Battery monomer and device, power utilization device, energy storage device and system, and charging network

Abstract

The utility model provides a battery monomer and device, a power utilization device, an energy storage device and system and a charging network, and relates to the field of batteries. The battery monomer comprises a shell, an electrode assembly and an end cover assembly, the end cover assembly comprises a cover plate and an electrode terminal, the electrode terminal comprises a first connecting part and a second connecting part, the first connecting part is located on the side, facing the electrode assembly, of the cover plate and is electrically connected with the electrode assembly, the second connecting part penetrates through a mounting hole of the cover plate, and the orthographic projection area of the first connecting part on the cover plate is larger than the area of the mounting hole; a diaphragm of the electrode assembly comprises a first main body part opposite to the active material region of the negative plate, and a first exceeding part exceeding the active material region of the negative plate along a first direction parallel to the thickness of the cover plate; the size of the first exceeding part in the first direction is larger than or equal to 2.3 mm and smaller than or equal to 4.3 mm.

Description

[0001] Cross-referencing

[0002] This application incorporates, in its entirety, patent application No. PCT / CN2025 / 140452, filed on December 5, 2025, entitled “Battery cell and device, power device, energy storage device and system, charging network”. Technical Field

[0003] This application relates to the field of battery technology, and in particular to a battery cell and device, an electrical device, an energy storage device and system, and a charging network. Background Technology

[0004] Energy conservation and emission reduction are key to the sustainable development of the automotive industry, and electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of this sustainable development. For electric vehicles, battery technology is a crucial factor in their development.

[0005] During the charging and discharging process, as the amount of gas produced and the expansion intensify, the internal electrode plates of the battery may become misaligned, which may lead to lithium plating or short circuit risks, and improvements are urgently needed. Utility Model Content

[0006] This application aims to at least solve one of the technical problems existing in the prior art. To this end, one object of this application is to provide battery cells and devices, power-consuming devices, energy storage devices and systems, and charging networks to improve battery life.

[0007] An embodiment of the first aspect of this application provides a battery cell, comprising: a housing including a receiving cavity with an opening; an electrode assembly disposed within the receiving cavity, the electrode assembly including a negative electrode sheet and a separator; and an end cap assembly covering the opening, the end cap assembly including a cover plate and electrode terminals, the cover plate having mounting holes, the electrode terminals including a first connecting portion and a second connecting portion connected together, the first connecting portion being located on the side of the cover plate facing the electrode assembly and electrically connected to the electrode assembly, the second connecting portion passing through the mounting holes, the orthogonal projection area of ​​the first connecting portion on the cover plate being larger than the area of ​​the mounting holes; wherein the separator includes a first main body portion facing the active material region of an adjacent negative electrode sheet, and a first protruding portion extending beyond the active material region of the negative electrode sheet along a first direction parallel to the thickness of the cover plate, the dimension of the first protruding portion along the first direction being greater than or equal to 2.3 mm and less than or equal to 4.3 mm.

[0008] The technical scheme of the embodiment of the application can effectively reduce the risk of lithium deposition or short circuit caused by the dislocation of the pole piece by optimizing the size relationship between the separator and the negative pole piece in the battery monomer, and can also take into account the space arrangement in the battery monomer, thereby improving the energy density of the battery monomer, reducing the force between the electrode assembly and the end cover assembly in the later cycle stage, and combining the cross-sectional area of the first connecting part of the electrode terminal in the accommodating cavity being greater than the area of the mounting hole, so that the electrode terminal can be tightly attached to the side surface of the electrode assembly facing the cover plate when the pressure in the battery monomer increases, thereby being more conducive to the sealing of the position of the electrode terminal, reducing the probability of failure of the shell sealing, and improving the reliability and service life of the battery.

[0009] In some embodiments, the size of the first overhanging part in the first direction is greater than or equal to 2.5 mm and less than or equal to 4 mm. By reasonably limiting the size of the overhanging part, the size adaptation relationship between the separator and the negative pole piece can be further improved, thereby improving the service life of the battery.

[0010] In some embodiments, the first overhanging part includes a first sub-overhanging part close to one side of the cover plate and a second sub-overhanging part away from the side of the cover plate; the difference between the size of the first sub-overhanging part and the size of the second sub-overhanging part in the first direction is less than or equal to 0.1 mm. This can better provide uniform insulation spacing for the two ends of the negative active material area in the first direction, reduce the risk of short circuit, and improve the reliability and service life of the battery.

[0011] In some embodiments, the electrode assembly further includes a positive pole piece, and the positive pole piece is arranged on the side of the separator away from the negative pole piece; the active material area of the negative pole piece includes a second main part opposite to the active material area of the adjacent positive pole piece and a second overhanging part extending beyond the active material area of the positive pole piece in the first direction, and the size of the second overhanging part in the first direction is greater than or equal to 1.6 mm and less than or equal to 7 mm. This can take into account the energy density of the battery monomer and the risk of lithium deposition or short circuit during the cycle process, thereby improving the reliability and service life of the battery.

[0012] In some embodiments, the size of the second overhanging part in the first direction is greater than or equal to 1.6 mm and less than or equal to 5.5 mm. This can improve the size adaptation of the negative pole piece and the positive pole piece, balance the capacity of the positive and negative poles and the utilization rate of the electrode material, and take into account the energy density of the battery monomer and the service life of the battery.

[0013] In some embodiments, the second overhanging part includes a third sub-overhanging part close to one side of the cover plate and a fourth sub-overhanging part away from the side of the cover plate; the difference between the size of the third sub-overhanging part and the size of the fourth sub-overhanging part in the first direction is less than or equal to 0.1 mm. This can uniformly wrap the two end edges of the positive pole in the first direction, reduce the risk of short circuit caused by lithium dendrites, and improve the reliability and service life of the battery.

[0014] In some embodiments, the negative tab, the separator, and the positive tab are stacked along a second direction; the active material area of the negative tab further comprises a third overhanging part along a third direction beyond the active material area of the positive tab, a dimension of the third overhanging part along the third direction is less than or equal to a dimension of the second overhanging part along the first direction, and the third direction, the second direction, and the first direction are perpendicular to each other. In this way, the arrangement inside the battery cell can be better adapted, and the risk of lithium precipitation or short circuit can be reduced.

[0015] In some embodiments, the dimension of the third overhanging part along the third direction is greater than or equal to 1.6 mm and less than or equal to 3 mm. By reasonably setting the third overhanging part dimension of the negative tab and the positive tab along the third direction, the adaptation between the negative tab and the positive tab can be improved, thereby facilitating the improvement of the energy density of the battery cell, the cycle performance of the battery cell, and the service life.

[0016] In some embodiments, the third overhanging part comprises a fifth sub-overhanging part and a sixth sub-overhanging part spaced apart along the third direction, and a difference between the dimensions of the fifth sub-overhanging part and the sixth sub-overhanging part along the third direction is less than or equal to 0.1 mm. In this way, the uniformity of current distribution can be improved, the risk of uneven force on different sides leading to sliding and warping deformation can be reduced, and the compactness of the electrode assembly structure can be improved, thereby improving the service life and energy density of the battery cell.

[0017] In some embodiments, the end cover assembly further comprises a sealing ring, the sealing ring is sleeved on the outer periphery of the second connecting part, and at least a part of the sealing ring is clamped between the first connecting part and the cover plate. When the internal pressure of the battery cell increases, the first connecting part of the electrode terminal will move away from the electrode assembly under the action of the pressure, thereby pressing the sealing ring and improving the reliability of the installation interface seal between the electrode terminal and the cover plate.

[0018] In some embodiments, the sealing ring comprises a first step part and a second step part connected to each other; the first step part is clamped between the first connecting part and the cover plate, and the second step part is clamped between the second connecting part and the inner wall of the cover plate forming the mounting hole. In this way, independent sealing interfaces can be respectively formed between the first connecting part and the cover plate and between the second connecting part and the inner wall of the cover plate forming the mounting hole, thereby reducing the probability of leakage and improving the reliability of the seal.

[0019] In some embodiments, the first step portion further comprises a first sub-step portion and a second sub-step portion connected in sequence, the second sub-step portion is located between the first sub-step portion and the second step portion, and the second sub-step portion is in abutment with at least part of the surface of the first sub-step portion away from the side surface of the cover plate facing the electrode assembly. The first step portion is provided as a multi-step structure to achieve multi-level sealing, so as to always maintain the effectiveness and reliability of the sealing even in harsh working conditions, thereby improving the service life of the battery monomer.

[0020] In some embodiments, the end cover assembly further comprises a first insulating member arranged on the side surface of the cover plate facing the electrode assembly; the first insulating member comprises a number of avoiding holes equal to the number of electrode terminals, and the avoiding holes are configured to allow the corresponding electrode terminals and the sealing ring to pass through. By arranging the first insulating member, the insulation effect inside the battery monomer can be further improved, thereby improving the reliability of the battery.

[0021] In some embodiments, in a plane perpendicular to the thickness direction of the cover plate, the first insulating member defines a normal projection of the inner edge of the avoiding hole, which falls completely within the normal projection range of the first connecting portion. In this way, the electrode terminal can be provided with a limit in the third direction, and the direct contact between the first connecting portion and the cover plate due to structural deformation can be reduced, better meeting the sealing reliability and electrical connection reliability requirements when the internal pressure of the battery monomer is large.

[0022] In some embodiments, the electrode terminal further comprises a third connecting portion arranged on the side of the cover plate away from the electrode assembly and fixedly connected with the end of the second connecting portion away from the first connecting portion; the end cover assembly further comprises a second insulating member clamped between the third connecting portion and the cover plate. In this way, the connectable area of the electrode terminal outside the battery monomer can be increased, thereby facilitating the subsequent electrical connection with the busbar. At the same time, the third connecting portion and the first connecting portion are clamped on both sides of the cover plate, which reduces the probability or degree of deformation of the electrode terminal when the internal pressure of the battery monomer is large, so that the sealing ring can play a better sealing role, and the installation and fixation between the electrode terminal and the cover plate are more reliable, which is more conducive to maintaining the reliability of the electrical connection between the electrode terminal and the outside.

[0023] In some embodiments, the cover plate comprises a center portion and an overlapping portion surrounding the outer periphery of the center portion, the overlapping portion is used for fixedly connecting with the end face of the opening in the shell, and a part of the center portion extends into the accommodation cavity through the opening. In this way, the positioning before welding can be simplified, the probability of laser damage to the electrode assembly can be reduced, the yield of the battery monomer can be improved, and the battery monomer can better resist the swelling deformation during the charge and discharge cycle, thereby improving the overall performance of the battery monomer.

[0024] In some embodiments, the electrode assembly comprises a positive electrode sheet, and the active material of the active material region of the positive electrode sheet comprises a lithium phosphate salt. Such active material, in cooperation with the shell structure, can further improve the overall performance of the battery cell.

[0025] In some embodiments, at least one of the active material region of the positive electrode sheet and the active material region of the negative electrode sheet has a dimension along the first direction of 100-200 mm, preferably 160-200 mm. This can effectively balance the capacity of the battery cell and the risk of deformation or lithium precipitation, improving the reliability and service life of the battery cell.

[0026] Embodiments of the second aspect of the present application provide a battery device comprising the battery cell described above.

[0027] Embodiments of the third aspect of the present application provide a power consuming device, which comprises the battery device described above, and the battery device is used to provide electric energy.

[0028] Embodiments of the fourth aspect of the present application provide an energy storage device, which comprises a plurality of battery cells or a plurality of battery devices described above, and the battery cells or battery devices are used to store or provide electric energy.

[0029] Embodiments of the fifth aspect of the present application provide an energy storage system, which comprises a power conversion device and an energy storage device described above, and the power conversion device is used to electrically connect a power generation device and the energy storage device.

[0030] Embodiments of the sixth aspect of the present application provide a charging network, which comprises a charging pile and an energy storage device or an energy storage system described above, and the energy storage device or the energy storage system is used to provide electric energy for the charging pile.

[0031] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, the following specific embodiments of the present application can be implemented in accordance with the content of the description, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0032] In the drawings, the same reference numbers in the several drawings represent the same or similar components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments according to the present disclosure, and should not be considered as limiting the scope of the present application.

[0033] Figure 1 The exploded structural schematic diagram of the battery device provided by some embodiments of the present application;

[0034] Figure 2 The structural schematic diagram of the energy storage system provided by some embodiments of the present application;

[0035] Figure 3 Structural schematic diagram of charging network provided for some embodiments of the present application;

[0036] Figure 4 Exploded structural schematic diagram of battery monomer provided for some embodiments of the present application;

[0037] Figure 5 Structural schematic diagram of end cover assembly provided for some embodiments of the present application;

[0038] Figure 6 Exploded structural schematic diagram of end cover assembly provided for some embodiments of the present application;

[0039] Figure 7 Partial sectional view of electrode assembly provided for some embodiments of the present application Figure 1 ;

[0040] Figure 8 Partial sectional view of electrode assembly provided for some embodiments of the present application Figure 2 ;

[0041] Figure 9 Stacking schematic diagram of electrode sheet provided for some embodiments of the present application;

[0042] Figure 10 Structural schematic diagram of sealing ring provided for some embodiments of the present application. Figure 5 Cross-sectional view along A-A direction;

[0043] Figure 11 Partial enlarged view of B area in Figure 10 ;

[0044] Figure 12 Partial enlarged view of C area in Figure 10 ;

[0045] Figure 13 Structural schematic diagram of sealing ring provided for some embodiments of the present application.

[0046] Explanation of reference signs:

[0047] 100, battery device, 200, energy storage device, 300, power conversion equipment, 400, power generation equipment, 500, charging pile, 600, connector;

[0048] 10, box body, 11, first part, 12, second part;

[0049] 20, battery monomer;

[0050] 21. end cover assembly, 211. cover plate, 211a. mounting hole, 2111. lap joint, 2112. center portion, 212. electrode terminal, 2121. first connecting portion, 2122. second connecting portion, 2123. third connecting portion; 213. first insulating member, 213a. avoiding hole; 214. sealing ring, 2141. first step portion, 2141a. first sub-step portion, 2141b. second sub-step portion, 2142. second step portion, 215. second insulating member;

[0051] 22. housing, 221. first side wall, 222. second side wall, 223. bottom wall, 224. pressure relief mechanism;

[0052] 23. electrode assembly, 23a. tab, 231. negative electrode sheet, 2311. negative current collector, 2312. negative active material layer, 232. positive electrode sheet, 2321. positive current collector, 2322. positive active material layer, 233. separator, 2330. first overhanging portion, 2331. first main body portion, 2332. first sub-overhanging portion, 2333. second sub-overhanging portion, 2314. second overhanging portion, 2315. third overhanging portion, 231A. second main body portion, 231B. third sub-overhanging portion, 231C. fourth sub-overhanging portion, 231D. fifth sub-overhanging portion, 231E. sixth sub-overhanging portion;

[0053] X. first direction, Y. second direction, Z. third direction. DETAILED DESCRIPTION

[0054] The embodiments of the technical scheme of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical scheme of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; the terms "include" and "have" and any variations thereof used in the specification and the claims and the above description of drawings are intended to cover the non-exclusive inclusion.

[0056] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0057] Reference to“an embodiment” herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase“in an embodiment” in various places in the specification are not necessarily referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. As will be apparent to those of ordinary skill in the art, embodiments described herein can be combined with other embodiments in accordance with the application.

[0058] In the description of the embodiments of the application, the term“and / or” only means an association relationship of the associated objects, which can mean that there are three relationships, for example, A and / or B, which can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character“ / ” herein generally means that the front and rear associated objects are in an“or” relationship.

[0059] In the description of the embodiments of the application, the term“a plurality of” means two or more (including two), and similarly, “a plurality of groups” means two or more groups (including two groups), and “a plurality of pieces” means two or more pieces (including two pieces).

[0060] In the description of the embodiments of the application, the technical terms“center”,“longitudinal”,“transverse”,“length”,“width”,“thickness”,“upper”,“lower”,“front”,“rear”,“left”,“right”,“vertical”,“horizontal”,“top”,“bottom”,“inner”,“outer”,“clockwise”,“counterclockwise”,“axial”,“radial”,“circumferential” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the application.

[0061] In the description of the embodiments of the application, unless otherwise explicitly specified and limited, the technical terms“mounting”,“connection”,“connection”,“fixing” and the like should be understood broadly, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the application can be understood according to the specific circumstances.

[0062] At present, from the development of market situation, the application of power battery is more and more extensive. Power battery is not only applied to energy storage power supply system of hydropower, thermal power, wind power and solar power station, but also widely used in electric bicycles, electric motorcycles, electric vehicles and other electric vehicles, military equipment, aerospace and other fields. With the continuous expansion of the application field of power battery, the demand of its market is also increasing.

[0063] During the use of charging and discharging of the battery, gas will be generated by electrolyte decomposition, electrode material reaction, etc. The accumulation of gas in the sealed battery, combined with the volume change of the electrode material, will cause the internal pressure of the battery to rise and the whole to expand. The internal stress generated by the expansion will destroy the fit state between the pole piece and the diaphragm. Under long-term cycling, repeated expansion and contraction will exacerbate the displacement of the pole piece, and the edge of the pole piece may shift, the interlayer may slip or even wrinkle, thereby causing lithium precipitation or short circuit risk. Especially as the size of the battery monomer increases, the size of the pole piece of the battery monomer also increases, and the stress accumulation and structural instability problems caused by gas expansion will be amplified, eventually leading to the risk of pole piece misalignment, lithium precipitation and short circuit. In addition, excessive internal pressure of the battery will also cause deformation around the mounting hole of the electrode terminal, thereby causing sealing failure, causing the leakage of substances inside the battery monomer, and seriously restricting the service life of the battery.

[0064] Based on the above, the application provides a battery monomer, comprising: a shell comprising a containing cavity with an opening; an electrode assembly disposed in the containing cavity, the electrode assembly comprising a negative pole piece and a diaphragm; and an end cover assembly covering the opening, the end cover assembly comprising a cover plate and an electrode terminal, the cover plate being provided with a mounting hole, the electrode terminal comprising a first connecting portion and a second connecting portion connected thereto, the first connecting portion being located on the side of the cover plate facing the electrode assembly and electrically connected to the electrode assembly, the second connecting portion being provided through the mounting hole, the first connecting portion having a projection area on the cover plate greater than the area of the mounting hole; wherein the diaphragm comprises a first main body portion opposite to the active material area of the adjacent negative pole piece, and a first overhanging portion beyond the active material area of the negative pole piece along a first direction parallel to the thickness of the cover plate, the size of the first overhanging portion along the first direction being greater than or equal to 2.3mm and less than or equal to 4.3mm.

[0065] By optimizing the size relationship between the separator and the negative plate inside the battery monomer, the risk of plate misalignment leading to lithium precipitation or short circuit can be effectively reduced, and the space arrangement inside the battery monomer is also considered, which is beneficial to improve the energy density of the battery monomer. In addition, the force between the electrode assembly and the end cover assembly in the later stage of the cycle can be reduced. In combination with the fact that the cross-sectional area of the first connecting part of the electrode terminal located in the accommodating cavity is larger than the area of the mounting hole, the electrode terminal can be tightly attached to the side surface of the electrode assembly facing the cover plate when the pressure inside the battery monomer increases. This is more conducive to sealing the position of the electrode terminal and reduces the probability of failure of the shell seal, thereby improving the reliability and service life of the battery.

[0066] The battery monomer disclosed in the embodiments of the present application can be used in, but is not limited to, an electric device such as a vehicle, a ship or an aircraft. The power supply system of the electric device can be composed of a battery monomer and a battery disclosed in the present application. In this way, the risk of lithium precipitation or short circuit caused by expansion can be alleviated, and the reliability and service life of the battery can be improved.

[0067] The embodiments of the present application provide an electric device using a battery as a power supply. The electric device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, etc. The electric toy can include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric plane toy, etc. The spacecraft can include an airplane, a rocket, a space shuttle, a spacecraft, etc.

[0068] The embodiments of the present application also provide an energy storage device using a battery as a power supply. The energy storage device can be, but is not limited to, an energy storage container, an energy storage cabinet, an energy storage power station, an energy storage battery pack, or a portable energy storage system, etc.

[0069] The following embodiments are described by taking a battery device of an embodiment of the present application as an example for convenience of description.

[0070] Please refer to Figure 1 , Figure 1Figure 1 shows a schematic diagram of a battery device according to some embodiments of the present application. The battery device 100 comprises a box 10 and a plurality of battery cells 20 accommodated in the box 10. The box 10 is configured to provide a space for accommodating the battery cells 20. In some embodiments, the box 10 can comprise a first part 11 and a second part 12. The first part 11 and the second part 12 are configured to cover each other and together define a space for accommodating the battery cells 20. The second part 12 can be a hollow structure with one open end, and the first part 11 can be a plate structure configured to cover the open end of the second part 12. Alternatively, the first part 11 and the second part 12 can both be hollow structures with one open end, and the open end of the first part 11 is configured to cover the open end of the second part 12. Of course, the box 10 formed by the first part 11 and the second part 12 can have other shapes, such as a cylinder or a cuboid.

[0071] In the battery device 100, the plurality of battery cells 20 can be connected in series, in parallel or in a mixed manner. The mixed manner means that the plurality of battery cells 20 are connected in series and in parallel. The plurality of battery cells 20 can be directly connected in series, in parallel or in a mixed manner, and then accommodated in the box 10. Alternatively, the plurality of battery cells 20 can be connected in series, in parallel or in a mixed manner to form a plurality of battery modules, and then the plurality of battery modules are connected in series, in parallel or in a mixed manner to form a whole and accommodated in the box 10. The battery device 100 can further comprise other structures, for example, the battery device 100 can further comprise a current collecting component configured to electrically connect the plurality of battery cells 20.

[0072] Each of the battery cells 20 can be a secondary battery or a primary battery, and can be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited thereto. The battery cells 20 can have a cylindrical shape, a flat shape, a cuboid shape or other shapes.

[0073] Figure 1 shows a schematic diagram of a battery device according to some embodiments of the present application. The battery device 100 comprises a box 10 and a plurality of battery cells 20 accommodated in the box 10. The box 10 is configured to provide a space for accommodating the battery cells 20. In some embodiments, the box 10 can comprise a first part 11 and a second part 12. The first part 11 and the second part 12 are configured to cover each other and together define a space for accommodating the battery cells 20. The second part 12 can be a hollow structure with one open end, and the first part 11 can be a plate structure configured to cover the open end of the second part 12. Alternatively, the first part 11 and the second part 12 can both be hollow structures with one open end, and the open end of the first part 11 is configured to cover the open end of the second part 12. Of course, the box 10 formed by the first part 11 and the second part 12 can have other shapes, such as a cylinder or a cuboid. Figure 2 Figure 2 ​A schematic diagram of an energy storage system is provided for some embodiments of the present application. An energy storage device 200 is provided in embodiments of the present application, which includes one or more battery clusters to increase the voltage and capacity of the energy storage device 200. The battery cluster can include a plurality of battery devices 100, which are connected in series through busbars to increase the voltage of the energy storage device 200. When the energy storage device 200 includes a plurality of battery clusters, the plurality of battery clusters are connected in parallel to increase the capacity of the energy storage device 200. The energy storage device 200 can be used in an energy storage power station, a wind power system, a solar power system, a mobile power system, or a temporary power supply system, etc. The energy storage device 200 can store electrical energy as needed and output the electrical energy at an appropriate time. For example, the energy storage device 200 can store electrical energy during a low electricity consumption period and provide electrical energy to relevant users or electrical equipment during a high electricity consumption period. The energy storage system provided in embodiments of the present application can be any power system that needs to use the energy storage device 200. In some embodiments, the energy storage device 200 is an energy storage container or an energy storage cabinet.

[0074] In some embodiments, the energy storage device 200 can include a cabinet body and one or more battery clusters, which are accommodated in the cabinet body.

[0075] In some embodiments, the energy storage device 200 can include a thermal management module, a master control module, a general control module, a power distribution module, and a fire-fighting module, etc.

[0076] As an example, the thermal management module can include a liquid cooling unit, which provides cooling liquid for adjusting the temperature of the battery monomer 20 to each battery device 100 through a pipeline.

[0077] As an example, the master control module can serve as a battery management unit of the battery cluster, which is used to monitor and manage the battery cluster. The master control module can monitor information such as current, voltage, power, or temperature of the battery cluster. For example, the charging and discharging current and voltage of the battery cluster can be controlled. The master control module includes a slave battery management unit SBMU, a fusion switch, and other modules.

[0078] As an example, the master control module can be used as a battery management unit of the energy storage device 200, for monitoring and managing the energy storage device 200. The master control module can monitor information such as current, voltage, power, state of charge, or temperature of the energy storage device 200. For example, the charging and discharging current, voltage, etc. of the energy storage device 200 can be controlled. As an example, the master control module includes an insulation monitoring module IMM (Insulation Monitoring Module, IMM), a master battery management unit MBMU (Master Battery Management Unit, MBMU), an Ethernet ETH (Ether Net, ETH), and an optical fiber conversion module, etc.

[0079] As an example, the fire-fighting system includes a control panel, a detector, an alarm device, etc., for detecting, alarming, or extinguishing the energy storage system.

[0080] As an example, the power distribution device can be used to distribute power to the power consumption module of the energy storage device 200.

[0081] In some embodiments, the energy storage system can include one or more energy storage devices 200 and a power conversion device 300 (Power Converter System, PCS) connected between the power generation device 400 and the energy storage device 200. The power generation device 400 is used to generate electric energy, and the electric energy generated by the power generation device 400 can be stored in the energy storage device 200 through the power conversion device 300, and the electric energy stored in the energy storage device 200 can be released to the power generation device 400 through the power conversion device 300. As an example, the power generation device 400 can be a power grid, a solar panel, a hydroelectric power generation device 400, a thermal power generation device 400, a wind power generation device 400, etc. The specific type of the power generation device 400 is not limited in the present application.

[0082] Please refer to Figure 3 , Figure 3 The structure of the charging network provided by some embodiments of the present application is shown in the figure. The present application provides a charging network including a charging pile 500 and an energy storage device 200, the charging pile 500 is electrically connected with the energy storage device 200, and the energy storage device 200 is used to provide electric energy for the charging pile 500. The charging pile 500 is electrically connected with the battery device 100 in the energy storage device 200 through a cable, and the battery device 100 can provide the electric energy stored by itself to the charging pile 500. The charging pile 500 has one or more connectors 600, which are used to connect with the power consumption equipment (such as a vehicle), so as to supply energy to the power consumption equipment.

[0083] The energy storage device 200 can be located inside the charging pile 500 (e.g., an integrated energy storage and charging unit) or outside the charging pile 500.

[0084] Please refer to Figure 4 , Figure 4 This is an exploded structural diagram of a battery cell provided in some embodiments of this application. The battery cell 20 refers to the smallest unit that makes up the battery. For example... Figure 4 The battery cell 20 includes an end cap assembly 21, a housing 22, an electrode assembly 23, and other functional components.

[0085] End cap assembly 21 refers to a component that covers the opening of housing 22 to isolate the internal environment of battery cell 20 from the external environment. End cap assembly 21 includes cover plate 211 and electrode terminals 212. The shape of cover plate 211 can be adapted to the shape of housing 22 to fit it. Optionally, cover plate 211 can be made of a material with certain hardness and strength (such as aluminum alloy), so that cover plate 211 is not easily deformed under pressure and impact, enabling battery cell 20 to have higher structural strength and improved safety performance. Functional components such as electrode terminals 212 can be provided on cover plate 211. Electrode terminals 212 can be used for electrical connection with electrode assembly 23 to output or input electrical energy to battery cell 20. The material of cover plate 211 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose special limitations on this. In some embodiments, a first insulating member 213 may be provided on the inner side of the cover plate 211. The first insulating member 213 can be used to isolate the electrical connection components inside the housing 22 from the cover plate 211 to reduce the risk of short circuit. For example, the insulating member may be made of plastic, rubber, etc.

[0086] The housing 22 is a component used to cooperate with the cover plate 211 to form the internal environment of the battery cell 20. This internal environment can accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and the cover plate 211 can be independent components. An opening can be provided on the housing 22, and the cover plate 211 can be used to close the opening to form the internal environment of the battery cell 20. Alternatively, the cover plate 211 and the housing 22 can be integrated. Specifically, the cover plate 211 and the housing 22 can form a common connecting surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 22, the cover plate 211 closes the housing 22. The housing 22 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the electrode assembly 23. The material of the housing 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. This application embodiment does not impose any special limitations on this.

[0087] The electrode assembly 23 is a component in which electrochemical reactions occur in the battery cell 20. One or more electrode assemblies 23 can be contained within the casing 22. The electrode assembly 23 is mainly formed by winding or layering a positive electrode sheet 232 and a negative electrode sheet 231, and a separator 233 is usually provided between the positive electrode sheet 232 and the negative electrode sheet 231. The positive electrode sheet 232 and the negative electrode sheet 231 have portions with active materials that constitute a main body of the electrode assembly, and portions without active materials that each constitute a tab 23a. The positive and negative electrode tabs can be located together at one end of the main body or at opposite ends of the main body. During charging and discharging of the battery, the positive and negative active materials react with the electrolyte, and the tabs 23a connect to the electrode terminals to form a current loop.

[0088] Please refer to Figures 4-7 , Figure 4 a battery cell provided for some embodiments of the present application; Figure 5 a structure diagram of an end cover assembly provided for some embodiments of the present application; Figure 6 a structure diagram of an end cover assembly provided for some embodiments of the present application; Figure 7 a partial sectional view of an electrode assembly provided for some embodiments of the present application Figure 1 .

[0089] Some embodiments of the present application provide a battery cell 20, which includes a casing 22, an electrode assembly 23, and an end cover assembly 21. The casing 22 includes a receiving cavity with an opening; the electrode assembly 23 is arranged in the receiving cavity, and includes a negative electrode sheet 231 and a separator 233; and the end cover assembly 21 covers the opening, and includes a cover plate 211 and an electrode terminal 212. The cover plate 211 is provided with a mounting hole 211a, and the electrode terminal 212 includes a first connecting portion 2121 and a second connecting portion 2122 connected to each other. The first connecting portion 2121 is located on a side of the cover plate 211 facing the electrode assembly 23 and is electrically connected to the electrode assembly 23. The second connecting portion 2122 passes through the mounting hole 211a. The area of the projection of the first connecting portion 2121 on the cover plate 211 is greater than the area of the mounting hole 211a. The separator 233 includes a first main body portion 2331 opposite the active material area of the adjacent negative electrode sheet 231, and a first overhanging portion that overhangs the active material area of the negative electrode sheet 231 along a first direction X parallel to the thickness direction of the cover plate 211. The dimension of the first overhanging portion 2330 along the first direction X is greater than or equal to 2.3 mm and less than or equal to 4.3 mm.

[0090] The end cover assembly 21 and the casing 22 can be arranged along the first direction X, and the cover plate 211 is perpendicular to the first direction X, or in other words, the thickness direction of the cover plate 211 is parallel to the first direction X. In some examples, the first direction X is parallel to the direction of gravity of the battery cell 20.

[0091] The negative electrode sheet 231 can include a negative electrode current collector 2311 and a negative electrode active material layer 2312 coated on part of the surface of the negative electrode current collector 2311. The active material region of the negative electrode sheet 231 refers to the part of the negative electrode sheet 231 coated with the negative electrode active material layer. Similarly, the positive electrode sheet 232 includes a positive electrode current collector 2321 and a positive electrode active material layer 2322, and the active material region of the positive electrode sheet 232 refers to the part of the positive electrode sheet 232 coated with the positive electrode active material layer 2322.

[0092] For example, the dimension of the first overhanging portion in the first direction X can be 2.3 mm, 2.5 mm, 2.8 mm, 3 mm, 3.2 mm, 3.5 mm, 3.8 mm, 4 mm, 4.1 mm, 4.2 mm, 4.3 mm, or a value between any two of the above values.

[0093] It should be noted that the size of the first overhanging portion 2330 has an important influence on the performance of the battery cell. In the case of a certain internal space of the battery cell shell, if the dimension of the first overhanging portion 2330 in the first direction X is too large, too much separator occupies the effective space inside the battery, resulting in a decrease in the loading capacity of the electrode material and a decrease in the energy density of the battery. Excessive separator can form wrinkles and stacking in the battery, and stress concentration is easy to occur in the wrinkle area during charging and discharging, which can aggravate the risk of electrode sheet misalignment and separator damage. If the dimension of the first overhanging portion 2330 in the first direction X is too small, it is difficult to meet the isolation between the electrode sheets when the internal pressure of the battery increases and the deformation of the battery intensifies, which can further cause lithium precipitation or short circuit risk.

[0094] The calculation of the dimension of the first overhanging portion 2330 in the first direction X needs to consider three core factors: mechanical tolerance, material expansion, and electrochemical performance. The contribution value of each influencing item is quantified to derive the result.

[0095] The dimension of the first overhanging portion 2330 in the first direction X can be determined as follows: (隔-阳min) =O 机械 +O 膨胀 +O 电化学 ; wherein O 机械 is a mechanical tolerance compensation term, O 膨胀 is an expansion compensation term, and O 电化学 is an electrochemical compensation term.

[0096] The mechanical tolerance compensation term mainly compensates for the cutting accuracy of the electrode sheet, the alignment deviation, the burr control, and the strength of the thin base film.

[0097] The pole piece cutting precision compensation is a compensation item set based on the pole piece cutting process precision. In particular, for the die cutting used in the winding process, transverse deviation accumulation will also occur when cutting a pole piece with a large width. According to the different widths of the pole piece, the tolerance range is ±0.3-0.4mm, among which the narrow pole piece is usually ±0.3mm, and the wide pole piece (width of 180-200mm) is ±0.4mm; the pole piece width refers to the size along the first direction X or along the thickness direction of the cover plate 211.

[0098] The alignment deviation compensation is a compensation item set based on the transverse deviation of the separator caused by uneven tension when winding or stacking the pole piece. According to the different widths of the pole piece, the corresponding deviation range is ±0.2-0.3mm.

[0099] The burr control compensation is a compensation item set based on the burr height of the edge of the pole piece. According to the maximum burr height of the edge of the pole piece, 0.25mm needs to be compensated.

[0100] The thin base film strength compensation is a compensation set based on the fact that the base film of the separator is relatively thin (only 4-6μm) and has low mechanical strength, and is prone to local stretching deviation when winding the pole piece. Therefore, an additional compensation of 0.2mm is required.

[0101] Based on the above analysis, the above compensation items are added, and the mechanical tolerance compensation item O 机械 is obtained. The value range of O 机械 is 1.450-2.00mm, among which the larger the width of the pole piece, the larger the corresponding value.

[0102] The expansion compensation item O 膨胀 is a compensation item made based on the thermal expansion of the material. It includes not only the thermal expansion difference between the pole piece and the separator, but also the redundancy left due to uneven expansion. In some examples, the thermal expansion coefficient of the negative copper foil is = 18×10 -6 K -1 , the separator is a PE film base film with a ceramic coating on the surface, the base film thickness is 4-6μm, the total thickness is 7-10μm, and the thermal expansion coefficient is =9×10 -6 K -1 ; the long-term operating temperature of the battery cell is 30~55℃, and the extreme thermal runaway warning temperature is 120℃. For ease of calculation, the temperature is taken as ΔT=90 K, and the expansion difference is calculated in combination with the width of the pole piece, which is 0.146-0.162mm. Considering the deformation difference caused by uneven expansion, the corresponding redundancy is 0.4mm, and finally the value range of the expansion compensation item is 0.546-0.80 mm.

[0103] The electrochemical compensation item is O 电化学is a compensation term based on the difference in current concentration effect of the pole piece. The wider the pole piece, the more uneven the current distribution. Specifically, it can be determined according to the product of the characteristic diffusion length of lithium ions in the negative electrode and the current concentration coefficient. In some examples, since the SEI film at the edge of the pole piece is prone to cracking due to stress concentration, a compensation of 0.3-0.35 mm needs to be reserved. Therefore, the electrochemical compensation term is O 电化学 The corresponding value range can be 0.303-0.5 mm.

[0104] The above compensation terms are added to obtain O (隔-阳min) =O 机械 +O 膨胀 +O 电化学 =(1.450~2.00)+(0.546~0.80)+(0.303~0. 50)=2.299~3.3mm, further considering parameter fluctuations, a certain fluctuation margin needs to be added, and finally the size range of the first overhanging part 2330 along the first direction X is determined to be 2.3~4.3mm.

[0105] The size detection of the first overhanging part 2330 can adopt a non-destructive detection method, such as obtaining the internal image of the battery monomer by X-ray, and determining the corresponding size according to the image recognition software. It can also be detected by a destructive detection method of disassembling the battery monomer, such as disassembling the electrode assembly in the glove box, and detecting the corresponding size by measuring instruments (such as micrometer).

[0106] By optimizing the size relationship between the separator and the negative pole piece inside the battery monomer, the risk of lithium precipitation or short circuit caused by pole piece misalignment can be effectively reduced, and the space arrangement inside the battery monomer is also considered, which is beneficial to improve the energy density of the battery monomer. It can also reduce the force between the electrode assembly and the end cover assembly in the later stage of the cycle. Combined with the fact that the cross-sectional area of the first connecting part of the electrode terminal located in the accommodation cavity is larger than the area of the mounting hole, it can tightly adhere to the surface of the side of the electrode assembly when the pressure inside the battery monomer increases. It is more conducive to sealing the position of the electrode terminal, reduces the probability of failure of the shell seal, and improves the reliability and service life of the battery.

[0107] According to some embodiments of the present application, the size of the first overhanging part 2330 along the first direction X is greater than or equal to 2.3 mm and less than or equal to 4 mm.

[0108] In some examples, the product of the characteristic diffusion length of lithium ions in the negative electrode and the current concentration coefficient in the electrochemical compensation term is much smaller than the compensation amount of 0.3-0.35 mm reserved, and the compensation amount can be considered together with the compensation amount set for other redundancy purposes, without separate compensation.

[0109] For example, the size of the first overhang 2330 along the first direction X can be 2.3 mm, 2.5 mm, 2.8 mm, 3 mm, 3.2 mm, 3.5 mm, 3.8 mm, 4 mm, or a value between any two of the above values.

[0110] By reasonably limiting the size of the overhang, the adaptation relationship between the separator and the negative electrode sheet can be further improved, and the service life of the battery can be improved.

[0111] According to some embodiments of the present application, the first overhang 2330 includes a first sub-overhang 2332 close to one side of the cover plate 211 and a second sub-overhang 2333 away from the other side of the cover plate 211. The difference between the size of the first sub-overhang 2332 and the size of the second sub-overhang 2333 along the first direction X is less than or equal to 0.1 mm.

[0112] The first sub-overhang 2332 and the second sub-overhang 2333 are respectively located at both ends of the first main body part 2331 along the first direction X. In the case where the thickness direction of the cover plate 211 is parallel to the height direction of the battery cell, the size of the first sub-overhang 2332 and the second sub-overhang 2333 along the thickness direction of the cover plate 211 is the height thereof.

[0113] Since the electrode terminal is arranged on the cover plate 211, the first sub-overhang 2332 and the tab 23a are located on the same side of the first main body part 2331. Correspondingly, the second sub-overhang 2333 and the tab 23a are located on the opposite sides of the first main body part 2331.

[0114] For example, the difference between the size of the first sub-overhang 2332 and the size of the second sub-overhang 2333 along the first direction X can be 0, 0.02 mm, 0.04 mm, 0.06 mm, 0.08 mm, 0.1 mm, or a value between any two of the above values.

[0115] The difference between the size of the first sub-excess part 2332 and the size of the second sub-excess part 2333 is controlled within a reasonable range, which is more conducive to the positioning between the pole piece and the diaphragm, facilitates the lamination or winding, reduces the short circuit risk of the region, and improves the reliability and service life of the battery.

[0116] Please refer to Figure 8 , Figure 8 Partial cross-sectional view of the electrode assembly provided for some embodiments of the present application Figure 2 .

[0117] According to some embodiments of the present application, the electrode assembly 23 further comprises a positive pole piece 232, which is arranged on the side of the diaphragm 233 away from the negative pole piece 231; the active material area of the negative pole piece 231 comprises a second main body part 231A opposite the active material area of the adjacent positive pole piece 232, and a second excess part 2314 exceeding the active material area of the positive pole piece 232 along the first direction X, the size of the second excess part 2314 along the first direction X is greater than or equal to 1.6 mm and less than or equal to 7 mm.

[0118] The second main body part 231A is the part of the active material area of the negative pole piece 231 opposite the active material area of the adjacent positive pole piece 232.

[0119] The second excess part 2314 can exceed both ends of the active material area of the positive pole piece 232 along the first direction X, so that the active material area of the negative pole piece 231 can completely cover the active material area of the positive pole piece 232 in the first direction, thereby providing sufficient intercalation sites for lithium ions extracted from the positive pole and reducing the risk of lithium precipitation.

[0120] In some examples, the size of the second excess part 2314 along the first direction X can be 1.6 mm, 1.8 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm or a value between any two of the above values.

[0121] The size of the second excess part 2314 along the first direction X can be determined in the following manner: O (阳-阴min ) =O 机械 +O 膨胀 +O 电化学 ; wherein O 机械 is a mechanical tolerance compensation term, O 膨胀 is an expansion compensation term, and O 电化学 is an electrochemical compensation term.

[0122] The mechanical tolerance compensation term O 机械 mainly compensates for the mechanical allowance of the alignment deviation of the pole piece and the diaphragm offset; specifically, it can be calculated using the following formula: O 机械= 2 x (d1 + d2 + d3), where d1 represents a pole piece cutting tolerance, d2 is a pole piece radial runout tolerance, and d3 is a diaphragm offset tolerance. Considering the possibility of bidirectional deviation of the positive pole piece and the negative pole piece, the above tolerance compensation value is multiplied by 2 to determine the mechanical tolerance compensation term O 机械 with a value range of 0.5-1.3 mm.

[0123] The expansion compensation term O 膨胀 is mainly used to compensate for the change in the outer dimension caused by the lithium expansion of the negative pole piece. Specifically, it can be determined by the volume expansion rate of the negative material, the width of the negative pole piece, and a safety factor. In some examples, the expansion rate of the graphite negative electrode is 5%-12%, the width of the active material area of the negative pole piece is 100-200 mm, and the safety factor is a coefficient set based on the width direction contraction caused by the expansion in the thickness direction of the pole piece and the non-uniformity of the expansion, with a value range of 0.12-0.15. Based on the above aspects, the expansion compensation term O 膨胀 is determined to be 0.36-3.6 mm.

[0124] Similar to the foregoing embodiments, the electrochemical compensation term is O 电化学 , which is a compensation term based on the current concentration effect difference of the pole piece. Specifically, it can be determined according to the product of the characteristic diffusion length of lithium ions in the negative electrode and the edge current concentration coefficient of the positive electrode, which is the ratio of the current density of the edge region to the center region of the positive electrode, with a value range of 1.2-2.0. The value can be selected according to the size of the charging current (whether fast charging). The larger the charging current, the larger the corresponding value. For example, O 电化学 is calculated to have a value range of 0.0301-0.0384 mm, and in the fast charging scenario of more than 1C, O 电化学 is calculated to have a value range of 0.027-0.0362 mm. In addition, a pole piece edge geometry redundancy needs to be added on this basis, which is based on the possibility of burrs, coating steps, and the like at the edge of the positive pole piece. The value range of the pole piece edge geometry redundancy is 0.5 mm-1 mm, which can be determined according to the CB value (negative capacity divided by positive capacity). When CB is greater than or equal to 1.2, the risk of lithium excess supply is reduced, and the lower limit value of the pole piece edge geometry redundancy can be 0.5 mm. When CB is 1.03-1.1, the upper limit value of 1 mm needs to be taken to avoid lithium precipitation. Based on the above aspects, the electrochemical compensation term is O 电化学 with a value range of 0.527-1.0384 mm.

[0125] Based on the above three aspects, while considering the process (including the winding process and the lamination process), a redundant amount of 0.5-1 mm needs to be reserved, and the size O of the second overhanging portion 2314 along the first direction X is finally determined (阳-阴min ) =1.6-7mm.

[0126] The second overhanging portion 2314 can adopt the same detection method as the first overhanging portion 2330, such as non-destructive detection or destructive detection, and the embodiments of the present application do not limit this.

[0127] By reasonably setting the size of the overhanging portion of the active material area of the negative plate 231 and the positive plate 232 along the first direction X, the energy density of the battery monomer and the risk of lithium precipitation or short circuit during the cycle process can be considered, and the reliability and service life of the battery can be improved.

[0128] According to some embodiments of the present application, the size of the second overhanging portion 2314 along the first direction X is greater than or equal to 1.6 mm and less than or equal to 5.5 mm.

[0129] The redundant amount and safety factor in the mechanical tolerance compensation term, the expansion compensation term and the electrochemical compensation term can be considered comprehensively. In some examples, the edge geometry redundancy of the plate can be considered by other redundant amounts, and the safety factor in the expansion compensation term can also be reduced according to the upper limit value of the plate width, so that the overhanging size of the second overhanging portion 2314 of the negative active material area along the first direction X beyond the positive active material area can be determined to be between 1.6-5.5 mm.

[0130] For example, the size of the second overhanging portion 2314 along the first direction X can be 1.6 mm, 1.8 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm or a value between any two of the above values.

[0131] By further optimizing the value range of the size of the second overhanging portion 2314 along the first direction X, the size adaptability of the negative plate 231 and the positive plate 232 can be improved, the capacity and electrode material utilization of the positive and negative electrodes can be balanced, and the energy density of the battery monomer and the service life of the battery can be considered.

[0132] According to some embodiments of the present application, as Figure 8 shown, the second overhanging portion 2314 includes a third sub-overhanging portion 231B close to one side of the cover plate 211, and a fourth sub-overhanging portion 231C away from one side of the cover plate 211, and the difference between the size of the third sub-overhanging portion 231B along the first direction X and the size of the fourth sub-overhanging portion 231C along the first direction X is less than or equal to 0.1 mm.

[0133] The third sub-excess portion 231B and the fourth sub-excess portion 231C are respectively located at two ends of the second main body portion 231A along the first direction X. Among them, the third sub-excess portion 231B is located on the same side of the second main body portion 231A as the tab 23a, and the fourth sub-excess portion 231C is located on the different side of the second main body portion 231A along the first direction X as the tab 23a.

[0134] In some examples, along the first direction X, the difference between the size of the third sub-excess portion 231B and the size of the fourth sub-excess portion 231C can be 0, 0.02 mm, 0.04 mm, 0.06 mm, 0.08 mm, 0.1 mm, or a value between any two of the above.

[0135] Making the size of the third sub-excess portion 231B along the first direction X as close as possible or the same as the size of the fourth sub-excess portion 231C can more evenly wrap the two end edges of the active material area of the positive electrode sheet 232, and can avoid the situation that one end is too redundant and the other end is insufficiently wrapped due to deviation during the stacking or winding process, thereby reducing the risk of lithium dendrite-induced short circuit and improving the reliability and service life of the battery.

[0136] Please refer to Figure 9 , Figure 9 The provided is a schematic diagram of the electrode sheet stacking of some embodiments of the present application.

[0137] According to some embodiments of the present application, the negative electrode sheet 231, the separator 233, and the positive electrode sheet 232 are stacked along the second direction Y; the active material area of the negative electrode sheet 231 further includes a third excess portion 2315 that exceeds the active material area of the positive electrode sheet 232 along a third direction Z, and the size of the third excess portion 2315 along the third direction Z is less than or equal to the size of the second excess portion 2314 along the first direction X; the third direction Z, the second direction Y, and the first direction X are perpendicular to each other.

[0138] The second direction Y is parallel to the thickness direction of the electrode sheet. In the present embodiment, the electrode sheets and the separator in the electrode assembly 23 are stacked to form a stacked electrode assembly. Compared with the winding process, the active material area of the negative electrode sheet 231 not only needs to exceed the active material area of the positive electrode sheet 232 in the first direction X, but also needs to exceed the active material area of the positive electrode sheet 232 in the third direction Z to prevent incomplete wrapping of the two end edges of the positive electrode sheet 232 along the third direction Z, which may cause lithium precipitation or short circuit.

[0139] The tab 23a is arranged on one side of the electrode sheet along the first direction X. Considering that tab welding may cause problems such as welding residue and current concentration, and in order to reserve the arrangement space of the components of the tab and the adapter piece, the electrode assembly 23 may move along the first direction X, and the risk of misalignment of the electrode sheet along the first direction X is relatively high.

[0140] In the embodiments of the present application, the dimension of the second overhanging part 2314 along the first direction X is greater than the dimension of the third overhanging part 2315 along the third direction Z, which can better adapt to the arrangement form inside the battery monomer and reduce the risk of lithium precipitation or short circuit.

[0141] According to some embodiments of the present application, the dimension of the third overhanging part 2315 along the third direction Z is greater than or equal to 1.6 mm and less than or equal to 3 mm.

[0142] For example, the dimension of the third overhanging part 2315 along the third direction Z can be 1.6 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm or a value between any two of the above values.

[0143] By reasonably setting the dimension of the third overhanging part 2315 along the third direction, the adaptability between the negative plate 231 and the positive plate 232 can be improved, thereby facilitating the improvement of the energy density of the battery monomer and the cycle performance of the battery monomer and the improvement of the service life.

[0144] According to some embodiments of the present application, as shown in Figure 9 , the third overhanging part 2315 further includes a fifth sub-overhanging part 231D and a sixth sub-overhanging part 231E arranged along the third direction Z; the difference between the dimensions of the fifth sub-overhanging part 231D and the sixth sub-overhanging part 231E along the third direction Z is less than or equal to 0.1 mm.

[0145] The dimensions of the fifth sub-overhanging part 231D and the sixth sub-overhanging part 231E along the third direction Z are as close as possible or equal, and the difference between them is also not more than 0.1 mm. For example, the difference between them can be 0.02 mm, 0.05 mm, 0.08 mm or 0.1 mm.

[0146] The dimension of the part of the third overhanging part 2315 along the third direction Z beyond the two ends of the positive plate 232 is set to be as close as possible or equal, which is conducive to improving the uniformity of current distribution, reducing the risk of uneven force on different sides causing sliding and warping deformation, and also can improve the compactness of the electrode assembly structure, and improve the service life and energy density of the battery monomer.

[0147] Please refer to Figures 10-12 , Figure 10 for Figure 5 a sectional view along the A-A direction; Figure 11 for Figure 10 a partial enlarged view of the B region in FIG. 8; Figure 12 for Figure 10 a partial enlarged view of the C region in FIG. 8.

[0148] According to some embodiments of the present application, the end cover assembly 21 further comprises a sealing ring 214, which is sleeved on the outer periphery of the second connecting portion 2122, and at least a part of the sealing ring 214 is clamped between the first connecting portion 2121 and the cover plate 211.

[0149] The sealing ring 214 is hollow in the middle to facilitate sleeving on the outer periphery of the second connecting portion 2122. The structural shape of the sealing ring 214 can match the shape of the second connecting portion 2122, for example, the second connecting portion 2122 is in a cylindrical shape, and the sealing ring 214 can be an O-ring. The sealing ring 214 can be an elastic sealing ring, and the material can be any material that meets the sealing requirements, such as fluororubber.

[0150] The sealing ring 214 can be partially or entirely clamped between the first connecting portion 2121 and the cover plate 211 to seal the installation interface therebetween.

[0151] When the internal pressure of the battery cell increases, the first connecting portion 2121 of the electrode terminal 212 will move away from the electrode assembly 23 under the pressure, thereby pressing the sealing ring 214 and improving the reliability of the installation interface between the electrode terminal 212 and the cover plate 211.

[0152] Please refer to Figure 12 According to some embodiments of the present application, the sealing ring 214 comprises a first step portion 2141 and a second step portion 2142 connected to each other; the first step portion 2141 is clamped between the first connecting portion 2121 and the cover plate 211, and the second step portion 2142 is clamped between the second connecting portion 2122 and the inner wall of the cover plate 211 forming the mounting hole.

[0153] The second step portion 2142 is clamped between the second connecting portion 2122 and the inner wall of the cover plate 211 forming the mounting hole.

[0154] The sealing ring 214 can be configured as a stepped shape as a whole, and the second step portion 2142 can be protruded relative to the first step portion 2141, so as to be inserted between the second connecting portion 2122 and the inner wall of the cover plate 211 forming the mounting hole 211a.

[0155] The sealing ring 214 can be configured as a stepped shape, so as to form independent sealing interfaces between the first connecting portion 2121 and the cover plate 211 and between the second connecting portion 2122 and the inner wall of the cover plate 211 forming the mounting hole, respectively, thereby reducing the probability of leakage and improving the reliability of the sealing.

[0156] Please refer to Figure 12According to some embodiments of the present application, the first stepped portion 2141 further comprises a first sub-stepped portion 2141a and a second sub-stepped portion 2141b connected in sequence, the second sub-stepped portion 2141b is located between the first sub-stepped portion 2141a and the second stepped portion 2142, and the second sub-stepped portion 2141b abuts against the side surface of the cover plate 211 facing the electrode assembly 23.

[0157] The first stepped portion 2141 can be further provided as a structure containing multiple levels of steps, the first sub-stepped portion 2141a and the second sub-stepped portion 2141b are arranged along the first direction X, and the cross-sectional area of the first sub-stepped portion 2141a is greater than that of the second sub-stepped portion 2141b.

[0158] During installation, the second sub-stepped portion 2141b abuts against the side surface of the cover plate 211 facing the electrode assembly 23, and is elastically deformed to seal the interface between the first connecting portion 2121 and the cover plate 211 under the extrusion of the first connecting portion 2121.

[0159] In some cases, the second sub-stepped portion 2141b may be broken or damaged under excessive pressure, at which time the first sub-stepped portion 2141a can abut against the side surface of the cover plate 211 facing the electrode assembly 23 under the action of the first connecting portion 2121, thereby continuing to maintain effective sealing.

[0160] Providing the first stepped portion 2141 as a multi-level stepped structure can achieve multi-level sealing, so that the effectiveness and reliability of the sealing can always be maintained even in harsh working conditions, thereby improving the service life of the battery monomer 20.

[0161] According to some embodiments of the present application, as shown in Figure 6 and Figure 10 The end cover assembly 21 further comprises a first insulating member 213, which is arranged on the side surface of the cover plate 211 facing the electrode assembly 23; the first insulating member 213 comprises a number of avoiding holes 213a equal to the number of electrode terminals 212, which are configured to allow the corresponding electrode terminals 212 and sealing rings 214 to pass through.

[0162] The first insulating member 213 can be fixedly installed on the side surface of the cover plate 211 facing the electrode assembly 23 by any feasible means. In some embodiments, the first insulating member 213 can be provided with at least one hot melt column, and the fixed connection of the first insulating member 213 to the cover plate 211 can be achieved by hot melting of the hot melt column.

[0163] The number of avoiding holes 213a can be the same as that of the electrode terminals 212, for example, two, and are arranged at intervals along the third direction Z.

[0164] The material of the first insulating member 213 can be polypropylene, polyethylene, polyvinyl chloride, polycarbonate, or the like. The first insulating member 213 can be used to separate the electrode assembly 23 and the cover plate 211, so as to avoid short circuit caused by short circuiting of the two. The first insulating member 213 can be used to separate the electrode assembly 23 and the cover plate 211, so as to avoid short circuit caused by short circuiting of the two.

[0165] In some embodiments, the avoiding hole 213a can be a circular hole. It can be understood that the opening size (hole diameter) of the avoiding hole 213a is greater than the outer diameter size of the sealing ring 214, so that the second connecting portion 2122 and the sealing ring 214 are arranged in the avoiding hole 213a.

[0166] By arranging the first insulating member 213, the insulation effect inside the battery monomer 20 can be further improved, so as to improve the reliability of the battery.

[0167] Please refer to Figure 6 , Figure 10 and Figure 11 According to some embodiments of the present application, in a plane perpendicular to the thickness direction of the cover plate 211, the first insulating member 213 defines that the orthographic projection of the inner edge of the avoiding hole 213a completely falls within the orthographic projection range of the first connecting portion 2121.

[0168] In a plane perpendicular to the thickness direction of the cover plate 211, that is, in any plane perpendicular to the first direction X, the orthographic projection of the avoiding hole 213a is completely located within the orthographic projection range of the first connecting portion 2121, so that the first connecting portion 2121 can completely cover the avoiding hole 213a, so that a part of the first insulating member 213 will be inserted between the first connecting portion 2121 and the cover plate 211.

[0169] It can be understood that the shape of the avoiding hole 213a can be similar to the shape of the first connecting portion 2121, for example, both are circular, or can be different, for example, the avoiding hole 213a is a circular hole, and the first connecting portion 2121 is rectangular.

[0170] The hardness of the first insulating member 213 is usually higher than that of the sealing ring 214, so the part of the first insulating member 213 located between the first connecting portion 2121 and the cover plate 211 can provide limiting for the electrode terminal 212 along the first direction X, and reduce the direct contact between the first connecting portion 2121 and the cover plate 211 caused by structural deformation, so as to better meet the sealing reliability and electrical connection reliability requirements when the internal pressure of the battery monomer 20 is large.

[0171] According to some embodiments of the present application, the electrode terminal 212 further comprises a third connecting portion 2123, which is arranged on the side of the cover plate 211 away from the electrode assembly 23 and is fixedly connected with the end of the second connecting portion 2122 away from the first connecting portion 2121; the end cover assembly 21 further comprises a second insulating member 215, which is arranged between the third connecting portion 2123 and the cover plate 211. ​

[0172] The third connecting portion 2123 can be fixedly connected to the second connecting portion 2122 by welding or riveting. The projected area of the third connecting portion 2123 on the cover plate 211 can be greater than or equal to the projected area of the first connecting portion 2121 on the cover plate 211.

[0173] The second insulating member 215 can be made of any material that meets the insulation requirements, such as polypropylene, polyethylene, polyamide, polycarbonate, etc. The material of the second insulating member 215 can be the same as or different from that of the first insulating member 213.

[0174] The second insulating member 215 is clamped between the third connecting portion 2123 and the cover plate 211 to achieve insulation therebetween.

[0175] By providing the third connecting portion 2123, the connectable area of the electrode terminal 212 outside the battery monomer can be increased, thereby facilitating subsequent electrical connection with the tab. Meanwhile, the third connecting portion 2123 and the first connecting portion 2121 are clamped on both sides of the cover plate 211. When the pressure inside the battery monomer 20 is relatively large, the deformation probability or degree of the electrode terminal 212 is reduced, the sealing ring 214 can play a better sealing role, and more reliable installation and fixation between the electrode terminal 212 and the cover plate 211 are achieved, which is more conducive to maintaining the reliability of the electrical connection between the electrode terminal 212 and the outside.

[0176] Please refer to Figure 13 , Figure 13 The sealing ring provided by some embodiments of the present application is shown in the structural schematic diagram.

[0177] According to some embodiments of the present application, the cover plate 211 includes a center portion 2112 and a lap portion 2111 surrounding the outer periphery of the center portion 2112, the lap portion 2111 is used to be fixedly connected with the end face where the opening in the shell 22 is located, and a part of the center portion 2112 extends into the accommodating cavity through the opening.

[0178] The center portion 2112 is a part of the central region of the cover plate 211, the lap portion 2111 is an edge part surrounding the outer periphery of the center portion 2112, and the center portion 2112 and the lap portion 2111 are integrally formed and protrude to the side where the electrode assembly 23 is located relative to the lap portion 2111.

[0179] The thickness of the lap portion 2111 along the third direction Z is less than the thickness of the center portion 2112 along the third direction Z. In some examples, the thickness of the lap portion 2111 is greater than or equal to 0.3 mm and less than or equal to 1 mm.

[0180] When the cover plate 211 is butted against the shell 22, the lap joint portion 2111 is in abutment with the end face of the shell 22, which is conducive to installation positioning before welding. The welding mode between the lap joint portion 2111 and the shell 22 can be laser welding. A part of the center portion 2112 protruding will extend into the accommodating cavity, so as to block the laser penetrating from the gap between the lap joint portion 2111 and the end face of the shell 22.

[0181] By arranging the lap joint portion 2111 to be in abutment with the end face of the shell 22, the positioning before welding can be simplified, the probability of laser damaging the electrode assembly can be reduced, and the yield of the battery monomer can be improved. In addition, the expansion of the battery monomer in the later stage of the cycle can be better resisted, and the comprehensive performance of the battery monomer can be improved.

[0182] According to some embodiments of the present application, the electrode assembly 23 includes a positive electrode sheet 232, and the active material of the active material area of the positive electrode sheet 232 includes a lithium phosphate salt.

[0183] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material on the surface of the positive electrode current collector. The positive electrode active material can include a lithium phosphate salt, for example, one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium cobalt phosphate, lithium vanadium phosphate, etc.

[0184] The active material containing a lithium phosphate salt has good positive electrode stability, and can alleviate the deformation risk caused by uneven edge current to a certain extent. In combination with the shell structure of the battery monomer 20 of the present application, the reliability of the battery monomer 20 can be improved.

[0185] According to some embodiments of the present application, at least one of the active material area of the positive electrode sheet 232 and the active material area of the negative electrode sheet 231 has a size of 100-200 mm along the first direction X. Preferably, 160-200 mm.

[0186] The size of the active material area of the positive electrode sheet 232 along the first direction X is actually the effective height size of the positive electrode sheet 232. Correspondingly, the size of the active material area of the negative electrode sheet 231 along the first direction X is actually the effective height size of the negative electrode sheet 231. The increase of the height of the electrode sheet will amplify the uneven current distribution. When charging and discharging, the bending and warping deformation in the height direction of the electrode sheet is more obvious, which will lead to a significant increase in the risk of lithium precipitation, short circuit, thermal runaway, etc. On the other hand, the increase of the height of the electrode sheet can increase the effective active material area and improve the capacity of the battery monomer.

[0187] For example, at least one of the active material region of the positive electrode sheet 232 and the active material region of the negative electrode sheet 231 has a size of 100 mm, 120 mm, 150 mm, 160 mm, 180 mm, or 200 mm along the first direction X. In some embodiments, at least one of the active material region of the positive electrode sheet 232 and the active material region of the negative electrode sheet 231 can also have a size greater than or equal to 160 mm and less than or equal to 200 mm along the first direction X.

[0188] By reasonably setting the height of the electrode sheet, the capacity of the battery monomer and the risk of deformation or lithium precipitation can be effectively balanced, and the reliability and service life of the battery monomer can be improved.

[0189] The battery device 100 provided in the embodiments of the present application includes the battery monomer 20 provided in the above embodiments.

[0190] The battery device 100 provided in the embodiments of the present application includes the battery monomer 20 provided in the above embodiments.

[0191] The battery device 100 provided in the embodiments of the present application includes the battery monomer 20 provided in the above embodiments.

[0192] The battery device 100 provided in the embodiments of the present application includes the battery monomer 20 provided in the above embodiments.

[0193] The battery device 100 provided in the embodiments of the present application includes the battery monomer 20 provided in the above embodiments.

[0194] The battery device 100 provided in the embodiments of the present application includes the battery monomer 20 provided in the above embodiments.

[0195] The battery device 100 provided in the embodiments of the present application includes the battery monomer 20 provided in the above embodiments.

[0196] The battery device 100 provided in the embodiments of the present application includes the battery monomer 20 provided in the above embodiments.

[0197] The battery device 100 provided in the embodiments of the present application includes the battery monomer 20 provided in the above embodiments.

[0198] The charging network in this embodiment has the same technical effect as the energy storage system of energy storage device 200 or more in the above embodiment, and will not be described again here.

[0199] The battery cell of this application will be further described below with reference to specific embodiments.

[0200] like Figures 4-13 As shown, the battery cell 20 includes a housing 22, an electrode assembly 23, and an end cap assembly 21.

[0201] The housing 22 includes two first sidewalls 221 opposite each other along a first direction X, two second sidewalls 222 opposite each other along a second direction Y, and a bottom wall 223 connected to the first sidewalls 221 and the second sidewalls 222 respectively; the first sidewalls 221, the second sidewalls 222 and the bottom wall 223 together form an accommodating cavity with an opening.

[0202] Electrode assembly 23 is disposed within a receiving cavity. Electrode assembly 23 includes a negative electrode 231 containing graphite, a positive electrode 232 containing lithium phosphate, and a separator 233. The negative electrode 231 includes a negative current collector 2311 and a negative active material layer 2312 coated on the surface of the negative current collector 2311. The area with the negative active material layer 2312 is the active material area of ​​the negative electrode 231, and the portion without the negative active material layer 2312 forms a negative electrode tab. The positive electrode 232 includes a positive current collector 2321 and a positive active material layer 2322 coated on the surface of the positive current collector 2321. The area with the positive active material layer 2322 is the active material area of ​​the positive electrode 232, and the portion without the positive active material layer 2322 forms a positive electrode tab.

[0203] The diaphragm 233 includes a first main body portion 2331 facing the active material region of the adjacent negative electrode 231, and a first extension portion 2330 extending beyond the active material region of the negative electrode 231 along the first direction X. The first extension portion 2330 includes a first sub-extension portion 2332 near the cover plate 211 and a second sub-extension portion 2333 away from the cover plate 211. Along the first direction X, the size of the first extension portion 2330 is greater than or equal to 2.3 mm and less than or equal to 4.3 mm.

[0204] In some examples, the difference between the dimension of the first sub-extension 2332 along the first direction X and the dimension of the second sub-extension 2333 along the first direction X is less than or equal to 0.1 mm.

[0205] The active material region of the negative electrode sheet 231 includes a second main portion 231A that is directly opposite the active material region of the adjacent positive electrode sheet 232, and a second overhanging portion 2314 that overhangs the active material region of the positive electrode sheet 232 in the first direction X, the second overhanging portion 2314 including a third sub-overhanging portion 231B proximal to the side of the cover plate 211, and a fourth sub-overhanging portion 231C distal to the side of the cover plate 211, the second overhanging portion 2314 having a dimension in the first direction X that is greater than or equal to 1.6 mm and less than or equal to 7 mm.

[0206] In some embodiments, the negative electrode sheet 231, the separator 233, and the positive electrode sheet 232 are stacked along a second direction Y; the active material region of the negative electrode sheet 231 further includes a third overhanging portion 2315 that overhangs the active material region of the positive electrode sheet 232 in a third direction Z, the third overhanging portion 2315 including a fifth sub-overhanging portion 231D and a sixth sub-overhanging portion 231E that are spaced apart along the third direction Z; the third direction Z, the second direction Y, and the first direction X are all perpendicular to each other; the third overhanging portion 2315 has a dimension in the third direction Z that is greater than or equal to 1.6 mm and less than or equal to 3 mm.

[0207] In some examples, the dimension of the second overhanging portion 2314 in the first direction X is greater than or equal to the dimension of the third overhanging portion 2315 in the third direction Z.

[0208] In some examples, the difference between the dimension of the third sub-overhanging portion 231B in the first direction X and the dimension of the fourth sub-overhanging portion 231C in the first direction X is less than or equal to 0.1 mm.

[0209] In some examples, the difference between the dimension of the fifth sub-overhanging portion 231D in the third direction Z and the dimension of the sixth sub-overhanging portion 231E in the third direction Z is less than or equal to 0.1 mm.

[0210] The electrode terminal 212 includes a first connecting portion 2121 located within the accommodation cavity, a third connecting portion 2123 located outside the accommodation cavity, and a second connecting portion 2122 that passes through the mounting hole 211a and connects the first connecting portion 2121 and the third connecting portion 2123, respectively.

[0211] The sealing ring 214 includes a first step portion 2141 and a second step portion 2142 that are connected; the first step portion 2141 is clamped between the first connecting portion 2121 and the cover plate 211, and the second step portion 2142 is clamped between the second connecting portion 2122 and the inner wall of the cover plate 211 that forms the mounting hole. The first step portion 2141 further includes a first sub-step portion 2141a and a second sub-step portion 2141b that are arranged along the third direction Z. The second sub-step portion 2141b abuts against the side surface of the cover plate 211 that faces the electrode assembly 23, away from at least part of the surface of the first sub-step portion 2141a.

[0212] The cover plate 211 comprises a center portion 2112 and a lap portion 2111 surrounding the outer periphery of the center portion 2112, the lap portion 2111 being used to be fixedly connected with the end face of the housing 22 where the opening is located, and a part of the center portion 2112 extends into the accommodating cavity through the opening.

[0213] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized by, The application relates to a battery, comprising: a housing including a receiving cavity with an opening; an electrode assembly arranged in the receiving cavity, the electrode assembly including a negative electrode sheet and a separator; and an end cover assembly covering the opening, the end cover assembly including a cover plate and an electrode terminal, the cover plate being provided with a mounting hole, the electrode terminal including a first connecting portion and a second connecting portion connected with each other, the first connecting portion being located on a side of the cover plate facing the electrode assembly and being electrically connected with the electrode assembly, the second connecting portion penetrating through the mounting hole, and a projection area of the first connecting portion on the cover plate being greater than an area of the mounting hole; wherein the separator includes a first main body portion opposite to an active material area of an adjacent negative electrode sheet and a first overhanging portion overhanging the active material area of the negative electrode sheet in a first direction parallel to a thickness direction of the cover plate, a dimension of the first overhanging portion in the first direction being greater than or equal to 2.3 mm and less than or equal to 4.3 mm.

2. The battery cell of claim 1, wherein, The dimension of the first overhanging portion in the first direction is greater than or equal to 2.3 mm and less than or equal to 4 mm.

3. The battery cell of claim 1, wherein, The first overhanging portion includes a first sub-overhanging portion close to the cover plate and a second sub-overhanging portion away from the cover plate; a difference between a dimension of the first sub-overhanging portion and a dimension of the second sub-overhanging portion in the first direction is less than or equal to 0.1 mm.

4. The battery cell of claim 1, wherein, The electrode assembly further includes a positive electrode sheet arranged on a side of the separator away from the negative electrode sheet; The active material area of the negative electrode sheet includes a second main body portion opposite to an active material area of an adjacent positive electrode sheet and a second overhanging portion overhanging the active material area of the positive electrode sheet in the first direction, a dimension of the second overhanging portion in the first direction being greater than or equal to 1.6 mm and less than or equal to 7 mm.

5. The battery cell of claim 4, wherein, The dimension of the second overhanging portion in the first direction is greater than or equal to 1.6 mm and less than or equal to 5.5 mm.

6. The battery cell of claim 4, wherein, The second overhanging portion includes a third sub-overhanging portion close to the cover plate and a fourth sub-overhanging portion away from the cover plate; a difference between a dimension of the third sub-overhanging portion and a dimension of the fourth sub-overhanging portion in the first direction is less than or equal to 0.1 mm.

7. The battery cell of claim 4, wherein, The negative electrode sheet, the separator and the positive electrode sheet are arranged in a stacking manner in a second direction; The active material area of the negative electrode sheet further includes a third overhanging portion overhanging the active material area of the positive electrode sheet in a third direction, a dimension of the third overhanging portion in the third direction being less than or equal to a dimension of the second overhanging portion in the first direction; the third direction, the second direction and the first direction are perpendicular to each other.

8. The battery cell of claim 7, wherein, The dimension of the third overhanging portion in the third direction is greater than or equal to 1.6 mm and less than or equal to 3 mm.

9. The battery cell of claim 8, wherein, The third overhanging portion includes a fifth sub-overhanging portion and a sixth sub-overhanging portion arranged in a spacing manner in the third direction; A difference between the dimensions of the fifth sub-overhanging portion and the sixth sub-overhanging portion in the third direction is less than or equal to 0.1 mm.

10. The battery cell of any one of claims 1-9, wherein, The end cover assembly further includes: a sealing ring sleeved on an outer periphery of the second connecting portion, and at least a part of the sealing ring being clamped between the first connecting portion and the cover plate.

11. The battery cell of claim 10, wherein, The sealing ring comprises a first step portion and a second step portion connected to each other. The first step portion is arranged between the first connecting portion and the cover plate, and the second step portion is arranged between the second connecting portion and an inner wall of the cover plate forming the mounting hole.

12. The battery cell of claim 11, wherein, The first step portion further comprises a first sub-step portion and a second sub-step portion connected to each other, the second sub-step portion is arranged between the first sub-step portion and the second step portion, and at least part of a surface of the second sub-step portion away from the first sub-step portion abuts against a side surface of the cover plate facing the electrode assembly.

13. The battery cell of claim 10, wherein, The end cover assembly further comprises: a first insulating member arranged on a side surface of the cover plate facing the electrode assembly; The first insulating member comprises a number of avoiding holes equal to that of the electrode terminals, and the avoiding holes are configured to allow the corresponding electrode terminals and the sealing ring to pass through.

14. The battery cell of claim 13, wherein, In a plane perpendicular to the thickness direction of the cover plate, a normal projection of an inner edge of the avoiding hole defined by the first insulating member falls within a normal projection range of the first connecting portion.

15. The battery cell of any one of claims 1-9, wherein, The electrode terminal further comprises a third connecting portion arranged on a side of the cover plate away from the electrode assembly and fixedly connected to an end of the second connecting portion away from the first connecting portion. The end cover assembly further comprises a second insulating member arranged between the third connecting portion and the cover plate.

16. The battery cell of any one of claims 1-9, wherein, The cover plate comprises a center portion and a lap portion arranged around an outer periphery of the center portion, the lap portion is used to be fixedly connected to an end surface of the housing where the opening is located, and a part of the center portion extends into the accommodating cavity through the opening.

17. The battery cell of any one of claims 1-9, wherein, The electrode assembly comprises a positive electrode sheet containing an active material of lithium phosphate salt.

18. The battery cell of claim 17, wherein, At least one of an active material region of the positive electrode sheet and an active material region of the negative electrode sheet has a dimension of 100-200 mm along the first direction.

19. A battery device characterized by comprising: The battery device comprises the battery cell according to any one of claims 1-18.

20. An electrical device, comprising: The battery device is used to provide electric energy.

21. An energy storage device, comprising: The energy storage device comprises a plurality of battery cells according to any one of claims 1-18 or a plurality of battery devices according to claim 19, and the battery cells or the battery devices are used to store or provide electric energy.

22. An energy storage system characterized by, The energy storage device comprises a power conversion device and the energy storage device according to claim 21, and the power conversion device is used to electrically connect a power generation device and the energy storage device.

23. A charging network characterized by, The energy storage device comprises a charging pile and the energy storage device according to claim 21 or the energy storage system according to claim 22, and the energy storage device or the energy storage system is used to provide electric energy for the charging pile.

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