Battery cell and preparation method therefor, battery device, electric device, energy storage device and energy storage system

Abstract

Provided in the present application are a battery cell and a preparation method therefor, a battery device, an electric device, an energy storage device and an energy storage system. The battery cell comprises: a casing, which comprises an opening and an accommodating cavity in communication with each other, the length L, thickness D and height H of the casing satisfying L>D and L>H, wherein 270mm≤L≤3000mm; an end cover covering the opening of the casing, the end cover comprising at least one explosion-proof valve, and the total area S of the at least one explosion-proof valve satisfying S≥1000mm2; and at least one electrode assembly arranged in the accommodating cavity, the electrode assembly comprising a main body portion and a tab portion, wherein the tab portion is connected to the main body portion and extends from the main body portion, and the tab portion comprises a positive tab and a negative tab, and the ratio of the tab length l of the positive tab and / or the negative tab to the length L of the casing satisfies a range of 0.08 to 0.16.

Description

Battery cells and their preparation methods, battery devices, electrical devices, energy storage devices and energy storage systems

[0001] Cross-references to related applications

[0002] This application claims priority to patent application PCT / CN2025 / 140517, filed on December 5, 2025; priority to patent application PCT / CN2025 / 140531, filed on December 5, 2025; priority to patent application PCT / CN2025 / 140529, filed on December 5, 2025; and priority to patent application PCT / CN2025 / 140531, filed on December 5, 2025. Priority is claimed to PCT / CN2025 / 140513, priority to patent application PCT / CN2025 / 140527 filed on December 5, 2025, priority to patent application PCT / CN2025 / 140521 filed on December 5, 2025, and priority to patent application PCT / CN2025 / 140521 filed on December 5, 2025 entitled "Battery Cell, Battery Device, Electrical Device, Energy Storage Device and Energy Storage System" filed on December 5, 2025. Priority to patent application 0532, priority to patent application PCT / CN2025 / 140522 filed on December 5, 2025, priority to patent application PCT / CN2025 / 140453 filed on December 5, 2025, priority to patent application PCT / CN2025 / 140528 filed on December 5, 2025, and priority to patent application PCT / C filed on December 5, 2025. Priority is claimed to N2025 / 140456, priority to patent application PCT / CN2025 / 140452 filed on December 5, 2025, priority to patent application PCT / CN2025 / 140362 filed on December 5, 2025, and priority to patent application PCT / CN2025 / 085921 filed on March 28, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, specifically to a battery cell and its preparation method, a battery device, an electrical device, an energy storage device, and an energy storage system. Background Technology

[0004] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric car toys, electric toy ships, electric toy airplanes, and power tools.

[0005] In the development of battery cells, how to balance the reliability and cycle life of battery cells is also an urgent problem to be solved. Summary of the Invention

[0006] This application provides a battery cell and its preparation method, a battery device, an electrical device, an energy storage device, and an energy storage system, which enable the battery cell to have high energy density, long cycle life, and long-term reliability.

[0007] In a first aspect, embodiments of this application provide a battery cell, comprising: a casing including an opening and a receiving cavity that are interconnected, wherein the length L, thickness D, and height H of the casing satisfy L > D, L > H, wherein 270mm ≤ L ≤ 3000mm; an end cap covering the opening of the casing, the end cap including at least one explosion-proof valve; the total area S of the at least one explosion-proof valve ≥ 1000mm². 2 At least one electrode assembly is disposed within a receiving cavity. The electrode assembly includes a main body and an electrode tab. The electrode tab is connected to the main body and extends out of the main body. The electrode tab includes a positive electrode tab and a negative electrode tab. The ratio of the length l of at least one of the positive electrode tab and the negative electrode tab to the length L of the housing satisfies 0.08 to 0.16.

[0008] In this embodiment, the casing length of the battery cell is within the above-mentioned range, which is suitable for high-capacity battery cells. The total area of ​​the explosion-proof valve is within the above-mentioned range, which is beneficial for discharging the gas generated inside the battery cell, controlling the gas discharge rate, reducing the risk of thermal runaway, and improving the reliability of the battery cell.

[0009] By controlling the ratio of the tab length l to the casing length L within the above range, the problem of uneven current density distribution in the battery cell is improved, thereby reducing internal temperature differences in the cell, reducing gas production, and lowering risks; enabling the battery cell to balance long-term cycle life and long-term reliability.

[0010] Furthermore, controlling the ratio of the tab length l to the shell length L within the above range is beneficial for controlling the internal resistance of the battery cell and improving the energy efficiency of the battery cell.

[0011] In some embodiments, the length l of at least one of the positive and negative electrode tabs is ≥25mm, and can be selected as 30mm to 60mm. This is beneficial for controlling the internal resistance of the cell, giving the cell good energy efficiency; at the same time, it can effectively control the current distribution inside the cell, resulting in a higher degree of consistency of current and temperature inside the battery cell, and improving the reliability of the battery cell.

[0012] In some embodiments, in a cross-section perpendicular to the height of the housing, the length of the main body is W along the length direction of the housing; the distance between one of the positive and negative electrode tabs and the end of the main body cross-section is k1×W, and the distance between the other and the end of the same cross-section of the main body is k2×W, where k1 satisfies 0.15≤k1≤0.35, and k2 satisfies 0.65≤k2≤0.85; optionally, k1 is 0.25, and k2 is 0.75. Thus, the distance between the center point of the electrode tab and the center point of the electrode plate in the electrode assembly can be controlled within a suitable range, controlling the current path of the cell and giving the cell good energy efficiency; it also ensures a high degree of consistency in current and temperature within the battery cell, improving the reliability of the battery cell.

[0013] In some embodiments, the housing has a first surface perpendicular to the housing thickness direction, and the area S1 of the first surface is ≥ 56000 mm². 2 Optionally, the value of S1 can be in the range of 58000 mm. 2 ~62500mm 2 The area of ​​the first surface can improve the effective welding area, solve the problem of abnormal overcurrent temperature rise, make the internal temperature of the cell more uniform, and improve the reliability of the battery cell.

[0014] In some embodiments, the battery cell includes: electrode terminals disposed on an end cap; and tabs welded to the electrode terminals to form a solder mark with a cross-sectional area of ​​80 mm². 2 ~200mm 2 This increases the current-carrying area of ​​the battery cell, making the current distribution inside the cell more uniform and improving the reliability of the individual battery cells.

[0015] In some embodiments, the main body includes a positive electrode sheet, which includes a positive electrode active material; the chemical formula of the positive electrode active material is: Li x A y Me a M b P 1-c X c Y zWherein, A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F; 0≤x≤1.3, 0≤y≤1.3, 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5. This positive electrode active material has good electrochemical stability, which is beneficial for the balanced current distribution in the positive electrode sheet during battery cell operation. The addition of V within the above range can reduce the lithium-ion diffusion barrier and expand the volume of the diffusion channel; Ti 4+ Doping can alter the local energy levels of the crystal, significantly improving conductivity; it comprehensively improves the stability of the cathode structure, increases the lithium-ion diffusion rate and conductivity, improves the lithium insertion / extraction depth of the material, reduces electrode polarization, and enhances the capacity and cycle performance of the battery cell.

[0016] In some embodiments, the chemical formula of the positive electrode active material is Li x A y Me a M b P 1-c P c O z Wherein, A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; optionally, M includes one or more of Ti and V, where 0.005 ≤ b ≤ 0.20, or optionally 0.05 ≤ b ≤ 0.15. This is beneficial for improving the nominal capacity and cycle performance of the battery cell.

[0017] In some embodiments, the positive electrode sheet includes a positive active material layer, the compaction density of which is 1.5 g / cm³. 3 ~3.5g / cm 3 2.3g / cm³ is an option. 3 Up to 3.3 g / cm 3 ; a further option is 2.4 g / cm³. 3 Up to 3.0 g / cm 3 .

[0018] When the compaction density of the positive electrode active material layer is within the above range, it can take into account the capacity, energy density and cycle performance of the battery cell.

[0019] In some embodiments, perpendicular to the winding direction TD of the positive electrode sheet, the positive electrode active material layer includes a plurality of first regions, and the compaction density deviation of the plurality of first regions is less than or equal to 0.5 g / cm³. 3 This helps to improve the uniformity of the compaction density of the positive electrode active material layer in the TD direction, resulting in a more uniform current density distribution and improved cycle life and reliability of the battery cells.

[0020] In some embodiments, along the winding direction MD of the positive electrode sheet, the positive electrode active material layer includes a plurality of second regions, and the compaction density deviation of the plurality of second regions is less than or equal to 0.5 g / cm³. 3 This helps to improve the uniformity of the compaction density of the positive electrode active material layer in the MD direction, resulting in a more uniform current density distribution and improved cycle life and reliability of the battery cell.

[0021] In some embodiments, the nominal capacity Q of a single battery cell is 500Ah to 3000Ah, optionally 800Ah to 2000Ah, or optionally 1000Ah to 2000Ah. When the nominal capacity of a single battery cell is within the above range, the battery cell can effectively balance high energy density, long cycle life, and long-term reliability.

[0022] In some embodiments, the battery cell includes an electrolyte.

[0023] In some embodiments, the electrolyte includes dimethyl carbonate; optionally, based on the total mass of the electrolyte, the mass percentage of dimethyl carbonate is 3% to 50%, thereby effectively improving the energy conversion efficiency of the battery; it can also improve the deterioration of gas production caused by uneven current or temperature, and improve the reliability of the battery cell.

[0024] In some embodiments, the electrolyte includes vinylene carbonate; optionally, based on 100% of the total mass of the electrolyte, the mass percentage of vinylene carbonate is 1% to 7%. Vinylene carbonate participates in the formation of a solid electrolyte membrane, which can improve the side reactions between the components in the electrolyte and the negative electrode, reduce gas production, improve the heat generation of the cell, thereby further reducing gas production and improving the reliability of the battery cell.

[0025] In some embodiments, the electrolyte includes hexafluorophosphate ions and difluorosulfonyl imide ions; optionally, based on 100% of the total mass of the electrolyte, the mass percentage of difluorosulfonyl imide ions is 0.25% to 10%; optionally, based on 100% of the total mass of the electrolyte, the mass percentage of hexafluorophosphate ions is 0.25% to 8%.

[0026] During the electrochemical cycling process of a battery cell, hexafluorophosphate ions can improve the cycle performance of the battery cell, while difluorosulfonyl imide ions can reduce the amount of HF generated and control the amount of gas produced. Difluorosulfonyl imide ions can also improve side reactions and reduce the amount of gas produced, thereby improving the reliability of the battery cell.

[0027] In some embodiments, the main body includes a positive electrode sheet, which includes a CEI film on the surface of the positive electrode active material. The CEI film includes Si and B elements. Thus, the B element can significantly improve the capacity retention rate of the battery cell during high-voltage cycling, while also improving coulombic efficiency and increasing the discharge capacity of the battery cell; the Si element can give the battery cell higher nominal capacity, energy density, and cycle life.

[0028] In some embodiments, the main body includes a negative electrode sheet, which includes a solid electrolyte membrane located on the surface of the negative electrode active material. The solid electrolyte membrane includes one or more elements selected from F, Si, P, and C. This improves gas generation, enhances the thermal stability of the battery, and increases the reliability of the individual battery cells.

[0029] In some embodiments, a single battery cell satisfies: V T -V J -V S -V D = k × Q; k represents a coefficient, the unit of k is Ah / ml, k is 2.5 to 4.5, Q represents the nominal capacity of the battery cell 7, the unit of Q is Ah;

[0030] V S This refers to the volume of the mechanical components inside a battery cell, excluding the electrode assembly, when the battery cell is fully discharged.

[0031] V D V represents the volume of electrolyte inside a battery cell when it is fully discharged; T This indicates the volume of the cavity containing a single battery cell when it is fully discharged.

[0032] V J This indicates the total volume of at least one electrode assembly when the battery cell is fully discharged.

[0033] This effectively controls the remaining volume of the internal cavity of the battery cell, improving the cycle life and reliability of the battery cell.

[0034] In some embodiments, the battery cell satisfies: 2% ≤ (S0-S1) / S0 < 25%;

[0035] S0 represents the area of ​​the cavity in a cross-section perpendicular to the height of the casing when the battery cell is fully discharged.

[0036] S1 represents the total area of ​​at least one electrode assembly when the battery cell is fully discharged. Therefore, there is a certain space between the electrode assembly and the casing. This space can be used to store some free electrolyte and also to provide space for subsequent gas generation by the electrode assembly.

[0037] In some embodiments, the total area of ​​at least one explosion-proof valve is 1100 mm². 2 ~1500mm 2 This design ensures the end cap has good mechanical strength while allowing gas to escape promptly in the event of thermal runaway in a battery cell, controlling the venting rate and further improving the reliability of the battery cell.

[0038] In some embodiments, the total area S of the explosion-proof valve in the projection along the height direction of the housing accounts for 5% to 15% of the projected area of ​​the end cap. This is beneficial for balancing mechanical strength and venting rate, ensuring good reliability for the battery cell.

[0039] In some embodiments, the thickness difference between the edges of the housing and the end cap is ≤0.04mm; thereby, the welding uniformity can be effectively controlled, the weld has a certain welding strength, and the connection between the housing and the end cap has good tightness when the exhaust pressure and exhaust gas flow rate are large.

[0040] In some embodiments, the housing satisfies: 60mm≤D≤100mm; thereby, it is beneficial to increase the size of the battery cell and improve the nominal capacity of the battery cell.

[0041] In some embodiments, the casing satisfies the following condition: 200mm ≤ H ≤ 300mm. This facilitates the increase in the size of the battery cell and the increase in its nominal capacity.

[0042] Secondly, embodiments of this application provide a method for preparing a single battery cell, comprising the following steps:

[0043] The system provides a housing, end caps, and at least one electrode assembly. The housing includes interconnected openings and receiving cavities. The length L, thickness D, and height H of the housing satisfy L > D, L > H, and 270 mm ≤ L ≤ 2000 mm. The end caps are provided with at least one explosion-proof valve. The total area S of the at least one explosion-proof valve is ≥ 1000 mm². 2 The electrode assembly includes a main body and a tab, the tab being connected to and extending out of the main body, and the tab including a positive tab and a negative tab.

[0044] At least one electrode assembly is disposed within the housing through an opening;

[0045] Electrolyte is injected into the casing and end caps are assembled to the opening to seal the casing, thereby obtaining a battery cell. The ratio of the length l of the positive electrode tab and / or the negative electrode tab to the length L of the casing satisfies 0.08 to 0.16.

[0046] In this embodiment, the casing length of the battery cell is within the above-mentioned range, which is suitable for battery cells with high nominal capacity systems. The total area of ​​the explosion-proof valve is within the above-mentioned range, which is beneficial for the discharge of gas generated in the battery cell with high nominal capacity system, controls the gas discharge rate, reduces the risk of thermal runaway, and improves the reliability of the battery cell.

[0047] Controlling the ratio of the length l of the electrode tab to the length L of the casing within the above range is beneficial for controlling the internal resistance of the cell and improving the energy efficiency of the cell; it also helps to improve the uneven distribution of current density in the battery cell, thereby improving the internal temperature difference of the cell, thus improving gas production and reducing risks; and it enables the battery cell to balance long-term cycle life and long-term reliability.

[0048] In some embodiments, the electrolyte includes lithium salt, additives, and organic solvents.

[0049] In some embodiments, the lithium salt includes lithium bis(fluorosulfonyl)imide; optionally, the electrolyte also includes lithium hexafluorophosphate.

[0050] In some embodiments, the mass percentage of lithium bis(fluorosulfonyl)imide is 0.25% to 10% based on 100% of the total mass of the electrolyte; optionally, the mass percentage of lithium hexafluorophosphate is 0.25% to 8% based on 100% of the total mass of the electrolyte. During the electrochemical cycling of the battery cell, lithium hexafluorophosphate can improve the cycle performance of the battery cell, lithium bis(fluorosulfonyl)imide can reduce the amount of HF generated and control the amount of gas produced; the bis(fluorosulfonyl)imide ion can improve side reactions and improve the amount of gas produced, thereby improving the reliability of the battery cell.

[0051] In some embodiments, the additive includes trimethylfluorosilane; optionally, the mass percentage of trimethylfluorosilane is 0.03% to 0.5% based on 100% of the total mass of the electrolyte; thereby, gas generation can be improved, the thermal stability of the battery can be improved, and the reliability of the battery cell can be increased.

[0052] In some embodiments, the additive includes tris(trimethylsilyl)phosphite; optionally, the mass percentage of tris(trimethylsilyl)phosphite is 0.03% to 0.5% based on 100% of the total mass of the electrolyte. This can improve gas generation, enhance the thermal stability of the battery, and increase the reliability of the battery cells.

[0053] In some embodiments, the additive includes tris(trimethylsilyl)borate; optionally, the mass percentage of tris(trimethylsilyl)borate is 0.03% to 0.5% based on 100% of the total mass of the electrolyte. Thus, element B can significantly improve the capacity retention of the battery cell during high-voltage cycling, while also improving coulombic efficiency and increasing the discharge capacity of the battery cell; element Si can enable the battery cell to possess both high capacity, energy density, and cycle life.

[0054] In some embodiments, the organic solvent includes dimethyl carbonate and vinylene carbonate; optionally, the mass ratio of dimethyl carbonate to vinylene carbonate is 1:(0.2-0.6). This is beneficial for further reducing gas production and improving the reliability of the battery cell.

[0055] In some embodiments, the main body includes a positive electrode sheet, which includes a positive active material layer with a porosity of 2.8% to 30.6%. A porosity within this range is beneficial for improving the current distribution of the positive electrode sheet and mitigating gas generation problems caused by localized overcharging / over-discharging. It can also improve localized electrolyte decomposition and side reaction gas generation problems, thereby reducing gas generation and enabling the battery cell to achieve both high energy density and good reliability.

[0056] In some embodiments, the main body includes a negative electrode sheet with a porosity of 10.1% to 37.8%. A porosity within this range for the negative electrode active material layer is beneficial for improving the current distribution of the positive electrode sheet and mitigating gas generation problems caused by localized overcharging / over-discharging. It can also improve localized electrolyte decomposition and side reaction gas generation problems, enabling the battery cell to achieve both high energy density and good reliability.

[0057] In some embodiments, the negative electrode sheet includes a negative electrode active material layer, which includes graphite, and the compaction density of the negative electrode active material layer is 1.0 g / cm³. 3 ~2.0g / cm 3 This helps improve gas production, enabling battery cells to achieve both high energy density and good reliability.

[0058] Thirdly, this application proposes a battery device that includes a plurality of battery cells according to any embodiment of the first aspect of this application.

[0059] Fourthly, this application proposes an electrical device, which includes a battery device according to any embodiment of the second aspect of this application.

[0060] Fifthly, this application proposes an energy storage device, which includes the battery device of any example in the second aspect of this application.

[0061] Fifthly, this application proposes an energy storage system, which includes an energy storage device according to any embodiment of the fourth aspect of this application. Attached Figure Description

[0062] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0063] Figure 1 is a schematic diagram of the structure of an electrical device provided in some embodiments of this application;

[0064] Figure 2 is a schematic diagram of the structure of a battery pack provided in some embodiments of this application;

[0065] Figure 3 is a schematic diagram of the structure of a battery module provided in some embodiments of this application;

[0066] Figure 4 is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0067] Figure 5 is an exploded view of a battery cell provided in some embodiments of this application;

[0068] Figure 6 is a schematic diagram of the structure of the electrode assembly of a battery cell provided in some embodiments of this application;

[0069] Figure 7 is a schematic diagram showing the unfolded positive electrode sheet and positive electrode tab of a battery cell provided in some embodiments of this application;

[0070] Figure 8 shows a cross-sectional view of a battery cell along the height direction in some embodiments;

[0071] Figure 9 is a schematic diagram showing the unfolded positive electrode of a battery cell provided in some embodiments of this application;

[0072] Figure 10 is a schematic diagram showing the unfolded positive electrode of a battery cell provided in some embodiments of this application.

[0073] The accompanying drawings may not be drawn to scale.

[0074] The following is an explanation of the reference numerals in the accompanying drawings: X, thickness direction of the battery cell; Z, length direction of the battery cell; Y, height direction of the battery cell; 1, vehicle; 2, battery pack; 3, controller; 4, motor; 5, housing; 5a, first housing section; 5b, second housing section; 5c, storage space; 6, battery module; 7, battery cell; 10, electrode assembly; 101, main body section; 102, tab section; 1021, positive tab; 1022, negative tab; 11, positive electrode plate; 1111, first region; 1112, second region; 12, negative electrode plate; 13, separator; 20, outer casing; 21, housing; 22, end cap; 31, first electrode terminal; 32, second electrode terminal. Detailed Implementation

[0075] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the battery cell and its preparation method, battery device, power consumption device, energy storage device, and energy storage system of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0076] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, it is also expected that ranges of 60 to 110 and 80 to 120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise stated, the numerical range "a to b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 and 5" have been listed in this article; "0 to 5" is just a shortened representation of these numerical combinations. In addition, when a parameter is stated as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0077] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0078] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0079] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0080] Unless otherwise specified, in this application, the term "active ion" refers to ions that can be inserted and extracted back and forth between the positive and negative electrodes of a battery cell, including but not limited to lithium ions, sodium ions, etc.

[0081] In this application, "multiple" refers to two or more, including two. "Multiple types" refers to two or more, including two.

[0082] In this application, the battery cell may include lithium-ion secondary battery cell, lithium-ion primary battery cell, lithium-sulfur battery cell, sodium-ion secondary battery cell, sodium-ion primary battery cell, etc., and the embodiments of this application are not limited thereto. The battery cell may be flat, cuboid, or other shapes, and the embodiments of this application are not limited thereto.

[0083] The battery cells disclosed in this application can be used, but are not limited to, in electrical devices, energy storage devices, or energy storage systems such as vehicles, ships, or aircraft. Systems comprising the electrical devices or energy storage devices can be composed of the battery cells and batteries disclosed in this application, which is beneficial for improving the overall performance of equipment such as battery cells, electrical devices, battery devices, energy storage devices, and energy storage systems.

[0084] The energy storage system provided in this application can be any power system that requires energy storage devices. The energy storage system may include one or more energy storage devices and a power conversion system (PCS), with the power conversion system connecting the power generation equipment and the energy storage devices. The power generation equipment generates electrical energy, which can be stored in the energy storage device through the power conversion system. For example, the power generation equipment may specifically be a solar panel, hydroelectric power generation equipment, thermal power generation equipment, wind power generation equipment, etc.

[0085] 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, energy storage devices can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours.

[0086] In some implementations, the energy storage device is an energy storage container or an energy storage cabinet.

[0087] In some embodiments, the energy storage device may include a cabinet and one or more battery clusters housed within the cabinet. The battery clusters may include multiple battery units connected in series and / or in parallel via a busbar.

[0088] In some implementations, 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.

[0089] 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.

[0090] 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 a slave battery management unit (SBMU), a fusion switch, and other modules.

[0091] 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.

[0092] 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.

[0093] As an example, the power distribution unit can be used to distribute power to the power modules of the energy storage device.

[0094] Electrical devices can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of this application do not impose special limitations on the above-mentioned electrical devices.

[0095] Figure 1 is a schematic diagram of the structure of an electrical device provided in some embodiments of this application.

[0096] As shown in Figure 1, a battery device is installed inside the vehicle 1. The battery device can be located at the bottom, front, or rear of the vehicle 1. The battery device can be used to power the vehicle 1; for example, the battery device can serve as the operating power source for the vehicle 1.

[0097] Vehicle 1 may also include controller 3 and motor 4. Controller 3 is used to control the battery device to supply power to motor 4, for example, for the power needs of vehicle 1 during starting, navigation and driving.

[0098] In some embodiments of this application, the battery device can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0099] The battery device (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.

[0100] In some implementations, a battery cell assembly is typically formed by arranging multiple battery cells.

[0101] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0102] In some embodiments, the battery device may be a battery pack 2, for example, as shown in Figure 1, where the battery pack 2 is located inside the vehicle 1.

[0103] The battery pack 2 includes a housing and one or more battery cell assemblies, which are housed within the housing.

[0104] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0105] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0106] Figure 2 is a schematic diagram of the structure of a battery pack provided in some embodiments of this application.

[0107] As shown in Figure 2, the battery pack 2 includes a housing 5 and individual battery cells (not shown in Figure 2), with the individual battery cells housed within the housing 5.

[0108] The housing 5 is used to house individual battery cells, and the housing 5 can have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, which overlap each other, and together define a housing space 5c for housing the individual battery cells. The second housing portion 5b may be a hollow structure with an opening on one side, and the first housing portion 5a may be a plate-like structure, with the first housing portion 5a covering the opening side of the second housing portion 5b to form a housing 5 with the housing space 5c; alternatively, both the first housing portion 5a and the second housing portion 5b may be hollow structures with an opening on one side, with the opening side of the first housing portion 5a covering the opening side of the second housing portion 5b to form a housing 5 with the housing space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as cylinders, cuboids, etc.

[0109] To improve the sealing performance after the first housing part 5a and the second housing part 5b are connected, a sealing element, such as sealant or sealing ring, can also be provided between the first housing part 5a and the second housing part 5b.

[0110] Assuming that the first box section 5a covers the top of the second box section 5b, the first box section 5a can also be called the upper box cover, and the second box section 5b can also be called the lower box.

[0111] In battery pack 2, there can be one or more battery cells. If there are multiple battery cells, they can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells are connected in both series and parallel configurations. Multiple battery cells can be directly connected in series, parallel, or in a mixed configuration and then housed in housing 5. Alternatively, multiple battery cells can first be connected in series, parallel, or in a mixed configuration to form battery module 6, and then multiple battery modules 6 can be connected in series, parallel, or in a mixed configuration to form a whole and housed in housing 5.

[0112] A single battery cell can be the smallest unit that makes up a battery device.

[0113] Figure 3 is a schematic diagram of the structure of a battery module provided in some embodiments of this application.

[0114] In some embodiments, as shown in Figure 3, there are multiple battery cells 7. These multiple battery cells 7 are first connected in series, parallel, or in a mixed manner to form a battery module 6. The multiple battery modules 6 are then connected in series, parallel, or in a mixed manner to form a whole, which is housed in a casing.

[0115] Multiple battery cells 7 in battery module 6 can be electrically connected through a busbar to achieve parallel, series, or mixed connection of multiple battery cells 7 in battery module 6. There can be one or more busbars, each used to electrically connect at least two battery cells 7.

[0116] In recent years, with the rapid development of energy storage systems, the demand for large-capacity, high-cycle-life battery cells has been increasing. Especially in large-cell applications, the nominal capacity of batteries is typically high, such as exceeding 500Ah, and increasing cell size, particularly in the length direction, has become a common design trend to improve energy density. Furthermore, with the development of energy storage system technology, the reliability requirements for battery cells in energy storage systems are constantly increasing.

[0117] During the use of a battery cell, the organic solvents in the electrolyte are prone to reaction, leading to gas production. At higher battery system temperatures, the internal gas pressure increases, and the generated gas may rupture the end cap. When the gas ruptures the end cap, it rubs against the edge of the end cap, generating sparks, which can lead to a violent explosion in severe cases. Current methods to prevent battery explosions typically involve installing an explosion-proof valve on the end cap. When the internal gas pressure reaches the valve's burst pressure, the valve's rupture disc breaks, allowing the gas to escape from the valve opening. This reduces the risk of the battery cell exploding due to gas expansion. Properly sized explosion-proof valves ensure that the end cap maintains good mechanical strength while allowing for timely gas release, thus improving the reliability of the battery cell.

[0118] In large-capacity battery cells, the larger the capacity, the more significant the side reactions, further exacerbating gas production.

[0119] Research has revealed that issues with gas generation and venting in individual battery cells, as well as the use of larger or longer cells, can lead to uneven current distribution and interfacial reactions, resulting in inconsistent heat generation and temperature variations. This non-uniformity not only disrupts the overall consistency of the cell but also exacerbates gas generation under abnormal conditions such as overcharging, short circuits, or thermal runaway. Furthermore, localized anomalies in current or temperature distribution can induce lithium plating, further leading to internal short circuits and creating a vicious cycle of heat generation and gas generation, severely impacting the reliability of individual battery cells.

[0120] Further research revealed that if the ratio of the tab length to the casing length is not coordinated in larger battery cells, it may lead to insufficient current-carrying area, exacerbating localized heating and gas generation. Therefore, adjusting the tab length and other parameters to improve current distribution can link the cell's chemical gas generation mechanism with its physical structure and the venting capacity of the explosion-proof valve, addressing the issue of insufficient venting efficiency even during peak gas generation under abnormal conditions.

[0121] In view of the above problems, this application proposes a battery cell with a length within a suitable range to be adapted to high-capacity battery cell systems. An explosion-proof valve of appropriate area is provided on the end cap to solve the problem of venting efficiency. At least one electrode assembly is provided in the housing cavity, and the ratio of the length l of the positive electrode tab and / or negative electrode tab in the electrode assembly to the length L of the shell is controlled to be appropriate to improve gas production. This enables the battery cell to achieve both good energy density and good reliability.

[0122] Figure 4 is a structural schematic diagram of a battery cell provided in some embodiments of this application, and Figure 5 is an exploded schematic diagram of a battery cell provided in some embodiments of this application.

[0123] As shown in Figures 4 and 5, in some embodiments, the battery cell 7 includes a housing 20, at least one electrode assembly 10, and an electrolyte. The housing 20 includes a casing 21 and an end cap 22. The casing 21 includes a receiving cavity 210 with an opening, and the end cap 22 covers the opening. The electrode assembly 10 and the electrolyte are disposed within the receiving cavity 210.

[0124] The housing 21 can have various shapes, such as a cuboid. The shape of the housing 21 can be determined according to the specific shape of the electrode assembly 10. If the electrode assembly 10 is a cuboid structure, the housing 21 can also be a cuboid structure. Optionally, the electrode assembly 10 is a cuboid structure.

[0125] In some embodiments, the length L, thickness D, and height H of the housing 21 satisfy L > D, L > H, where 270 mm ≤ L ≤ 3000 mm. Optionally, the length L of the housing 21 can be 270 mm, 280 mm, 290 mm, 300 mm, 310 mm, 320 mm, 330 mm, 340 mm, 350 mm, 360 mm, 370 mm, 380 mm, 390 mm, 400 mm, or a range of any two of the above values. The length L shown in Figure 4 represents the length of the outer casing 20 along the length direction Z of the battery cell.

[0126] Therefore, the casing 21 with the above-mentioned length can be adapted to the battery cell 7 of the high-capacity system, and is also conducive to improving the total capacity and energy density of the battery cell 7.

[0127] In some embodiments, the housing 21 satisfies: 60mm ≤ D ≤ 100mm; optionally, the thickness D of the housing 21 can be 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, or 100mm.

[0128] The thickness of the battery cell 7 can be any value or a range thereof; for example, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, or any two of the above values. A thickness within the above range is beneficial for increasing the capacity of the battery cell 7. In Figure 4, D represents the length of the casing 20 along the thickness direction X of the battery cell.

[0129] In some embodiments, the housing 21 satisfies: 200mm ≤ H ≤ 300mm. Optionally, the height H of the housing 21 can be any value or a range of combinations thereof from 200mm, 210mm, 220mm, 230mm, 240mm, 250mm, 260mm, 270mm, 280mm, 290mm, and 300mm; thereby, it is advantageous to increase the size of the battery cell 7 and increase the capacity of the battery cell 7. In Figure 4, H represents the length of the housing 20 along the height direction Y of the battery cell.

[0130] In some embodiments, the housing 21 has a first surface perpendicular to the thickness direction of the housing 21, and the area S1 of the first surface is ≥ 56000 mm². 2 Optionally, the value of S1 can be in the range of 58000 mm. 2 ~62500mm 2 Optionally, the area of ​​the first surface can be 56000 mm². 2 58000mm 2 59000mm 2 60000mm 2 61000mm 2 62000mm2 62500mm 2 Any value in or a range thereof.

[0131] Understandably, the first surface is formed by the length L and height H of the battery cell 7. The area of ​​the first surface can improve the effective welding area, solve the problem of abnormal temperature rise caused by overcurrent, make the internal temperature of the cell more uniform, and improve the reliability of the battery cell 7.

[0132] The housing 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and this application does not impose any special limitations on this. Optionally, the inner wall of the housing 21 may also include an insulating element, which can exist in the form of a film layer, and the insulating layer can separate the housing 21 from the electrode assembly 10. The material of the insulating layer can be selected from materials commonly used in the art, and is not particularly limited here.

[0133] The end cap 22 closes onto the opening of the housing 21 to isolate the internal environment of the battery cell 7 from the external environment. The end cap 22 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiments of this application do not impose any special limitations on this.

[0134] In some embodiments, the end cap 22 includes at least one explosion-proof valve.

[0135] In some embodiments, the total area S of at least one explosion-proof valve is ≥ 1000 mm². 2 ; 1100~1500mm is optional 2 Optionally, the total area of ​​at least one explosion-proof valve can be 1100 mm². 2 1150mm 2 1200mm 2 1250mm 2 1300mm 2 1350mm 2 1400mm 2 1450mm 2 1500mm 2 Any value or range of its composition in the range; so that the end cap 22 has good mechanical strength, and the gas can be discharged in time when the battery cell 7 experiences thermal runaway, thereby controlling the exhaust rate and further improving the reliability of the battery cell 7.

[0136] In cases of abnormal conditions in battery cell 7, such as overcharging, short circuits, or thermal runaway, more gas is generated, potentially leading to localized lithium plating, irreversible capacity degradation, and other safety hazards. The explosion-proof valve is the last line of defense for the stable operation of battery cell 7. When abnormal gas generation occurs inside the cell, it opens to release excess gas, reducing the risk of cell malfunction. Therefore, appropriately sized explosion-proof valves can effectively improve the reliability of battery cell 7, especially reducing risks under abnormal conditions, in large-capacity cells.

[0137] In addition, it can effectively improve or solve the problem of battery gas generation caused by the long length of the casing 21.

[0138] In some embodiments, in the projection along the height direction of the housing 21, the total area S of the explosion-proof valve accounts for 5% to 15% of the projected area of ​​the end cover 22; optionally, the total area S of the explosion-proof valve accounts for any value or a range of combinations thereof from 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, and 15%.

[0139] In the projection along the height direction of the housing 21, the total area of ​​the explosion-proof valve is the area ratio relative to the projected area of ​​the end cover 22. This value can reflect the size of the area occupied by the explosion-proof valve of the battery cell 7, that is, the size of the area where the gas is discharged.

[0140] When the area ratio is too small, the capacity of the battery cell 7 is relatively large, resulting in a relatively increased amount of gas production; however, the total area of ​​the explosion-proof valve is too small, which increases the risk of the battery cell 7 bulging or even rupturing.

[0141] If the area ratio is too large, the capacity of the battery cell 7 will be relatively large, and the amount of gas produced will increase relatively. Setting the total area of ​​the explosion-proof valve too large may affect the airtightness of the battery cell 7, the mechanical strength of the end cover 22, and the setting of other components.

[0142] This area ratio is within an appropriate range, which can provide high capacity for the battery cell 7, and also provide a sufficiently large exhaust channel for gas generation within the system, thereby reducing the risk that the battery cell 7 will be affected by the exhaust speed.

[0143] This helps to balance mechanical strength and exhaust rate, ensuring good reliability for the battery cell 7.

[0144] In some embodiments, a gap exists between the housing 21 and the end cap 22 before welding them, with the gap having a range of <0.04 mm in either the length or width direction of the housing 21. This facilitates welding, improves welding strength, and enhances the airtightness of the battery cell 7.

[0145] In some embodiments, the thickness difference between the edges of the housing 21 and the end cap 22 is ≤0.04mm; for example, the thickness difference between the edges of the housing 21 and the end cap 22 can be 0.01mm, 0.02mm, 0.03mm, 0.04mm, etc.

[0146] Thickness range refers to the difference between the maximum and minimum thickness values ​​measured on the same batch of products in the measurement areas specified by the edges of the casing or end caps. It represents a dispersion statistic commonly used in manufacturing and measurement. A smaller range indicates stronger consistency in battery performance, which is beneficial to the performance of individual battery cells.

[0147] The thickness of the edges of the housing 21 and the end cap 22 can be measured using a micrometer. There can be multiple measurement positions, and multiple thickness values ​​can be measured. The thickness range of the edges of the housing 21 and the end cap 22 can be calculated separately.

[0148] Therefore, the uniformity of welding can be effectively controlled, the weld has a certain welding strength, and the connection between the shell 21 and the end cap 22 has good tightness when the exhaust pressure and exhaust gas flow rate are large.

[0149] In some embodiments, at the assembly point of the end cap 22 and the housing 21, the outer periphery of the end cap 22 is provided with an end cap 22 sealing portion, the cross-sectional profile of the end cap 22 sealing portion having a first arc segment with a radius of R1; the inner wall of the inner cavity of the housing 21 near the opening is provided with a housing 21 mating portion that mates with the end cap 22 sealing portion, the cross-sectional profile of the housing 21 mating portion having a second arc segment with a radius of R2; wherein, the end cap 22 sealing portion and the housing 21 mating portion achieve sealing by the mutual contact of the first arc segment and the second arc segment, and satisfy R1 <R2。

[0150] This facilitates the assembly and processing of the battery cell 7, and makes it easier to weld the end cap 22 and the housing 21, thereby enhancing the airtightness of the battery cell 7.

[0151] In some embodiments, the end cap 22 includes a cover plate body and a sealing edge extending downward from the cover plate body. Along the height direction of the battery cell 7, the sealing edge has a straight edge segment with a length of H1. The inner cavity of the housing 21 has a stepped portion near the opening that mates with the sealing edge. The stepped portion includes a supporting surface, and the depth of the supporting surface from the edge of the opening is H2. The length of the straight edge segment and the depth of the supporting surface from the edge of the opening satisfy: H1 ≤ H2. This enhances the airtightness of the battery cell 7 and improves its reliability.

[0152] Figure 6 is a schematic diagram of the electrode assembly of a battery cell provided in some embodiments of this application; Figure 7 is a schematic diagram of the unfolded positive electrode sheet and positive electrode tab of a battery cell provided in some embodiments of this application.

[0153] Figure 6 shows an electrode assembly 10 in a battery cell 7. The electrode assembly 10 includes a main body 101 and a tab 102. The tab 102 is connected to and extends out of the main body 101. The tab 102 includes a positive tab 1021 and a negative tab 1022. The main body 101 includes a positive electrode 11, a negative electrode 12, and a separator 13. The tab 102 can be located on either the positive electrode 11 or the negative electrode 12. The figure shows the position of the tab 102 within the main body 101. There can be multiple tabs 102. The tab 102 can include multiple positive tabs 1021 and multiple negative tabs 1022.

[0154] The main body 101 includes a positive electrode 11, a separator 13, and a negative electrode 12. The separator 13 is disposed between the positive electrode 11 and the negative electrode 12. During the charging and discharging process of the battery cell 7, active ions (e.g., lithium ions) repeatedly insert and extract between the positive and negative electrodes. Optionally, the electrode assembly 10 also includes the separator 13 disposed between the positive and negative electrodes. The separator 13 can reduce the risk of short circuit between the positive and negative electrodes while allowing active ions to pass through.

[0155] There may be one or more electrode assemblies 10 located within the housing 21. The electrode assembly 10 may be a stacked structure or a wound structure.

[0156] As shown in Figure 7, multiple positive electrode tabs 1021 can be provided in the positive electrode plate 11. l represents the length of the positive electrode tab 1021 after it is unfolded.

[0157] Referring to Figures 5 to 7, the ratio of the length l of at least one of the positive and negative electrode tabs to the length L of the housing satisfies 0.08 to 0.16. For example, the ratio of the length l of the positive electrode tab 1021 to the length L of the housing 21 satisfies 0.08 to 0.16.

[0158] In this embodiment, the length of the casing 21 of the battery cell 7 is within the above-mentioned range, which is suitable for high-capacity battery cells 7. The ratio of the length l of the electrode tab to the length L of the casing 21 is controlled within the above-mentioned range, which is beneficial to control the internal resistance of the cell and improve the energy efficiency of the cell. It also improves the uneven distribution of current density in the battery cell 7, thereby improving the internal temperature difference of the cell, thus improving gas production and reducing risks. This allows the battery cell 7 to take into account both long-term cycle life and long-term reliability.

[0159] For example, the ratio of the average length of the positive electrode tab 1021 to the length L of the housing 21 can be any value or a range of combinations thereof from 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, and 0.16.

[0160] The positive electrode tab 1021 can be either a bent structure or a non-bent structure. When the positive electrode tab 1021 is a bent structure, after unfolding and laying the positive electrode tab 1021 flat, the dimension of the positive electrode tab 1021 along its own length direction is measured, that is, the length of the positive electrode tab 1021.

[0161] If the l / L ratio is too small, the tab length l will be relatively short, which can lead to an increase in the internal resistance of the cell and a deterioration in the energy efficiency of the cell. If the tab length l is insufficient, it can lead to uneven current distribution inside the cell. Due to the increased internal resistance of the cell, its effect is more significant, further deteriorating the consistency of current and temperature of the battery cell 7 and reducing the reliability of the battery cell 7. In addition, insufficient tab length l also leads to insufficient solder area during welding, further deteriorating the imbalance of current and temperature inside the battery cell 7.

[0162] An excessively high l / L ratio and a relatively long tab length l can lead to uneven current distribution within the cell, further deteriorating the internal residual space and reducing the energy density of the battery cell 7. During the fabrication of the battery cell 7, the positive tab 1021 and negative tab 1022 are more prone to being folded and inserted upside down into the bare cell, resulting in wrinkles and folds, which can easily lead to short circuits, posing a risk of thermal runaway and affecting the processing and yield of the battery cell 7.

[0163] In addition, the length of the positive electrode tab 1021 is relatively suitable, the positive electrode tab 1021 is not easy to break, and the positive electrode tab 1021 is easy to assemble and connect, which improves the connection stability of the positive electrode tab 1021, makes the current distribution in each positive electrode tab 1021 uniform, and does not increase the current density of adjacent positive electrode tabs 1021.

[0164] In some embodiments, the ratio of the tab length l of the negative electrode tab 1022 to the length L of the housing 21 can also satisfy 0.08 to 0.16. Exemplarily, the ratio of the average length of the negative electrode tab 1022 to the length L of the housing 21 can be any value or a range of combinations thereof from 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, and 0.16.

[0165] In some embodiments, the tab length l of the positive electrode tab 1021 is ≥25mm, and can be selected from 30mm to 60mm; optionally, the length l can be any value or a range of combinations thereof from 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, and 60mm. This is beneficial for controlling the internal resistance of the cell, resulting in good energy efficiency; at the same time, it can effectively control the current distribution inside the cell, resulting in a higher degree of consistency of current and temperature inside the battery cell 7, thus improving the reliability of the battery cell 7.

[0166] The negative electrode tab 1022 and its tab length l are described with reference to the positive electrode tab 1021.

[0167] As an example, the tab length l of the negative electrode tab 1022 is ≥25mm, and can be selected from 30mm to 60mm; optionally, the length l can be any value or a range of combinations thereof from 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, and 60mm. This is beneficial for controlling the internal resistance of the cell, resulting in good energy efficiency; at the same time, it can effectively control the current distribution inside the cell, resulting in a higher degree of consistency of current and temperature within the battery cell 7, thus improving the reliability of the battery cell 7.

[0168] Please refer to Figure 5. The battery cell 7 includes: electrode terminals disposed on the end cover 22. The electrode terminals include a first electrode terminal 31, which is disposed on the end cover 22 and connected to the positive electrode tab 1021. The electrode terminals also include a second electrode terminal 32, which is disposed on the end cover 22 and connected to the negative electrode tab 1022.

[0169] In some embodiments, the tab is welded to the electrode terminal to form a solder mark, the cross-sectional area of ​​which is 80 mm². 2 ~200mm 2 Optionally, the cross-sectional area of ​​the solder mark can be 80 mm². 2 90mm 2 100mm 2 120mm 2 150mm 2 180mm 2 200mm 2 Any value or range of its composition in the range. This improves the current-carrying area of ​​the cell, resulting in a more uniform current distribution within the cell and enhancing the reliability of the battery cell 7.

[0170] Optionally, the electrode terminals may include a positive terminal and a negative terminal, both of which may be disposed on the end cap 22. The positive and negative terminals can be used to electrically connect with the electrode assembly 10 for outputting or inputting electrical energy to the battery cell 7.

[0171] In some embodiments, the battery cell 7 may also include a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of the battery cell 7 reaches a threshold. For example, when the amount of gas generated inside the cell accumulates to a certain level, the internal pressure becomes very high, and a valve can be opened to release the pressure.

[0172] Referring to Figure 6, in a cross-section perpendicular to the height of the housing 21, along the length of the housing 21, the length of the main body 101 is W; the distance between one of the positive electrode tabs 1021 and the negative electrode tab 1022 and one end of the cross-section of the main body 101 is k1×W, and the distance between the other and the end of the same cross-section of the main body 101 is k2×W, and k1 satisfies 0.15≤k1≤0.35, and the coefficient k1 can be any value or a range of combinations of 0.15, 0.20, 0.25, 0.30, 0.35; k2 satisfies 0.65≤k2≤0.85, and the coefficient k2 can be any value or a range of combinations of 0.65, 0.70, 0.75, 0.80, 0.85. Therefore, the distance between the center point of the tab and the center point of the electrode in the electrode assembly 10 can be controlled within a suitable range, the current path of the cell can be controlled, the cell can have good energy efficiency, and the consistency of current and temperature inside the battery cell 7 can be improved, thus enhancing the reliability of the battery cell 7.

[0173] In some embodiments, the nominal capacity Q of the battery cell 7 is 500Ah to 3000Ah, and can be selected as 800Ah to 2000Ah; or can be selected as 1000Ah to 2000Ah.

[0174] Optionally, the nominal capacity Q of the battery cell 7 can be any value or a range of combinations thereof from 500Ah, 600Ah, 650Ah, 700Ah, 800Ah, 900Ah, 1000Ah, 1200Ah, 1400Ah, 1600Ah, 1800Ah, 2000Ah, 2200Ah, 2400Ah, 2600Ah, 2800Ah, and 3000A.

[0175] The nominal capacity Q of the battery cell 7 is known in this application and can be tested using equipment and methods known in the art. For example, at 25°C and normal pressure, the battery cell 7 is charged to the upper limit of the charging voltage, such as 3.65V, at a power of 0.25P, left to stand for 10 minutes, and then discharged to the discharge cutoff voltage, such as 2.5V, at a power of 0.25P, left to stand for 10 minutes, and the above charging and discharging process is repeated 3 times.

[0176] The discharge capacity of the third discharge is recorded as the capacity C0 of battery cell 7, and the discharge voltage plateau V0 of battery cell 7 is also recorded. The volumetric energy density VED of battery cell 7 = capacity C0 of battery cell 7 * voltage plateau V0 / volume of battery cell 7; the volume of battery cell 7 = width of battery cell 7 * height of battery cell 7 * thickness of battery cell 7.

[0177] In this embodiment of the application, the nominal capacity of the battery cell 7 can be adjusted by adjusting any of the following parameters: the volume of the casing 21, the material of the positive electrode active material, the coating weight and compaction density of the positive electrode active material layer 111, the material of the negative electrode active material, and the coating weight and compaction density of the negative electrode active material layer 121.

[0178] For example, the larger the volume of the casing 21, the more active materials it can hold, and the higher the capacity of the battery cell 7.

[0179] For example, as the coating weight increases, the capacity of the battery cell 7 increases; as the compaction density increases, the capacity of the battery cell 7 also increases.

[0180] Figure 8 shows a cross-sectional view of the battery cell 7 along the height direction in some embodiments.

[0181] Please refer to Figure 8. The total area S1 of the electrode assembly 10 can be considered as the area enclosed by the outer electrode plates of the electrode assembly 10. The areas S0 and S1 are shown in Figure 8.

[0182] The battery cell 7 satisfies: 2% ≤ (S0-S1) / S0 < 25%; optionally, the area ratio of (S0-S1) / S0 can be any value or a range of combinations thereof from 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, and 25%.

[0183] S0 represents the area of ​​the cavity in the cross-section perpendicular to the height of the casing 21 when the battery cell 7 is fully discharged.

[0184] S1 indicates that the total area of ​​at least one electrode assembly 10 in the fully discharged state of the battery cell 7 is S1. Thus, a certain area is provided between the electrode assembly 10 and the housing 21, which can provide reserved space and exhaust channel for subsequent gas generation of the electrode assembly 10, which is beneficial to improving the reliability of the battery cell 7.

[0185] S0-S1 represents the cross-sectional area of ​​the receiving cavity 210 minus the total area of ​​all electrode assemblies 10 in the cross-section perpendicular to the height of the housing 21. This value can reflect the size of the space inside the battery cell 7 that is not occupied by the electrode assemblies 10, i.e. the size of the spare space.

[0186] (S T -SJ ) / S T Within an appropriate range, it can coordinate with the gas production within the system, reserve exhaust channels and storage space for the gas, reduce the risk of swelling of the battery cell 7, and improve the reliability of the battery cell 7.

[0187] In some embodiments, the battery cell 7 satisfies: V T -V J -V S -V D = k × Q; k represents a coefficient, the unit of k is Ah / ml, k is 2.5 to 4.5, Q represents the nominal capacity of the battery cell 7, the unit of Q is Ah;

[0188] Optionally, k can be any value or a range of combinations thereof from 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, and 4.5.

[0189] V S The volume displacement method can be used to determine the volume. Specifically, after discharging the battery cell 7 to a fully discharged state, the battery casing is removed and the electrode assembly 10 is taken out, leaving the mechanical parts inside the battery cell except for the electrode assembly. The mechanical parts are placed in a graduated cylinder or measuring cup, and the total volume of the mechanical parts is read by observing the change in liquid volume. This volume is V. S .

[0190] V D This indicates the volume of electrolyte inside battery cell 7 when it is fully discharged. The volume of electrolyte inside battery cell 7 can be determined by volume displacement method, by pouring the electrolyte into a graduated cylinder or measuring cup with precise markings.

[0191] V T This indicates the volume of the cavity containing the battery cell 7 when it is fully discharged; it can be determined by the volume replacement method or calculated directly.

[0192] V J This indicates the total volume of at least one electrode assembly 10 when the battery cell 7 is fully discharged.

[0193] It is understandable that: V T It can be represented as the product of S0 and the height of the receiving cavity 210. S0 represents the cross-section perpendicular to the height direction of the housing 21, and the area of ​​the receiving cavity 210. The height of the receiving cavity 210 can be understood as the internal height of the housing, which is the length along the height direction Y of the battery cell.

[0194] V JS1 can be represented as the product of the length of the electrode assembly 10 along the height Z direction, where S1 represents the cross-section perpendicular to the height direction of the housing 21, and the total area of ​​at least one electrode assembly 10.

[0195] The total volume of at least one electrode assembly 10 represents the sum of the volumes of all electrode assemblies 10 within the battery cell 7.

[0196] V T -V J -V S -V D It can characterize the volume of the spare space in the cavity 210 that is not occupied by the electrode assembly 10. This volume is within the above range. While providing high capacity, it ensures that the remaining space is not excessive. It can reduce the moisture content that may be introduced during the assembly process. It can also provide space for the volume expansion and / or gas generation of the electrode assembly 10, reduce the risk of the battery cell 7 bulging or even the casing 21 cracking, and improve the reliability of the battery cell 7 in the long-term cycle process.

[0197] Therefore, a certain amount of space can be reserved between the electrode assembly 10 and the housing 21. This space can be used to store part of the free electrolyte and can also provide reserved space for subsequent gas generation by the electrode assembly 10, effectively controlling the remaining volume of the internal cavity of the battery cell 7 and improving the cycle life and reliability of the battery cell 7.

[0198] In some embodiments, V T -V J -V S -V D 240cm 3 ~3000ccm 3 For example, V T -V J -V S -V D It can be 240cm 3 250cm 3 300cm 3 350cm 3 400cm 3 450cm 3 500cm 3 600cm 3 700cm 3 800cm 3 900cm 3 1000cm 3 and 3000cm 3 Or a range consisting of any two of the above values.

[0199] In this embodiment, the electrode assembly 10 can be a stacked structure or a wound structure. When the electrode assembly 10 is a wound structure, the electrode assembly 10 includes a flat region and a bent region. The higher the proportion of the bent region, the higher the amount of extra space inside the battery cell 7.

[0200] In some embodiments, there is at least one electrode assembly 10, which may be at least two or at least four. When there are at least two electrode assemblies 10, the at least two electrode assemblies 10 are stacked along the thickness direction X or the length direction Z of the battery cell 7.

[0201] [Positive electrode plate]

[0202] In some embodiments, the electrode assembly 10 includes a main body 101, which includes a positive electrode 11. The electrode assembly 10 includes a positive electrode 11.

[0203] In some embodiments, the positive electrode 11 includes a positive current collector and a positive active material layer disposed on at least one side of the positive current collector. As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0204] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be made by forming a metal material, such as aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, on the polymer substrate. The polymer substrate may include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and other substrates.

[0205] In some embodiments, the thickness of the positive current collector is 4μm-20μm; optionally 6μm-18μm, and further optionally 8μm-16μm.

[0206] In some embodiments, the positive electrode active material layer includes a positive electrode active material, which may be a positive electrode active material known in the art for use in battery cell 7.

[0207] For example, when the battery cell 7 is a lithium-ion battery cell 7, the positive electrode active material may include one or more of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides may include one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their respective modified compounds. Examples of lithium-containing phosphates may include one or more of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their respective modified compounds. This application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials may also be used.

[0208] In some embodiments, the chemical formula of the positive electrode active material is: Li x A y Me a M b P 1-c X c Y z Wherein, A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F; 0≤x≤1.3, 0≤y≤1.3, 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5. This positive electrode active material has good electrochemical stability, which is beneficial for the balanced current distribution in the positive electrode sheet 11 during the operation of the battery cell 7. When the amount of V added is within the above range, it can reduce the lithium-ion diffusion barrier and increase the volume of the diffusion channel; Ti 4+ Doping can alter the local energy levels of the crystal, significantly improving conductivity; it comprehensively improves the stability of the cathode structure, increases the lithium-ion diffusion rate and conductivity, improves the lithium insertion / extraction depth of the material, reduces electrode polarization, and enhances the capacity and cycle performance of the battery cell 7.

[0209] In some embodiments, the chemical formula of the positive electrode active material is Li x A y Me a M b P 1-c P c O zWherein, A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; optionally, M includes one or more of Ti and V, where 0.005 ≤ b ≤ 0.20, and optionally 0.05 ≤ b ≤ 0.15. This is beneficial for improving the capacity and cycle performance of the battery cell 7.

[0210] In some embodiments, the positive electrode active material may include lithium iron phosphate (LiFePO4), lithium manganese phosphate (LiMnPO4), and lithium manganese iron phosphate (LiMn). 0.4 Fe 0.6 One or more of the following: lithium vanadium phosphate (Li3V2(PO4)3), lithium cobalt phosphate (LiCoPO4), and lithium nickel phosphate (LiNiPO4).

[0211] In this embodiment, the elemental content in the positive electrode active material has a meaning known in the art and can be detected using equipment and methods known in the art. For example, referring to EPA 6010D-2014, it can be tested by inductively coupled plasma atomic emission spectrometry (ICP-OES, instrument model: Thermo ICAP7400). After discharging the battery cell 7 to 0% SOC, the positive electrode 11 is disassembled, cleaned with dimethyl carbonate (DMC), dried, and then calcined at high temperature to remove impurities. 0.4g of the positive electrode active material is weighed and 10ml (50% concentration) of aqua regia is added. Then it is placed on a plate at 180℃ for 30min. After digestion on the plate, the volume is adjusted to 100mL, and quantitative testing is performed using the standard curve method.

[0212] In some embodiments, to further improve the energy density of the battery cell 7, the positive electrode active material may include materials of the general formula Li. a Ni b Co c M d O e A f Lithium transition metal oxides. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes one or more of N, F, S and Cl.

[0213] For example, the positive electrode active material may include LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.15 Al 0.05 One or more of O2.

[0214] When the secondary battery is a sodium-ion battery cell 7, the positive electrode active material may include one or more of the following: sodium-containing transition metal oxides, polyanionic materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue materials.

[0215] For example, the positive electrode active material may include NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue materials, with the general formula X p M' q (PO4) r O x Y 3-x One or more of the materials. In general formula X p M' q (PO4) r O x Y 3-x In the given condition, 0 < p ≤ 4, 0 < q ≤ 2, 1 ≤ r ≤ 3, 0 ≤ x ≤ 2, and X includes elements selected from H. + Li + Na + K + and NH4 +One or more of the following, M' is a transition metal cation, which may be selected from one or more of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halide anion, which may be selected from one or more of F, Cl and Br.

[0216] In some embodiments, the positive electrode 11 includes a CEI film located on the surface of the positive electrode active material, the CEI film comprising Si and B elements. Thus, the B element can significantly improve the capacity retention rate of the battery cell 7 during high-voltage cycling, while also improving coulombic efficiency and increasing the discharge capacity of the battery cell 7; the Si element enables the battery cell 7 to possess both high capacity, energy density, and cycle life.

[0217] A sample of the positive electrode 11 was taken, and the positive electrode active material in the positive electrode 11 was analyzed using energy-dispersive X-ray spectroscopy (TEM-EDX) with transmission electron microscopy. Specifically, elemental analysis was performed on the outer periphery of the positive electrode active material particles in the TEM image using EDX to detect the elemental types of the solid electrolyte membrane therein.

[0218] In some embodiments, the positive electrode active material layer may optionally include a binder. As an example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0219] In some implementations, the weight percentage of the binder in the positive electrode active material layer is greater than or equal to 0.5%, which is beneficial for obtaining good adhesion performance.

[0220] In some embodiments, the positive electrode active material layer further includes a conductive agent. As an example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0221] In some embodiments, the compaction density of the positive electrode active material layer is 1.5 g / cm³. 3 ~3.5g / cm 3 ; 2.3g / cm³ is optional 3 Up to 3.3 g / cm 3 ; a further option is 2.4 g / cm³. 3 Up to 3.0 g / cm 3 .

[0222] Optionally, the compaction density of the positive electrode active material layer can be 1.5 g / cm³. 3 1.6g / cm 3 1.7g / cm 31.8g / cm 3 1.9g / cm 3 2.0g / cm 3 2.1g / cm 3 2.2g / cm 3 2.3g / cm 3 2.4g / cm 3 2.5g / cm 3 2.6g / cm 3 2.7g / cm 3 2.8g / cm 3 2.9g / cm 3 3.0g / cm 3 3.1g / cm 3 3.2g / cm 3 3.3g / cm 3 3.4g / cm 3 and 3.5g / cm 3 Any value or range of its composition in the range; for example, the compaction density of the positive electrode active material layer can be 2.3 g / cm³. 3 -3.3g / cm 3 Optional 2.4g / cm 3 -3.0g / cm 3 Optional 2.5g / cm 3 -2.9g / cm 3 Optional 2.54g / cm 3 -2.8g / cm 3 Optional 2.6g / cm 3 -2.7g / cm 3 When the compaction density of the positive electrode active material layer is within the above range, it can balance the capacity, energy density, and cycle performance of the battery cell 7.

[0223] In this embodiment, the compaction density of the positive electrode active material layer can be the compaction density of the positive electrode active material layer of the battery cell 7 in a fully discharged state.

[0224] The compaction density and single-sided coating weight of the positive electrode active material layer can be tested using the following method: Disassemble the positive electrode sheet 11 from the battery cell 7 at 0% state of charge (SOC), and determine the compaction density of the positive electrode active material layer. For example, take a single-sided coated positive electrode sheet 11 (if it is a double-sided coated sheet, the positive electrode active material layer on one side can be wiped off first), cut it into a small circular piece with an area of ​​S1, weigh it, record its mass as M1, and measure its thickness H1. Then wipe off the positive electrode active material layer of the weighed positive electrode sheet 11, weigh the positive electrode current collector, record its mass as M0, and measure its thickness H0. The single-sided coating weight of the positive electrode active material layer = (mass of positive electrode sheet 11 M1 - mass of positive electrode current collector M0) / S1, the thickness of the positive electrode active material layer = thickness of positive electrode sheet 11 H1 - thickness of positive electrode current collector H0, and the compaction density of the positive electrode active material layer = single-sided coating weight of the positive electrode active material layer / thickness of the positive electrode active material layer.

[0225] In the embodiments of this application, the thickness of the positive electrode active material layer and the positive electrode current collector are known in the art and can be detected using equipment and methods known in the art. For example, the thickness of the positive electrode sheet 11 can be measured with a micrometer, the film layer on the surface of the positive electrode current collector can be removed, and the thickness of the positive electrode current collector can be measured with a micrometer. When the positive electrode active material layer is coated on one side, the thickness of the positive electrode active material layer is the thickness of the positive electrode sheet 11 minus the thickness of the positive electrode current collector. When the positive electrode active material layer is coated on both sides, the thickness of the positive electrode active material layer is (the thickness of the positive electrode sheet 11 minus the thickness of the positive electrode current collector) / 2.

[0226] Figure 9 is a schematic diagram showing the unfolded positive electrode of a battery cell provided in some embodiments of this application.

[0227] The positive electrode 11 in Figure 9 includes a positive active material layer. Multiple first regions 1111 can be taken along the winding direction TD of the positive active material layer to detect the compaction density deviation of the first region 1111.

[0228] In some embodiments, perpendicular to the winding direction TD of the positive electrode sheet 11, the positive electrode active material layer includes a plurality of first regions 1111, and the compaction density deviation of the plurality of first regions 1111 is less than or equal to 0.5 g / cm³. 3 Optionally, the compaction density deviation of the multiple first regions 1111 can be 0.0 g / cm³. 3 0.1g / cm 3 0.2g / cm 3 0.3g / cm 3 0.4g / cm 3 0.5g / cm 3Any value or range of its composition in the range; thereby, it is beneficial to improve the uniformity of the compaction density of the positive electrode active material layer in the TD direction, so as to make the current density distribution uniform and improve the cycle life and reliability of the battery cell 7.

[0229] Figure 10 is a schematic diagram showing the unfolded positive electrode of a battery cell provided in some embodiments of this application.

[0230] The positive electrode 11 in Figure 10 includes a positive electrode active material layer. Multiple second regions 1112 can be taken along the winding direction MD of the positive electrode 11 to detect the compaction density deviation of the second region 1112.

[0231] In some embodiments, along the winding direction MD of the positive electrode sheet 11, the positive electrode active material layer includes a plurality of second regions 1112, and the compaction density deviation of the plurality of second regions 1112 is less than or equal to 0.5 g / cm³. 3 Optionally, the compaction density deviation of the multiple second regions 1112 can be 0.0 g / cm³. 3 0.1g / cm 3 0.2g / cm 3 0.3g / cm 3 0.4g / cm 3 0.5g / cm 3 Any value or range of its composition in the range; thereby, it is beneficial to improve the uniformity of the compaction density of the positive electrode active material layer in the MD direction, so as to make the current density distribution uniform and improve the cycle life and reliability of the battery cell 7.

[0232] The compaction density of the positive electrode active material layer can be detected using the above method. During the test, the compaction density of the positive electrode active material layer at multiple different locations can be tested, and the average value obtained is taken as the compaction density of the positive electrode active material layer. The compaction density deviation can be calculated based on the compaction density of multiple measured positive electrode active material layers.

[0233] The compaction density deviation σ can be calculated using the following method:

[0234] The compaction density at different locations of the positive electrode active material layer was obtained and denoted as D. p1 D p2 D p3 ... D pn n is a positive integer greater than or equal to 15.

[0235] in, The average compaction density of the positive electrode active material layer is expressed in g / cm³. 3 .

[0236] During testing, one of the first regions 1111 in the winding direction of the positive electrode 11 can be used as one of a plurality of second regions 1112 perpendicular to the winding direction of the positive electrode 11. Similarly, it can be understood that a certain second region 1112 may be used as one of the first regions 1111.

[0237] In summary, the compaction density deviation of the positive electrode active material layer is small in both the winding direction (MD, Machine Direction) and the transverse direction (TD, Transverse Direction) of the positive electrode 11. As a result, the current density distribution in the battery cell 7 is relatively balanced during operation, which can reduce side reactions, reduce electrode polarization, improve the capacity and cycle performance of the battery cell 7, and reduce gas production.

[0238] In some embodiments, the porosity of the positive electrode active material layer is 2.8% to 30.6%; optionally, the porosity of the positive electrode active material layer can be any value or a range of combinations thereof from 10.1%, 11.0%, 12.0%, 13.0%, 14.0%, 15.0%, 16.0%, 20.0%, 25.0%, 26.0%, 27.0%, 28.0%, 29.0%, 30.0%, and 30.6%. A porosity within the above range is beneficial for improving the current distribution of the positive electrode 11, mitigating gas generation problems caused by localized overcharging / over-discharging, and improving localized electrolyte decomposition and side reaction gas generation problems, thereby improving gas generation and enabling the battery cell 7 to achieve both high energy density and good reliability.

[0239] The porosity of the positive electrode active material layer was measured in a freshly prepared positive electrode sheet 11. This positive electrode sheet 11 had not undergone electrochemical cycling in the battery cell 7.

[0240] The porosity of the positive electrode active material layer was obtained by true density testing. Small circular samples of a certain area were punched from the positive electrode sheet 11, and the apparent volume V1 was calculated. Referring to GB / T24586-2009, using an inert gas (such as helium or nitrogen) as the medium, the gas displacement method was employed, and the true volume V2 was measured using a true density meter (such as a Micromeritics AccuPycII1340 true density meter). The porosity of the positive electrode active material layer = (V1 - V2) / V1 × 100%.

[0241] In some embodiments, the positive electrode 11 can be prepared by dispersing the above-mentioned components for preparing the positive electrode 11, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive current collector, and after drying, cold pressing and other processes, the positive electrode 11 can be obtained.

[0242] [Negative electrode plate]

[0243] In some embodiments, the negative electrode 12 includes a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material.

[0244] For example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector. The negative electrode current collector can be made of materials such as metal foil, carbon-coated metal foil, or porous metal plate, and copper foil is optional.

[0245] For example, the negative electrode active material layer includes a negative electrode active material, an optional conductive agent, and an optional binder. The conductive agent is used to improve the conductivity of the negative electrode active material layer, and the binder is used to firmly bond the negative electrode active material and the binder to the negative electrode current collector. This application does not specifically limit the types of conductive agents and binders, which can be selected according to actual needs.

[0246] For example, the negative electrode active material may include one or more of natural graphite, artificial graphite, mesophase micro carbon spheres (MCMB), hard carbon, and soft carbon.

[0247] For example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; the binder may include one or more of styrene-butadiene rubber (SBR), styrene-butadiene rubber (SBCs), water-based acrylic resin, and carboxymethyl cellulose (CMC).

[0248] The negative electrode active material layer may also optionally include a thickener, such as sodium carboxymethyl cellulose (CMC).

[0249] In some embodiments, the main body 101 includes a negative electrode 12 with a porosity of 10.1% to 37.8%. Optionally, the porosity of the negative electrode active material layer can be any value or a range thereof from 2.8%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, 10.0%, 15.0%, 20.0%, 25.0%, 27.0%, 28.0%, 29.0%, 30.0%, and 30.6%. A porosity within the above range is beneficial for improving the current distribution of the positive electrode 11, mitigating gas generation problems caused by localized overcharging / over-discharging, and improving localized electrolyte decomposition and side reaction gas generation problems, enabling the battery cell 7 to achieve both high energy density and good reliability.

[0250] In some embodiments, the negative electrode 12 includes a negative electrode active material layer, which includes graphite, and the compaction density of the negative electrode active material layer is 1.0 g / cm³. 3 ~2.0g / cm 3 Optionally, the compaction density of the negative electrode active material layer can be 1.0 g / cm³. 3 1.1g / cm 3 1.2g / cm 3 1.3g / cm 3 1.4g / cm 3 1.5g / cm 3 1.6g / cm 3 1.7g / cm 3 1.8g / cm 3 1.9g / cm 3 2.0g / cm 3 Any value or range of its composition in the range. This is beneficial for improving gas production, allowing the battery cell 7 to achieve both high energy density and good reliability.

[0251] The porosity and compaction density of the negative electrode active material layer were tested in the freshly prepared positive electrode sheet 11. This positive electrode sheet 11 had not undergone electrochemical cycling in the battery cell 7.

[0252] The porosity of the negative electrode active material layer was obtained by true density testing. A small circular sample of a certain area was punched from the negative electrode sheet 12, and the apparent volume V1 was calculated. Referring to GB / T24586-2009, using an inert gas (such as helium or nitrogen) as the medium, the true volume V2 was measured using a gas displacement method and a true density meter (such as a Micromeritics AccuPycII1340 true density meter). The porosity of the negative electrode active material layer = (V1 - V2) / V1 × 100%.

[0253] The compaction density of the negative electrode active material layer was measured using freshly prepared negative electrode sheet 12. The measurement method was the same as that for the compaction density of the positive electrode active material layer.

[0254] In some embodiments, the negative electrode 12 includes a solid electrolyte membrane located on the surface of the negative electrode active material, the solid electrolyte membrane comprising one or more elements selected from F, Si, P, and C. This improves gas generation, enhances the thermal stability of the battery, and increases the reliability of the battery cell 7.

[0255] A sample of the negative electrode 12 was taken, and the negative electrode active material in the negative electrode 12 was analyzed using energy-dispersive X-ray spectroscopy (TEM-EDX) with transmission electron microscopy. Specifically, elemental analysis was performed on the outer periphery of the negative electrode active material particles in the TEM image using EDX to detect the types of elements present.

[0256] [Isolation Component]

[0257] In some embodiments, the separator 13 may be a separator membrane. The separator membrane is disposed between the positive electrode 11 and the negative electrode 12 to isolate the positive electrode 11 and the negative electrode 12.

[0258] In some embodiments, the separating membrane comprises a porous base membrane.

[0259] In some embodiments, the base film includes one or more of glass fiber, nonwoven fabric, and polyolefin. The base film can be a single-layer film or a multi-layer composite film, without particular limitation. When the base film is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0260] Alternatively, the polyolefin includes one or more of polyethylene, polypropylene, and polyvinylidene fluoride.

[0261] In some implementations, the separator can be a base membrane.

[0262] In some embodiments, the separator further includes a functional layer disposed on at least one side of the base film. The functional layer may include inorganic particles to improve the heat resistance of the separator and enhance the reliability of the battery cell 7. Optionally, the functional layer is disposed on both sides of the base film. Specifically, the functional layer is disposed on both sides of the base film along the thickness direction of the separator itself.

[0263] For example, the inorganic particles include one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. These inorganic particles can improve the heat resistance of the functional layer and enhance the reliability of the battery cell 7.

[0264] Optionally, the functional layer may further include an adhesive. The adhesive may include one or more of fluorinated adhesives or polyacrylic adhesives. Specifically, the fluorinated adhesive includes one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, and tetrafluoroethylene-hexafluoropropylene copolymer. The polyacrylic adhesive includes one or more of polyacrylic acid and fluorinated acrylate resins.

[0265] Electrolyte

[0266] In some embodiments, the battery cell 7 includes an electrolyte.

[0267] During the charging and discharging process of the battery cell 7, active ions such as lithium ions are inserted and extracted back and forth between the positive electrode 11 and the negative electrode 12, and the electrolyte plays the role of conducting active ions between the positive electrode 11 and the negative electrode 12.

[0268] In some embodiments, the electrolyte includes an electrolyte salt, an additive, and an organic solvent.

[0269] Taking lithium battery cell 7 as an example, the electrolyte salt may include, but is not limited to, one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0270] Taking sodium battery cell 7 as an example, the electrolyte salt may include, but is not limited to, one or more of the following: sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium difluorosulfonylimide (NaFSI), sodium difluoromethanesulfonylimide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalate borate (NaDFOB), sodium dioxalate borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorodioxalate phosphate (NaDFOP), and sodium tetrafluorooxalate phosphate (NaTFOP).

[0271] In some embodiments, the electrolyte includes hexafluorophosphate ions and bis(fluorosulfonyl)imide ions. During the electrochemical cycling of the battery cell 7, hexafluorophosphate ions can improve the cycle performance of the battery cell 7, while bis(fluorosulfonyl)imide ions can reduce the amount of HF generated and control the amount of gas produced; bis(fluorosulfonyl)imide ions can improve side reactions and reduce the amount of gas produced, thereby improving the reliability of the battery cell 7.

[0272] In some embodiments, the mass percentage of difluorosulfonyl imide ions is 0.25% to 10% based on 100% of the total mass of the electrolyte; optionally, the mass percentage of difluorosulfonyl imide ions can be any value or range of the following: 0.25%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%.

[0273] In some embodiments, the mass percentage of hexafluorophosphate ions is 0.25% to 8% based on 100% of the total mass of the electrolyte. Optionally, the mass percentage of hexafluorophosphate ions can be any value or a range of combinations thereof from 0.25%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, and 8%.

[0274] In summary, hexafluorophosphate ions and difluorosulfonamide ions in the electrolyte can be measured in cell 7 after electrochemical cycling.

[0275] In some embodiments, the organic solvent may include, but is not limited to, one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl ester carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone (ESE), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ether.

[0276] In some embodiments, the electrolyte includes dimethyl carbonate; optionally, the mass percentage of dimethyl carbonate is 3% to 50% based on 100% of the total mass of the electrolyte; optionally, the mass percentage of dimethyl carbonate can be any value or range of its composition from 3%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50%; thereby, the energy conversion efficiency of the battery can be effectively improved; it can also improve the deterioration of gas production caused by uneven current or temperature, and improve the reliability of the battery cell 7.

[0277] If the battery cell 7 is too long or too large, the potential for uneven current or temperature distribution within it increases, leading to deterioration in DMC gas production. Controlling the DMC content in the electrolyte can further improve the reliability of the battery cell 7.

[0278] In some embodiments, the electrolyte includes vinylene carbonate; optionally, based on 100% of the total mass of the electrolyte, the mass percentage of vinylene carbonate is 1% to 7%; optionally, the mass percentage of vinylene carbonate can be any value or range of 1%, 2%, 3%, 4%, 5%, 6%, 7% or its composition; vinylene carbonate participates in the formation of a solid electrolyte membrane, which can improve the side reactions between the components in the electrolyte and the negative electrode, reduce gas production, improve the heat generation of the cell, and at the same time improve the stability of the SEI (Solid Electrolyte Interface) membrane, improve the cycle capability of the negative electrode, and reduce irreversible capacity; thereby further reducing gas production and improving the reliability and cycle performance of the battery cell 7.

[0279] In some embodiments, the organic solvent includes dimethyl carbonate and vinylene carbonate; the mass ratio of dimethyl carbonate to vinylene carbonate is 1:(0.2-0.6). This reduces the side reactions of DMC, lowers cell heat generation, and allows VC to participate in the negative electrode film formation, replacing some of the film-forming reactions involving DMC, which further reduces gas production and improves the reliability of the battery cell 7.

[0280] In summary, dimethyl carbonate and vinylene carbonate in the electrolyte can be measured in cell 7 after electrochemical cycling.

[0281] In some implementations, the electrolyte may also include additives.

[0282] Adding certain substances, such as additives, to the electrolyte can have a significant impact on the electrolyte. Because these additives contribute to the film formation on the surface of active materials, their content in the electrolyte of battery cell 7 varies depending on the formation process, the battery's lifespan, and its storage condition. Therefore, the additive content in freshly prepared electrolyte may differ from that in electrolyte obtained from reverse-engineered batteries. However, those skilled in the art can determine the approximate range of the relevant substances' content in the freshly prepared electrolyte based on the battery cell 7's performance level (e.g., cycle count) and residual content. Similarly, those skilled in the art can determine the approximate range of the additive content in the non-freshly prepared (i.e., reverse-engineered) electrolyte based on the freshly prepared additive content and the performance requirements and storage environment of the battery cell 7.

[0283] Therefore, the additive content mentioned in the technical solution of this application can be the content of additives actively added to fresh electrolyte, or the content of residual additives detected by reverse detection based on the actual battery state.

[0284] In some embodiments, the method for preparing the electrolyte includes mixing lithium salt, additives and organic solvent to obtain the electrolyte.

[0285] In some embodiments, the lithium salt added during the preparation of the electrolyte may include one or both of lithium hexafluorophosphate (LiPF6) and lithium bisfluorosulfonylimide (LiFSI); lithium hexafluorophosphate (LiPF6) is optional. Lithium bisfluorosulfonylimide (LiFSI) is optional.

[0286] According to the embodiments of this application, any one or a combination of the above-mentioned lithium salts are selected. All of the above-mentioned lithium salts have high electrical conductivity, which can improve the cycle performance of the battery cell 7.

[0287] During the electrochemical cycling process of battery cell 7, lithium hexafluorophosphate can improve the cycle performance of battery cell 7, lithium bisfluorosulfonylimide can reduce the amount of HF generated and control the amount of gas produced; bisfluorosulfonylimide ions can improve side reactions and improve the amount of gas produced, thereby improving the reliability of battery cell 7.

[0288] In some embodiments, the mass percentage of lithium bisfluorosulfonylimide is 0.25% to 10% based on 100% of the total mass of the electrolyte. Optionally, the mass percentage of lithium bisfluorosulfonylimide can be any value or range of a combination thereof from 0.25%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, and 7.0%.

[0289] During preparation, the mass of lithium bis(fluorosulfonyl)imide can be added according to the total mass of the electrolyte.

[0290] In some embodiments, the mass percentage of lithium hexafluorophosphate is 0.25% to 8% based on 100% of the total mass of the electrolyte. Optionally, the mass percentage of lithium hexafluorophosphate can be any value or a range of combinations thereof from 0.25%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, and 7.0%.

[0291] During preparation, the mass of lithium hexafluorophosphate can be added according to the total mass of the electrolyte.

[0292] In some embodiments, the additive includes trimethylfluorosilane; optionally, the mass percentage of trimethylfluorosilane is 0.03% to 0.5% based on 100% of the total mass of the electrolyte; optionally, the mass percentage of trimethylfluorosilane can be any value or range of its composition from 0.03%, 0.04%, 0.05%, 0.06%, 0.08%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, and 0.5%. This improves gas production, enhances the thermal stability of the battery, and increases the reliability of the battery cell 7.

[0293] When preparing the electrolyte, trimethylfluorosilane at the above-mentioned mass content can be added.

[0294] In some embodiments, the additive includes tris(trimethylsilyl)phosphite.

[0295] In some embodiments, the mass percentage of tris(trimethylsilyl)phosphite is 0.03% to 0.5% based on 100% of the total mass of the electrolyte. Optionally, the mass percentage of tris(trimethylsilyl)phosphite can be any value or range thereof from 0.03%, 0.04%, 0.05%, 0.06%, 0.08%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, and 0.5%. This improves gas generation, enhances the thermal stability of the battery, and increases the reliability of the battery cell 7.

[0296] When preparing the electrolyte, tris(trimethylsilyl)phosphite of the above-mentioned mass content can be added.

[0297] In some embodiments, the additive includes tris(trimethylsilyl)borate.

[0298] In some embodiments, the mass percentage of tris(trimethylsilyl)borate is 0.03% to 0.5% based on 100% of the total mass of the electrolyte. Optionally, the mass percentage of tris(trimethylsilyl)borate can be any value or range of its composition from 0.03%, 0.04%, 0.05%, 0.06%, 0.08%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, and 0.5%. Thus, element B can significantly improve the capacity retention of battery cell 7 during high-voltage cycling, while also improving coulombic efficiency and increasing the discharge capacity of battery cell 7; element Si can enable battery cell 7 to possess both high capacity, energy density, and cycle life.

[0299] When preparing the electrolyte, tris(trimethylsilyl)borate esters of the above-mentioned mass content can be added.

[0300] In the embodiments of this application, the types and contents of inorganic components / lithium salts in the electrolyte are known in the art and can be detected using equipment and methods known in the art. For example, the inorganic components / lithium salts in the electrolyte can be qualitatively or quantitatively analyzed by referring to standards JY / T 0575-2020 "General Rules for Ion Chromatography Analysis" and GB / T 6040-2019 "General Rules for Infrared Spectroscopy Analysis". In the embodiments of this application, freshly prepared electrolyte can be used as a sample, the free electrolyte of a fresh battery can be used as a sample, or a fully discharged battery cell 7 (discharged to the discharge cutoff voltage so that the state of charge of the battery cell 7 is about 0% SOC) can be disassembled in reverse, and the free electrolyte obtained from the battery cell 7 can be used as a sample for detection.

[0301] In the embodiments of this application, the types and contents of organic components in the electrolyte are known in the art and can be detected using equipment and methods known in the art. For example, the organic components of the electrolyte can be qualitatively and quantitatively analyzed by gas chromatography using GB / T 9722-2023 "General Rules for Gas Chromatography of Chemical Reagents".

[0302] [Preparation methods for battery cells]

[0303] This application provides a method for preparing a battery cell 7, comprising the following steps:

[0304] The system provides a housing 21, an end cap 22, and at least one electrode assembly 10. The housing 21 includes interconnected openings and receiving cavities. The length L, thickness D, and height H of the housing 21 satisfy L > D, L > H, and 270 mm ≤ L ≤ 2000 mm. The end cap 22 is provided with at least one explosion-proof valve. The total area S of the at least one explosion-proof valve is ≥ 1000 mm². 2The electrode assembly 10 includes a main body 101 and an electrode tab 102. The electrode tab 102 is connected to the main body 101 and extends out of the main body 101. The electrode tab 102 includes a positive electrode tab 1021 and a negative electrode tab 1022.

[0305] At least one electrode assembly 10 is disposed within the housing 21 through an opening;

[0306] Electrolyte is injected into the housing 21 and end cap 22 is assembled to the opening to seal the housing 21, thereby obtaining a battery cell 7, wherein the ratio of the tab length l of the positive electrode tab 1021 and / or the negative electrode tab 1022 to the length L of the housing 21 satisfies 0.08 to 0.16.

[0307] In this embodiment, the length of the casing 21 of the battery cell 7 is within the above-mentioned range, which is suitable for high-capacity battery cells 7. The total area of ​​the explosion-proof valve is within the above-mentioned range, which is beneficial for the discharge of gas generated in the high-capacity battery cell 7, controlling the gas discharge rate, reducing the risk of thermal runaway, and improving the reliability of the battery cell 7.

[0308] Controlling the ratio of the length l of the control tab to the length L of the casing 21 within the above range is beneficial for controlling the internal resistance of the cell and improving the energy efficiency of the cell; it also improves the uneven distribution of current density in the battery cell 7, thereby improving the internal temperature difference of the cell, thus improving gas production and reducing risk; and it enables the battery cell 7 to take into account both long-term cycle life and long-term reliability.

[0309] Example

[0310] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0311] Example 1

[0312] 1. Preparation of positive electrode sheet

[0313] The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is uniformly coated on both sides of the positive current collector, which is a 13μm aluminum foil.

[0314] Positive electrode active material layer: The positive electrode active material lithium iron phosphate, the binder polyvinylidene fluoride PVDF, and the conductive agent acetylene black are mixed in the solvent N-methylpyrrolidone (NMP) at a mass ratio of 97:2:1 to prepare the positive electrode slurry; the positive electrode slurry is uniformly coated on the surface of the positive electrode current collector, and the positive electrode active material layer is formed after drying and cold pressing. Then, the positive electrode tabs are welded so that the length of the positive electrode tabs is 37.5 mm.

[0315] 2. Preparation of negative electrode sheet

[0316] The negative electrode sheet includes a negative current collector and a negative active material layer. The negative active material layer is uniformly coated on both sides of the negative current collector, and the negative current collector is a 6μm copper foil.

[0317] Negative electrode active material layer: A negative electrode slurry is prepared by mixing artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose in a mass ratio of 97:0.5:1.5:1, using water as the solvent. This slurry is then uniformly coated onto the surface of the negative electrode current collector. After drying and cold pressing, a film layer is formed, thus obtaining the negative electrode active material layer. Negative electrode tabs are then welded on, with a length of 37.5 mm. The compacted density of the negative electrode active material layer is 1.55 g / cm³. 3 The single-sided coating weight is 0.135g / 1540.25mm. 2 .

[0318] Along the length of the shell, the length of the main body is W; the distance between the positive electrode tab and the end of the main body section is k1×W, and the distance between the negative electrode tab and the end of the same section of the main body is k2×W, where k1 is 0.25 and k2 is 0.75.

[0319] 3. Isolation components

[0320] The insulating component includes a base film and a coating. The base film is made of polyethylene (PE), and the coating material is modified from ceramic substances and PVDF, which mainly increases adhesion and insulation.

[0321] 4. Preparation of electrolyte

[0322] The electrolyte consists of organic solvents, lithium salts, and additives.

[0323] The components of each organic solvent are mixed, and lithium salt and additives are added to prepare an electrolyte.

[0324] Based on the total mass of the electrolyte, the organic solvents include 23% dimethyl carbonate (DMC), 22.4% vinylene carbonate (VC), 20.5% ethyl methyl carbonate (EMC), and 23.7% ethylene carbonate (EC).

[0325] Based on the total mass of the electrolyte, the lithium salt comprises 7.6% lithium hexafluorophosphate (LiPF6) and 2.8% lithium bisfluorosulfonyl imide (LiFSI) by mass.

[0326] 5. Preparation of battery cells

[0327] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation, thus forming an electrode assembly. This assembly is then placed inside a housing, with the positive and negative terminals positioned on the end caps. After baking, electrolyte is injected (multiple injections may be necessary). Following vacuum sealing, settling, formation, and shaping processes, a battery cell is obtained. The battery cell housing has a length of 275mm, a width of 75mm, and a height of 225mm. The nominal capacity of the battery cell is 625Ah. With the explosion-proof valve open, the measured exhaust velocity at this location is 10.8m / s, corresponding to a nominal capacity gas production coefficient of 0.6736L / Ah. The explosion-proof valve area is 1037mm². 2 .

[0328] Examples 2-5

[0329] The preparation method of the battery cell is similar to that in Example 1, except that the lengths of the positive electrode tab and the negative electrode tab are adjusted to make the ratio of the tab length l to the shell length L different, as detailed in Table 1. In Example 5, only the ratio of the positive electrode tab length l to the shell length L is 0.14, and the ratio of the positive electrode tab length l to the shell length L is 0.06.

[0330] Examples 6-7

[0331] The preparation method of the battery cell is similar to that in Example 1, except that the lengths of the positive and negative electrode tabs, as well as the length of the casing, are adjusted so that the ratio of the tab length l to the casing length L is 0.14. See Table 1 for details. It is worth noting that in Example 7, the casing length is 3000 mm, corresponding to an explosion-proof valve area of ​​1237 mm². 2 .

[0332] Comparative Examples 1-2

[0333] The preparation method of the battery cell is similar to that in Example 1, except that the lengths of the positive electrode tab and the negative electrode tab are adjusted so that the ratio of the tab length l to the shell length L is different, as detailed in Table 1.

[0334] Comparative Examples 3-4

[0335] The preparation method of the battery cell is similar to that of Example 1, except that the length of the casing is adjusted so that the ratio of the tab length l to the casing length L is the same as in Example 1. The lengths of the positive and negative tabs are adjusted accordingly, as detailed in Table 1. It is worth noting that in Comparative Example 4, the casing length is 3200 mm, corresponding to an explosion-proof valve area of ​​1267 mm². 2 .

[0336] Test section

[0337] 1. Cycle performance test of individual battery cells

[0338] At 25°C, the battery cells were subjected to charge-discharge cycle tests on a charge-discharge tester. They were charged at a 0.5C rate to the upper limit cutoff voltage, for example, 3.65V, and allowed to stand for 30 minutes. Then, they were charged at a 0.05C rate to the upper limit cutoff voltage. Finally, they were discharged at a 0.5C rate to the lower limit cutoff voltage, for example, 2.5V, and allowed to stand for 30 minutes. Then, they were discharged at a 0.05C rate to the lower limit cutoff voltage.

[0339] The battery was subjected to a 0.5C charge-discharge cycle at 25℃, and the nominal capacity value was taken as the discharge capacity of the second cycle at 2.5V.

[0340] After allowing the charge and discharge cycles to stand for 30 minutes, calculate the capacity retention rate after each cycle.

[0341] The capacity retention rate after the cycle is: Capacity retention rate after the 10,000th cycle = (Discharge capacity after the 10,000th cycle / Discharge capacity in the first cycle) × 100%.

[0342] The higher the capacity retention rate, the better the cycle performance of the battery cell.

[0343] 2. Battery cell volume expansion test

[0344] Before the cycle test of a single battery cell, the thickness of the battery cell is measured as the initial thickness.

[0345] After a single battery cell has been cycled 10,000 times, the thickness of the battery cell is measured, and this is the thickness after cycling.

[0346] The volume expansion rate of a single battery cell is 100% × (post-cycle thickness - initial thickness) / initial thickness.

[0347] The higher the volume expansion rate of a battery cell, the more gas is produced, and the higher the risk of the battery cell bulging; the lower the volume expansion rate of a battery cell, the less gas is produced, and the higher the reliability of the battery cell.

[0348] 4. Battery Cell Energy Efficiency Test: At 25℃ and normal pressure, the battery cell under test is charged to 3.65V at a power of 0.25P, allowed to rest for 10 minutes, and then discharged to 2.5V at a power of 0.25P, allowed to rest for 10 minutes, and this charge-discharge cycle is repeated 3 times. The energy efficiency of the last two cycles is calculated, and the average value is recorded as the 0.25P energy efficiency of the cell. Energy efficiency per cycle = (discharge energy / charge energy) × 100%.

[0349] 5. Thermal runaway test of individual battery cells: The thermal runaway test is conducted according to GB / T-36276-2023: At 25℃ and normal pressure, the individual battery cells are charged to 3.65V at 0.33C. Then, they are charged at a constant current of 0.5C while simultaneously heating the individual cells to trigger thermal runaway. After thermal runaway, charging and heating are terminated, and the cells are observed for 1 hour. The highest temperature of the first side of the individual battery cell is recorded. If fire occurs, the highest temperature of the first side within 10 minutes from the moment of fire is recorded as the highest temperature of the first side. Whether the individual battery cell catches fire or explodes is the standard for passing the thermal runaway test: no fire or explosion is considered passing; fire without explosion is considered failing.

[0350] 6. Battery Energy Density Test Method

[0351] The battery cells prepared in each embodiment and comparative example were left to stand at 25°C for 2 hours to ensure the temperature of the battery cells remained at 25°C. The battery cells were then charged at 1 / 3C at 25°C to the charging cutoff voltage of 3.65V, and then continued to be charged at this charging cutoff voltage under constant voltage until the current reached 0.05C, at which point charging was stopped. Here, C represents the rated capacity of the battery cell. After leaving the battery cells to stand at 25°C for 1 hour, the battery cells were discharged at 0.33C at 25°C to the discharge cutoff voltage of 2.5V, and the total discharge energy of the battery cells was recorded as E0.

[0352] Calculate the volume of a battery cell using its length, width, and height: V'0 = length × width × height. The volumetric energy density of a battery cell = discharge energy of the battery cell E0 / volume of the battery cell V'0.

[0353] 7. Exhaust rate of individual battery cells: The exhaust rate can be measured by connecting a flow meter to the exhaust valve and recording the cumulative average speed over 5 minutes as the exhaust rate of the individual battery cells.

[0354] The performance test results are detailed in Table 1.

[0355] Table 1

[0356] In Table 1, l / L represents the ratio of the tab length l to the shell length L. " / " indicates that the parameter is difficult to measure or cannot be accurately represented in the table.

[0357] The battery cells in the above embodiments and comparative examples have an energy density of over 410Wh / L, and these battery cells have high energy density and high nominal capacity.

[0358] Based on the data from Examples 1 to 7 and Comparative Examples 1 to 4 in Table 1, by rationally designing the tab length l, the casing length L, and the casing length of the battery cell, the battery cell can have good nominal capacity, cell energy efficiency, and good cycle life, and the battery cell can pass the thermal runaway test. The highest temperature on the first surface reflects the reliability of the battery cell; a suitable temperature indicates good reliability, while a higher temperature poses a risk of explosion and fire.

[0359] Example 8

[0360] The preparation method of the battery cell is similar to that in Example 1, except that the area of ​​the explosion-proof valve is adjusted to 1210 mm². 2 The lengths of the positive and negative electrode tabs, and the ratio of the tab length l to the shell length L are the same as in Example 1, as detailed in Table 2.

[0361] Comparative Example 5

[0362] The preparation method of the battery cell is similar to that in Example 1, except that the area of ​​the explosion-proof valve is adjusted to 850 mm². 2 The lengths of the positive and negative electrode tabs, and the ratio of the tab length l to the shell length L are the same as in Example 1, as detailed in Table 2.

[0363] Table 2

[0364] In Table 2, the nominal capacity, cell energy efficiency, and volumetric energy density of the battery cells in each embodiment and comparative example are basically the same. The battery cells can pass the thermal runaway test, and the highest temperature on the first side is basically the same.

[0365] Based on the data from Examples 1, 8 and Comparative Example 5 in Table 2, by reasonably designing the tab length l and the shell length L in the battery cell, as well as the shell length and the explosion-proof valve area, the battery cells in the examples can have good exhaust speed, cell energy efficiency, volume expansion rate and cycle life. However, the explosion-proof valve area in the comparative example is set too small, which is not conducive to exhaust, and the exhaust speed is too large, which greatly affects the cycle life of the battery cell.

[0366] Examples 9-10

[0367] The preparation method of the battery cell is similar to that of Example 1, except that the distance between the positive electrode tab and the end of the main body section and the distance between the negative electrode tab and the end of the main body section are adjusted, and the values ​​of k1 and k2 are adjusted as shown in Table 3.

[0368] Table 3

[0369] The nominal capacity, cycle life, and volumetric energy density of the battery cells in the various embodiments in Table 3 are basically the same.

[0370] Along the length of the casing, the length of the main body is W. Adjusting the distance between the positive electrode tab and the end of the main body section, and adjusting the distance between the negative electrode tab and the end of the same section of the main body, affects the cell energy efficiency and the highest temperature on the first surface. This shows that the position of the positive or negative electrode tab affects the distribution of the current density inside the battery cell and the internal temperature.

[0371] Examples 11 to 13

[0372] Battery cells were prepared using a method similar to that in Example 1, except that the compaction density of the positive and negative electrodes or the single-sided coating weight of the positive and negative electrodes was adjusted.

[0373] The test results are shown in Table 4.

[0374] Table 4

[0375] The battery cells in the various embodiments in Table 4 have basically the same cell energy efficiency and exhaust rate, and the battery cells can pass the thermal runaway test.

[0376] Within a certain range, as the compaction density of the positive electrode active material layer decreases, although the nominal capacity of the battery cell decreases moderately, it is more beneficial to cycle life and volumetric energy density; it may moderately increase the volume expansion rate.

[0377] Therefore, setting the compaction density of the positive electrode active material layer within an appropriate range can effectively balance high nominal capacity, excellent cycle performance, and low volume expansion rate. Similarly, setting the single-sided coating weight of the positive electrode active material layer within an appropriate range can effectively balance high nominal capacity, excellent cycle performance, and low volume expansion rate.

[0378] Examples 13 to 15

[0379] Battery cells were prepared using a method similar to that of Example 1, except that the electrolyte formulation was adjusted, as shown in Table 5.

[0380] The test results are shown in Table 5.

[0381] Table 5

[0382] In Table 5, LiPF6 represents lithium hexafluorophosphate, and LiFSI represents lithium difluorosulfonylimide.

[0383] In Table 5, the nominal capacity of each embodiment is basically the same as that of Embodiment 1, and the energy density and cell energy efficiency of each embodiment are basically the same as the energy density of Embodiment 1. The battery cells can pass the thermal runaway test.

[0384] The addition of lithium bis(fluorosulfonyl)imide can reduce the amount of lithium hexafluorophosphate used. Lithium bis(fluorosulfonyl)imide has high ionic conductivity, which can effectively improve ion conduction. It is not easily reacted with water, and its decomposition products can optimize the stability of the SEI film and further improve the gas generation phenomenon caused by side reactions, thereby improving the cycle performance and volume expansion rate of the battery cell.

[0385] Examples 16 to 21

[0386] Battery cells were prepared using a method similar to that of Example 1. The difference was that the electrolyte composition was adjusted, with different types and amounts of additives added to the electrolyte, correspondingly adjusting the mass content of dimethyl carbonate. Everything else was the same as in Example 1, as shown in Table 6.

[0387] The test results are shown in Table 6.

[0388] Table 6

[0389] As shown in Table 6, the types and mass contents of the additives in Example 1, when combined with the organic solvents and lithium salts in the electrolyte, can effectively improve the high-temperature stability of the battery cells, reduce local side reactions at high temperatures, reduce gas production, and improve the cycle life and volume expansion rate of the battery cells.

[0390] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A single battery cell, comprising: The shell includes interconnected openings and receiving cavities, wherein the length L, thickness D, and height H of the shell satisfy L > D and L > H, where 270 mm ≤ L ≤ 3000 mm; An end cover is arranged in covering manner in the opening of the housing, the end cover comprising at least one explosion vent; the total area S of the at least one explosion vent is ≥ 1000 mm 2 ; At least one electrode assembly is disposed within the receiving cavity. The electrode assembly includes a main body and an electrode tab. The electrode tab is connected to and extends out of the main body. The electrode tab includes a positive electrode tab and a negative electrode tab. The ratio of the length l of at least one of the positive electrode tab and the negative electrode tab to the length L of the housing satisfies 0.08 to 0.

16.

2. The battery cell of claim 1, wherein, The length l of at least one of the positive electrode tab and the negative electrode tab is ≥25mm, and can be selected as 30mm to 60mm.

3. The battery cell of claim 1 or 2, wherein, In a cross-section perpendicular to the height of the shell, the length of the main body along the length of the shell is W; The distance between one of the positive electrode tabs and the cross-sectional end of the main body is k1×W, and the distance between the other electrode tab and the same cross-sectional end of the main body is k2×W, where k1 satisfies 0.15≤k1≤0.35 and k2 satisfies 0.65≤k2≤0.

85. Optionally, k1 is 0.25 and k2 is 0.

75.

4. The battery cell according to any one of claims 1 to 3, wherein The shell has a first face perpendicular to the thickness direction of the shell, and the area S1 of the first face is ≥56000mm 2 ; optionally, S1 is in the range of 58000mm 2 ~62500mm 2 .

5. The battery cell according to any one of claims 1 to 4, wherein, The battery cell comprises: an electrode terminal provided on the end cover; the tab and the electrode terminal are welded to form a welding mark, the cross-sectional area of the welding mark is 80mm 2 ~200mm 2 .

6. The battery cell according to any one of claims 1 to 5, wherein The main body includes a positive electrode sheet, and the positive electrode sheet includes a positive electrode active material; the chemical formula of the positive electrode active material is: Li x A y Me a M b P 1-c X c Y z Wherein, A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F; 0≤x≤1.3, 0≤y≤1.3, 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5.

7. The battery cell of claim 6, wherein, The chemical formula of the positive electrode active material is Li x A y Me a M b P 1-c P c O z Wherein, A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; optionally, M includes one or more of Ti and V, 0.005≤b≤0.20, and optionally 0.05≤b≤0.

15.

8. The battery cell according to claim 6 or 7, wherein, The positive electrode tab includes a positive electrode active material layer, the compaction density of the positive electrode active material layer is 1.5 g / cm 3 ~ 3.5 g / cm 3 , and is optionally 2.3 g / cm 3 ~ 3.3 g / cm 3 ; and is further optionally 2.4 g / cm 3 ~ 3.0 g / cm 3 .

9. The battery cell of claim 8, wherein, The positive electrode active material layer includes a plurality of first regions having a compaction density deviation of less than or equal to 0.5 g / cm2in a direction perpendicular to the positive electrode tab winding direction TD. 3 .

10. The battery cell according to claim 8 or 9, wherein, The positive electrode active material layer includes a plurality of second regions having a compaction density deviation of less than or equal to 0.5 g / cm3 along the winding direction MD of the positive electrode tab 3 .

11. The battery cell according to any one of claims 1 to 10, wherein, The nominal capacity Q of the battery cell is 500Ah to 3000Ah, and can be selected from 800Ah to 2000Ah; or can be selected from 1000Ah to 2000Ah.

12. The battery cell according to any one of claims 1 to 11, wherein, The battery cell includes an electrolyte, which includes dimethyl carbonate; optionally, based on the total mass of the electrolyte, the mass percentage of dimethyl carbonate is 3% to 50%.

13. The battery cell according to any one of claims 1 to 12, wherein, The battery cell includes an electrolyte, which includes vinylene carbonate; optionally, based on 100% of the total mass of the electrolyte, the mass percentage of vinylene carbonate is 1% to 7%.

14. The battery cell according to any one of claims 1 to 13, wherein, The battery cell includes an electrolyte comprising bis(fluorosulfonyl)imide ions; optionally, the electrolyte further includes hexafluorophosphate ions; optionally, based on 100% of the total mass of the electrolyte, the mass percentage of bis(fluorosulfonyl)imide ions is 0.25% to 10%; optionally, based on 100% of the total mass of the electrolyte, the mass percentage of hexafluorophosphate ions is 0.25% to 8%.

15. The battery cell according to any one of claims 6 to 14, wherein, The main body includes a positive electrode sheet, which includes a CEI film located on the surface of the positive electrode active material, and the CEI film includes Si and B elements.

16. The battery cell according to any one of claims 1 to 15, wherein, The main body includes a negative electrode sheet, which includes a solid electrolyte membrane located on the surface of the negative electrode active material. The solid electrolyte membrane includes one or more of the elements F, Si, P, and C.

17. The battery cell according to any one of claims 1 to 16, wherein, The battery cell satisfies: V T -V J -V S -V D = k x Q; k represents a coefficient, the unit of k is Ah / ml, k is 2.5-4.5, Q represents the nominal capacity of the battery cell 7, the unit of Q is Ah; V S represents the volume of the mechanical parts inside the battery cell other than the electrode assembly in the full discharge state of the battery cell; V D represents the volume of the electrolyte inside the battery cell at full discharge state; V T represents the volume of the accommodation cavity at full discharge state of the battery cell; V J represents the total volume of the at least one electrode assembly in the fully discharged state of the battery cell.

18. The battery cell according to any one of claims 1 to 17, wherein, The battery cell satisfies the following condition: 2% ≤ (S0-S1) / S0 < 25%; S0 represents the area of ​​the receiving cavity in a cross-section perpendicular to the height of the casing when the battery cell is fully loaded; S1 indicates that the total area of ​​the at least one electrode assembly is S1 when the battery cell is in a fully discharged state.

19. The battery cell according to any one of claims 1 to 18, wherein, The total area of the at least one explosion relief valve is 1100-1500 mm 2 .

20. The battery cell according to any one of claims 1 to 18, wherein, In the projection along the height of the housing, the total area S of the explosion-proof valve accounts for 5% to 15% of the area of ​​the projected end cap.

21. The battery cell according to any one of claims 1 to 20, wherein, The battery cell satisfies one or more of the following conditions: (1) The thickness difference between the edges of the shell and the end cap is ≤0.04mm respectively; (2) 60mm≤D≤100mm; (3) 200mm≤H≤300mm.

22. A method for preparing a single battery cell, comprising the following steps: The system provides a housing, an end cap, and at least one electrode assembly. The housing includes interconnected openings and receiving cavities. The length L, thickness D, and height H of the housing satisfy L > D, L > H, and 270 mm ≤ L ≤ 2000 mm. The end cap is provided with at least one explosion-proof valve. The total area S of the at least one explosion-proof valve is ≥ 1000 mm². 2 The electrode assembly includes a main body and a tab, the tab being connected to and extending out of the main body, and the tab including a positive tab and a negative tab. At least one of the electrode components is disposed within the housing through the opening; Electrolyte is injected into the housing; The end cap is assembled to the opening to close the housing, thereby obtaining the battery cell. The ratio of the length l of the positive electrode tab and / or the negative electrode tab to the length L of the housing satisfies 0.08 to 0.

16.

23. The method of making according to claim 22, wherein, The electrolyte comprises lithium salt, additives, and organic solvent, and the electrolyte satisfies one or more of the following conditions: (1) The lithium salt includes lithium difluorosulfonylimide; optionally, the electrolyte also includes lithium hexafluorophosphate; optionally, based on 100% of the total mass of the electrolyte, the mass percentage of lithium difluorosulfonylimide is 0.25% to 10%; optionally, based on 100% of the total mass of the electrolyte, the mass percentage of lithium hexafluorophosphate is 0.25% to 8%. (2) The additive includes trimethylfluorosilane; optionally, based on 100% of the total mass of the electrolyte, the mass percentage of trimethylfluorosilane is 0.03% to 0.5%; (3) The additive includes tris(trimethylsilyl)phosphite; optionally, based on 100% of the total mass of the electrolyte, the mass percentage of tris(trimethylsilyl)phosphite is 0.03% to 0.5%; (4) The additive includes tris(trimethylsilyl)boronic acid ester; optionally, based on 100% of the total mass of the electrolyte, the mass percentage of the tris(trimethylsilyl)boronic acid ester is 0.03% to 0.5%; (5) The organic solvent includes dimethyl carbonate and vinylene carbonate; optionally, the mass ratio of dimethyl carbonate and vinylene carbonate is 1:(0.2 to 0.6).

24. The preparation method according to claim 22 or 23, wherein, The main body includes a positive electrode sheet, which includes a positive electrode active material layer with a porosity of 2.8% to 30.6%.

25. The method of manufacturing according to claims 22-24, wherein, The main body includes a negative electrode sheet with a porosity of 10.1% to 37.8%.

26. The preparation method according to claim 25, wherein, The negative electrode sheet includes a negative electrode active material layer including graphite, the negative electrode active material layer having a compacted density of 1.0 g / cm 3 ~ 2.0 g / cm 3 .

27. A battery device, wherein, This includes the battery cell according to any one of claims 1 to 21 or the battery cell prepared by the preparation method according to claims 22 to 26.

28. An electrical appliance, wherein, Includes the battery cell according to any one of claims 1 to 21, or the battery cell prepared by the preparation method according to claims 22 to 26, or the battery device according to claim 27.

29. An energy storage device comprising the battery device according to claim 27.

30. An energy storage system comprising the energy storage device according to claim 29.

Images