Battery cell, battery device, and electric device

Abstract

The application provides a battery monomer, a battery device and a power utilization device, and belongs to the technical field of batteries. The battery monomer comprises an electrode assembly and an outer packaging diaphragm, the electrode assembly comprises a pole piece and a spacing diaphragm, the pole piece comprises a first pole piece and a second pole piece with opposite polarities, the spacing diaphragm separates the first pole piece from the second pole piece, and the pole piece forms an outer circumferential surface of the electrode assembly; the outer packaging diaphragm is wrapped around the outer circumference of the electrode assembly, and the outer packaging diaphragm has a weak structure. The battery monomer of the application can strengthen the constraint on the electrode assembly while facilitating the release of the swelling force, thereby improving the stability and reliability of the battery monomer.

Description

Technical Field

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

[0002] Energy conservation and emission reduction are key to the sustainable development of the automotive industry, and electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of this sustainable development. For electric vehicles, battery technology is a crucial factor in their development. However, problems such as electrode misalignment exist during the manufacturing or use of battery cells, affecting their reliability. Utility Model Content

[0003] This application provides a battery cell, a battery device, and an electrical device, which helps to improve the stability and reliability of the battery cell.

[0004] In a first aspect, embodiments of this application provide a battery cell, including: an electrode assembly and an outer separator. The electrode assembly includes an electrode sheet and a spacer membrane. The electrode sheet includes a first electrode sheet and a second electrode sheet with opposite polarities. The spacer membrane separates the first electrode sheet and the second electrode sheet. The electrode sheet forms the outer peripheral surface of the electrode assembly. The outer separator covers the outer periphery of the electrode assembly and has a weak structure.

[0005] In the above technical solution, by setting an outer separator, the constraint on the electrode assembly is enhanced. During the processing and use of the battery cell, the displacement and movement of the electrode plates are reduced, improving the reliability of the battery cell. Furthermore, by setting a weak structure on the outer separator, when the electrode assembly expands in volume during charge and discharge cycles, the areas with the weak structure on the outer separator preferentially undergo elastic / plastic deformation, converting the expansion force into its own deformation. This absorbs and disperses stress to a certain extent, reducing stress concentration and releasing the expansion force. This reduces the possibility of problems such as electrode extrusion damage, electrode displacement, and separator rupture. At the same time, the weak structure only locally weakens the constraint of the outer separator on the electrode assembly, while the outer separator as a whole still maintains its constraint effect on the electrode assembly. This reduces the problem of misalignment of the second positive electrode plate, enhances the stability of key parameters such as the gap between electrodes and between electrodes and the separator, and improves the structural stability and reliability of the battery cell during production and use.

[0006] In some embodiments, the weak structure penetrates the outer diaphragm along the thickness direction of the outer diaphragm.

[0007] In the above technical solution, the weak structure penetrates the outer diaphragm along the thickness direction, disrupting the continuous tension of the diaphragm. This prevents the tension of the outer diaphragm from being continuously transmitted in the plane, and the electrode expansion force preferentially acts on the weak structure, causing the weak structure to undergo elastic / plastic deformation. The area of ​​the weak structure remains in a low stress state, thereby reducing the constraint on the expansion force and reducing the possibility of problems such as electrode extrusion damage, electrode displacement, and diaphragm rupture.

[0008] In some embodiments, the weak structure includes a through-hole.

[0009] In the above technical solution, on the one hand, the through-holes disrupt the tension continuity of the outer diaphragm. Under stress, the force is distributed around the holes, making the diaphragm with the perforated area more easily deformable. The diaphragm around the through-holes can stretch moderately, providing a certain range of expansion space for the electrode assembly. On the other hand, the electrolyte inside the electrode assembly can flow out through the through-holes, releasing the expansion force and dispersing the internal pressure of the electrode assembly to a certain extent, thus reducing stress concentration and decreasing the possibility of problems such as electrode extrusion damage, electrode displacement, and diaphragm rupture. In addition, after perforating the outer diaphragm to form through-holes, the electrolyte can penetrate and diffuse more quickly.

[0010] In some embodiments, there are multiple through holes, the diameter of the through holes is less than or equal to 2.5 mm, and the center-to-center distance between adjacent through holes is greater than or equal to twice the diameter of the through holes.

[0011] The above technical solution can fully release the expansion force of the electrode sheet while reducing the risk of separator damage, improving the reliability of the separator's binding and isolation functions, thereby improving the stability and reliability of the battery cell.

[0012] In some embodiments, the weak structure includes a crack.

[0013] In the above technical solution, when the electrode assembly expands and generates stress, the outer separator can deform at the crack, thereby releasing the stress in the crack area and improving the reliability of the battery cell.

[0014] In some embodiments, the crack includes a multidirectional crack, which includes a plurality of intersecting stripes.

[0015] The above technical solution enables stress release at the crack when the battery cell is subjected to stress in different directions, thereby improving the reliability of stress release.

[0016] In some embodiments, there are multiple multidirectional cracks, the minimum circumscribed circle diameter of the multidirectional crack is less than or equal to 2.5 mm, and the center-to-center distance between adjacent multidirectional cracks is greater than or equal to 5 mm.

[0017] The above technical solution can fully release the expansion force of the electrode sheet while reducing the risk of separator damage, improving the reliability of the separator's binding and isolation functions, thereby improving the stability and reliability of the battery cell.

[0018] In some embodiments, an outer diaphragm covers at least one layer of the electrode assembly, and at least a portion of the weak structure is disposed in the innermost layer of the outer diaphragm.

[0019] In the above technical solution, since the innermost layer is the innermost ring that binds the electrode assembly, during the charging and discharging process of the battery cell, the expansion and deformation of the electrode assembly will first exert force on the innermost layer of the outer separator. The weak structure on the innermost layer can play its role first, release the expansion force in time, reduce the accumulation of expansion force inside the electrode assembly, reduce the possibility of problems such as electrode sheet compression damage, and improve the reliability of the battery cell.

[0020] In some embodiments, the electrode assembly is covered by more than one outer diaphragm, which includes an innermost layer and other layers covering the innermost layer, with weak structures disposed in the other layers.

[0021] In the above technical solution, the innermost layer of the outer separator tightly wraps around the electrode assembly, providing basic protection and fixation. The remaining layers further reinforce the constraint of the outer separator on the electrode assembly. The weak structure is located on the remaining layers; even if it undergoes some deformation or damage to release stress, it will not directly expose the electrode assembly. This reduces the direct impact of the weak structure on the internal structure of the electrode assembly, lowers the possibility of internal short circuits due to the failure of the weak structure, and improves the reliability of the battery cell.

[0022] In some embodiments, both sides of the electrode assembly in the thickness direction are large surface sides, the portion of the outer diaphragm covering the large surface sides is a first portion, and the weak structure includes a first weak structure disposed on at least one first portion.

[0023] In the above technical solution, during the charging and discharging process, the electrode assembly of the battery cell expands, generating internal stress. Placing the first weakest structure on the larger surface area allows for more effective stress absorption and dispersion. When the stress reaches a certain level, the first weakest structure preferentially deforms, releasing the expansion force on the larger surface area and reducing the likelihood of stress accumulation leading to internal structural damage to the battery cell, such as electrode misalignment, electrode compression damage, separator rupture, and internal short circuits. This improves the reliability of the battery cell.

[0024] In some embodiments, the electrode assembly includes a main body and tabs. The two sides of the main body in a first direction are side edges, and the tabs are disposed on both sides of the main body in the first direction and protrude from the side edges. The first direction is perpendicular to the thickness direction of the electrode assembly, and the distance between the first weak structure and the side edges along the first direction is greater than 1 / 4 of the distance between the two side edges along the first direction.

[0025] In the above technical solution, the first weak structure is located in the middle region of the large surface side away from the side edges on both sides, which can improve the problem of damage to the central region of the large surface side due to insufficient release of expansion force, and improve the reliability and cycle life of the battery cell.

[0026] In some embodiments, the area of ​​the first weak structure covering the first portion of the single layer does not exceed 30%.

[0027] In the above technical solution, the outer diaphragm of the first part has relatively sufficient structural strength to maintain the constraint on the large surface side, improve the uniformity of the force on the large surface side, improve the flatness of the battery cell, and thus improve the performance of the battery cell.

[0028] In some embodiments, the electrode assembly includes a main body and a tab, the tab protruding from the main body, the main body being a rectangle in the thickness direction of the electrode assembly, one side of the rectangle being a facet side of the electrode assembly in the width direction, the portion of the outer diaphragm covering the facet side being a second part, and the weak structure including a second weak structure disposed on at least one second part.

[0029] In the above technical solution, the second weak structure is set on the small side, thereby reducing the need to set a weak structure on the large side of the battery cell. This helps to improve the uniformity of the constraint force of the outer separator on the large side, and helps to improve the flatness of the battery cell, thereby improving the performance of the battery cell.

[0030] In some embodiments, the width direction of the rectangle is the direction of gravity, and a second weak structure is located on the second portion at the bottom of the electrode assembly.

[0031] In the above technical solution, when the second weak structure is in the form of penetrating the outer membrane, the electrolyte can penetrate and diffuse more quickly, which is beneficial to improving the wetting effect of the electrode assembly.

[0032] In some embodiments, the second weak structure covers 30%-80% of the area of ​​the second portion of the single layer.

[0033] In the above technical solution, on the one hand, it is beneficial to fully release the expansion force, and on the other hand, it is beneficial to provide enough permeation channels for the electrolyte.

[0034] In some embodiments, the outer diaphragm includes an adhesive application area, and the weak structure is arranged to avoid the adhesive application area.

[0035] In the above technical solution, the arrangement of the weak structure to avoid the adhesive application area ensures that the adhesive application area does not cover the weak structure, thereby ensuring that the weak structure can reliably play its role in releasing stress. Moreover, the arrangement of the weak structure to avoid the adhesive application area also ensures that the weak structure will not affect the adhesion of the adhesive application area, thus ensuring that the outer diaphragm is reliably fixed at the end.

[0036] In some embodiments, the entire outer diaphragm is uniformly distributed with weak structures.

[0037] In the above technical solution, the uniformly distributed weak structure throughout the outer separator can uniformly disperse stress, alleviate stress concentration, and reduce the risk of the outer separator rupture due to excessive stress, thereby improving the reliability of the battery cell. Furthermore, the uniformly distributed weak structure throughout the outer separator helps reduce the processing difficulty of the outer separator.

[0038] In some embodiments, the electrode assembly is in the form of a stack, with the first electrode and the second electrode alternately stacked along the thickness direction of the electrode assembly.

[0039] In the above technical solutions, due to its structural characteristics, the stacked form is more prone to problems such as electrode displacement during production or use. By setting an outer separator to surround the electrode assembly at least once, and setting a weak structure on the outer separator, it can play a role in both constraining the electrode assembly and releasing expansion force, reducing the problems caused by electrode displacement, improving the stability and reliability of the battery cell, and reducing failure problems such as electrode compression damage, active material peeling, separator rupture, and internal short circuit caused by electrode assembly expansion.

[0040] In some embodiments, the battery cell includes a separator, which is a continuous separator and includes a spacer separator and an outer separator. The spacer separator includes a plurality of sub-extensions that extend back and forth. Adjacent sub-extensions are sandwiched on both sides of a single-layer electrode in the electrode assembly, and two adjacent electrodes are separated by the single-layer sub-extensions.

[0041] The above technical solution is beneficial to improving the reliability of positive and negative electrode isolation and is easy to process and manufacture.

[0042] In some embodiments, the outer diaphragm is connected to one end of the spacer diaphragm and surrounds the electrode assembly at least once; or, the outer diaphragm includes a first outer portion and a second outer portion, the first outer portion and the second outer portion being connected to both ends of the spacer diaphragm respectively, the two side surfaces of the electrode assembly in the thickness direction being a first surface and a second surface respectively, the first outer portion being connected to the end of the spacer diaphragm near the first surface and covering the first surface, the second outer portion being connected to the end of the spacer diaphragm near the second surface and surrounding the electrode assembly at least once, the first outer portion covering the second outer portion, the first outer portion and the second outer portion together defining the innermost layer of the outer diaphragm.

[0043] The above technical solution facilitates the flexible placement of the outer diaphragm during the assembly process.

[0044] Secondly, embodiments of this application provide a battery device, including: a plurality of battery cells according to any of the above embodiments.

[0045] Thirdly, embodiments of this application provide an electrical device, including: a battery cell as described in any of the above embodiments or a battery device as described in any of the above embodiments. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This application provides schematic diagrams of the structure of an energy storage system according to some embodiments. Figure 2 This is a schematic diagram of the structure of a charging network provided in some embodiments of this application; Figure 3 This application provides structural schematic diagrams of vehicles for some embodiments; Figure 4 Exploded views of the structure of the battery device provided in some embodiments of this application; Figure 5 A cross-sectional view of a battery cell provided in one embodiment of this application; Figure 6 A schematic diagram of the small facet side of an electrode assembly provided in one embodiment of this application; Figure 7 A schematic diagram of the small facet side of an electrode assembly provided in another embodiment of this application; Figure 8 for Figure 7 Enlarged view of the multidirectional cracks shown; Figure 9 A cross-sectional view of an electrode assembly provided in one embodiment of this application; Figure 10 A cross-sectional view of an electrode assembly provided in another embodiment of this application; Figure 11 A schematic diagram of the large-area side of an electrode assembly provided in one embodiment of this application; Figure 12 A cross-sectional view of a battery cell provided in another embodiment of this application; Figure 13A cross-sectional view of an electrode assembly provided in another embodiment of this application.

[0048] Figure label: 1000 energy storage devices; 2000 power conversion devices; 3000 power generation devices; 4000 charging piles; 5000 connectors; Vehicle 10,000; Battery unit 100; Controller 200; Motor 300; Box 10; First box body 101; Second box body 102; 20 battery cells; First direction F1; Width direction F2; Thickness direction F3; Housing 201; Electrode assembly 202; First surface S1; Second surface S2; Diaphragm 203; Electrode 1; First electrode 11; Second electrode 12; Large surface side 1a; Small surface side 1b; Spacer diaphragm 21; Sub-extension 211; Outer diaphragm 22; innermost layer 221; remaining layers 222; First outsourcing section 22a; Second outsourcing section 22b; Part 1 223; Part 2 224; Adhesive application area 225; Weak structure 23; First weak structure 231; Second weak structure 232; Through hole 23a; crack 23b; multidirectional crack 233; stripe mark 2331; 3. Electrode; 4. Main body; 41. Side edge. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0050] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0051] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0052] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0053] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0054] In this application, "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0055] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0056] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0057] Battery cells can be cylindrical, flat, cuboid, or other shapes, and this application embodiment is not limited to any of these. Battery cells are generally classified into three types according to their packaging method: cylindrical battery cells, square battery cells, and pouch battery cells, and this application embodiment is not limited to any of these types either.

[0058] A battery cell includes a casing, electrode components, and electrolyte. The casing houses the electrode components and electrolyte. The electrode components consist of a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrode components. The positive electrode includes a positive current collector and a positive electrode coating. The positive current collector includes a current collector body and a positive electrode tab. The positive electrode coating is applied to the surface of the current collector body, while the positive electrode tab is not coated and protrudes from the current collector body. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative electrode coating. The negative current collector includes a current collector body and a negative electrode tab. The negative electrode coating is applied to the surface of the current collector body, while the negative electrode tab is not coated and protrudes from the current collector body. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon or silicon, etc. To ensure that a large current can be passed without melting, there are multiple positive electrode tabs stacked together, and there are multiple negative electrode tabs stacked together.

[0059] The membrane material can be PP (polypropylene) or PE (polyethylene), etc.

[0060] The electrode assembly can be either wound or stacked. However, regardless of the form, electrode displacement is prone to occur during the production of battery cells, affecting the stability and reliability of the battery cells.

[0061] For example, when processing stacked electrode assemblies, during the process of moving the electrode and separator before hot pressing, the relatively weak constraint between the electrode and separator allows for relative sliding and displacement of the positive and negative electrodes. This causes changes in the gaps between electrodes and between the electrode and separator, affecting the stability and reliability of the battery cell. For instance, in a lithium-ion battery, if the negative electrode does not completely cover the projected area of ​​the positive electrode, lithium ions may "overflow" into inactive areas during migration, leading to "lithium plating." This can result in reduced initial efficiency, decreased discharge capacity, and shortened cycle life. In severe cases, lithium dendrites formed by lithium plating may pierce the separator, causing internal short circuits and thermal runaway within the battery cell.

[0062] In addition, during normal charge and discharge cycles, individual battery cells are inevitably subjected to vibration. The external force generated by the vibration will disrupt the relative positional relationship between the electrodes and between the electrodes and the separator. Furthermore, the expansion and contraction of the electrode assembly will also disrupt the relative positional relationship between the electrodes and between the electrodes and the separator, resulting in the misalignment of the positive and negative electrodes and causing changes in parameters such as the gap between the electrodes and between the electrodes and the separator.

[0063] Similarly, for battery cells using wound electrode assemblies, vibration may loosen the wound electrode assemblies, causing changes in the interlayer gaps of the electrode sheets, which can also lead to problems such as misalignment and thus affect the capacity, cycle life, and reliability of the battery cell.

[0064] Based on this, this application proposes a battery cell in which the separator, in addition to separating the positive and negative electrode sheets, also encapsulates the electrode assembly. This effectively restricts the movement space of the electrode sheets, reduces the possibility of electrode movement, and improves the stability and reliability of the battery cell. For example, after stacking the separator with the positive and negative electrode sheets in a Z-shape to obtain the electrode assembly, the separator is further wound around the electrode assembly to form a separator around the electrode assembly, followed by final application of adhesive. In this way, the multi-wound separator can constrain the stacked positive and negative electrode sheets within the electrode assembly, limiting the range of motion of the electrode sheets, improving the structural stability of the battery cell during production and use, and mitigating problems caused by electrode displacement.

[0065] However, although the separator wrapped around the electrode assembly can effectively fix the position of the electrode and prevent interlayer misalignment, when the battery cell expands in volume during charge and discharge cycles, the constraint of the separator will hinder the stress release of the electrode, causing stress to accumulate between the electrode layers. The stress concentration phenomenon can cause electrode compression damage, active material peeling, or even separator rupture, ultimately leading to battery cell capacity decay, internal short circuit and other failure problems.

[0066] In this embodiment, a weak structure is provided on the portion of the separator that covers the electrode assembly. When the electrode assembly expands in volume during charge-discharge cycles, the area with the weak structure on the separator preferentially undergoes elastic / plastic deformation, converting the expansion force into its own deformation. This absorbs and disperses stress to a certain extent, reducing stress concentration and releasing the expansion force. This reduces the likelihood of problems such as electrode compression damage, electrode displacement, and separator rupture. At the same time, the weak structure only locally weakens the separator's constraint on the electrode assembly, while the separator as a whole still maintains its constraint on the electrode assembly. This reduces problems caused by electrode misalignment and enhances the stability of key parameters such as the gap between electrodes and between electrodes and the separator, thereby improving the structural stability and reliability of the battery cell during production and use.

[0067] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via busbars.

[0068] The energy storage device mentioned in the embodiments of this application includes one or more battery clusters to increase the voltage and capacity of the energy storage device. A battery cluster may include multiple battery devices connected in series via a busbar to increase the voltage of the energy storage device. When the energy storage device includes multiple battery clusters, the multiple battery clusters are connected in parallel to increase the capacity of the energy storage device.

[0069] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, an energy storage device can store electrical energy during off-peak hours and provide power to relevant users or electrical devices during peak hours. The energy storage system provided in this application embodiment can be any power system that requires energy storage devices.

[0070] In some embodiments, the energy storage device is an energy storage container or an energy storage cabinet.

[0071] In some embodiments, the energy storage device may include a cabinet and one or more battery clusters housed within the cabinet.

[0072] In some embodiments, the energy storage device may include modules such as a thermal management module, a main control module, a central control module, a power distribution module, and a fire protection module.

[0073] As an example, the thermal management module may include a liquid cooling unit that supplies coolant to each battery device via piping to regulate the temperature of the individual battery cells.

[0074] As an example, the main control module can serve as the battery management unit for the battery cluster, used to monitor and manage the battery cluster. The main control module can monitor information such as the current, voltage, power, or temperature of the battery cluster. For instance, it can control the charging and discharging current and voltage of the battery cluster. The main control module includes modules such as an auxiliary battery management unit (SBMU) and a fusion switch.

[0075] As an example, the central control module can serve as the battery management unit for an energy storage device, used to monitor and manage the device. The central control module can monitor information such as the energy storage device's current, voltage, power, state of charge, or temperature. For instance, it can control the charging and discharging current and voltage of the energy storage device. As an example, the central control module includes modules such as an Insulation Monitoring Module (IMM), a Master Battery Management Unit (MBMU), an Ethernet (ETH) module, and a fiber optic conversion module.

[0076] As an example, a fire protection system includes control panels, detectors, alarm devices, etc., used to detect, alarm, or extinguish fires in energy storage systems.

[0077] As an example, the power distribution unit can be used to distribute power to the power modules of the energy storage device.

[0078] In some embodiments, such as Figure 1 As shown, the energy storage system may include one or more energy storage devices 1000 and a power converter system (PCS) 2000, which is connected between the power generation device 3000 and the energy storage device 1000. The power generation device 3000 generates electrical energy, which can be stored in the energy storage device 1000 via the power converter system 2000. As an example, the power generation device 3000 may specifically be a solar panel, hydroelectric power generation equipment, thermal power generation equipment, wind power generation equipment, etc. The specific type of the power generation device 3000 is not limited in this application.

[0079] Please refer to Figure 2 This application provides a charging network including a charging pile 4000 and an energy storage device 1000. The charging pile 4000 is electrically connected to the energy storage device 1000, which provides power to the charging pile 4000. The charging pile 4000 is electrically connected to a battery device in the energy storage device 1000 via a cable, and the battery device can provide its stored energy to the charging pile 4000. The charging pile 4000 has one or more connectors 5000 for connecting to an electrical device (such as a vehicle) to replenish power to the device.

[0080] Energy storage devices can be located inside the charging pile (e.g., an integrated energy storage and charging unit) or outside the charging pile.

[0081] This application provides an electrical device that uses a single battery cell, battery device, energy storage device, or energy storage system as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, and spacecraft. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft.

[0082] For ease of explanation, the following embodiments will be described using a vehicle 10000 as an example of an electrical device according to an embodiment of this application.

[0083] Please refer to Figure 3 , Figure 3 This is a schematic diagram of the structure of a vehicle 10000 provided in some embodiments of this application. The vehicle 10000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is installed inside the vehicle, and the battery device 100 can be located at the bottom, front, or rear of the vehicle. The battery device 100 can be used to power the vehicle; for example, the battery device 100 can serve as the vehicle's operating power source. The vehicle may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle during starting, navigation, and driving.

[0084] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle, but also as the driving power source for the vehicle, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle.

[0085] Please refer to Figure 4 , Figure 4This is an exploded view of the structure of a battery device 100 provided in some embodiments of this application. The battery device 100 includes a housing 10 and a plurality of battery cells 20, with the battery cells 20 housed within the housing 10. The housing 10 provides assembly space for the battery cells 20, and the housing 10 can adopt various structures. In some embodiments, the housing 10 may include a first housing body 101 and a second housing body 102, which overlap each other, and together define an assembly space for accommodating the battery cells 20. The second housing body 102 may be a hollow structure open at one end, and the first housing body 101 may be a plate-like structure, covering the open side of the second housing body 102 so that the first housing body 101 and the second housing body 102 together define the assembly space; alternatively, the first housing body 101 and the second housing body 102 may both be hollow structures open on one side, with the open side of the first housing body 101 covering the open side of the second housing body 102. Of course, the box 10 formed by the first box body 101 and the second box body 102 can be of various shapes, such as cylinder, cuboid, etc.

[0086] In the battery device 100, multiple battery cells 20 can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed configuration, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery device 100 can also consist of multiple battery cells 20 first connected in series, parallel, or in a mixed configuration to form battery modules, and then these battery modules are connected in series, parallel, or in a mixed configuration to form a whole, which is then housed within the housing 10. The battery device 100 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 20.

[0087] Please refer to Figure 4 , Figure 4 This is a partial structural schematic diagram of a battery device 100 provided in some embodiments of this application. The battery device 100 includes multiple rows of battery cells 20, which are arranged along the length of the housing 10. Each row of battery cells 20 includes multiple battery cells 20 arranged along the width of the housing 10.

[0088] Please refer to Figure 4 and Figure 5This application provides a battery cell 20, including an electrode assembly 202 and an outer separator 22. The electrode assembly 202 includes an electrode 1 and a spacer 21. The electrode 1 includes a first electrode 11 and a second electrode 12 with opposite polarities. The spacer 21 separates the first electrode 11 and the second electrode 12. The electrode 1 forms the outer peripheral surface of the electrode assembly 202. The outer separator 22 covers the outer periphery of the electrode assembly 202 and has a weak structure 23 on the outer separator 22.

[0089] In this configuration, both the first electrode 11 and the second electrode 12 are electrode 1, with one of the first electrode 11 and the second electrode 12 being a positive electrode and the other being a negative electrode.

[0090] The electrode assembly 202 can be in the form of a wound or a stacked form. In the form of a wound, the first electrode 11 or the second electrode 12 can form the outer peripheral surface of the electrode assembly 202 on its own. In the form of a stacked, the first electrode 11 and / or the second electrode 12 can form the outer peripheral surface of the electrode assembly 202.

[0091] The form of the spacer 21 is not limited. It can be a continuous diaphragm that extends in a Z-shape, interleaving multiple first electrodes 11 and second electrodes 12. In this case, the folding corners of the spacer 21 also form a local area on the outer peripheral surface of the electrode assembly 202, but the area here is small and negligible. Alternatively, the spacer 21 can also be multiple independent diaphragms, with each spacer 21 between each first electrode 11 and second electrode 12 being independent.

[0092] Exemplarily, the spacer diaphragm 21 and the outer diaphragm 22 are a single, continuous diaphragm (i.e., diaphragm 203). Diaphragm 203 includes the continuously disposed spacer diaphragm 21 and the outer diaphragm 22. The spacer diaphragm 21 is the portion of diaphragm 203 used to separate the first electrode 11 and the second electrode 12, while the outer diaphragm 22 is the remaining portion of diaphragm 203 excluding the spacer diaphragm 21. Of course, this application is not limited to this; the spacer diaphragm 21 and the outer diaphragm 22 may not be a single, continuous diaphragm, but rather separate diaphragms.

[0093] In the above technical solution, by setting the outer separator 22, the constraint on the electrode assembly 202 is enhanced. During the processing and use of the battery cell 20, the displacement and movement of the electrode plates 1 (such as the first electrode plate 11 and the second electrode plate 12) are reduced, improving the reliability of the battery cell 20. Furthermore, by setting a weak structure 23 on the outer separator 22, when the volume of the electrode assembly of the battery cell 20 expands during charge and discharge cycles, the area with the weak structure 23 on the outer separator 22 preferentially undergoes elastic / plastic deformation, converting the expansion force into its own deformation, and absorbing and mitigating the expansion force to a certain extent. By dispersing stress and reducing stress concentration, the expansion force is released, thereby reducing the possibility of problems such as electrode extrusion damage, electrode displacement, and rupture of the separator 21. At the same time, the weak structure 23 only locally weakens the constraint of the outer separator 22 on the electrode assembly 202, while the outer separator 22 as a whole still maintains the constraint effect on the electrode assembly 202, thereby reducing the problem of electrode 1 misalignment and enhancing the stability of key parameters such as the gap between positive and negative electrodes and between electrode 1 and separator, thus improving the structural stability and reliability of the battery cell 20 during production and use.

[0094] In the embodiments of this application, the weak structure 23 refers to a deformable region formed on the outer separator 22, so that it preferentially deforms when the electrode assembly 202 expands, thereby releasing stress. The location of the weak structure 23 is not limited. The weak structure 23 can be evenly distributed on the entire surface of the outer separator 22, so that the pressure release performance of the electrode assembly 202 is consistent in all directions; or the weak structure 23 can be concentrated in a specific area of ​​the outer separator 22, such as an area where stress of the electrode assembly 202 is prone to concentrate, so that pressure can be preferentially released at a specific location according to the actual use and stress characteristics of the battery cell 20, thereby improving the stability and reliability of the battery cell 20.

[0095] The specific form of the weak structure 23 is not limited. For example, by changing the separator manufacturing process, the thickness of certain areas of the outer separator 22 is reduced to form the weak structure 23. The shape of the thinned area is not limited, for example, it can be circular, rectangular, etc. As a result, the weak structure 23 is more prone to deformation than other areas of the outer separator 22, thereby forming a stress buffer area on the outer separator 22, reducing stress transmission to the electrode and causing damage, maintaining the overall structural integrity of the separator, and thus improving the reliability of the battery cell 20.

[0096] Alternatively, by way of example, the weak structure 23 may also be in the form of penetrating the outer diaphragm 22 along its thickness direction, wherein penetrating means that the weak structure 23 completely penetrates from one surface of the outer diaphragm 22 in its thickness direction to the other surface of the outer diaphragm 22 in its thickness direction. For example, the weak structure 23 may be in the form of a through hole 23a having a certain area in the outer diaphragm 22 (e.g., combined with...). Figure 6 It can also be a crack without area, form 23b (e.g., a combination). Figure 7 The weak structure 23 penetrates the outer diaphragm 22 along its thickness direction, disrupting the continuous tension of the outer diaphragm 22. This prevents the tension of the outer diaphragm 22 from being continuously transmitted in the plane, causing the expansion force to preferentially act on the weak structure 23, resulting in elastic / plastic deformation of the weak structure 23 (such as deformation around the through hole 23a and stretching of the thinning strip). The area of ​​the weak structure 23 remains in a low-stress state, thereby reducing the constraint on the expansion force and reducing the possibility of problems such as electrode extrusion damage, electrode displacement, and diaphragm rupture.

[0097] refer to Figure 6 In some embodiments, the weak structure 23 includes a through-hole 23a, where the outer diaphragm 22 forms an area gap. The through-hole 23a is a hole that penetrates the outer diaphragm 22, causing a portion of the outer diaphragm 22 to be missing. The shape of the through-hole 23a is not limited; it can be a regular or irregular shape such as a circle, square, or ellipse. However, setting the through-hole 23a to a circle or ellipse, i.e., a curved outer perimeter, allows it to withstand greater deformation and is less prone to breakage compared to shapes with corners, such as square shapes.

[0098] For example, the electrode assembly 202 uses silicon-based negative electrode material to make the negative electrode sheet. During the battery charge-discharge cycle, the silicon-based negative electrode material contracts and expands significantly, which increases the internal stress of the electrode assembly 202. The weak structure 23 is the through hole 23a. On the one hand, the through hole 23a disrupts the tension continuity of the outer separator 22. When under stress, the force is distributed around the hole, making the outer separator 22 with the perforated area more easily deformed. The outer separator 22 around the through hole 23a can stretch moderately, providing a certain range of expansion space for the electrode assembly 202. On the other hand, the electrolyte in the electrode assembly 202 can flow out through the through hole 23a, releasing the expansion force and dispersing the internal pressure of the electrode assembly 202 to a certain extent, thus reducing stress concentration and reducing the possibility of problems such as electrode sheet extrusion damage, electrode sheet displacement, and separator rupture.

[0099] Furthermore, by creating through-holes 23a in the outer separator 22, the electrolyte can penetrate and diffuse more quickly. The through-holes 23a provide additional channels for the electrolyte, allowing it to wet the positive and negative electrode materials of the electrode assembly 202 more rapidly and uniformly. Good electrolyte wetting enhances the activity of the electrochemical reaction, thereby improving the battery's charge / discharge efficiency and energy density, and extending the lifespan of the battery cell 20.

[0100] refer to Figure 7In some embodiments, there are multiple through holes 23a, with a hole diameter d1 less than or equal to 2.5 mm, and a center-to-center distance t1 between adjacent through holes 23a greater than or equal to twice the hole diameter d1. The multiple through holes 23a form a stress buffer region, whose deformation capacity is greater than other areas of the outer diaphragm 22, allowing expansion force to be released. This disperses the internal pressure of the electrode assembly 202 to a certain extent, reducing stress concentration and thus reducing the possibility of problems such as electrode extrusion damage, electrode displacement, and diaphragm rupture. It is worth noting that the distribution of the multiple through holes 23a is not limited. They can be uniformly arranged, such as in a multi-row, multi-column uniform array, facilitating processing; they can also be non-uniformly arranged (e.g., low hole density in the central region, high hole density in the edge region, or vice versa); or they can be arranged according to a pattern (e.g., radially). The shape of the through holes 23a is not limited. For example, the through holes 23a can be circular, elliptical, or polygonal (e.g., triangular, rectangular).

[0101] The aperture d1 of the through hole 23a is less than or equal to 2.5 mm. For example, it can be 2.5 mm, 2.3 mm, 2.1 mm, 1.9 mm, 1.7 mm, 1.5 mm, etc. This not only breaks the continuous stress around the through hole 23a, making it easier for deformation to occur around the through hole 23a, but also prevents the basic strength of the outer separator 22 and the overall structural stability of the battery cell 20 from being too large. The center-to-center distance t1 between adjacent through holes 23a is greater than or equal to twice the aperture d1 of the through hole 23a. This allows the stress to be more evenly distributed around each through hole 23a when the electrode assembly 202 expands or is subjected to external forces. This reduces the possibility of stress concentration in one area leading to local rupture of the separator and improves the stability and reliability of the battery cell 20.

[0102] refer to Figure 6 In some embodiments, the weak structure 23 includes a crack 23b, where the outer separator 22 has no area loss. The crack 23b refers to a penetration mark formed on the surface of the outer separator 22 by mechanical processing or laser engraving. While the crack 23b does not create a removed area on the outer separator 22, it penetrates it. The crack 23b reduces the tensile strength of the area where it is located, making it more susceptible to deformation. Therefore, when the electrode assembly 202 expands and generates stress, the outer separator 22 can deform at the crack 23b, releasing the stress in the crack 23b area and improving the reliability of the battery cell 20.

[0103] The shape, orientation, and distribution of the cracks 23b are not limited and can be flexibly configured. For example, the direction of stress release can be controlled by adjusting the shape, orientation, and position of the cracks 23b. For instance, elongated cracks 23b can be configured so that when the electrode assembly 202 expands and generates stress, the deformation of the elongated cracks 23b can directionally release stress perpendicular to the orientation of the elongated cracks 23b, thereby improving the accuracy and control of the expansion force release.

[0104] refer to Figure 7 and Figure 8 In some embodiments, the crack 23b includes a multi-directional crack 233, which comprises multiple intersecting strip-shaped marks 2331. This allows the battery cell 20 to release stress at the crack 23b when subjected to stresses in different directions (such as anisotropic stresses generated by the expansion of the electrode assembly 202), improving the reliability of stress release. Compared to a single-directional crack 23b, the multi-directional crack can more evenly distribute stress, preventing localized stress concentration that could cause the outer separator 22 to tear at the crack 23b, thus improving the stability and reliability of the battery cell 20.

[0105] In the above embodiments, the number of multiple intersecting strip marks 2331 in multiple directions is not limited. For example, they can be two right-angled intersecting cracks 23b, or multiple acute-angled intersecting strip marks 2331, etc. The shape, direction, length and other parameters of each strip mark 2331 can also be different. For example, the strip mark 2331 in a certain direction is longer, so that the stress perpendicular to this direction is released more. For another example, the size of each strip mark 2331 can be the same.

[0106] refer to Figure 7 and Figure 8 In some embodiments, there are multiple multidirectional cracks 233, the minimum circumscribed circle diameter d2 of the multidirectional cracks 233 is less than or equal to 2.5 mm, and the center-to-center distance t2 between adjacent multidirectional cracks 233 is greater than or equal to 5 mm.

[0107] In the above technical solution, the minimum circumscribed circle diameter d2 of the multi-directional crack 233 is less than or equal to 2.5 mm, for example, it can be 2.5 mm, 2.3 mm, 2.1 mm, 1.9 mm, 1.7 mm, 1.5 mm, etc. This not only disrupts the continuous stress around the crack 23b, making it easier for deformation to occur around the crack 23b, but also prevents the basic strength of the outer separator 22 and the overall structural stability of the battery from being too large due to the crack 23b. The center-to-center distance t2 between adjacent multi-directional cracks 233 is greater than or equal to 5 mm, for example, it can be 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, etc., ensuring sufficient space between each multi-directional crack 233 and preventing mutual interference due to excessive density of multi-directional cracks 233. When subjected to stress, each multi-directional crack 233 can play a role in stress release, avoiding uneven stress release or the generation of new stress concentration points due to the interaction between multi-directional cracks 233, thus improving the reliability of the battery cell 20.

[0108] In the embodiments of this application, the outer diaphragm 22 covers at least one layer of the electrode assembly 202. That is, the outer diaphragm 22 covers one or more layers of the electrode assembly 202. When the outer diaphragm 22 covers one layer of the electrode assembly 202, the outer diaphragm 22 is always the innermost layer 221. When the outer diaphragm 22 covers more than one layer of the electrode assembly 202, the outer diaphragm 22 includes the innermost layer 221 and the remaining layers 222 covering the innermost layer 221. In other words, the remaining portion of the outer diaphragm 22 other than the innermost layer 221 is the remaining layers 222.

[0109] Here, "innermost layer 221" refers to the outermost layer of the diaphragm 22 closest to the electrode assembly 202, and covers the entire circumference of the electrode assembly 202. The innermost layer 221 can be defined by a continuous diaphragm (e.g., refer to...). Figure 9 It can also be assembled from discontinuous septa (e.g., reference). Figure 10 ).

[0110] For example, combining Figure 9 When the spacer 21 and the outer diaphragm 22 are a single continuous diaphragm (i.e., diaphragm 203), the outer diaphragm 22 can be connected to one end of the spacer 21, and the outer diaphragm 22 can surround the electrode assembly 202 at least once. The first circle of the outer diaphragm 22 around the electrode assembly 202 from the starting position (i.e., the position connected to the spacer diaphragm 21) (i.e., after one circle around the electrode assembly 202 from the starting position and then back to the starting position) is the innermost layer 221.

[0111] For example, combining Figure 10When the spacer diaphragm 21 and the outer diaphragm 22 are a single continuous diaphragm (i.e., diaphragm 203), the outer diaphragm 22 may include a first outer portion 22a and a second outer portion 22b. The first outer portion 22a and the second outer portion 22b are respectively connected to both ends of the spacer diaphragm 21. The two side surfaces on the thickness direction F3 of the electrode assembly 202 are the first surface S1 and the second surface S2, respectively. The first outer portion 22a is connected to the end of the spacer diaphragm 21 near the first surface S1 and covers the first surface S1. The second outer portion 22b is connected to the end of the spacer diaphragm 21 near the second surface S2 and surrounds the electrode assembly 202 at least once. The first outer portion 22a covers the second outer portion 22b. The first outer portion 22a and the second outer portion 22b together define the innermost layer 221 of the outer diaphragm 22. That is, the portion covering the first outer portion 22a is removed from the first circle around the electrode assembly 202 starting from the starting position (i.e., the position connected to the spacer diaphragm 21) and together with the first outer portion 22a, forms the innermost layer 221.

[0112] refer to Figure 9 In some embodiments, at least a portion of the weak structure 23 is disposed in the innermost layer 221 of the outer diaphragm 22. That is, the weak structure 23 may be partially disposed in the innermost layer 221 of the outer diaphragm 22, or it may be entirely disposed in the innermost layer 221 of the outer diaphragm 22.

[0113] In the above technical solution, during the charging and discharging process of the battery cell 20, the expansion and deformation of the electrode assembly 202 will first exert force on the innermost layer 221 of the outer separator 22. The weak structure 23 on the innermost layer 221 can play a role first, release the expansion force in time, reduce the accumulation of expansion force inside the electrode assembly 202, reduce the possibility of problems such as electrode extrusion damage, and improve the reliability of the battery cell 20.

[0114] refer to Figure 10In some embodiments, the weak structure 23 is disposed on the remaining layers 222. In the above technical solution, placing the weak structure 23 on the remaining layers 222 surrounding the innermost layer 221, rather than on the innermost layer 221 which is in direct contact with the electrode assembly 202, reduces the possibility of a short circuit in the electrode assembly 202 and improves the reliability of the battery cell 20. The innermost layer 221 of the outer separator 22 tightly wraps around the electrode assembly 202, providing basic protection and fixation. The continued wrapping of the remaining layers 222 further strengthens the constraint of the outer separator 22 on the electrode assembly 202. Since the weak structure 23 is on the remaining layers 222, even if it undergoes a certain degree of deformation or damage to release stress, it will not directly expose the electrode assembly 202. This reduces the direct impact of the weak structure 23 on the internal structure of the electrode assembly 202, lowers the possibility of an internal short circuit due to the failure of the weak structure 23, and improves the reliability of the battery cell 20.

[0115] Furthermore, compared to the innermost layer 221, the remaining layers 222 are easier to fabricate into weak structures 23 during processing. Also, the relatively larger space in the remaining layers 222 allows processing equipment to more easily approach and operate on them to create the weak structures 23, such as through cutting, drilling, and cracking. Moreover, the material in the remaining layers 222 experiences relatively less stretching and deformation after winding, reducing the likelihood of material breakage or uncontrolled deformation during processing, thus ensuring processing quality.

[0116] For the stacked form, the thickness direction F3 of the electrode assembly 202 is the thickness direction of the electrode 1, which is also the stacking direction of the positive and negative electrodes; for the wound form, the thickness direction F3 of the electrode assembly 202 is the direction perpendicular to the winding axis of the electrode 1 and perpendicular to the straight area of ​​the electrode 1.

[0117] Combination Figure 10 and Figure 11 In some embodiments, both sides of the electrode assembly 202 in the thickness direction F3 are large surface sides 1a, and the portion of the outer diaphragm 22 covering the large surface side 1a is a first portion 223. The weak structure 23 includes a first weak structure 231 disposed on at least one first portion 223. That is, the first weak structure 231 is provided on at least one layer of the first portion 223 on at least one large surface side 1a.

[0118] During charging and discharging, the electrode assembly 202 of the battery cell 20 expands, generating internal stress. The first weak structure 231 is positioned on the larger surface area 1a. Due to its larger area, the larger surface area 1a can more effectively bear and disperse stress. When the stress reaches a certain level, the first weak structure 231 preferentially deforms, thereby releasing the expansion force of the larger surface area 1a. This reduces stress accumulation, which can lead to problems such as misalignment of the electrode 1, damage from electrode compression, separator rupture, and short circuits within the electrode assembly 202, thus improving the reliability of the battery cell 20.

[0119] Furthermore, due to the large area of ​​the large side 1a, the first weak structure 231 can be positioned in multiple locations on the large side 1a. The position of the first weak structure 231 can be flexibly adjusted according to the design requirements of the battery cell 20, stress distribution characteristics, and processing technology to meet the needs of different battery products. Moreover, the larger area makes the processing equipment easier to operate, reducing the difficulty of achieving high processing precision. For example, when using a process of simultaneously winding and fabricating the first weak structure 231, it is easier to control the extent to which the first weak structure 231 falls on the large side 1a after winding, thereby improving production efficiency.

[0120] Combination Figure 10 and Figure 11 In some embodiments, the electrode assembly 202 includes a main body 4 and tabs 3. The two sides of the main body 4 in the first direction F1 are side edges 41. The tabs 3 are disposed on both sides of the main body 4 in the first direction F1 and protrude from the side edges 41. That is, the two sides of the electrode assembly 202 in the first direction F1 are side edges 41, and the electrode assembly 202 has tabs 3 protruding from the side edges 41 on both sides in the first direction F1. The first direction F1 is perpendicular to the thickness direction F3 of the electrode assembly 202. The distance L2 between the first weak structure 231 and the side edges 41 along the first direction F1 is greater than 1 / 4 of the distance L1 between the two side edges 41 along the first direction F1. For example, L2 can be 30%, 35%, 40%, etc. of L1. Wherein, the distance L1 between the electrode assembly 202 along the first direction F1 is the distance between the two side edges 41 along the first direction F1.

[0121] For example, in the stacked electrode assembly 202, both the positive and negative electrodes are rectangular sheets. The first direction F1 is the length direction of the positive and negative electrodes. The two side edges 41 of the electrode assembly 202 in the first direction F1 are the wide edges of the battery cell 20. The electrode assembly 202 has tabs 3 extending from both sides in the length direction. The distance L2 between the first weak structure 231 and the side edge 41 along the first direction F1 is greater than 1 / 4 of the distance L1 between the two side edges 41 along the first direction F1. That is, the first weak structure 231 is located in the middle region of the large surface side 1a along the first direction F1.

[0122] The electrode assembly 202 may have fixed structures (such as tab connection structures) or assembly relationships with other components on both sides in the first direction F1, which makes the stress distribution in these areas more complex. However, the central area of ​​the large surface side 1a is not bound by mechanical parts and does not need to be thinned. It has a larger expansion space during charging and discharging. By placing the first weak structure 231 away from the side edges 41 on both sides in the central area of ​​the large surface side 1a, the adverse effects caused by the large constraint force of the separator 203 required at the side edges 41 on the first weak structure 231 can be reduced. This improves the problem of damage caused by insufficient expansion force release in the central area of ​​the large surface side 1a, and improves the reliability and cycle life of the battery cell 20.

[0123] Furthermore, considering the internal spatial layout of the battery cell 20, the first weak structure 231 is set in the middle region of the large surface side 1a, which can meet the requirements of expansion force release without interfering with other structures of the battery cell 20 (such as tabs, thinning areas, etc.). In addition, the first weak structure 231 is set in the middle region of the large surface side 1a, which is relatively easy to implement in the production process and is conducive to improving production efficiency and product quality.

[0124] Combination Figure 10 and Figure 11 In some embodiments, the area of ​​the first weak structure 231 covering the first portion 223 of the single layer does not exceed 30%. When the area of ​​the first weak structure 231 covering the first portion 223 of the single layer does not exceed 30%, for example, the coverage area can be 20%, 25%, 30%, etc. This ensures that the outer separator 22 of the first portion 223 has relatively sufficient structural strength to maintain the constraint on the large surface side 1a, improves the uniformity of the force on the large surface side 1a, improves the flatness of the battery cell 20, and thus improves the performance of the battery cell 20. During the charging and discharging process of the battery, even if the electrode assembly 202 expands and generates stress, the first portion 223 without the first weak structure 231 can still provide sufficient constraint force, thereby reducing the possibility of the positive and negative electrode sheets becoming misaligned due to stress; at the same time, the area of ​​the first portion 223 where the first weak structure 231 is provided also achieves expansion force buffering, reducing problems such as electrode sheet compression damage, separator rupture, and internal short circuit caused by excessive stress accumulation, thereby improving the reliability of the battery cell 20.

[0125] Combination Figure 6 and Figure 12In some embodiments, the electrode assembly 202 includes a main body 4 and a tab 3. The tab 3 protrudes from the main body 4. The main body 4 is rectangular in its orthographic projection along the thickness direction F3 of the electrode assembly 202. One side of the rectangle in the width direction F2 is the facet side 1b of the electrode assembly 202. The portion of the outer diaphragm 22 covering the facet side 1b is the second portion 224. The weak structure 23 includes a second weak structure 232 disposed on at least one second portion 224. That is, the second weak structure 232 is provided on at least one layer of the second portion 224 on at least one side of the facet side 1b.

[0126] During charging and discharging, the electrode assembly 202 of the battery cell 20 expands, generating internal stress. By placing the second weak structure 232 on the smaller facet side 1b, the need for a weak structure 23 on the larger facet side 1a of the battery cell is reduced. This improves the uniformity of the constraint force exerted on the larger facet side 1a by the outer separator 22, enhancing the flatness of the battery cell 20 and thus improving its performance. Furthermore, the second weak structure 232 releases the expansion force on the smaller facet side 1b, reducing the possibility of stress accumulation leading to internal structural damage to the battery cell 20, such as misalignment of the positive and negative electrode plates, electrode compression damage, separator rupture, and internal short circuits, thereby improving the reliability of the battery cell 20.

[0127] Combination Figure 6 and Figure 12 In some embodiments, the orthographic projection of the electrode assembly 202 along the thickness direction F3 is a rectangle, and one side of the rectangle along the width direction F2 is the small facet side 1b of the electrode assembly 202. The width direction F2 of the rectangle is the direction of gravity, and a second weak structure 232 is provided on the second part 224 at the bottom of the electrode assembly 202. Thus, when the second weak structure 232 is in the form of penetrating the outer membrane 22, the electrolyte can penetrate and diffuse more quickly, and can more quickly and uniformly wet the positive and negative electrode materials and the membrane itself of the electrode assembly 202.

[0128] Specifically, since the width direction of the rectangle is the direction of gravity, and the second part 224 is located at the bottom of the electrode assembly 202, the electrolyte will wet the bottom of the electrode assembly 202 after being injected into the battery cell 20. When the second weak structure 232 is in the form of penetrating the outer separator 22, the second weak structure 232 set at the bottom provides a penetration channel for the electrolyte, allowing the electrolyte to enter the interior of the electrode assembly 202 more quickly and uniformly wet the positive and negative electrode materials and the separator itself, shortening the time required for the electrolyte to wet the electrode assembly 202 and improving the injection efficiency in the battery production process. The rapid and uniform electrolyte wetting makes the movement of charged ions between the positive and negative electrodes smoother, reduces the internal resistance of the battery cell 20, and improves the charging and discharging efficiency of the battery cell 20.

[0129] For example, the outer separator 22 terminates at the bottom of the electrode assembly 202. Under the influence of gravity, the termination of the outer separator 22 is less likely to be affected by expansion forces, causing it to shift to the large surface side 1a of the battery cell, thus improving the reliability of the battery cell 20. Alternatively, for example, when an adhesive application area 225 is provided at the termination position, and the weak structure 23 needs to be arranged to avoid the adhesive application area 225, terminating the outer separator 22 at the side of the battery cell 20 allows for the arrangement of more second weak structures 232 at the bottom of the battery cell 20.

[0130] In some embodiments, the second weak structure 232 covers 30%-80% of the area of ​​the second portion 224 of the single layer. For example, the coverage area can be 30%, 40%, 50%, 60%, 70%, 80%, etc. This facilitates both the full release of expansion force and the provision of sufficient permeation channels for the electrolyte. Within this coverage range, the electrolyte can penetrate the second portion 224 and enter the interior of the electrode assembly 202, significantly shortening the time required for the electrolyte to wet the electrode assembly 202 and improving the electrolyte injection efficiency during battery production. At the same time, retaining a certain proportion of the complete structure (i.e., the portion not covered by the second weak structure 232) ensures that the second portion 224 has a certain structural strength.

[0131] refer to Figure 10 In some embodiments, the outer diaphragm 22 includes an adhesive application area 225, and the weak structure 23 is arranged to avoid the adhesive application area 225. The adhesive application area 225 can be an area for attaching tape or an area with adhesive backing, used for finishing and fixing the outer diaphragm 22.

[0132] For example, the adhesive can be an adhesive coating. In this case, the adhesive area 225 is located on the side of the outer diaphragm 22 near the electrode assembly 202. The adhesive coating is applied to the end section of the outer diaphragm 22. When the end is fixed, the adhesive coating is adhered between the two outer diaphragms 22.

[0133] For example, the adhesive can also be double-sided tape. In this case, the adhesive area 225 is located on the side of the outer diaphragm 22 that is close to the electrode assembly 202. The double-sided tape is pasted on the end section of the outer diaphragm 22. When the end is fixed, the double-sided tape is pasted between the two layers of the outer diaphragm 22.

[0134] For example, the adhesive can also be a single-sided adhesive, with the adhesive area 225 located on the side of the outer diaphragm 22 away from the electrode assembly 202. When fixing the end, the single-sided adhesive is pasted on the side of the two outer diaphragms 22 away from the electrode assembly 202.

[0135] The arrangement of the weak structure 23 to avoid the adhesive application area 225 ensures that the adhesive application area 225 does not cover the weak structure 23, thereby ensuring that the weak structure 23 can reliably play its role in releasing stress. Moreover, the arrangement of the weak structure 23 to avoid the adhesive application area 225 also ensures that the weak structure 23 will not affect the adhesion of the adhesive application area 225, thus ensuring that the outer diaphragm 22 is reliably fixed at the end.

[0136] refer to Figure 13 In some embodiments, the entire outer diaphragm 22 has a uniformly distributed weak structure 23.

[0137] For example, the entire outer diaphragm 22 is uniformly distributed with through holes 23a. When the through holes 23a are uniformly distributed, the through holes 23a on the adjacent layers of the outer diaphragm 22 can be arranged facing each other, thereby forming a direct channel for the electrolyte, which helps the electrolyte to wet. The through holes 23a on the adjacent layers of the outer diaphragm 22 can also be staggered, thereby reducing the risk of short circuits and facilitating processing.

[0138] During the use of the battery cell 20, the electrode assembly 202 expands and contracts due to factors such as charge-discharge cycles and temperature changes, thereby generating stress on the outer separator 22. The uniformly distributed weak structure 23 throughout the outer separator 22 can uniformly disperse stress, alleviate stress concentration, and reduce the risk of the outer separator 22 breaking due to excessive stress, thus improving the reliability of the battery cell 20. Moreover, the uniform distribution of weak structure 23 throughout the outer separator 22 helps to reduce the processing difficulty of the outer separator 22.

[0139] Furthermore, when the thin structure 23 is evenly distributed throughout the outer membrane 22, and the thin structure 23 penetrates the outer membrane 22, the electrolyte can enter the electrode assembly 202 from multiple directions. This reduces the possibility of local electrolyte accumulation or insufficient wetting, allowing the electrolyte to diffuse evenly in the electrode assembly 202 and improving the consistency of the battery cell 20's performance. Since the thin structure 23 allows the electrolyte to evenly wet the electrode assembly 202, it also helps to evenly distribute heat inside the electrode assembly 202, reducing the performance degradation and shortened lifespan of the battery cell 20 caused by uneven temperature.

[0140] refer to Figure 5In some embodiments, the electrode assembly 202 is in the form of a stack, with the first electrode 11 and the second electrode 12 alternately stacked along the thickness direction F3 of the electrode assembly 202. Due to their structural characteristics, stacked battery cells are more prone to problems such as electrode displacement during production or use. By providing an outer separator 22 that surrounds the electrode assembly 202 at least once, and having a weak structure 23 on the outer separator 22, it can both constrain the electrode assembly 202 and release expansion force, reducing problems caused by electrode displacement, and mitigating failures such as electrode compression damage, active material peeling, separator rupture, and internal short circuits caused by the expansion of the electrode assembly 202, thereby improving the stability and reliability of the battery cell 20.

[0141] Of course, when the electrode assembly 202 is in a wound form, that is, when the positive electrode, negative electrode and separator are stacked and wound, by setting the outer separator 22 to surround the electrode assembly 202 at least once, and the outer separator 22 is provided with a weak structure 23, it can also play the role of constraining the electrode assembly 202 and releasing the expansion force, reducing the problems caused by electrode displacement, reducing the failure problems such as electrode extrusion damage, active material peeling, separator rupture, and internal short circuit caused by the expansion of the electrode assembly 202, and improving the stability and reliability of the battery cell 20.

[0142] refer to Figure 13 In some embodiments, the battery cell 20 includes a separator 203, which is a continuous separator and includes a spacer separator 21 and an outer separator 22. The spacer separator 21 includes a plurality of reciprocatingly folded sub-extensions 211, with adjacent sub-extensions 211 sandwiched between the two sides of the single-layer electrode 1 in the electrode assembly 1. Two adjacent electrode 1s are separated by the single-layer sub-extensions 211, that is, the spacer separator 21 is formed in a Z-shaped reciprocating folding form. This improves the reliability of the separation between the positive and negative electrode sheets and facilitates manufacturing. For example, the plurality of reciprocatingly folded sub-extensions 211 form a regular spacing structure. During the assembly of the electrode assembly 202, the positive electrode sheet, negative electrode sheet, and spacer separator 21 can be stacked in a predetermined manner, simplifying the assembly process and improving production efficiency. For example, when using an automated production line, the regular spacing structure makes it easier for robotic arms to accurately grasp and place the electrode, reducing manual intervention and lowering production costs.

[0143] For example, combined Figure 9 The outer diaphragm 22 is connected to one end of the spacer diaphragm 21 and surrounds the electrode assembly 202 at least once.

[0144] As described above, at this time, the innermost layer 221 of the outer diaphragm 22 can be defined by a continuous diaphragm (e.g., refer to...). Figure 9That is, the first loop of the outer diaphragm 22 around the electrode assembly 202 from the starting position (i.e., the position connected to the spacer diaphragm 21) is the innermost layer 221.

[0145] Or, for example, in combination Figure 10 The outer diaphragm 22 includes a first outer portion 22a and a second outer portion 22b. The first outer portion 22a and the second outer portion 22b are respectively connected to both ends of the spacer diaphragm 21. The two side surfaces of the electrode assembly 202 in the thickness direction F3 are the first surface S1 and the second surface S2, respectively. The first outer portion 221 is connected to the end of the spacer diaphragm 21 near the first surface S1 and covers the first surface S1. The second outer portion 22b is connected to the end of the spacer diaphragm 21 near the second surface S2 and surrounds the electrode assembly 202 at least once. The first outer portion 22a is covered inside the second outer portion 22b. The first outer portion 22a and the second outer portion 22b together define the innermost layer 221 of the outer diaphragm 22.

[0146] As described above, at this time, the innermost layer 221 of the outer diaphragm 22 can be formed by splicing discontinuous diaphragms (e.g., see reference). Figure 10 That is, the portion covering the first outer portion 22a is removed from the first circle around the electrode assembly 202 starting from the starting position (i.e., the position connected to the spacer diaphragm 21) and together with the first outer portion 22a, forms the innermost layer 221.

[0147] In the above technical solution, the outer diaphragm 22 is easy to wrap flexibly and is easy to process and set.

[0148] According to some embodiments of this application, this application also provides a battery device 100, which includes a battery cell 20 of any embodiment.

[0149] According to the battery device 100 provided in the embodiments of this application, by setting the battery cell 20 in any embodiment, the possibility of problems such as electrode extrusion damage, electrode displacement, and separator rupture is reduced, thereby improving the structural stability and reliability of the battery device 100 during production and use.

[0150] According to some embodiments of this application, this application also provides an energy storage device 1000, which includes a plurality of battery cells 20 of any kind, the battery cells 20 being used to store or provide electrical energy; or the energy storage device 1000 includes a plurality of battery devices 100 of any kind, the battery devices 100 being used to store or provide electrical energy.

[0151] The energy storage device 1000 provided in the embodiments of this application improves the structural stability and reliability of the energy storage device 1000.

[0152] According to some embodiments of this application, this application also provides an electrical device. The electrical device includes a battery cell 20 of any of the above schemes, the battery cell 20 being used to store or provide electrical energy; or the electrical device includes a battery device 100 of any of the above schemes, the battery device 100 being used to store or provide electrical energy; or the electrical device includes an energy storage device 1000 of any of the above schemes, the energy storage device 1000 being used to store or provide electrical energy.

[0153] The electrical device provided according to the embodiments of this application improves the structural stability and reliability of the electrical device.

[0154] The electrical device can be any of the aforementioned devices or systems that utilize battery devices.

[0155] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. For example, at least one of the first weak structure 231 and the second weak structure 232 can be a through hole 23a; as another example, at least one of the first weak structure 231 and the second weak structure 232 can be a crack 23b; for example, the weak structure 23 can simultaneously include a through hole 23a and a crack 23b. For example, the outer diaphragm 22 can have weak structures 23 on both the large surface side 1a and the small surface side 1b; as another example, the outer diaphragm 22 can have weak structures 23 on both the innermost layer 221 and the remaining layers 222.

[0156] The following describes a specific embodiment of a battery cell 20 according to this application, wherein the battery cell 20 is a high-silicon system.

[0157] The battery cell 20 includes an electrode assembly 202 and a separator 203. The separator 203 includes a continuously arranged spacer separator 21 and an outer separator 22. The electrode assembly 202 includes a first electrode 11 and a second electrode 12 with opposite polarities, and a spacer separator 21. The electrode assembly 202 is in the form of a stack. The first electrode 11 and the second electrode 12 are alternately stacked along the thickness direction F3 of the electrode assembly 202. The spacer separator 21 is spaced between the first electrode 11 and the second electrode 12. The outer separator 22 surrounds the electrode assembly 202 at least once. The spacer separator 21 extends in a Z-shape to include a plurality of reciprocating sub-extensions 211. Adjacent sub-extensions 211 are sandwiched on both sides of the single-layer electrode 1 in the electrode assembly 202. Two adjacent electrodes 1 in the electrode assembly 202 are separated by single-layer sub-extensions 211. The outer separator 22 has a weak structure 23, which is in the form of a through hole 23a or a crack 23b.

[0158] In the above embodiments, by providing a weak structure 23 on the outer diaphragm 22, when the expansion coefficient reaches the set gap boundary, the weak structure 23 can release the expansion force, reduce the compression of the electrode assembly 202 in the outer diaphragm 22, and improve the failure problems such as electrode extrusion damage, active material peeling, diaphragm rupture, and internal short circuit caused by expansion.

[0159] Of course, the battery cell 20 in this embodiment may not be a high-silicon system.

[0160] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized by, include: An electrode assembly, the electrode assembly including an electrode sheet and a spacer membrane, the electrode sheet including a first electrode sheet and a second electrode sheet with opposite polarities, the spacer membrane separating the first electrode sheet and the second electrode sheet, the electrode sheet forming the outer peripheral surface of the electrode assembly; An outer diaphragm is provided, which covers the outer periphery of the electrode assembly and has a thin structure.

2. The battery cell of claim 1, wherein, The weak structure penetrates the outer diaphragm along its thickness direction.

3. The battery cell of claim 2, wherein, The weak structure includes through holes.

4. The battery cell of claim 3, wherein, There are multiple through holes, the diameter of each through hole is less than or equal to 2.5 mm, and the center-to-center distance between adjacent through holes is greater than or equal to twice the diameter of the through hole.

5. The battery cell of claim 2, wherein, The weak structure includes cracks.

6. The battery cell of claim 5, wherein, The crack includes multidirectional cracks, which include multiple intersecting strip-shaped marks.

7. The battery cell of claim 6, wherein, There are multiple multidirectional cracks, the smallest circumscribed circle diameter of each multidirectional crack is less than or equal to 2.5 mm, and the center-to-center distance between adjacent multidirectional cracks is greater than or equal to 5 mm.

8. The battery cell according to any one of claims 1-7, characterized in that, The outer diaphragm covers at least one layer of the electrode assembly, and at least a portion of the weak structure is located in the innermost layer of the outer diaphragm.

9. The battery cell of any one of claims 1-7, wherein, The outer diaphragm covers the electrode assembly in more than one layer. The outer diaphragm includes an innermost layer and other layers covering the innermost layer. The weak structure is located in the other layers.

10. The battery cell of claim 1, wherein, Both sides of the electrode assembly in the thickness direction are large surface sides, the portion of the outer diaphragm covering the large surface sides is the first part, and the weak structure includes a first weak structure disposed on at least one of the first parts.

11. The battery cell of claim 10, wherein, The electrode assembly includes a main body and tabs. The two sides of the main body in a first direction are side edges. The tabs are disposed on both sides of the main body in the first direction and protrude from the side edges. The first direction is perpendicular to the thickness direction of the electrode assembly. The distance between the first weak structure and the side edges along the first direction is greater than 1 / 4 of the distance between the two side edges along the first direction.

12. The battery cell according to claim 10 or 11, characterized in that The area of ​​the first weak structure covering the first portion of the single layer does not exceed 30%.

13. The battery cell of claim 1, wherein, The electrode assembly includes a main body and a tab, the tab protruding from the main body. The orthographic projection of the main body along the thickness direction of the electrode assembly is rectangular. One side of the rectangle in the width direction is the small facet side of the electrode assembly. The portion of the outer diaphragm covering the small facet side is a second part. The weak structure includes a second weak structure disposed on at least one of the second parts.

14. The battery cell of claim 13, wherein, The width direction of the rectangle is the direction of gravity, and the second part located at the bottom of the electrode assembly has the second weak structure.

15. The battery cell according to claim 13 or 14, characterized in that, The second weak structure covers 30%-80% of the area of ​​the second part of the single layer.

16. The battery cell of claim 1, wherein, The outer diaphragm includes an adhesive application area, and the weak structure is arranged to avoid the adhesive application area.

17. The battery cell of any one of claims 1-7, wherein, The entire outer diaphragm is uniformly distributed with the weak structure.

18. The battery cell of claim 1, wherein, The electrode assembly is in the form of a stack, with the first electrode and the second electrode alternately stacked along the thickness direction of the electrode assembly.

19. The battery cell of claim 18, wherein, The battery cell includes a separator, which is a continuous separator and includes the spacer separator and the outer separator. The spacer separator includes a plurality of sub-extensions that extend back and forth. Adjacent sub-extensions are sandwiched on both sides of a single-layer electrode in the electrode assembly, and two adjacent electrodes are separated by the single-layer sub-extensions.

20. The battery cell of claim 19, wherein, The outer diaphragm is connected to one end of the spacer diaphragm and surrounds the electrode assembly at least once; or, the outer diaphragm includes a first outer portion and a second outer portion, the first outer portion and the second outer portion being connected to both ends of the spacer diaphragm respectively, the two side surfaces of the electrode assembly in the thickness direction being a first surface and a second surface respectively, the first outer portion being connected to the end of the spacer diaphragm near the first surface and covering the first surface, the second outer portion being connected to the end of the spacer diaphragm near the second surface and surrounding the electrode assembly at least once, the first outer portion being covered within the second outer portion, and the first outer portion and the second outer portion together defining the innermost layer of the outer diaphragm.

21. A battery device, characterized in that, include: Multiple battery cells according to any one of claims 1-20.

22. An electrical device, comprising: include: The battery cell as described in any one of claims 1-20 or the battery device as described in claim 21.

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