Sodium-ion battery, battery pack and electric device

Abstract

The application discloses a sodium ion battery, a battery pack and a power utilization device, relates to the technical field of batteries, and the sodium ion battery comprises a shell, a cover plate, a battery output end and a battery core; the battery core comprises a pole piece assembly and a tab assembly, the tab assembly is welded to the battery output end and forms a welding area, and the area ratio of the welding area to the area of a single tab assembly is E%; an insulating piece is arranged between the cover plate and the battery core, the insulating piece comprises an insulating piece body and a protruding portion; the length dimension of the protruding portion protruding from the insulating piece body is H (mm), the capacity of the sodium ion battery is V (Ah), and the range of H*E / V is 1.60*10 ‑2 - 265.85*10 ‑2 The application selects H*E / V in the range of 1.60*10 ‑2 - 265.85*10 ‑2 , so that the problem that the pressure increasing rate in the shell is too fast and the shell is broken and electrolyte is leaked can be avoided, and the problem that the risk of positive and negative electrode overlap is high can be avoided.

Description

Technical Field

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

[0002] Sodium-ion batteries, based on the abundant reserves of sodium, offer advantages such as low cost, excellent low-temperature performance, and high thermal stability, leading to their increasingly widespread application in the field of new energy batteries. However, in practical use, it has been found that sodium-ion batteries are prone to bulging and severe casing deformation, which in severe cases may lead to casing rupture, electrolyte leakage, and even thermal runaway.

[0003] Therefore, how to reduce the risk of casing deformation, cracking, and electrolyte leakage is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a sodium-ion battery to reduce the risk of casing deformation, cracking and electrolyte leakage;

[0005] Another object of this application is to provide a battery pack and an electrical device having the above-mentioned battery.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] The first aspect of this application provides a sodium-ion battery, which includes a casing, a cover plate, a battery output terminal, and a battery cell. At least one end of the casing has an opening, the cover plate blocks the opening of the casing and forms a receiving cavity with the casing, the battery cell is disposed in the receiving cavity, and the battery output terminal is fixed to the cover plate and electrically connected to the battery cell.

[0008] The battery cell includes an electrode assembly and a tab assembly connected to the electrode assembly. The tab assembly is welded to the output terminal of the battery, and a welding area is formed on the tab assembly. The area of ​​the welding area is E% of the area of ​​a single tab assembly.

[0009] An insulating component is provided between the cover plate and the battery cell. The insulating component is fixedly connected to the cover plate. The insulating component includes an insulating component body and a protrusion that connects to the insulating component body and protrudes toward the battery cell. A receiving groove is formed between the protrusion and the insulating component body.

[0010] Along a direction perpendicular to the plane containing the large surface of the cover plate, the protrusion extends out of the insulating body by a length of H (mm), the sodium-ion battery has a capacity of V (Ah), and the range of H×E / V is 1.60×10⁻⁶. -2 -265.85×10-2 .

[0011] The sodium-ion battery disclosed in the above technical solution optimizes the length H (mm) of the protrusion from the insulating body, the ratio E% of the area of ​​the welding area to the area of ​​a single electrode assembly, and the rated capacity V (Ah) of the sodium-ion battery, so that the composite parameter H×E / V is at 1.60×10. -2 -265.85×10 -2 Within this range, it avoids problems caused by excessively small H (mm) (i.e., by optimizing the protrusion of the protrusion beyond the insulation body length) due to an excessively small H×E / V, and / or excessively small E% (i.e., the ratio of the weld area to the area of ​​a single tab assembly), and / or excessively large V (Ah) (the rated capacity of the sodium-ion battery). Specifically, it avoids the problem of insufficient gas storage space in the sodium-ion battery due to an excessively small H (mm), resulting in a rapid increase in internal pressure during gas generation, leading to abnormal valve opening and pressure leakage. It also avoids the problem of insufficient current overcurrent performance due to an excessively small E%, leading to severe heat generation in the sodium-ion battery, which in turn causes severe gas generation and casing deformation. Furthermore, it avoids the problem of excessively large V (Ah), resulting in a large amount of gas generation and a tendency for casing deformation.

[0012] This application also avoids problems caused by excessively large H×E / V, resulting in excessively large H (mm) (i.e., the protrusion protruding beyond the length of the insulating component), and / or excessively large E% (i.e., the ratio of the area of ​​the welding area to the area of ​​a single tab assembly), and / or excessively small V (Ah) (the rated capacity of the sodium-ion battery). Specifically, it avoids the problem of excessively large H (mm) leading to a larger distance between the cover plate and the electrode assembly, requiring a larger design for the tab assembly to extend from the electrode assembly, and an excessively large free section of the tab (the part from the root of the tab assembly to the welding area), making it easy for the tab assembly to be inserted backwards into the electrode assembly of the cell, causing a short circuit due to positive and negative electrode contact. It also avoids the problem of excessive heat generation during welding due to excessively large E%, causing the cell's separator to shrink due to heat, leading to contact between the positive and negative electrodes of the electrode assembly and increasing the risk of short circuits. Finally, it avoids the problem of excessively small V (Ah) resulting in excessively low energy density of the sodium-ion battery.

[0013] This application sets H×E / V at 1.60×10 -2 -265.85×10 -2 Choosing within a certain range can avoid problems such as excessive gas production in the battery due to an excessively small H×E / V ratio, resulting in a rapid increase in pressure inside the casing, severe deformation of the casing, or even casing rupture leading to electrolyte leakage; it can also avoid problems such as low energy density and high risk of short circuit between positive and negative electrodes due to an excessively large H×E / V ratio.

[0014] A second aspect of this application provides a battery pack comprising a sodium-ion battery as described in any of the preceding claims. Since this battery pack incorporates the aforementioned sodium-ion battery, it possesses all the technical advantages of the sodium-ion battery, which will not be elaborated upon herein.

[0015] A third aspect of this application provides an electrical device that includes the battery pack described above. Since this electrical device has the aforementioned battery pack, it possesses all the technical advantages of the aforementioned battery pack, which will not be elaborated upon here. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the sodium-ion battery disclosed in the embodiments of this application;

[0018] Figure 2 This is a cross-sectional view of the sodium-ion battery disclosed in an embodiment of this application.

[0019] Figure 3 This is a partially enlarged cross-sectional view of the sodium-ion battery disclosed in the embodiments of this application;

[0020] Figure 4 This is a partial cross-sectional view of the sodium-ion battery disclosed in an embodiment of this application;

[0021] Figure 5 This is a partially enlarged cross-sectional view of a sodium-ion battery disclosed in another embodiment of this application;

[0022] Figure 6 This is a schematic diagram of the structure of the sodium-ion battery disclosed in this application after removing the casing;

[0023] Figure 7 This is a schematic diagram of the structure of a sodium-ion battery after removing the casing, as disclosed in another embodiment of this application;

[0024] Figure 8 This is a schematic diagram of the structure of the insulating component disclosed in the embodiments of this application;

[0025] Figure 9 This is a schematic diagram of the structure of an insulating component disclosed in another embodiment of this application;

[0026] Figure 10 This is a schematic diagram of the structure of the electrode assembly disclosed in the embodiments of this application;

[0027] Figure 11 This is a cross-sectional view of the electrode assembly disclosed in the embodiments of this application;

[0028] Figure 12 This is an exploded view of the cover plate, insulating component, and gas adsorption device disclosed in the embodiments of this application;

[0029] Figure 13 This is an exploded view of the battery pack disclosed in the embodiments of this application;

[0030] Figure 14 This is a schematic diagram of the structure of the electrical device disclosed in the embodiments of this application.

[0031] The meanings of the various reference numerals in the figure are as follows:

[0032] Vehicle 01; Battery unit 02; Controller 03;

[0033] Battery pack 10; casing 20; casing cover 30;

[0034] Casing 100;

[0035] Cover plate 200;

[0036] Battery output terminal 300; terminal post 310; adapter plate 320;

[0037] Battery cell 400; electrode assembly 410; first electrode portion 411; second electrode portion 412; bent electrode portion 413; electrode assembly 420; first polarity electrode 421; second polarity electrode 422; separator 423; insulating adhesive layer 424;

[0038] Insulating component 500; protrusion 510; insulating component body 520; insulating component main body portion 521; insulating component recessed portion 522; second through hole 530;

[0039] Gas adsorption device 600. Detailed Implementation

[0040] This application discloses a sodium-ion battery to reduce the risk of casing deformation, cracking, and electrolyte leakage;

[0041] This application also discloses a battery pack and an electrical device having the above-described sodium-ion battery.

[0042] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0043] A battery stores chemical energy and converts it into electrical energy in a controllable manner. In recyclable batteries, the active materials can be reactivated by charging after discharge, allowing for continued use. A battery generally consists of a casing and battery cells housed inside the casing.

[0044] A battery cell is the component in a battery where electrochemical reactions occur; it is the smallest unit in a battery capable of performing electrochemical reactions such as charging and discharging. A battery cell is the basic unit of a battery and typically includes a positive electrode, a negative electrode, and a separator. Sodium-ion batteries primarily function by the intercalation and deintercalation of sodium ions between the positive and negative electrodes. In cylindrical cells, a three-layer thin-film structure is wound into a cylindrical electrode assembly, while in cuboid cells, the thin-film structure is wound or stacked into an electrode assembly with a roughly cuboid shape.

[0045] A positive electrode generally includes a positive current collector and a positive active material layer. The positive active material layer is coated on at least one surface of the positive current collector and includes: a positive active material, a conductive agent, and a binder. The positive current collector includes a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium with a silver-plated surface, or a carbon-coated metal foil. The positive current collector can also include a composite current collector, which may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polyethylene, etc. substrate).

[0046] The positive electrode conductive agent includes, but is not limited to, one or more combinations of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon nanotubes, graphene and carbon nanofibers.

[0047] The positive electrode binder includes, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0048] The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector. The negative electrode current collector is a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium with a silver-plated surface, or a metal foil with a carbon-coated surface. The negative electrode current collector may also include a composite current collector, which may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polyethylene, etc. substrate). The negative electrode active layer includes a negative electrode active material, conductive components, adhesives, etc.

[0049] During battery charging, active ions from the positive electrode are embedded in the negative electrode, while electrons from the positive electrode are transferred to the negative electrode through an external circuit to maintain charge balance. During discharge, active ions (such as sodium ions) previously embedded in the negative electrode can be released, while electrons from the negative electrode are transferred to the negative electrode through an external circuit to maintain charge balance, thus achieving energy storage and release.

[0050] The current output section of the battery cell includes a tab assembly, which comprises multiple individual tabs. Each individual tab is positioned on one side of the positive / negative current collector of the battery cell and is either separate from or integrally formed with the current collector. It is electrically connected to the current collector to conduct current through it. When the individual tab and current collector are separate, they can be connected by welding. The individual tabs are made of a highly conductive metal material (such as copper, aluminum, or nickel).

[0051] A housing is a component used to provide a space to house the battery output terminal and other components and isolate them from the outside environment. A housing generally includes a body with an opening at at least one end and a receiving cavity. The opening of the housing can be closed by a cover plate to seal and isolate the internal environment of the battery from the external environment. Typically, the cover plate is welded to the opening of the housing.

[0052] The materials used for the casing include, but are not limited to, copper, iron, aluminum, titanium, stainless steel, aluminum alloy, titanium alloy, and plastic.

[0053] A cover is a component that seals the opening of the battery cell to isolate the internal environment of the battery cell from the external environment. Materials used for cover include, but are not limited to, copper, iron, aluminum, titanium, stainless steel, aluminum alloy, titanium alloy, and plastic.

[0054] An electrolyte is provided inside the shell. The electrolyte is a liquid electrolyte that transports active ions.

[0055] The electrolyte in a sodium-ion battery is an ion charge carrier medium that plays a role in ion conduction between the positive and negative electrodes. It provides a transport channel for the reversible migration of sodium ions and participates in the formation of the solid electrolyte interface film, directly determining the battery's electrochemical stability window, ionic conductivity, cycle life, and safety.

[0056] Organic liquid electrolytes consist of three parts: sodium salt, organic solvent, and functional additives.

[0057] Sodium salts (with sodium hexafluorophosphate (NaPF6) and sodium perchlorate (NaClO4) as the mainstream in the industry, and sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium tetrafluoroborate (NaBF4), etc.) provide sodium ion sources and affect interfacial stability.

[0058] Organic solvents are divided into two major systems: carbonates (cyclic carbonates such as ethylene carbonate (EC) and propylene carbonate (PC) are compounded with chain carbonates such as dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC), which have high conductivity and good antioxidant properties) and ethers (ethylene glycol dimethyl ether (DME), diethylene glycol dimethyl ether (DEGD), etc., which have thinner and more uniform solid electrolyte interface films and support sodium-solvent co-intercalation with graphite).

[0059] Functional additives (film-forming additives such as fluoroethylene carbonate (FEC) and vinylene carbonate (VC), flame-retardant additives such as trimethyl phosphate (C3H9O4P) and other phosphorus compounds, and overcharge protection additives such as biphenyl) are added in small amounts to specifically optimize the quality of the interfacial film, safety, and specific electrochemical performance. During actual use, the applicant discovered that sodium-ion batteries are prone to bulging and severe casing deformation, which in severe cases may lead to casing rupture, electrolyte leakage, and even thermal runaway.

[0060] Research revealed that sodium, being more chemically reactive than lithium, causes a more intense and sustained decomposition reaction of the electrolyte on the electrode surface (primarily the negative electrode active material), resulting in continuous gas production even under static conditions. In particular, the unique adsorption-desorption mechanism of hard carbon (the negative electrode active material) leads to the concentrated release of gases (hydrogen, carbon dioxide, ethylene, etc.) during discharge. While hard carbon, a non-graphitized carbon material with large interlayer spacing and abundant pores, can stably intercalate sodium ions, the electrolyte easily decomposes within the pores during the first charge, generating gas and causing cell bulging and failure. Furthermore, sodium-ion batteries exhibit significantly higher H2 and CO evolution rates, which continue to increase throughout the cycle. The SEI film in sodium-ion batteries has higher solubility or is more prone to rupture / reconstruction during cycling, leading to continuous gas generation. Therefore, the gas production rate of sodium-ion batteries is significantly higher than that of lithium-ion batteries.

[0061] To compensate for the lower energy density, sodium-ion batteries often employ a large capacity design, which further exacerbates gas production. The accumulated gas causes increased pressure inside the casing, leading to severe battery bulging, casing deformation, and even rupture. Once the casing ruptures under pressure, the accumulated gas is ejected from the rupture. The ejected gas contains flammable components; if the sodium-ion battery experiences thermal runaway due to an internal short circuit or overheating, these flammable gases can ignite instantly, causing a violent fire or even an explosion.

[0062] Based on this, this application discloses a sodium-ion battery to reduce the risk of casing deformation, cracking, and electrolyte leakage.

[0063] like Figures 1-5 as well as Figure 10 As shown, the sodium-ion battery disclosed in this application includes a casing 100, a cover plate 200, a battery output terminal 300, a battery cell 400, and an insulating component 500.

[0064] At least one end of the housing 100 has an opening. A cover plate 200 seals the opening of the housing 100, and together they form a receiving cavity for accommodating the battery cell 400, which is disposed within the receiving cavity. Specifically, the cover plate 200 and the housing 100 can be connected by welding, riveting, or adhesive bonding to form a sealed receiving cavity. Welding can include one or more of laser welding, ultrasonic welding, and resistance welding. The housing 100 can include five faces with an opening at one end, or it can include four faces with openings at both ends.

[0065] The battery output terminal 300 is fixedly mounted on the cover plate 200 and electrically connected to the battery cell 400 in the receiving cavity, for leading out the current generated by the battery cell 400.

[0066] The battery output terminal 300 serves as the external current output terminal of the battery, enabling electrical connection between the battery cell 400 and the external environment. It can be electrically connected to external electrical devices or realize the series and parallel connection of multiple batteries. The battery output terminal 300 and the cover plate 200 can be fixedly connected by riveting, snap-fitting, flanging, injection molding, etc.

[0067] The battery cell 400 includes an electrode assembly 420 and a tab assembly 410 connected to, and extending from, the electrode assembly 420. The tab assembly 410 is electrically connected to the battery output terminal 300 by welding, and the welding operation forms a welding area 414 on the tab assembly 410. Figure 10 The black-filled area on the middle electrode assembly 410 is the area of ​​the schematic welding area 414.

[0068] The tab assembly 410 is disposed on one side of the positive current collector (the positive tab is located on one side of the positive current collector) or the negative current collector (the negative tab is located on one side of the negative current collector). It can be separate from the current collector or integrally formed with it, as long as it is electrically connected to the current collector to conduct current from the corresponding current collector. The tab assembly 410 is made of a metal material with good conductivity (such as copper, aluminum, or nickel). In sodium-ion batteries, aluminum or aluminum alloy is preferably used for both the positive and negative current collectors to achieve overcurrent balance between the positive and negative tabs. Of course, copper can also be chosen for the negative current collector.

[0069] The tab assembly 410 serves as the current output terminal of the cell 400, and is led out from at least one end of the electrode. The electrode includes a current collector and an active material layer coated on at least one surface of the current collector. The current collector extends beyond the active material layer to form a single tab, and multiple single tabs converge along the electrode stacking direction to form the tab assembly 410.

[0070] The battery output terminal 300 may include a terminal post 310, or a terminal post 310 and an adapter piece 320. The terminal post 310 can be directly welded to the tab assembly 410 to achieve direct connection of the tab assembly and shorten the current transmission path. Alternatively, the terminal post 310 can be welded to the tab assembly via the adapter piece 320, with the adapter piece 320 electrically connected to both the tab assembly 410 and the terminal post 310. The cover plate 200 has a through hole through which at least part of the terminal post 310, the tab assembly 410, or the adapter piece 320 passes.

[0071] Terminal 310 is used for electrical connection between the electrode assembly located inside the housing and external devices (adjacent batteries or other electrical devices) located outside the housing. The battery can discharge to external devices through the cell output terminal (tab assembly 410) and the external device output terminal (terminal 310). An external power source can charge the battery through terminal 310 and tab assembly 410. Terminal 310 can be directly electrically connected to tab assembly 410, or it can be electrically connected to tab assembly 410 through a metal adapter. The material of terminal 310 includes, but is not limited to, metals such as copper, aluminum, aluminum alloy, and copper-aluminum alloy.

[0072] The ratio of the area of ​​the welding area 414 to the area of ​​a single tab assembly 410 is denoted as E%. The area of ​​the welding area 414 refers to the area of ​​the region enclosed by the outer contour of the welding area 414 on the tab assembly 410. It should be noted that there can be one or more welding areas 414 on a single tab assembly 410. When there are multiple welding areas 414, the area of ​​the welding area 414 is the total area of ​​all welding areas 414 on the single tab assembly 410 (usually referring to the area of ​​the region enclosing each welding area 414, that is, the area enclosed by the outer contour of the region where the weld line is located on the single tab assembly 410. The outer contour usually forms a complete rectangular region, and the area of ​​the welding area 414 can be calculated by measuring the length and width of the rectangular region).

[0073] A single tab assembly 410 refers to a tab assembly 410 that typically has a positive tab assembly and a negative tab assembly. The positive tab assembly and the negative tab assembly are respectively welded to the battery output terminal 300 of the corresponding polarity. Therefore, each tab assembly 410 (positive tab assembly and negative tab assembly) has a welding area 414 formed on it. Thus, the aforementioned ratio E% refers to the ratio of the area of ​​the welding area 414 on a single tab assembly 410 to the area of ​​the tab assembly 410 (i.e., the area of ​​the surface welded to the battery output terminal 300).

[0074] It should be noted that the area of ​​a single tab assembly 410 is measured from the root of the tab connected to the electrode assembly 420; if the tab assembly 410 is composed of multiple tabs and the areas of the tabs are not completely equal, the area of ​​the tab with the median area is taken as the area of ​​a single tab assembly 410.

[0075] An insulating component 500 is disposed between the cover plate 200 and the battery cell 400, serving both insulation and support functions. The insulating component 500 and the cover plate 200 can be fixedly connected, specifically, through at least one fixing method such as snap-fit, screw-fit, welding, or heat fusion.

[0076] The insulating component 500 is used to insulate the cell 400 from the cover plate 200, and also to insulate the terminal 310 from the lower surface (or bottom surface) of the battery casing to reduce the risk of short circuits. The insulating component 500 can be made of plastic, rubber, or other insulating materials. Plastics can be polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), polyvinyl chloride (PVC), and rubbers can be fluororubber, nitrile rubber, or isobutyl rubber, etc.

[0077] Preferably, a support block is provided on the insulating component 500 to withstand the high temperature of thermal runaway during battery thermal runaway. When the insulating component 500 melts and deforms due to high temperature, it supports the battery cell 400, preventing the battery cell 400 from being pushed towards the explosion-proof valve by high-pressure gas and ultimately pressing against the explosion-proof valve, causing blockage and affecting the pressure relief efficiency. The support block is made of any one or more of the following materials: phenolic molding compound, ceramic, mica, stainless steel, aluminum alloy, nickel-based alloy, or titanium alloy.

[0078] In this embodiment, the rated capacity of the sodium-ion battery is V (Ah). The insulating member 500 includes an insulating member body 520 and a protrusion 510 formed by connecting the insulating member body 520 and protruding toward the cell 400. A gas-retaining groove is formed between the protrusion 510 and the insulating member body 520. The provision of the gas-retaining groove increases the internal gas storage space of the battery and improves the safety of battery use.

[0079] The thickness of the insulating body 520 ranges from 0.6mm to 3mm. For example, the thickness can be 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3mm, etc. This embodiment does not limit the specific value of the thickness; those skilled in the art can select a value within the range of 0.6mm to 3mm according to their needs.

[0080] In this embodiment, the thickness of the insulating body 520 is selected within the range of 0.6mm-3mm, which can ensure the connection strength with the cover plate 200, while avoiding the problem of insufficient internal gas storage space caused by the insulating body 520 being too thick.

[0081] Along a direction perpendicular to the plane containing the largest surface of the cover plate 200 (i.e., the height direction of the battery), the protrusion 510 extends out of the insulating body 520 by a length of H (mm). In other words, along a direction perpendicular to the large surface of the cover plate 200, the minimum distance between the end face of the protrusion 510 facing the cell 400 and the surface of the insulating body 520 facing the cell 400 is H (mm). The protrusion 510 extends out of the insulating body 520, providing additional gas storage space in the space formed by the protrusion 510 and the insulating body 520. This space can accommodate more gases (such as hydrogen and carbon dioxide) generated by side reactions in the cell, thereby effectively slowing down the rate of pressure rise inside the casing and reducing the risk of bulging and plastic deformation of the casing 100.

[0082] In this embodiment, the protrusion 510 protrudes from the insulation body 520. The composite parameter H×E / V, which is the ratio of the area of ​​the welding area 414 to the area of ​​a single tab assembly 410, and the rated capacity V (Ah) of the sodium-ion battery, is limited to a specific range, namely, the range of H×E / V is 1.60×10. -2 -265.85×10 -2 .

[0083] In this embodiment, the range of H×E / V is 1.60×10 -2 -265.85×10 -2 For example, H×E / V can be 1.60×10. -2 2.22×10 -2 3.43×10 -2 4.7×10 -2 8.2×10 -2 15.73×10 -2 20.48×10 -2 23.97×10 -2 34.67×10 -2 39.35×10 -2 46.25×10 -2 52.69×10 -2 58.23×10 -2 69.99×10 -2 77.10×10 -2 89.01×10 -2 95.97×10 -2 103.42×10 -2 114.85×10 -2 118.35×10 -2 134.48×10 -2 159.96×10 -2 166.91×10 -2 178.67×10 -2 191.35×10 -2 204.04×10 -2 209.22×10 -2 228.10×10 -2 247.29×10 -2 257.73×10 -2 265.85×10 -2"etc." can also be any range formed by any two of the above values. This embodiment does not limit the specific value of H×E / V; those skilled in the art can use values ​​such as 1.60×10 as needed. -2 -265.85×10 -2 Choose from the range.

[0084] In this embodiment, by providing a protrusion 510 that protrudes beyond the insulating body 520, a gap is formed between the protrusion 510 and the insulating body 520. This gap can form a gas storage space, thereby increasing the gas storage space of the sodium-ion battery and reducing the internal pressure of the casing. It should be noted that H cannot be increased indefinitely; otherwise, the length of the free section of the tab assembly 410 from the lead-out point of the cell 400 to the welding area 414 will increase. When installing the cover plate 200, the excessively long free section of the tab is prone to bending and inverting into the electrode assembly 420 of the cell 400, resulting in a direct short circuit between the positive and negative electrodes.

[0085] Increasing the area percentage of the welding area 414 (hereinafter referred to as the area percentage of the welding area 414) can improve the overcurrent capacity at the connection between the tab assembly 410 and the battery output terminal 300, reduce Joule heating at this point, and thus reduce gas generation caused by local overheating from the source. However, the area percentage of the welding area 414, E%, should not be too large. An excessively large welding area means that the total heat input during welding is higher, and it is easier to conduct heat to the separator inside the cell 400, causing the separator to shrink and also triggering an internal short circuit.

[0086] Therefore, this embodiment achieves synergistic optimization of battery gas production (which is pressure-related) and short-circuit risk by controlling H×E / V within a reasonable range.

[0087] The sodium-ion battery disclosed in this application optimizes the length H (mm) of the protrusion 510 protruding from the insulating body 520, the ratio E% of the area of ​​the welding area 414 to the area of ​​a single electrode assembly 410, and the rated capacity V (Ah) of the sodium-ion battery, so that the composite parameter H×E / V is at 1.60×10. -2 -265.85×10 -2Within this range, it can avoid problems caused by an excessively small H (mm) (i.e., the length dimension of the protrusion 510 protruding from the insulating body 520 through optimization) due to an excessively small H×E / V, and / or an excessively small E% (i.e., the ratio of the area of ​​the welding area 414 to the area of ​​a single tab assembly 410), and / or an excessively large V (Ah) (the rated capacity of the sodium-ion battery). This avoids the problem of insufficient gas storage space in the sodium-ion battery due to an excessively small H, resulting in a rapid increase in pressure inside the casing 100 when the sodium-ion battery produces gas, leading to abnormal valve opening and pressure relief. It also avoids the problem of insufficient current overcurrent performance due to an excessively small E, leading to severe heat generation in the sodium-ion battery, which in turn leads to severe gas generation and deformation of the casing 100. Furthermore, it avoids the problem of excessively large V, resulting in a large amount of gas generation in the sodium-ion battery, which easily causes deformation of the casing 100.

[0088] In this embodiment, problems caused by excessively large H×E / V, resulting in excessively large H (mm) (i.e., the length dimension of the protrusion 510 protruding from the insulating body 520), and / or excessively large E% (i.e., the ratio of the area of ​​the welding area 414 to the area of ​​a single tab assembly 410), and / or excessively small V (Ah) (the rated capacity of the sodium-ion battery), can be avoided. Specifically, excessively large H would result in a large distance between the cover plate and the electrode assembly 420, leading to a larger size for the tab assembly 410 to be extended from the electrode assembly 420, and an excessively large free section of the tab (the portion from the root of the tab assembly 410 to the welding area 414), making it easy for the tab assembly 410 to be inserted backwards into the electrode assembly 420 of the cell, causing a short circuit due to positive and negative electrode overlap. Excessively large E would also prevent excessive heat generation during welding, causing the cell's separator to shrink due to heat, leading to overlap of the positive and negative electrodes of the electrode assembly 420 and increasing the risk of a short circuit. It can also avoid the problem of sodium-ion batteries having too low energy density due to an excessively small V.

[0089] In this application embodiment, H×E / V is 1.60×10 -2 -265.85×10 -2 Choosing within a certain range can avoid the problems of excessive gas production in the battery and rapid pressure increase rate in the casing 100 due to an excessively small H×E / V, resulting in severe deformation of the casing 100; it can also avoid the problems of low energy density and high risk of short circuit between positive and negative electrodes due to an excessively large H×E / V.

[0090] Preferably, the range of H×E / V can be 8.2×10. -2 -118.35×10 -2 For example, H×E / V can be 8.2×10. -2 16.07×10 -2 23.94×10 -231.8×10 -2 39.67×10 -2 47.54×10 -2 55.41×10 -2 63.27×10 -2 71.14×10 -2 79.01×10 -2 86.88×10 -2 94.75×10 -2 102.61×10 -2 110.48×10 -2 118.35×10 -2 "etc." can also be any range formed by any two of the above values. This embodiment does not limit the specific value of H×E / V; those skilled in the art can adjust it according to their needs, such as 8.2×10. -2 -118.35×10 -2 Choose from the range.

[0091] When H×E / V meets the above-mentioned preferred range, the deformation of the casing 100 can be further reduced, and the short-circuit risk of positive and negative electrode connection can be significantly reduced. In a specific embodiment of this application, the range of H is 1-5. For example, H can be 1.0, 1.1, 1.2, 1.4, 1.5, 1.7, 1.8, 2, 2.3, 2.6, 3, 3.3, 3.4, 3.5, 3.7, 3.8, 4, 4.1, 4.4, 4.6, 4.8, 5.0, etc., or it can be any range formed by any two of the above values. This embodiment does not limit the specific value of H, and those skilled in the art can select it within the range of 1-5 according to their needs.

[0092] In this embodiment, H is selected within the range of 1-5. This avoids the problem that if H is too small, the gas storage space of the sodium-ion battery will be insufficient, and the pressure inside the casing 100 will increase rapidly when the sodium-ion battery produces gas, leading to abnormal valve opening and pressure leakage. It also avoids the problem that if H is too large, the distance between the cover plate and the electrode assembly 420 will be too large, resulting in a larger size of the tab assembly 410 leading out of the electrode assembly 420. This would make the free section of the tab (the part from the root of the tab assembly 410 to the welding area 414) too large, making it easy for the tab assembly 410 to be inserted backward into the electrode assembly 420 of the cell, resulting in a short circuit between the positive and negative electrodes.

[0093] Preferably, the preferred range for H is 1.5-3.8. For example, H can be 1.5, 1.7, 1.9, 2.1, 2.3, 2.5, 2.7, 2.9, 3.1, 3.3, 3.5, 3.7, 3.8, or any range formed by any two of the above values. This embodiment does not limit the specific value of H; those skilled in the art can select a value within the range of 1.5-3.8 according to their needs.

[0094] When H meets the above preferred range, it can further improve the situation of abnormal valve opening and pressure relief of the battery, and at the same time, significantly improve the problem of short circuit between positive and negative electrodes.

[0095] In a specific embodiment of this application, the range of E is 2.04-33.33. Exemplarily, E can be 2.04, 2.59, 4.08, 5.83, 6.67, 8.2, 8.75, 10.46, 10.98, 13.34, 15.2, 17.69, 18.97, 19.92, 20.38, 21.17, 21.48, 22.59, 23.67, 24.6, 27.75, 28.86, 30.21, 31.10, 33.33, etc., or it can be any interval formed by any two of the above values. This embodiment does not limit the specific value of E; those skilled in the art can select it within the range of 2.04-33.33 according to their needs.

[0096] In this embodiment, E is selected within the range of 2.04-33.33. This avoids the problem that if E is too small, the current overcurrent performance will be insufficient, leading to severe heat generation in the sodium-ion battery, which in turn will cause severe gas generation in the sodium-ion battery and deformation of the casing 100. It also avoids the problem that if E is too large, excessive heat will be generated during welding, causing the separator of the cell to shrink due to heat, resulting in the positive and negative electrode plates of the electrode assembly 420 overlapping and increasing the risk of short circuit.

[0097] In one specific embodiment of this application, the area of ​​the welding zone 414 ranges from 17.27 mm. 2 -150mm 2 For example, the area of ​​the weld zone 414 can be 17.27 mm². 2 27.0mm 2 36.7mm 2 46.5mm 2 56.2mm 2 66.0mm 2 75.7mm 2 85.5mm 2 95.2mm 2 105.0mm 2 114.7mm 2124.5mm 2 134.2mm 2 144.0mm 2 150.0mm 2 "etc." can also be a range formed by any two of the above values. This embodiment does not limit the specific value of the area of ​​the welding zone 414; those skilled in the art can determine the value based on requirements, such as 17.27 mm. 2 -150mm 2 Choose from the range.

[0098] It should be noted that when the tab assembly 410 is welded to the adapter piece, the area of ​​the welding area 414 is 45mm. 2 -150mm 2 When the tab assembly 410 is directly welded to the terminal post 310, the area of ​​the welding zone 414 is 17.27 mm². 2 -78.5mm 2 .

[0099] In one specific embodiment of this application, the area of ​​a single tab assembly 410 is 450 mm². 2 -2200mm 2 For example, the area of ​​a single tab assembly 410 can be 450 mm². 2 575 mm 2 700 mm 2 825 mm 2 950 mm 2 1075 mm 2 1200 mm 2 1325 mm 2 1450 mm 2 1575 mm 2 1700 mm 2 1825 mm 2 1950 mm 2 2075 mm 2 2200 mm 2 "etc." can also be a range formed by any two of the above values. This embodiment does not limit the specific value of the area of ​​a single tab assembly 410; those skilled in the art can determine the appropriate value based on requirements, such as 450 mm². 2 -2200mm 2 Choose from the range.

[0100] When the tab assembly 410 is rectangular, its width ranges from 22.5mm to 55mm. For example, the width of the tab assembly 410 can be 22.5mm, 25.0mm, 27.5mm, 30.0mm, 32.5mm, 35.0mm, 37.5mm, 40.0mm, 42.5mm, 45.0mm, 47.5mm, 50.0mm, 52.5mm, 55.0mm, etc., or it can be a range formed by any two of the above values. This embodiment does not limit the specific value of the width of the tab assembly 410; those skilled in the art can select a value within the range of 22.5mm to 55mm according to their needs.

[0101] When the tab assembly 410 is rectangular, its height ranges from 20mm to 40mm. For example, the height of the tab assembly 410 can be 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, 29mm, 30mm, 31mm, 32mm, 33mm, 34mm, 35mm, 36mm, 37mm, 38mm, 39mm, 40mm, etc., or it can be a range formed by any two of the above values. This embodiment does not limit the specific value of the height of the tab assembly 410; those skilled in the art can select a value within the 20mm-40mm range according to their needs.

[0102] When the tab assembly 410 is trapezoidal, the width of the root of the tab assembly 410 (i.e., the end closest to the electrode body) ranges from 25mm to 60mm. For example, the root width of the tab assembly 410 can be 25mm, 27.5mm, 30mm, 32.5mm, 35mm, 37.5mm, 40mm, 42.5mm, 45mm, 47.5mm, 50mm, 52.5mm, 55mm, 57.5mm, 60mm, etc., or it can be a range formed by any two of the above values. This embodiment does not limit the specific value of the root width of the tab assembly 410; those skilled in the art can select a value within the range of 25mm-60mm according to their needs.

[0103] When the tab assembly 410 is trapezoidal, the width of the top of the tab assembly 410 (i.e., the end furthest from the electrode body) ranges from 20mm to 50mm. For example, the root width of the tab assembly 410 can be 20mm, 23mm, 26mm, 30mm, 33mm, 37mm, 40mm, 43mm, 46mm, 50mm, etc., or it can be a range formed by any two of the above values. This embodiment does not limit the specific value of the top width of the tab assembly 410; those skilled in the art can select a value within the range of 20mm-50mm according to their needs.

[0104] It should be noted that when the tab assembly 410 is trapezoidal, the top width of the tab assembly 410 is smaller than the root width of the tab assembly 410. When a trapezoidal tab is used, the tab is less prone to wrinkling during the manufacturing process. At the same time, the wider root of the tab connecting the tab assembly 410 to the electrode sheet allows for higher current transfer efficiency between the electrode sheet and the tab assembly 410, reducing the battery's internal resistance. This reduces heat generation during battery charging and discharging, thereby reducing gas production in sodium-ion batteries.

[0105] When the tab assembly 410 is trapezoidal, its height ranges from 20mm to 40mm. For example, the height of the tab assembly 410 can be 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, 29mm, 30mm, 31mm, 32mm, 33mm, 34mm, 35mm, 36mm, 37mm, 38mm, 39mm, 40mm, etc., or it can be a range formed by any two of the above values. This embodiment does not limit the specific value of the height of the tab assembly 410; those skilled in the art can select a value within the 20mm-40mm range according to their needs.

[0106] Preferably, the preferred range for E is 8.2-24.6. For example, E can be 8.2, 10.0, 11.8, 13.7, 15.5, 17.3, 19.1, 21.0, 22.8, 24.6, etc., or any interval formed by any two of the above values. This embodiment does not limit the specific value of E; those skilled in the art can select from the range of 8.2-24.6 according to their needs.

[0107] When E meets the above preferred range, it can further improve the problem of severe heat generation caused by insufficient overcurrent performance and reduce the problem of severe gas generation caused by heat generation; at the same time, it can significantly improve the problem of excessive heat generation during welding, which causes the separator of the battery cell to shrink due to heat and causes the positive and negative electrode plates of the electrode assembly 420 to overlap.

[0108] In a specific embodiment of this application, V ranges from 50 to 202. Exemplarily, V can be 50, 56, 60, 62, 68, 71, 75, 80, 83, 88, 93, 99, 108, 114, 128, 133, 142, 150, 159, 179, 184, 188, 191, 202, etc., or it can be any range formed by any two of the above values. This embodiment does not limit the specific value of V; those skilled in the art can select it within the range of 50-202 according to their needs.

[0109] In this embodiment, V is selected within the range of 50-202. This avoids the problem that if V is too large, the sodium-ion battery will produce a large amount of gas, which may easily cause the casing to deform. It also avoids the problem that if V is too small, the energy density of the sodium-ion battery will be too low.

[0110] Preferably, the preferred range for V is 75-150. For example, V can be 75, 80, 83, 85, 88, 90, 93, 95, 99, 100, 105, 108, 110, 114, 115, 120, 125, 128, 130, 133, 135, 140, 142, 145, 150, etc., or any range formed by any two of the above values. This embodiment does not limit the specific value of V; those skilled in the art can select it within the range of 75-150 according to their needs.

[0111] When V meets the above preferred range, the problem of large gas production in sodium-ion batteries can be further improved while ensuring the energy density of sodium-ion batteries.

[0112] like Figures 6-9 As shown in a specific embodiment of this application, the large surface of the cover plate 200 is rectangular, with long and short sides that are perpendicular to each other. At least a portion of the first side of the insulating body 520 (i.e., the side closest to the long side of the large surface of the cover plate 200) has a protrusion 510. It should be noted that "rectangular" is a broad definition; the long and short sides of the large surface of the cover plate 200 can be connected at right angles, or they can be connected by a rounded corner.

[0113] In this embodiment, the protrusion 510 is mainly located on the long side near the cover plate 200, so that the protrusion 510 has a larger installation space. When the battery cell expands, it can press down a larger area of ​​the battery cell, preventing the battery cell from expanding excessively and squeezing the gas storage space, and reducing the pressure inside the casing.

[0114] Furthermore, at least a portion of the second side of the insulating body 520 (i.e., the side with the shorter side closer to the larger surface of the cover plate 200) is also formed with a protrusion 510. The protrusion 510 can extend continuously from the first side to the second side of the insulating body 520, covering the corner area where the first and second sides of the insulating body 520 meet.

[0115] By only placing the protrusion 510 on the first side of the insulating body 520 (i.e., the long side near the large surface of the cover plate 200), the protrusion 510 is at greater risk of deformation. In this embodiment, by also providing the protrusion 510 on the second side of the insulating body 520 (i.e., the short side near the large surface of the cover plate 200), a more continuous support structure is formed along the edge of the insulating component 500, thereby creating a more stable gas storage space. This allows for more even absorption and distribution of pressure inside the shell, avoiding localized pressure concentration. Furthermore, corners are typically stress concentration areas; providing the protrusion 510 at these locations further enhances the deformation resistance of the insulating component 500.

[0116] In one specific embodiment of this application, along the direction perpendicular to the large surface of the cover plate 200, the height of the protrusion 510 on the first side of the insulating body 520 is greater than the height of at least a portion of the protrusion 510 on the second side of the insulating body 520. This arrangement improves the structural strength of the protrusion 510 while ensuring adequate venting space inside the battery, allowing gas located between the cell 400 and the casing 100 to be quickly stored in the receiving groove.

[0117] In one specific embodiment of this application, the protrusion 510 includes at least two parts. For ease of understanding, these at least two protrusions 510 are defined as the first protrusion and the second protrusion. The first protrusion and the second protrusion are respectively disposed on opposite sides of the long side of the large surface of the cover plate 200. That is, along the extension direction of the long side, one of the first protrusion and the second protrusion is disposed near one end of the long side, and the other is disposed near the other end of the long side. This arrangement can form a more stable support. The gas expansion in the middle of the battery cell 400 is large. The first protrusion and the second protrusion respectively support the edge of the long side of the large surface of the cover plate 200, and the gas is stored in the middle, which improves the structural strength of the protrusion 510, prevents the protrusion 510 from being crushed during vibration, and ensures a reliable gas storage space.

[0118] Furthermore, the first and second protrusions are arranged symmetrically, meaning that the first and second protrusions have the same axial structure and are symmetrical along the midline of the long side of the large surface of the cover plate 200. The symmetrical structure of the first and second protrusions provides reliable support. It should be noted that the first and second protrusions can also adopt non-axially symmetrical structures; this embodiment does not limit the arrangement of the first and second protrusions.

[0119] In one specific embodiment of this application, the protrusion 510 and the edge of the long side of the large surface of the cover plate 200 are spaced apart, and the spacing ranges from 1.5mm to 5.2mm. For example, the spacing can be 1.5mm, 1.8mm, 2.1mm, 2.4mm, 2.7mm, 3.0mm, 3.3mm, 3.6mm, 3.9mm, 4.2mm, 4.5mm, 4.8mm, 5.1mm, 5.2mm, etc., or it can be a range formed by any two of the above values. This embodiment does not limit the specific value of the spacing; those skilled in the art can select a value within the range of 1.5mm to 5.2mm according to their needs.

[0120] In this embodiment, by designing the protrusion 510 to be spaced apart from the long edge of the large surface of the cover plate 200, the gas between the cell 400 and the housing 100 can also be stored through the space (the space between the protrusion 510 and the cover plate 200), avoiding the accumulation of gas between the cell 400 and the housing 100. In particular, the large surface of the housing is prone to expansion, and the internal gas will continue to accumulate, making the bonding wire between the housing 100 and the cover plate 200 prone to cracking.

[0121] In this embodiment, the aforementioned spacing is selected within the range of 1.5mm-5.2mm. This avoids the situation where the protrusion 510 is too close to the weld line between the housing 100 and the cover plate 200 due to an excessively small spacing. This would cause the heat during welding to affect the insulating body 520, resulting in melting and deformation of the insulating body 520 and affecting the internal insulation performance of the battery. At the same time, it reduces the space available for gas storage, increases the risk of cracking of the weld line between the cover plate 200 and the housing 100, and causes stress concentration in the protrusion 510, making it prone to collapse. It also avoids the problem that an excessively large spacing would limit the size of the accommodating groove, leading to an increased risk of cracking of the weld line between the cover plate 200 and the housing 100.

[0122] In one specific embodiment of this application, the electrode assembly 420 includes an electrode body and a separator. The electrode body includes a first polarity electrode and a second polarity electrode with opposite polarities. That is, one of the first polarity electrode and the second polarity electrode is a positive electrode, and the other is a negative electrode. The first polarity electrode and the second polarity electrode are separated by the separator.

[0123] A separator is disposed between the positive and negative electrode plates to separate them and prevent short circuits caused by contact. The separator can be at least one of glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride (PVDF). A coating can also be applied to the surface of the separator. This coating can be an inorganic coating and / or an organic coating. The inorganic coating material includes at least one of alumina, silicon dioxide, titanium dioxide, magnesium oxide, zirconium oxide, and boehmite; the organic coating includes at least one of aramid coating and polyvinylidene fluoride (PVDF) coating.

[0124] The first polarity electrode, the second polarity electrode, and the separator can be fabricated by lamination or winding. The protrusion 510 (on the side closest to the electrode body) is spaced apart from the electrode body (on the side closest to the cover plate 200), with a minimum spacing ranging from 2mm to 6mm. It should be noted that the protrusion 510 is allowed to press against the separator of the electrode assembly 420.

[0125] For example, the minimum interval distance mentioned above can be 2mm, 3mm, 4mm, 5mm, 6mm, etc., or it can be a range formed by any two of the above values. This embodiment does not limit the specific value of the minimum distance mentioned above, and those skilled in the art can select it within the range of 2mm-6mm according to their needs.

[0126] The protrusion 510 is spaced apart from the electrode body, with the distance maintained within the range of 2mm-6mm. This spacing provides space for the expansion of the cell 400 during cycling, preventing the protrusion 510 from directly compressing the electrode body and causing the active materials of the first and second polar electrodes to detach or become structurally damaged. This embodiment provides gas storage while avoiding mechanical damage to the cell 400, ensuring the structural integrity and electrochemical performance of the cell 400.

[0127] This embodiment maintains the minimum spacing distance within the range of 2mm-6mm. This avoids the problem of interference with the electrode assembly due to the minimum spacing distance being too small, which could cause the electrode assembly to be squeezed, the active material on the electrode assembly to fall off, and the gas storage space to be squeezed. It also avoids the problem of the battery having an excessively large internal cavity due to the minimum spacing distance being too large, which could lead to poor battery energy density.

[0128] In one specific embodiment of this application, on the side facing the cover plate 200 (i.e., the top of the cell 400), the separator extends beyond the edge of the electrode body (the first polarity electrode and the second polarity electrode). That is, the separator extends beyond the electrode body on the side facing the cover plate 200, meaning that after both the separator and the electrode body are flattened towards the cover plate 200, the separator is closer to the cover plate 200.

[0129] In this embodiment, the length of the separator extending beyond the electrode body ranges from 1mm to 5mm. For example, the aforementioned length can be 1mm, 2mm, 3mm, 4mm, 5mm, or any range formed by any two of these values. This embodiment does not limit the specific value of the aforementioned length; those skilled in the art can select a value within the 1mm-5mm range according to their needs.

[0130] The portion of the separator extending beyond the electrode body may be slightly compressed during assembly, serving as insulation and buffering. When there is a gap between the protrusion 510 and the electrode body, this extended portion of the separator can better fill the gap, enhancing top insulation. This further improves the insulation reliability between the cover plate 200 and the electrode body, as well as the insulation reliability between the first polarity electrode and the second polarity electrode. Even when the separator has a certain circumference during the formation of the welding area 414, it can maintain the insulation between the first polarity electrode and the second polarity electrode, preventing short circuits due to contact between the first polarity electrode and the second polarity electrode.

[0131] Furthermore, along the arrangement direction of the cover plate 200 and the cell 400, at least a portion of the separator extending beyond the electrode extends into the gap area between the protrusion 510 and the insulating body 520.

[0132] The separator is typically thin and flexible, allowing it to conform to the shape of the protrusion 510. When the top of the cell 400 is subjected to pressure from the protrusion 510, this portion of the separator can be compressed into the space surrounding the protrusion 510. This embodiment makes full use of the space around the protrusion 510 that might otherwise be unused, providing more flexibility for the arrangement and compression of the separator, thus increasing the utilization rate of the battery's internal space.

[0133] In one specific embodiment of this application, along the direction of the large surface of the parallel cover plate 200, the protrusion 510 and the inner wall of the housing 100 are spaced apart, and the minimum distance between them ranges from 1.5mm to 5mm. For example, the minimum distance can be 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm, 5.0mm, etc., or it can be a range formed by any two of the above values. This embodiment does not limit the specific value of the minimum distance; those skilled in the art can select within the range of 1.5mm to 5mm according to their needs.

[0134] In this embodiment, the minimum distance between the protrusion 510 and the inner wall of the housing 100 is selected within the range of 1.5mm-5mm. This ensures sufficient heat insulation distance between the protrusion 510 and the housing 100, while allowing gas to flow between the inner wall of the housing 100 and the protrusion 510, resulting in a more balanced pressure distribution. This eliminates the problem of high-temperature deformation or even melting of the protrusion 510 during welding of the cover plate 200 due to excessively high temperature of the housing 100 caused by the lower protrusion 510 contacting the housing 100. Furthermore, the aforementioned spacing ensures the connectivity between the gas storage space and the battery body space, while also avoiding the problem of low space utilization caused by excessively large spacing.

[0135] In a specific embodiment of this application, the orthographic projection of the protrusion 510 onto the plane containing the large surface of the cover plate 200 is defined as the protrusion projection, and the orthographic projection of the insulating body 520 onto the plane containing the large surface of the cover plate 200 is defined as the body projection. The ratio of the area of ​​the protrusion projection to the area of ​​the body projection ranges from 0.04 to 0.5. For example, the above ratio can be 0.04, 0.08, 0.12, 0.16, 0.20, 0.24, 0.28, 0.32, 0.36, 0.40, 0.44, 0.48, 0.5, etc., or it can be a range formed by any two of the above values. This embodiment does not limit the specific value of the above ratio, and those skilled in the art can select it within the range of 0.04-0.5 according to their needs.

[0136] The ratio of the projected area of ​​the protrusion to the projected area of ​​the main body reflects the proportion of the gas storage space on the plane. In this embodiment, the ratio of the projected area of ​​the protrusion to the projected area of ​​the main body is selected within the range of 0.04-0.5. This avoids the problem that if the ratio is too small, the supporting force of the protrusion 510 will be insufficient, resulting in a large upward expansion of the battery cell and squeezing the gas storage space; it also avoids the problem that if the ratio is too large, the protrusion 510 will occupy too much gas storage space. By limiting the above ratio, the effectiveness of the gas storage space can be maximized while ensuring the overall mechanical strength of the insulating component 500.

[0137] In one specific embodiment of this application, the tab assembly 410 extends from the top of the electrode assembly 420 (towards the cover plate 200). At least a portion of the protrusion 510 is located between the tab assembly 410 and the inner wall of the housing 100. The protrusion 510 acts as an insulating barrier here. It physically separates the metal tab assembly 410 from the metal housing 100, effectively preventing short circuits caused by the tab assembly 410 and the housing 100 contacting each other in a vibrating environment or after the cell expands, thus improving the insulation safety of the sodium-ion battery.

[0138] In one specific embodiment of this application, the large surface of the cover plate 200 is rectangular. Along the length of the large surface of the cover plate 200, at least one end of the protrusion 510 extends beyond the edge of the tab assembly 410. It should be noted that one end of the protrusion 510 may extend beyond the corresponding edge of the tab assembly 410, or both ends of the protrusion 510 may extend beyond the corresponding edges of the tab assembly 410.

[0139] Taking the length direction of the large surface of the cover plate 200 as the left and right direction as an example, the left end of the protrusion 510 can be designed to extend beyond the left edge of the tab assembly 410, or the right end of the protrusion 510 can be designed to extend beyond the right edge of the tab assembly 410; or the left end of the protrusion 510 can be designed to extend beyond the left edge of the tab assembly 410, and the right end of the protrusion 510 can be designed to extend beyond the right edge of the tab assembly 410.

[0140] In this embodiment, the tab assembly 410 is provided with more comprehensive lateral insulation protection. Even if the tab assembly 410 is displaced in the length direction or there are manufacturing tolerances, the protrusion 510 can still ensure that it is located between the tab assembly 410 and the long side wall of the housing 100, maintaining a reliable insulation barrier.

[0141] like Figure 5 As shown in a specific embodiment of this application, the electrode assembly 410 includes a first electrode portion 411, a bent electrode portion 413, and a second electrode portion 412 connected in sequence. One end of the first electrode portion 411 extends from the electrode assembly 420 of the battery cell 400. The second electrode portion 412 is welded to the battery output terminal 300 to form a welding area 414. The bent electrode portion 413 is arranged closer to the protrusion 510 than the first electrode portion 411 and the second electrode portion 412.

[0142] In this embodiment, by designing the tab assembly 410 as a bent structure, the wiring path of the tab assembly 410 can be flexibly adjusted. This allows the tab assembly 410 to be arranged in a more compact path from the lead-out point of the electrode assembly 420 of the cell 400 to the solder point, helping to reduce the risk of the tab assembly 410 being inserted backwards into the electrode assembly 420 due to vibration. The bent tab portion 413 is close to the protrusion 510, which optimizes the bending layout and prevents the bent tab portion 413 from extending away from the protrusion 510, thus preventing short circuits.

[0143] In one specific embodiment of this application, along the arrangement direction of the cover plate 200 and the battery cell 400 (the height direction of normal battery placement), the bending point (i.e., the apex of the bend) of the bent tab 413 is higher than the target end face of the protrusion 510 (i.e., the end face of the protrusion 510 facing the electrode assembly 420 of the battery cell 400). That is, the bending point of the bent tab 413 is closer to the cover plate 200 than the target end face of the protrusion 510.

[0144] In this embodiment, the bending point of the bent tab 413 closest to the protrusion 510 after bending is ensured to be at a higher level, so as to avoid contact or friction between the bent tab 413 and the protrusion 510, thus ensuring the insulation effect between the tab assembly 410 and the housing 100 and further eliminating potential short circuit hazards.

[0145] In one specific embodiment of this application, the protrusion 510 includes a bottom wall (i.e., the surface facing the battery cell) and a side wall. The bottom wall of the protrusion 510 is connected to the insulating body 520 through the side wall of the protrusion 510. The bottom wall and / or side wall of the protrusion 510 are provided with through holes that extend through the wall thickness. The through holes on the bottom wall and / or side wall of the protrusion 510 can all serve as gas storage spaces, thereby increasing the gas storage space of the sodium-ion battery and reducing the pressure inside the casing.

[0146] Furthermore, the through holes opened on the bottom wall and / or side wall of the protrusion 510 are connected to the receiving groove, so that the gas in the receiving groove can enter the through holes, and the gas in the through holes can also quickly reach the receiving groove, reducing the local pressure inside the battery.

[0147] In one specific embodiment of this application, a first through hole 210 is provided on the cover plate 200 facing the battery cell 400. At least a portion of the structure of the battery output terminal 300 (such as the lower end of the terminal post 310) extends into the first through hole 210. The battery output terminal 300 may include the terminal post 310 and the adapter piece 320, or it may only include the terminal post 310, as long as a portion of its structure can extend into the first through hole 210.

[0148] The welding point or electrical connection point between the battery output terminal 300 and the tab assembly 410 is moved down through the first through hole 210. Specifically, the welding area 414 can be set at a position closer to the electrode assembly 420 than the cover plate 200.

[0149] This design shortens the distance from the lead-out point of the electrode assembly 420 of the cell 400 to the welding point of the tab assembly 410, thereby shortening the length of the free section of the tab. This directly reduces the risk of the tab assembly 410 swinging significantly and being inserted upside down during vibration, thus improving structural reliability.

[0150] Specifically, the welding position (i.e., welding area 414) between the battery output terminal 300 and the tab assembly 410 can be set inside the first through hole 210, or it can extend beyond the first through hole 210 and be directly arranged between the cover plate 200 and the electrode assembly 420 of the cell 400.

[0151] In one specific embodiment of this application, a second through hole 530 is correspondingly formed on the insulating member 500. A portion of the structure of the battery output terminal 300 extends further into the second through hole 530. Specifically, the welding area 414 can be positioned closer to the electrode assembly 420 than the insulating member body 520. The second through hole 530 cooperates with the first through hole 210 to provide a continuous channel for the downward extension of the battery output terminal 300, making the connection path of the electrode assembly 410 shorter and more direct. Simultaneously, it avoids interference from the insulating member 500 itself with the downward extension of the battery output terminal 300, providing structural assurance for achieving a shorter path design for the electrode assembly 410.

[0152] Specifically, the welding position (i.e., welding area 414) between the battery output terminal 300 and the tab assembly 410 can be set inside the second through hole 530, or it can extend beyond the second through hole 530 and be directly arranged between the insulating component 500 and the electrode assembly 420 of the cell 400.

[0153] like Figure 5 As shown in a specific embodiment of this application, the battery output terminal 300 includes a terminal post 310. The tab assembly 410 extends from the top of the cell 400 and is directly welded to the target end face of the terminal post 310 (i.e., the end face of the terminal post 310 facing the cell 400). In this embodiment, the direct connection of the tab assembly 410 to the terminal post 310 results in a shorter current transmission path, lower connection resistance, and reduced heat generation at the connection point, thereby indirectly reducing gas generation. Simultaneously, this structure typically allows for a shorter free section of the tab.

[0154] In one specific embodiment of this application, the welding area 414 is located on the target end face of the pole post 310, and the ratio of the area of ​​the welding area 414 to the area of ​​the target end face of the pole post 310 ranges from 0.25 to 0.64. For example, the above ratio can be 0.25, 0.28, 0.31, 0.34, 0.37, 0.40, 0.43, 0.46, 0.49, 0.52, 0.55, 0.58, 0.61, 0.64, etc., or it can be any range formed by any two of the above values. This embodiment does not limit the specific value of the above ratio; those skilled in the art can select a value within the range of 0.25-0.64 according to their needs.

[0155] In this embodiment, the ratio is selected within the range of 0.25-0.64 to ensure sufficient welding area for achieving a low-resistance, high-current-capacity connection. This avoids the problem of poor current-capacity and severe battery heat generation caused by an excessively small ratio. At the same time, it also avoids the problem of thermal damage to the cell 400 or separator below the terminal post 310 caused by an excessively large ratio (excessive welding area, requiring greater welding energy).

[0156] In a specific embodiment of this application, along the arrangement direction of the cover plate 200 and the cell 400, the distance from the target end face of the pole post 310 to the electrode assembly 420 of the cell 400 (for ease of understanding, this distance is defined as the first distance) is greater than or equal to the distance from the target end face of the insulating body 520 (the target end face of the insulating body 520 is the end face facing the electrode assembly 420) to the top electrode of the cell 400 (for ease of understanding, this distance is defined as the second distance).

[0157] In this embodiment, the first distance is greater than or equal to the second distance, that is, the lower end face of the pole post 310 is not lower than the lower end face of the insulating body 520. This arrangement ensures that the gas storage space between the cover plate 200 and the cell 400 is not excessively encroached upon by the pole post 310, and the gas storage space volume is maximized.

[0158] like Figure 4 As shown in a specific embodiment of this application, the battery output terminal 300 includes a terminal post 310 and an adapter piece 320. One end of the adapter piece 320 is used to electrically connect to the output terminal (tab assembly 410) of the battery cell, and the other end is used to electrically connect to the output terminal (terminal post 310) of the battery, so that the tab assembly 410 and the terminal post 310 form a current conduction.

[0159] Depending on the polarity, the adapter 320 includes a positive adapter and a negative adapter.

[0160] The positive electrode adapter is used to electrically connect the positive output terminal of the cell to the positive output terminal of the battery. Multiple positive electrode tabs stacked together are welded to one end of the positive electrode adapter, and the other end of the positive electrode adapter is welded to the positive terminal of the electrode post 310.

[0161] The negative electrode adapter is used to electrically connect the negative output terminal of the cell to the negative output terminal of the battery. Multiple negative electrode tabs stacked together are welded to one end of the negative electrode adapter, and the other end of the negative electrode adapter is welded to the negative electrode of the terminal post 310.

[0162] The adapter piece 320 can be made of aluminum, copper, nickel, or an alloy (such as steel), or other conductive materials. The specific material of the adapter piece 320 is selected based on the material of the battery's terminal post 310 and tab assembly 410. Generally, the material of the adapter piece 320 must be the same as the material of the battery's tab assembly 410 and / or terminal post 310 to ensure welding quality.

[0163] Typically, the thickness of the terminal post 310 is greater than the thickness of the adapter piece 320, and the thickness of the adapter piece 320 is generally greater than the thickness of the tab assembly 410. The thickness of the adapter piece, falling between the thickness of the terminal post 310 and the tab assembly 410, is beneficial for ensuring welding quality and improving the battery's current-carrying capacity when the adapter piece is welded to both the terminal post 310 and the tab assembly 410. This also avoids the problem of poor welding results caused by excessive thickness differences between the two components being welded.

[0164] In this embodiment, the tab assembly 410 and the terminal post 310 are electrically connected via an adapter plate 320. The tab assembly 410 is welded to the adapter plate 320 to form a welding area 414, and then electrically connected to the terminal post 310 via the adapter plate 320. The tab assembly 410 can be welded to the upper surface of the adapter plate 320 (i.e., the surface facing the terminal post 310), or the tab assembly 410 can be welded to the lower surface of the adapter plate 320 (i.e., the surface away from the terminal post 310).

[0165] Along the arrangement direction of the cover plate 200 and the cell 400, at least a portion of the structure of the adapter piece 320 is located between the pole post 310 and the electrode assembly 420 of the cell 400. Simultaneously, along the arrangement direction of the cover plate 200 and the cell 400, there is an overlapping area between the adapter piece 320 and the protrusion 510.

[0166] In this embodiment, an adapter piece 320 is used, and the welding area 414 can be set on the adapter piece 320 to facilitate the electrical connection between the tab assembly 410 and the terminal post 310. The adapter piece 320 can be set closer to the top of the cell 400, so the length of the tab assembly 410 can be made very short, further shortening the free section of the tab and greatly reducing the risk of reverse insertion. The adapter piece 320 and the protrusion 510 overlap in height, meaning that the space on the side of the protrusion 510 can be used to arrange the adapter piece 320, achieving efficient space reuse.

[0167] In a specific embodiment of this application, such as Figure 3 As shown, the insulating body 520 includes an insulating main body portion 521 and an insulating recess portion 522. Typically, the insulating recess portion 522 is located at a position corresponding to the battery output terminal 300. A protrusion 510 is provided on the insulating main body portion 521. The insulating recess portion 522 is recessed towards the side opposite to the battery cell 400 (i.e., towards the cover plate 200), forming a groove structure. The wall thickness of the groove bottom wall is less than or equal to the wall thickness of the insulating main body portion 521.

[0168] While ensuring basic insulation between the insulating component 500 and the cover plate 200, additional gas storage space is created by partially recessing towards the cover plate 200. The recessed portion 522 of the insulating component allows for the formation of a larger cavity, further increasing the gas storage volume of the battery without increasing the overall height of the battery. This helps to maximize the solution of gas generation pressure problems within a limited space.

[0169] In one specific embodiment of this application, the protrusion 510 has a hollow cavity inside, and the cavity is connected to the receiving cavity. This configuration significantly increases the gas storage space it can provide without increasing the external volume and weight of the protrusion 510, thereby improving space utilization efficiency.

[0170] This embodiment does not limit the shape of the cavity or the number of cavities, but it is necessary to ensure that the cavity is connected to the receiving cavity so that the cavity can contain the gas after the cell generates gas.

[0171] like Figure 10 and Figure 11 As shown in a specific embodiment of this application, the electrode assembly 420 includes an electrode body and a separator 423. The electrode body includes a first polarity electrode 421 and a second polarity electrode 422 with opposite polarities. The first polarity electrode 421 and the second polarity electrode 422 are separated by the separator 423.

[0172] The electrode body (first polarity electrode 421 and second polarity electrode 422, where first polarity electrode 421 can be a positive electrode and second polarity electrode 422 can be a negative electrode) includes a current collector and an active material layer coated on at least one side of the current collector (e.g., ...). Figure 10 The portion shown in the cross-section on the lower middle side (which can be understood as the active material layer) is coated with an insulating adhesive layer 424 on the edge of the current collector facing the tab assembly 410. The insulating adhesive layer 424 can bond the first polarity plate 421 and the second polarity plate 422 to the separator 423, thereby preventing gaps between the first polarity plate 421 and the second polarity plate 422 and the separator 423, and preventing the tab assembly 410 from being inserted backwards between the first polarity plate 421 and the second polarity plate 422 during the installation of the cover plate, which could cause an internal short circuit.

[0173] In one specific embodiment of this application, at least a portion of the insulating adhesive layer 424 extends to the tab assembly 410. That is, the adhesive coating extends from the edge of the electrode body to a certain height on the tab assembly 410. The height of the insulating adhesive layer 424 on the tab assembly 410 is defined as follows: after flattening the tab assembly 410 along the arrangement direction of the cover plate 200 and the battery cell 400, the height of the insulating adhesive layer 424 on the tab assembly 410 along the arrangement direction of the cover plate 200 and the battery cell 400.

[0174] In this embodiment, the height of the insulating adhesive layer 424 on the tab assembly 410 is L (mm), where L ranges from 1.5 to 7.5. For example, the height of the insulating adhesive layer 424 can be 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm, 5.0mm, 5.5mm, 6.0mm, 6.5mm, 7.0mm, 7.5mm, etc., or it can be a range formed by any two of the above values. This embodiment does not limit the specific value of the height of the insulating adhesive layer 424; those skilled in the art can select a value within the range of 1.5mm to 7.5mm according to their needs.

[0175] This design protects the current collector at the base of the tab assembly 410 from electrolyte corrosion and enhances the mechanical strength of the tab base, preventing tearing. Simultaneously, a suitable height for the insulating layer 424 (i.e., the height of the insulating layer 424 on the tab assembly 410 should not be too large) prevents the insulating layer 424 from contaminating the subsequent welding area 414, ensuring welding quality. Furthermore, a suitable height for the insulating layer 424 also ensures that the tab assembly 410 has a certain degree of deformability, facilitating bending and preventing the insulating layer 424 from hardening the tab assembly 410, which would hinder deformation.

[0176] In one specific embodiment of this application, the ratio of the width dimension of the welding area 414 to the total width dimension of the tab assembly 410 along the width direction of the tab assembly 410 ranges from 0.35 to 0.9. For example, the above ratio can be 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, etc., or it can be a range formed by any two of the above values. This embodiment does not limit the specific value of the above ratio; those skilled in the art can select a value within the range of 0.35-0.9 according to their needs.

[0177] The width direction of the tab assembly 410 refers to the following: after flattening the tab assembly 410 along the arrangement direction of the cover plate 200 and the battery cell 400, the width direction of the tab assembly 410 is perpendicular to the thickness direction of the tab assembly 410 and also perpendicular to the arrangement direction of the tab assembly 410 along the cover plate 200 and the battery cell 400. The total width of the tab assembly 410 refers to the maximum width dimension along the width direction of the tab assembly 410 (since the individual tabs of the tab assembly 410 cannot be strictly aligned, the maximum width dimension is taken as the total width of the tab assembly 410). The welding area 414 can be set in the middle area along the width direction of the tab assembly 410 to ensure the current carrying capacity.

[0178] In this embodiment, the ratio of the width of the welding area 414 to the total width of the tab assembly 410 is selected within the range of 0.35-0.9, which balances the current carrying capacity and the range of the welding heat-affected zone. This avoids the problem of poor current carrying capacity and severe battery heat generation caused by the ratio being too small; it also avoids the problem of thermal damage to the electrode assembly 420 or separator 423 of the cell 400 caused by the ratio being too large (requiring greater welding energy).

[0179] In one specific embodiment of this application, the distance from the welding area 414 to the root of the tab assembly 410 (i.e., the side connected to the electrode assembly 420) ranges from 5mm to 30mm. Exemplarily, the above distance can be 5mm, 8mm, 11mm, 15mm, 18mm, 21mm, 24mm, 27mm, 30mm, etc., or it can be a range formed by any two of the above values. This embodiment does not limit the specific value of the above distance; those skilled in the art can select a value within the range of 5mm-30mm according to their needs.

[0180] It should be noted that the distance from the welding area 414 to the root of the tab assembly 410 refers to the distance between the side of the welding area 414 closest to the root of the tab assembly 410 and the root of the tab assembly 410 after the tab assembly 410 is flattened along the arrangement direction of the cover plate 200 and the cell 400.

[0181] In this embodiment, the distance from the welding area 414 to the root of the tab assembly 410 is selected within the range of 5mm-30mm. This avoids the problem that if the distance is too small, the welding capacity will be conducted to the electrode assembly 420, causing thermal damage to the electrode assembly 420 or the separator 423 of the cell 400. It also avoids the problem that if the distance is too small, the area of ​​the welding area 414 will be too small, resulting in poor current flow capacity and severe heat generation in the battery.

[0182] In a specific embodiment of this application, when the battery cell 400 has a wound structure, the protrusion 510 protrudes beyond the insulation body 520 by a length H (mm), where H ranges from 1 to 3.8. For example, H can be 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, etc., or it can be a range formed by any two of the above values. This embodiment does not limit the specific value of H; those skilled in the art can select it within the range of 1-3.8 according to their needs.

[0183] The wound cell has an arc-shaped structure around it, and there is a large gap between the wound cell and the inner wall of the housing, thus having a large gas storage space, which can reduce the length of the protruding portion 510 protruding from the insulator body 520. This arrangement can avoid the problem that when H is excessively large, the lead-out dimension of the tab assembly 410 from the pole piece assembly 420 is large, and the dimension of the free section of the tab (the portion from the root of the tab assembly 410 to the welding area 414) is excessively large, so that the tab assembly 410 is easily reversely inserted into the pole piece assembly 420 of the cell, resulting in lap short circuit between the positive electrode and the negative electrode.

[0184] In a specific embodiment of the present application, the pole piece assembly 420 comprises a positive pole piece and a negative pole piece, the positive pole piece comprises a positive current collector and a positive active material coated on at least one side of the positive current collector, and the positive active material comprises one or more of sodium transition metal oxides, polyanionic compounds and Prussian blue compounds.

[0185] The polyanionic compound comprises at least one of sodium iron phosphate-sodium iron pyrophosphate mixed phase material, sodium iron pyrophosphate, sodium vanadium phosphate, sodium iron sulfate and sodium iron fluorophosphate. The general formula can specifically be Na n M p (X a O b ) c Z w ; wherein: M comprises at least one of Ti, V, Cr, Mn, Fe, Co, Ni, Ca, Mg, Al, Nb and Zr, X comprises at least one of Si, S, P, As, B, Mo, W and Ge, Z comprises at least one of F, O, Cl and OH, 2≤n≤7, 1≤p≤4, 1≤a≤2, 1≤b≤7, 1≤c≤5, 0≤w≤3.

[0186] The general formula of the sodium transition metal oxide can specifically be: NaFe x (Ni 0.5 Mn 0.5 ) 1-x O2; wherein, in the formula: 0≤x≤0.4.

[0187] The general formula of the sodium transition metal oxide can also be Na x Mn a Fe b Ni c L d O 2-e ; wherein: 0.7<x≤1.2, a>0, b≥0, 0.1<c≤0.3, d≥0, a+b+c+d+e=1, -0.1≤e≤0.1, L comprises at least one of Cu, Li, Ti, Zr, K, Nb, Mg, Ca, Mo, Zn, Cr, W, Bi, Sn, Ge, Al, Si, La, Ta, P and B.

[0188] The general formula for Prussian blue cathode materials can be: Na x MnFe(CN)6; where: 1.5≤x≤2.

[0189] The general formula for Prussian blue cathode materials can also be A a M b M' c (CN) 6•d H2O; where: A includes alkali metal cations, alkaline earth metal cations, and Zn. 2+ Al 3+ At least one of the following, M and M' each independently include at least one of Ni ion, Cu ion, Fe ion, Mn ion, Co ion, Zn ion, H2O is coordinated water, 0 <a≤2,0<b≤1,0<c≤1,0≤d≤2。

[0190] In one specific embodiment of this application, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material coated on at least one side of the negative electrode current collector. The negative electrode active material may include hard carbon, soft carbon, or sodium titanate (such as Na2Ti3O7, Na2Ti6O7). 13 One or more of the following (etc.). Hard carbon selects one or more of the following as carbon sources: pitch, coal tar, biochar, phenolic resin (PF), resorcinol-formaldehyde resin, polyacrylonitrile (PAN), etc.

[0191] Furthermore, the negative electrode active material includes hard carbon, with a preferred H value ranging from 1.5 to 5. Hard carbon produces a large amount of gas. Therefore, selecting H within the range of 1.5 to 5, and choosing a larger value for H, can avoid insufficient gas storage space in the sodium-ion battery due to excessively small H values. This prevents the sodium-ion battery from experiencing a rapid increase in pressure within the casing 100 during gas production, which could lead to abnormal valve opening and pressure leakage. In a specific embodiment of this application, the materials for the positive electrode current collector and / or the negative electrode current collector include aluminum. In sodium-ion batteries, aluminum can be used as the negative electrode current collector, unlike lithium-ion batteries (where copper is used for the negative electrode). The technical solution of this application is fully compatible with systems using aluminum as the current collector, and the structural design does not depend on a specific current collector material, exhibiting good versatility.

[0192] In a specific embodiment of this application, when the capacity of the sodium-ion battery is greater than or equal to 100Ah, the preferred range of E% for the ratio of the area of ​​the welding area 414 to the area of ​​a single tab assembly 410 is 2.04-24.6. Exemplarily, E can be 2.04, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 24.6, or any range formed by any two of the above values. This embodiment does not limit the specific value of E; those skilled in the art can select a value within the range of 2.04-24.6 according to their needs.

[0193] For high-capacity batteries, the operating current is relatively large. Based on this, this embodiment selects E within a larger range to ensure that the connection between the tab assembly 410 and the battery output terminal 300 has better overcurrent capability and lower connection resistance, thereby more effectively controlling the heat generation under high current and suppressing the more serious gas generation problem of high-capacity batteries from the source.

[0194] like Figure 12 As shown in a specific embodiment of this application, the sodium-ion battery may further include a gas adsorption device 600, which is at least partially disposed within a receiving groove. Specifically, the gas adsorption device 600 may be fixed to the side of the insulating member 500 facing the cell 400.

[0195] The materials used in gas adsorption devices may include one or more of the following: molecular sieves, graphene, activated carbon, fluoropolymers, and porous organic polymers.

[0196] This embodiment adds a gas adsorption device 600 inside the receiving groove, which can better adsorb and decompose the gas generated by the reaction between the negative electrode and the electrolyte in a timely manner, thereby alleviating the increase in internal pressure of the battery and improving the battery's service life.

[0197] The gas adsorption device 600 can be either physical adsorption or chemical adsorption. For example, it can utilize at least one of molecular sieves, graphene, activated carbon, porous organic polymer blocks, or porous organic polymer sheets. Fluoropolymers include at least one of polytetrafluoroethylene, perfluoroethylene-propyl, fluorinated polyimide, polychlorotrifluoroethylene, and polyvinylidene fluoride. Porous organic polymer blocks include at least one of styrene-based hypercrosslinked porous polymer blocks, polyaniline-based porous polymer blocks, self-contained microporous polymer blocks, conjugated porous polymer blocks, and porous polymer blocks based on aromatic ring coupling reactions. Porous organic polymer sheets include at least one of styrene-based hypercrosslinked porous polymer sheets, polyaniline-based porous polymer sheets, self-contained microporous polymer sheets, conjugated porous polymer sheets, and porous polymer sheets based on aromatic ring coupling reactions.

[0198] In one specific embodiment of this application, the thickness of the gas adsorption device 600 along the direction perpendicular to the large surface of the cover plate 200 ranges from 0.8mm to 5mm. Exemplarily, the thickness of the gas adsorption device 600 can be 0.8mm, 1.0mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3.0mm, 3.2mm, 3.4mm, 3.6mm, 3.8mm, 4.0mm, 4.2mm, 4.4mm, 4.6mm, 4.8mm, 5.0mm, etc., or it can be a range formed by any two of the above values. This embodiment does not limit the specific value of the thickness of the gas adsorption device 600; those skilled in the art can select a value within the range of 0.8mm to 5mm according to their needs.

[0199] This design avoids the problem that if the thickness of the gas adsorption device 600 is too small, the gas adsorption performance of the gas adsorption device 600 will be too poor, and it will not be able to effectively reduce the gas pressure inside the sodium-ion battery, causing the explosion-proof valve to open prematurely. It also avoids the problem that if the thickness of the gas adsorption device 600 is too large, it will occupy too much gas storage space inside the casing 100, and it will also affect the volume of the cell 400, thereby affecting the energy density of the sodium-ion battery and causing the energy density of the sodium-ion battery to be too low.

[0200] In one specific embodiment of this application, the orthographic projection area of ​​the large surface of the gas adsorption device 600 facing the cover plate 200 is 400 mm². 2 -4600mm 2 For example, the projected area could be 400 mm². 2 800mm 2 1200mm 2 1600mm 2 2000mm 2 2400mm 2 2800mm 2 3200mm 2 3600mm 2 4000mm 2 4400mm 2 4600mm 2 "etc." can also be a range formed by any two of the above values. This embodiment does not limit the specific value of the above-mentioned projected area; those skilled in the art can determine the appropriate value based on requirements, such as 400mm. 2 -4600mm 2 Choose from the range.

[0201] This design avoids the problem that the gas adsorption device 600's suction performance is too poor due to an excessively small projected area, which would prevent it from effectively reducing the gas pressure inside the sodium-ion battery and causing the explosion-proof valve to open prematurely. It also avoids the problem that an excessively large projected area would occupy too much gas storage space inside the casing 100 and would also affect the volume of the cell 400, thereby affecting the energy density of the sodium-ion battery and causing it to be too low.

[0202] like Figure 13 As shown in the illustration, this application also discloses a battery pack, including the sodium-ion battery disclosed in the above embodiments. Multiple sodium-ion batteries with similar capacity and internal resistance are connected in series or parallel to form a battery pack. Since the battery pack disclosed in the application embodiments has the aforementioned sodium-ion battery, it possesses all the technical effects of the aforementioned sodium-ion battery, which will not be elaborated upon here.

[0203] The battery pack of this embodiment can be configured inside an electric vehicle, and can be installed at the bottom, front, or rear of the vehicle. The battery pack provides power to the electric vehicle, for example, acting as its operating power source. The electric vehicle may also be equipped with a controller and a motor. The controller is used to schedule the battery pack to deliver electrical energy to the motor to meet the power needs of the electric vehicle during starting, navigation, and driving.

[0204] A battery pack, as a rechargeable battery device, is the power source for new energy vehicles. The battery pack includes a housing 20 and at least one battery pack 10 housed within the housing 20. The battery pack 10 includes multiple sodium-ion batteries as described above. The housing 20 provides housing space for the battery pack 10 and other components, while also providing dustproof, waterproof, and protective functions for the internal components. This reduces the adverse effects of external liquids or foreign objects on the effectiveness and performance of individual battery cells and other components, effectively extending the battery pack's lifespan. The shape of the housing 20 is not limited; for example, it can be a cuboid, cylinder, etc. The material of the housing 20 can also be flexibly selected; for example, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., are all suitable.

[0205] The battery pack in this embodiment includes multiple battery groups 10, with one battery group 10 disposed in each sub-accommodating space. Each battery group 10 includes multiple stacked battery cells, and the stacking direction of the battery cells can be parallel to the plane of the base plate. The battery pack also includes a battery management system (BMS), a thermal management system, an electrical connection system (high-voltage / low-voltage connectors, wiring harnesses, etc.), structural components (shell, brackets, etc.), and protective components, etc. The above components are placed inside the housing 20 and sealed by the housing cover 30, forming a complete functional unit that can directly output electrical energy.

[0206] The Battery Management System (BMS) is used to detect the operating status of the battery pack and its individual cells, and to manage the battery module and its individual cells. The BMS includes a Battery Management Unit (BMU), a Cell Measurement Circuit (CMC), sensors, and various electronic control devices. The BMS includes at least one processor and a memory. The memory can be built into the BMS or externally located, and can also be remotely configured and connected to the BMS via a network.

[0207] like Figure 14 As shown in the embodiments, this application also discloses an electrical device, which includes the battery pack disclosed in the above embodiments. The battery pack can serve as the operating power source for the electrical device, and also as the driving power source for the electrical device, replacing or partially replacing fuel or natural gas to provide driving power for vehicles. Electrical devices include those in numerous technical fields such as energy storage devices, electric ships, aircraft, laptops, power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. The electrical device disclosed in this application, having the aforementioned battery pack, possesses all the technical effects of the aforementioned battery pack, which will not be elaborated upon here.

[0208] The following example uses a vehicle as a specific example of an electrical device. Figure 14 As shown, the vehicle 01 can be a new energy vehicle, encompassing various types such as pure electric vehicles, hybrid electric vehicles, and range-extended electric vehicles. The battery device 02 can be located at the bottom, front, or rear of the vehicle 01, providing electrical support to the vehicle 01, for example, acting as its operating power source. Furthermore, the vehicle 01 typically also has a controller 03, which manages the discharge process of the battery device 02 to cover various power needs during vehicle 01 startup, navigation, and driving.

[0209] In some embodiments, the battery device 02 comprises one or more battery packs disclosed in the above embodiments. These battery packs can be connected in series, parallel, or a hybrid configuration, where a hybrid configuration refers to the simultaneous presence of series and parallel connections in the connection of multiple battery packs. In other embodiments, the battery device 02 is a cluster-level battery architecture composed of multiple battery packs connected in series, wherein the number of battery packs in each cluster is strictly configured according to voltage and capacity requirements. More specifically, the battery unit of the battery device 02 includes multiple batteries, some of which are connected in series to form a cluster that meets a preset power supply voltage requirement, and at least one spare battery among the multiple batteries is bypassed.

[0210] The measurement methods for dimensions, area, etc., disclosed in the embodiments of this application are as follows:

[0211] Use measuring instruments such as micrometers or calipers to measure parameters such as length, width, distance, and thickness. The area is calculated from the measured parameters. Measure each object three times and take the average value as the final value.

[0212] The method for measuring the ratio E% of the area of ​​the welding zone to the area of ​​a single tab assembly disclosed in this application embodiment is as follows:

[0213] Due to different welding processes, the welding area may present various forms of weld lines, such as multiple regularly arranged circular pits, multiple parallel linear weld lines, a complete welding area, or a combination of the above weld lines. The welding area refers to the area enclosed by the outer contour line of the area where the weld line is located on a single tab assembly. The outer contour usually forms a complete rectangular area. The length and width of the rectangular area are measured to calculate the area S1 of the welding area.

[0214] Method for measuring the area of ​​a single tab assembly 410: Cut the tab assembly along the connection points between the individual tabs in the tab assembly and the individual tab assemblies in the tab assembly. Visually estimate the area of ​​each layer of individual tabs. If the areas of the individual tabs in each layer are approximately the same, randomly measure the area of ​​5 individual tabs and take the average as the area S0 of the single tab assembly. If the areas of the individual tabs in each layer are not equal, measure the area of ​​each individual tab, sort them by size, and take the median as the area S0 of the single tab assembly. E% = (S1 / S0) × 100%.

[0215] The length H of the protrusion protruding from the body of the insulating component is measured using measuring instruments such as micrometers or calipers. The length is measured at more than 5 different positions on the protrusion, and the maximum value is taken as the final H.

[0216] The methods for measuring and controlling the capacity of sodium-ion batteries disclosed in this application are as follows:

[0217] The prepared sodium-ion battery was placed in a fixture, a force of 3000 N was applied, and it was charged to the upper limit voltage with a constant current of 0.33 C. After resting for 30 min, it was discharged to the lower limit voltage with a constant current of 0.33 C. After resting for 30 min, the cycle was repeated 3 times. The average value of the discharge capacity obtained from the 3 cycles was taken as the capacity of the battery (in Ah).

[0218] Different battery systems require corresponding adjustments to their upper and lower voltage limits: For positive electrode active materials including NFPP (sodium iron pyrophosphate) - upper limit voltage 3.65V, lower limit voltage 1.5V; For positive electrode active materials including NFS (sodium iron sulfate) - upper limit voltage 4.4V, lower limit voltage 2.6V.

[0219] The methods for regulating the capacity of sodium-ion batteries are as follows:

[0220] The capacity V of a sodium-ion battery can be controlled by increasing its size, i.e., by adjusting its length, width, and height. Battery length ranges from 100mm to 1000mm (e.g., 100mm, 150mm, 200mm, 300mm, 400mm, 500mm, 600mm, 700mm, 800mm, 900mm, 1000mm, etc.); battery width ranges from 30mm to 80mm (e.g., 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm); and battery height ranges from 70mm to 260mm (e.g., 70mm, 80mm, 90mm, 110mm, 130mm, 150mm, 170mm, 190mm, 210mm, 230mm, 250mm, 260mm). The larger the overall volume of the battery, the greater its achievable capacity.

[0221] The energy density of sodium-ion batteries can also be increased by increasing the coating thickness of the active material layer (range: 50μm to 1200μm, e.g., 50μm, 60μm, 70μm, 100μm, 200μm, 400μm, 600μm, 800μm, 1000μm, 1200μm), decreasing the thickness of the current collector (range: 6μm to 20μm, e.g., 6μm, 8μm, 10μm, 12μm, 15μm, 18μm, 20μm), and increasing the compaction density of the active material layer in the single electrode of the positive electrode of sodium-ion batteries, thereby enabling sodium-ion batteries to achieve a larger capacity V.

[0222] The method for preparing a sodium-ion battery disclosed in this application is as follows.

[0223] (1) Preparation of the positive electrode:

[0224] The prepared positive electrode active material NFPP (sodium iron pyrophosphate), conductive agent (e.g., acetylene black), and binder (e.g., polyvinylidene fluoride PVDF) are mixed, and solvent NMP is added. The mixture is stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector foil, air-dried at room temperature, and then transferred to an oven (100°C) for further drying. The positive electrode sheet is then obtained by rolling and slitting.

[0225] Specifically, based on the total mass of the solid components of the positive electrode slurry, the mass fraction of the positive electrode active material is 80%~98%, the mass fraction of the conductive agent is 1%~10%, and the mass fraction of the binder is 1%~10%.

[0226] (2) Preparation of negative electrode:

[0227] The negative electrode active material, hard carbon, conductive agent (e.g., acetylene black), thickener (e.g., carboxymethyl cellulose (CMC)), and binder (e.g., styrene-butadiene rubber (SBR)) are mixed, and deionized water is added as a solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of the negative electrode current collector foil, air-dried at room temperature, and then transferred to an oven (100°C) for further drying. Finally, the negative electrode sheet is obtained by rolling and slitting.

[0228] Specifically, based on the total mass of the solid components in the negative electrode slurry, the mass fraction of the negative electrode active material is 89%~96%, the mass fraction of the conductive agent is 2%~5%, the mass fraction of the thickener is 1%~2%, and the mass fraction of the binder is 1%~4%.

[0229] (3) Preparation of electrolyte:

[0230] Ethylene carbonate (EC) and propylene carbonate (PC) are mixed in a volume ratio of 1:1 to obtain an organic solvent. In an anhydrous and oxygen-free atmosphere (such as an argon glove box), fully dried sodium hexafluorophosphate (NaPF6) is dissolved in the above mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0231] (4) Preparation of the separating membrane:

[0232] The separator is made of polyethylene film.

[0233] (5) Preparation of sodium-ion batteries:

[0234] The positive electrode, separator, and negative electrode are stacked in sequence and formed into a bare cell by winding or stacking. The bare cell is then placed in a battery casing, which is a square metal shell. The battery is dried, injected with electrolyte, and then packaged, left to stand, formed, and tested for capacity to obtain a sodium-ion battery.

[0235] In addition to the above-mentioned battery material selection, this application may also select other materials, and is not limited to the materials limited by the above preparation method.

[0236] The positive electrode active material can be selected from one or more of polyanionic compound materials, sodium transition metal oxide materials, and Prussian blue compound materials. The polyanionic compound includes at least one of sodium iron phosphate-sodium pyrophosphate mixed phase material, sodium iron pyrophosphate, sodium vanadium phosphate, sodium iron sulfate and sodium iron fluorophosphate, and the general formula can specifically be Na n M p (X a O b ) c Z w , wherein: M includes at least one of Ti, V, Cr, Mn, Fe, Co, Ni, Ca, Mg, Al, Nb and Zr, X includes at least one of Si, S, P, As, B, Mo, W and Ge, Z includes at least one of F, O, Cl and OH, 2≤n≤7, 1≤p≤4, 1≤a≤2, 1≤b≤7, 1≤c≤5, 0≤w≤3. The general formula of sodium transition metal oxide can specifically be: NaFe x (Ni 0.5 Mn 0.5 ) 1-x O2, wherein in the formula: 0≤x≤0.4; the general formula can also be Na x Mn a Fe b Ni c L d O 2-e , wherein: 0.7<x≤1.2, a>0, b≥0, 0.1<c≤0.3, d≥0, a+b+c+d+e=1, -0.1≤e≤0.1, L includes at least one of Cu, Li, Ti, Zr, K, Nb, Mg, Ca, Mo, Zn, Cr, W, Bi, Sn, Ge, Al, Si, La, Ta, P and B. The general formula of Prussian blue-type positive electrode material can specifically be: Na x MnFe(CN)6, wherein: 1.5≤x≤2; the general formula can also be A a M b M' c (CN) 6·d H2O, wherein: A includes at least one of alkali metal cations, alkaline earth metal cations, Zn 2+ and Al 3+ , M and M' each independently include at least one of Ni ions, Cu ions, Fe ions, Mn ions, Co ions and Zn ions, H2O is coordinated water, 0<a≤2, 0<b≤1, 0<c≤1, 0≤d≤2.

[0237] The negative electrode active material can be selected from hard carbon, soft carbon, and sodium titanate (such as Na2Ti3O7, Na2Ti6O 13One or more of the following are negative electrode active materials: asphalt, coal tar, biochar, phenolic resin (PF), resorcinol-formaldehyde resin, polyacrylonitrile (PAN), etc. Hard carbon can be selected from one or more of the following as carbon sources: asphalt, coal tar, biochar, phenolic resin (PF), resorcinol-formaldehyde resin, polyacrylonitrile (PAN), etc.

[0238] The conductive agent includes, but is not limited to, one or more combinations of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon nanotubes, graphene, and carbon nanofibers.

[0239] The adhesive includes, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, waterborne acrylic resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0240] The solvent can be deionized water, NMP (N-methylpyrrolidone), alcohol, ether, ketone or other types of pyrrolidone, etc.

[0241] The positive electrode current collector foil can be a metal foil or a composite current collector, and can be a metal foil, a carbon-coated metal foil, etc., with aluminum foil being preferred. For example, as a metal foil, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium with a silver-plated surface can be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0242] The negative electrode current collector foil can be made of metal foil, carbon-coated metal foil, etc., with aluminum foil being preferred. For example, the metal foil can be made of stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc., with a surface silver plating treatment. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0243] This application discloses two performance testing methods, namely performance testing method 1 and performance testing method 2. Performance testing method 1 is a test of the degree of battery casing bulging after cycling, and performance testing method 2 is a test of the proportion of the battery that experiences a short circuit. The specific testing procedures of performance testing method 1 and performance testing method 2 are as follows.

[0244] Test Method 1: After cycling, test the degree of bulging of the battery casing.

[0245] According to the above sodium-ion battery preparation method, for any embodiment or comparative example, 100 individual cells from the same production batch, using the same manufacturing process and welding specifications, and with the same casing structure size were selected as test samples.

[0246] On the large side of the battery casing, select the geometric center of the large side as the test point, measure the battery thickness at this point, and record it as d1, with the unit being mm.

[0247] At room temperature (20°C), the battery is charged at a constant current rate of 2C until the battery voltage reaches the upper limit voltage. Then, it is switched to constant voltage charging until the battery current drops to 0.05C. After resting for 30 minutes, it is discharged at a rate of 1C until the lower limit voltage is reached. After resting for 30 minutes, this constitutes one charge-discharge cycle. The battery is subjected to a total of 300 charge-discharge cycles.

[0248] After the cycle is completed, the battery thickness is measured again at the geometric center of the large side of the battery as the test point, and recorded as d2 in mm.

[0249] The average value Δd of “d2-d1” of each battery in a group of batteries corresponding to each embodiment or comparative example is used as the measure of the degree of bulging of the battery casing. If the difference Δd is greater than 1.5mm, it is recorded as unqualified; if the difference Δd is greater than 0.5mm but less than or equal to 1.5mm, it is recorded as qualified; if the difference Δd is less than 0.5mm, it is recorded as good.

[0250] Different battery systems require corresponding adjustments to their upper and lower voltage limits: For positive electrode active materials including NFPP (sodium iron pyrophosphate) - upper limit voltage 3.65V, lower limit voltage 1.5V; For positive electrode active materials including NFS (sodium iron sulfate) - upper limit voltage 4.4V, lower limit voltage 2.6V.

[0251] Test Method 2: Battery Short Circuit Proportion Test.

[0252] According to the above battery pack preparation method, for any embodiment or comparative example, 200 individual cells from the same production batch, using the same manufacturing process and welding specifications, and with the same casing structure size were selected as test samples.

[0253] Two hundred batteries were glued together in the same direction onto a flat metal base plate as the test object. The test object was then mounted on a vibration table according to GB / T2423.43. The testing process was conducted according to GB / T2423.56. Random and fixed-frequency vibration loads were applied in each direction, preferably in the following order: random z-axis, fixed-frequency z-axis, random y-axis, fixed-frequency y-axis, random x-axis, fixed-frequency x-axis (the line connecting the front and rear of the battery is the x-axis direction, and the horizontal direction perpendicular to the x-axis is the y-axis direction). The vibration frequency, power spectral density (PSD), and vibration time are shown in Table 1 below.

[0254] Table 1 Vibration Parameter Table

[0255]

[0256] After vibration, remove the battery and charge it at a constant current rate of 1C at room temperature (20°C) until the battery voltage reaches the upper limit voltage. Then switch to constant voltage charging until the battery current drops to 0.05C. After resting for 30 minutes, discharge it at a rate of 1C until the lower limit voltage is reached. After resting for 30 minutes, this completes one charge-discharge cycle. Perform 100 charge-discharge cycles on the battery.

[0257] After the cycle is completed, the voltage between the positive and negative terminals of the sodium-ion battery is measured using a multimeter (DC voltage setting). If the battery voltage drops sharply to 0V or close to 0V, it is considered a short-circuited battery and is also counted as such. If the percentage of short-circuited batteries is greater than 4% of the total number of batteries, it is considered unqualified; if the percentage is less than or equal to 4% but greater than 2%, it is considered qualified; if the percentage is less than or equal to 2%, it is considered qualified.

[0258] Different battery systems require corresponding adjustments to their upper and lower voltage limits: For positive electrode active materials including NFPP (sodium iron pyrophosphate) - upper limit voltage 3.65V, lower limit voltage 1.5V; For positive electrode active materials including NFS (sodium iron sulfate) - upper limit voltage 4.4V, lower limit voltage 2.6V.

[0259] Table 2 Comparison of the two performance characteristics

[0260]

[0261] As can be seen from Table 2, the range of H×E / V values ​​for Examples 4-17 and Example 19 is 8.2×10⁻⁶. -2 ~265.85×10 -2 It satisfies the defined range of H×E / V of 1.60×10. -2 -265.85×10 -2Furthermore, the value is on the larger side of the H×E / V limit range. After testing, it can be seen that the degree of bulging of the battery casing is in good condition.

[0262] In Examples 1-3 and Example 18, the value of H×E / V ranges from 1.6×10⁻⁶. -2 ~4.7×10 -2 It satisfies the defined range of H×E / V of 1.60×10. -2 -265.85×10 -2 Furthermore, the value is on the smaller side of the H×E / V limit range. After testing, it can be seen that the degree of bulging of the battery casing is within acceptable limits.

[0263] In Examples 1-12 and Example 18, the value of H×E / V ranges from 1.60×10⁻⁶. -2 ~118.35×10 -2 It satisfies the defined range of H×E / V of 1.60×10. -2 -265.85×10 -2 Furthermore, the value is on the smaller side of the H×E / V limit range. After testing, it can be seen that the proportion of batteries experiencing short circuits is in good condition.

[0264] In Examples 13-17 and Example 19, the range of H×E / V is 134.48×10⁻⁶. -2 ~265.85×10 -2 It satisfies the defined range of H×E / V of 1.60×10. -2 -265.85×10 -2 Furthermore, the value is on the larger side of the H×E / V limit. After testing, it can be seen that the proportion of batteries experiencing short circuits is within acceptable limits.

[0265] In Examples 4-12, the value of H×E / V ranges from 8.2×10⁻⁶. -2 ~118.35×10 -2 It satisfies the defined range of H×E / V of 1.60×10. -2 -265.85×10 -2 After testing, it can be seen that the degree of bulging of the battery casing and the proportion of short circuits in the battery are both in good condition.

[0266] In Comparative Examples 1 and 3, the values ​​of H×E / V are 1.36×10⁻⁶ and 1.36×10⁻⁶, respectively. -2 and 1.38×10 -2 The H×E / V limit of 1.60×10⁻⁶ is not met. -2 -265.85×10 -2The value is below the lower limit of the H×E / V limit. After testing, it can be seen that although the proportion of short circuits in the battery is in good condition, the degree of bulging of the battery casing is unqualified.

[0267] In Comparative Examples 2 and 4, the values ​​of H×E / V were 282.78×10⁻⁶, respectively. -2 and 277.29×10 -2 The H×E / V limit of 1.60×10⁻⁶ is not met. -2 -265.85×10 -2 The value is higher than the upper limit of the H×E / V limit. After testing, it can be seen that although the battery casing is in good condition, the proportion of short circuits in the battery is unqualified.

[0268] In Comparative Example 5, the positive electrode active material in the battery cell was selected from LiNi. 0.6 Co 0.2 Mn 0.2 O2 and other positive electrode materials all meet the above test requirements. The mass ratio of positive electrode active material: conductive agent: binder meets 96:2:2. The negative electrode active material is selected from artificial graphite. The ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2.

[0269] The lithium-ion battery in Comparative Example 5 produces relatively little gas, exceeding the limit of H×E / V (in Comparative Example 5, H×E / V is 1.47×10). -2 Even if the value is lower than the lower limit of the H×E / V limit, the degree of bulging of the battery casing can still meet the qualification requirements.

[0270] As illustrated in this application, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements. An element defined by the phrase "comprising an..." does not exclude the presence of other identical elements in the process, method, product, or apparatus that includes the element.

[0271] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0272] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0273] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A sodium-ion battery, characterized in that, The device includes a housing (100), a cover plate (200), a battery output terminal (300), and a battery cell (400). At least one end of the housing (100) has an opening. The cover plate (200) blocks the opening of the housing (100) and forms a receiving cavity with the housing (100). The battery cell (400) is disposed in the receiving cavity. The battery output terminal (300) is fixed on the cover plate (200) and electrically connected to the battery cell (400). The battery cell (400) includes an electrode assembly (420) and a tab assembly (410) connected to the electrode assembly (420). The tab assembly (410) is welded to the battery output terminal (300), and a welding area (414) is formed on the tab assembly (410). The area of ​​the welding area (414) is E% of the area of ​​a single tab assembly (410). An insulating member (500) is provided between the cover plate (200) and the battery cell (400). The insulating member is fixedly connected to the cover plate. The insulating member (500) includes an insulating member body (520) and a protrusion (510) that connects to the insulating member body (520) and protrudes toward the battery cell (400). A receiving groove is formed between the protrusion (510) and the insulating member body (520). Along a direction perpendicular to the plane containing the large surface of the cover plate (200), the protrusion (510) protrudes from the insulating body (520) by a length dimension H (mm), the capacity of the sodium-ion battery is V (Ah), and the range of H×E / V is 1.60×10⁻⁶. -2 -265.85×10 -2 .

2. The sodium-ion battery according to claim 1, characterized in that, The cover plate (200) has a rectangular surface, and at least a portion of the first side of the insulating body (520) is provided with the protrusion (510). The first side of the insulating body (520) is the long side of the surface of the cover plate (200).

3. The sodium-ion battery according to claim 2, characterized in that, The protrusion (510) is provided in at least a portion of the second side of the insulating body (520), and the second side of the insulating body (520) is the short side of the large surface of the cover plate (200).

4. The sodium-ion battery according to claim 3, characterized in that, Along the direction perpendicular to the large surface of the cover plate (200), the height of the protrusion (510) on the first side of the insulating body (520) is greater than the height of at least part of the protrusion (510) on the second side of the insulating body (520).

5. The sodium-ion battery according to claim 2, characterized in that, The protrusion (510) includes at least two, and the at least two protrusions (510) include a first protrusion and a second protrusion, and the first protrusion and the second protrusion are respectively disposed on opposite sides of the long side of the large surface of the cover plate (200).

6. The sodium-ion battery according to claim 5, characterized in that, The first protrusion and the second protrusion are arranged symmetrically.

7. The sodium-ion battery according to claim 2, characterized in that, The protrusion (510) is spaced apart from the edge of the long side of the large surface of the cover plate (200), and the distance between the protrusions is in the range of 1.5mm-5.2mm.

8. The sodium-ion battery according to claim 1, characterized in that, The electrode assembly (420) includes an electrode body and a separator. The electrode body includes a first polarity electrode (421) and a second polarity electrode (422) with opposite polarities. The first polarity electrode (421) and the second polarity electrode (422) are separated by the separator (423). The protrusion (510) is arranged at a distance from the electrode body, and the minimum distance between the protrusion (510) and the electrode body is in the range of 2mm-6mm.

9. The sodium-ion battery according to claim 8, characterized in that, On the side facing the cover plate (200), the separator (423) extends beyond the electrode body, and the length of the extension ranges from 1 mm to 5 mm.

10. The sodium-ion battery according to claim 9, characterized in that, Along the arrangement direction of the cover plate (200) and the battery cell (400), at least a portion of the structure of the separator (423) extends between the protrusion (510) and the insulating body (520).

11. The sodium-ion battery according to claim 1, characterized in that, Along the direction parallel to the large surface of the cover plate (200), the protrusion (510) is spaced apart from the housing (100), and the minimum distance between the protrusion (510) and the housing (100) is in the range of 1.5mm-5mm.

12. The sodium-ion battery according to claim 1, characterized in that, The projection of the protrusion (510) onto the large surface of the cover plate (200) is the projection of the protrusion, and the projection of the insulating body (520) onto the large surface of the cover plate (200) is the projection of the body. The ratio of the area of ​​the projected protrusion to the area of ​​the projected body is in the range of 0.04-0.

5.

13. The sodium-ion battery according to any one of claims 1-12, characterized in that, The tab assembly (410) extends from the electrode assembly (420) toward the cover plate (200), and at least a portion of the protrusion (510) is located between the tab assembly (410) and the inner wall of the housing (100).

14. The sodium-ion battery according to claim 13, characterized in that, The large surface of the cover plate (200) is rectangular, and at least one end of the protrusion (510) extends beyond the edge of the tab assembly (410) along the length of the large surface of the cover plate (200).

15. The sodium-ion battery according to claim 13, characterized in that, The tab assembly (410) includes a first tab (411), a bent tab (413), and a second tab (412) connected in sequence. One end of the first tab (411) is led out from the electrode assembly (420). The second tab (412) is welded to the battery output terminal (300) and forms the welding area (414). The bent tab (413) is arranged closer to the protrusion (510) than the first tab (411) and the second tab (412).

16. The sodium-ion battery according to claim 15, characterized in that, Along the arrangement direction of the cover plate (200) and the cell (400), the bending point of the bent tab (413) is closer to the cover plate (200) than the target end face of the protrusion (510), and the target end face of the protrusion (510) is the end face facing the electrode assembly (420).

17. The sodium-ion battery according to any one of claims 1-12, characterized in that, The protrusion (510) includes a bottom wall and a side wall. The bottom wall of the protrusion (510) is connected to the insulating body (520) through the side wall of the protrusion (510). The bottom wall and / or side wall of the protrusion (510) are provided with through holes that extend through the wall thickness.

18. The sodium-ion battery according to claim 17, characterized in that, The through hole is connected to the receiving groove.

19. The sodium-ion battery according to any one of claims 1-12, characterized in that, The cover plate (200) has a first through hole (210), at least a portion of the structure of the battery output terminal (300) extends to the first through hole (210), and the welding area (414) is closer to the electrode assembly (420) than the cover plate (200).

20. The sodium-ion battery according to claim 19, characterized in that, The insulating component (500) has a second through hole (530), at least a portion of the structure of the battery output terminal (300) extends into the second through hole (530), and the welding area (414) is closer to the electrode assembly (420) than the insulating component body (520).

21. The sodium-ion battery according to any one of claims 1-12, characterized in that, The tab assembly (410) extends from the electrode assembly (420) toward the cover plate (200), the battery output terminal (300) includes a terminal post (310), the tab assembly (410) is welded to the target end face of the terminal post (310), and the target end face of the terminal post (310) is the end face facing the electrode assembly (420).

22. The sodium-ion battery according to claim 21, characterized in that, The ratio of the area of ​​the welding zone (414) to the area of ​​the target end face of the pole (310) is in the range of 0.25-0.

64.

23. The sodium-ion battery according to claim 21, characterized in that, Along the arrangement direction of the cover plate (200) and the cell (400), the distance from the target end face of the pole post (310) to the electrode assembly (420) is a first distance, and the distance from the target end face of the insulating body (520) to the electrode assembly (420) is a second distance. The first distance is greater than or equal to the second distance, and the target end face of the insulating body (520) is the end face facing the electrode assembly (420).

24. The sodium-ion battery according to any one of claims 1-12, characterized in that, The battery output terminal (300) includes a terminal post (310) and an adapter plate (320). The electrode assembly (410) and the terminal post (310) are electrically connected through the adapter plate (320). The electrode assembly (410) and the adapter plate (320) are welded to form the welding area (414). Along the arrangement direction of the cover plate (200) and the cell (400), at least a portion of the structure of the adapter piece (320) is disposed between the pole post (310) and the electrode assembly (420); Along the arrangement direction of the cover plate (200) and the battery cell (400), there is an overlapping area between the adapter piece (320) and the protrusion (510).

25. The sodium-ion battery according to any one of claims 1-12, characterized in that, The insulating body (520) includes an insulating main body (521) and an insulating recess (522). The protrusion (510) is disposed on the insulating main body (521). The insulating recess (522) is recessed toward the side opposite to the battery cell (400), and the wall thickness of the groove bottom wall of the insulating recess (522) is less than or equal to the wall thickness of the insulating main body (521).

26. The sodium-ion battery according to any one of claims 1-12, characterized in that, The protrusion (510) is provided with a cavity, and the cavity is in communication with the receiving cavity.

27. The sodium-ion battery according to any one of claims 1-12, characterized in that, The electrode assembly (420) includes an electrode body and a separator (423). The electrode body includes a first polarity electrode (421) and a second polarity electrode (422) with opposite polarities. The first polarity electrode (421) and the second polarity electrode (422) are separated by the separator (423). The electrode body includes a current collector and an active material layer coated on at least one side of the current collector, wherein the edge of the current collector facing the tab assembly (410) is coated with an insulating adhesive layer (424).

28. The sodium-ion battery according to claim 27, characterized in that, At least a portion of the structure of the insulating adhesive layer (424) extends to the tab assembly (410), and the height dimension of the insulating adhesive layer (424) on the tab assembly (410) is L (mm), where L ranges from 1.5 to 7.

5. The height dimension of the insulating adhesive layer (424) on the tab assembly (410) is: after the tab assembly (410) is flattened along the arrangement direction of the cover plate (200) and the battery cell (400), the height dimension of the insulating adhesive layer (424) on the tab assembly (410) along the arrangement direction of the cover plate (200) and the battery cell (400) is.

29. The sodium-ion battery according to any one of claims 1-12, characterized in that, Along the width direction of the tab assembly (410), the ratio of the width dimension of the welding area (414) to the total width dimension of the tab assembly (410) ranges from 0.35 to 0.

9. and or, The distance from the welding area (414) to the root of the tab assembly (410) ranges from 5mm to 30mm.

30. The sodium-ion battery according to any one of claims 1-12, characterized in that, The battery cell (400) is a wound battery cell, and the range of H is 1-3.

8.

31. The sodium-ion battery according to any one of claims 1-12, characterized in that, The electrode assembly (420) includes a positive electrode and a negative electrode. The positive electrode includes a positive current collector and a positive active material coated on at least one side of the positive current collector. The positive active material includes one or more of sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds.

32. The sodium-ion battery according to claim 31, characterized in that, The negative electrode sheet includes a negative electrode current collector and a negative electrode active material coated on at least one side of the negative electrode current collector, wherein the negative electrode active material includes one or more of hard carbon, soft carbon, and sodium titanate.

33. The sodium-ion battery according to claim 32, characterized in that, The negative electrode active material includes hard carbon, with H ranging from 1.5 to 5.

34. The sodium-ion battery according to claim 32, characterized in that, The material of the positive electrode current collector includes aluminum; And / or, The material of the negative electrode current collector includes aluminum.

35. The sodium-ion battery according to any one of claims 1-12, characterized in that, When the capacity of the sodium-ion battery is greater than or equal to 100 Ah, the range of E is 2.04-24.

6.

36. The sodium-ion battery according to any one of claims 1-12, characterized in that, H ranges from 1 to 5, and / or E ranges from 2.04 to 33.33, and / or V ranges from 50 to 202.

37. The sodium-ion battery according to any one of claims 1-12, characterized in that, It also includes a gas adsorption device (600), which is at least partially disposed within the receiving groove. The gas adsorption device (600) is made of one or more of molecular sieves, graphene, activated carbon, and porous organic polymers.

38. A battery pack, characterized in that, Including the sodium-ion battery as described in any one of claims 1-37.

39. An electrical appliance, characterized in that, Includes the battery pack as described in claim 38.

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