein, In the negative electrode active material layer, the mass percentage m of silicon element satisfies: 0.5% ≤ m ≤ 20%, and the thickness H of the buffer element (40) in the first direction (X) satisfies: 0.5 mm ≤ H ≤ 4 mm, or... In the negative electrode active material layer, the mass percentage m of silicon element satisfies: 20% < m ≤ 40%, and the thickness H of the buffer element (40) in the first direction (X) satisfies: 1 mm ≤ H ≤ 8 mm, or, In the negative electrode active material layer, the mass percentage m of silicon element satisfies: 40% < m ≤ 60%, and the thickness H of the buffer element (40) in the first direction (X) satisfies: 2mm ≤ H ≤ 12mm, or... In the negative electrode active material layer, the mass percentage m of silicon element satisfies: 60% < m ≤ 80%, and the thickness H of the buffer (40) in the first direction (X) satisfies: 3mm ≤ H ≤ 16mm.

14. The battery cell (20) according to any one of claims 1-13, wherein, The electrode assembly (30) is provided with one, and the buffer (40) is provided on at least one side of the electrode assembly (30) in a first direction (X).

15. The battery cell (20) according to any one of claims 1-14, wherein, Multiple electrode assemblies (30) are provided, and the multiple electrode assemblies (30) are arranged sequentially along the first direction (X). The buffer (40) is arranged between two adjacent electrode assemblies (30).

16. The battery cell (20) according to any one of claims 1-15, wherein, The electrode assembly (30) is provided in multiple ways. Among the multiple electrode assemblies (30), the two electrode assemblies (30) located at both ends of the first direction (X) are respectively the first electrode assembly and the second electrode assembly. The buffer (40) is arranged between the first electrode assembly and the housing (22), and / or the buffer (40) is arranged between the second electrode assembly and the housing (22).

17. The battery cell (20) according to any one of claims 1-16, wherein, The electrode assembly (30) is a wound electrode assembly, or the electrode assembly (30) is a stacked electrode assembly.

18. The battery cell (20) according to claim 17, wherein, The electrode assembly (30) is a wound electrode assembly. The electrode assembly (30) includes a straight section (31) and a corner section (32). The corner section (32) includes two sections, and the two corner sections (32) are respectively connected to the two sides of the straight section (31) in the second direction (Y). The buffer (40) includes a straight portion (41) and at least one corner portion (42) connected together. The straight portion (41) is stacked with the straight segment (31), and the corner portion (42) is stacked with the corner segment (32).

19. The battery cell (20) according to claim 18, wherein, The connection between the straight section (31) and the corner section (32) is a corner connection (33), and the end of the corner section (32) away from the straight section (31) is a corner tip (34). In the winding direction of the electrode assembly (30), the dimension from the corner connection (33) to the corner tip (34) is c1, and the dimension c2 of the corner portion (42) satisfies: 0 < c2 ≤ c1.

20. The battery cell (20) according to any one of claims 17-19, wherein, The electrode assembly (30) is a stacked electrode assembly with sheets stacked along the first direction (X). In the projection plane perpendicular to the first direction (X), the projection of the positive electrode sheet is located within the projection of the buffer (40).

21. The battery cell (20) according to any one of claims 1-20, wherein, The silicon material containing the silicon element in the negative electrode active material layer includes silicon, silicon-carbon, or silicon-oxygen.

22. The battery cell (20) according to any one of claims 1-21, wherein, The buffer (40) is composed of one of the following: foam material, porous foam, aerogel, silicone rubber, polyethylene, polypropylene and polyethylene terephthalate.

23. The battery cell (20) according to any one of claims 1-22, wherein, In the first direction (X), the size of the receiving cavity of the housing (22) is D1. When the electrode assembly (30) is a bare cell, the sum of the thicknesses of the electrode assembly (30) and the buffer (40) before compression is D2, satisfying: 90% ≤ D2 / D1 ≤ 97%; and / or, When the electrode assembly (30) is fully charged, the sum of the thicknesses of the electrode assembly (30) and the buffer (40) after compression is D3, which satisfies: 100% ≤ D2 / D1 ≤ 102%.

24. The battery cell (20) according to any one of claims 1-23, wherein, The buffer (40) is bonded to the electrode assembly (30), and / or, The battery cell (20) also includes an insulating film, and the electrode assembly (30) and the buffer (40) are covered within the insulating film.

25. The battery cell (20) according to any one of claims 1-24, wherein, The buffer (40) is a porous buffer with a porosity of 10% to 95%.

26. A battery device (100), wherein, include Box (10); The battery cell (20) according to any one of claims 1-25, wherein the battery cell (20) is located within the housing (10).

27. The battery device (100) according to claim 26, wherein, It also includes a heat insulation element arranged between two adjacent battery cells (20) and / or arranged between the battery cells (20) and the housing (10).

28. An electrical appliance, wherein, include: The battery device (100) according to claim 26 or 27.

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