Battery cells, batteries and power consumption devices

Abstract

Embodiments of this application provide a battery cell, a battery, and a power-consuming device. The battery cell includes an electrode assembly comprising a negative electrode plate, a positive electrode plate, and a separator member for separating the negative electrode plate from the positive electrode plate, wherein the ratio of the thickness of the separator member to the thickness of the negative electrode plate is 0.07 or greater. By controlling the thickness of the separator member and the negative electrode plate, the battery cell according to embodiments of this application can improve the ability to store the electrolyte of the battery, thereby slowing down the decomposition or volatilization of the electrolyte in the battery cell and improving the battery's cycle life.

Description

[Technical Field]

[0001] [Cross-reference of related applications] This application claims priority to Chinese patent application 202310443356.1, filed on 23 April 2023, titled "Battery Cell, Battery and Power Consumption Equipment," the entirety of which is incorporated herein by reference.

[0002] The embodiments of this application relate to the battery technology, and more particularly to battery cells, batteries, and power consumption devices. [Background technology]

[0003] With the continuous advancements in battery technology, various new energy industries that utilize batteries as energy storage devices are rapidly developing. Currently, the thickness of the negative electrode plate in metal battery cells is generally designed to be relatively thin, resulting in relatively poor ability to store electrolyte. During the charge-discharge cycle of the battery cell, the electrolyte is continuously consumed, leading to localized electrolyte depletion, which causes a decrease in the performance of the battery cell and further affects the battery cell's cycle life. [Overview of the project]

[0004] Embodiments of this application provide a battery cell, a battery, and a power-consuming device that can improve the cycle life of the battery cell.

[0005] According to a first embodiment, a battery cell is provided, the battery cell including an electrode assembly, the electrode assembly including a negative electrode plate, a positive electrode plate, and a separator member for separating the negative electrode plate and the positive electrode plate, wherein the ratio of the thickness H1 of the separator member to the thickness H2 of the negative electrode plate is 0.07 or more.

[0006] In the embodiments of this application, when the ratio of the thickness H1 of the separator member to the thickness H2 of the negative electrode plate is set to 0.07 or more, increasing the thickness H1 of the separator member allows for the storage of a relatively large amount of electrolyte, thereby mitigating the problem of performance degradation of the battery cell due to a relatively small amount of electrolyte or depletion of the electrolyte, and improving the cycle life of the battery cell.

[0007] In some implementations, the thickness H1 of the separator member and the thickness H2 of the negative electrode plate satisfy 0.07 ≤ H1 / H2 ≤ 241.18, and preferably, the thickness H1 of the separator member and the thickness H2 of the negative electrode plate satisfy 0.15 ≤ H1 / H2 ≤ 220.59.

[0008] In the embodiments of this application, when H1 / H2 < 0.07, setting the thickness H1 of the separator member to be relatively thin results in a relatively poor ability of the separator member to store electrolyte, which can easily lead to a decrease in the performance of the battery cell due to insufficient electrolyte or depletion of electrolyte, affecting the cycle life of the battery cell. When H1 / H2 > 241.18, setting the thickness H1 of the separator member to be relatively thick increases the ion transport pathway in the battery cell, further increases the liquid phase impedance of the battery cell, affects the gram capacity of the battery cell, and reduces the energy density of the battery cell. At the same time, due to the spatial limitations inside the battery cell, there is a certain upper limit to the thickness H1 of this separator member. Therefore, by setting the ratio of the separator thickness H1 to the negative electrode plate thickness H2 in the battery cell to 0.07 ≤ H1 / H2 ≤ 241.18, or by setting the ratio of the separator thickness H1 to the negative electrode plate thickness H2 in the battery cell to 0.15 ≤ H1 / H2 ≤ 220.59, it is possible to balance the internal space of the battery cell with the ability to store electrolyte, while effectively reducing the problem of battery performance degradation due to relatively little electrolyte or electrolyte depletion in the battery cell, thereby improving the cycle life of the battery cell and improving the gram capacity of the battery cell.

[0009] In some implementations, the thickness H1 of the separator member and the thickness H2 of the negative electrode plate satisfy 1.16 ≤ H1 / H2 ≤ 75, and preferably, the thickness H1 of the separator member and the thickness H2 of the negative electrode plate satisfy 1.16 ≤ H1 / H2 ≤ 21.43.

[0010] In the embodiments of this application, by setting the ratio of the thickness H1 of the separator member in the battery cell to the thickness H2 of the negative electrode plate to 1.16 ≤ H1 / H2 ≤ 75, or by setting the ratio of the thickness H1 of the separator member in the battery cell to the thickness H2 of the negative electrode plate to 1.16 ≤ H1 / H2 ≤ 21.43, a better balance is achieved between the space inside the battery cell and the ability of the battery cell to store the electrolyte, thereby effectively reducing the problem of performance degradation of the battery cell due to relatively little electrolyte or depletion of the electrolyte, and improving the cycle life of the battery cell.

[0011] In some implementations, the thickness H1 of the separator member and the thickness H2 of the negative electrode plate satisfy 1.20 ≤ H1 / H2 ≤ 10. By setting the thickness H1 of the separator member and the thickness H2 of the negative electrode plate to 1.20 ≤ H1 / H2 ≤ 10 in this way, a better balance is achieved between the space inside the battery cell and the ability to store the electrolyte in the battery cell. This effectively reduces the problem of performance degradation in the battery cell due to relatively low electrolyte levels or electrolyte depletion, and further improves the cycle life of the battery cell.

[0012] In some implementations, the separator component includes a separator body and a separator functional coating applied to the surface of the separator body, wherein the separator functional coating is applied to one or both sides of the surface of the separator body.

[0013] In the embodiments of the present application, by providing a separator functional coating on the surface of one or both sides of the separator body of the separator member, the ability of the separator member to store the electrolyte can be improved by the installed separator functional coating, so that when the electrolyte in the battery cell is relatively less or the electrolyte is depleted, the electrolyte can be replenished in a timely manner, effectively reducing the decrease in the performance of the battery cell and improving the cycle life of the battery cell.

[0014] In some implementation manners, the material of this separator functional coating includes at least one of polyvinylidene fluoride copolymer, sodium carboxymethyl cellulose, polystyrene-butadiene copolymer, hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-isoprene block copolymer, ethylene-butene copolymer, polypropylene-octene thermoplastic elastomer, ethylene-octene thermoplastic elastomer, and propylene-ethylene copolymer.

[0015] In the embodiments of the present application, by setting the material of the separator functional coating of the separator member in the battery cell to at least one of polyvinylidene fluoride copolymer, sodium carboxymethyl cellulose, polystyrene-butadiene copolymer, hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-isoprene block copolymer, ethylene-butene copolymer, polypropylene-octene thermoplastic elastomer, ethylene-octene thermoplastic elastomer, and propylene-ethylene copolymer, the reversible compression ability of the separator functional coating of this separator member can be significantly improved, and it can play a buffering role against the volume expansion of the negative electrode plate during the charge and discharge process of the battery cell, thereby alleviating the decrease in the performance of the battery cell.

[0016] In some implementation manners, the thickness of this separator body is 3μm - 250μm.

[0017] In the embodiments of the present application, when the thickness of the separator body is set to be less than 3 μm, by setting the thickness of the separator body to be relatively thin, the ability of the entire separator member to store the electrolyte becomes relatively poor. When there is too little electrolyte in the battery cell or the electrolyte is depleted, it becomes difficult to replenish the electrolyte in the battery cell, which affects the cycle life of the battery cell. When the thickness of the separator body is set to be greater than 250 μm, the thickness of the separator body is set to be relatively thick, increasing the ion transport path in the battery cell, further increasing the liquid-phase impedance of the battery cell, affecting the exertion of the gram capacity of the battery cell, reducing the energy density of the battery cell. At the same time, due to the space limitation inside the battery cell, there is a certain upper limit for the thickness of this separator body. By setting the thickness of this separator body to be 3 μm - 250 μm, while balancing the internal space of the battery cell and the ability to store the electrolyte, the reduction in the performance of the battery cell can be effectively reduced, and the cycle life of the battery cell can be improved.

[0018] In some implementation manners, the thickness of this separator body is 5 μm - 50 μm. In this way, the internal space of the battery cell and the ability to store the electrolyte are better balanced, reducing the problem of performance degradation of the battery cell caused by relatively little electrolyte or depleted electrolyte in the battery cell, and improving the cycle life of the battery cell.

[0019] In some implementation manners, the thickness of this separator functional coating is 0.1 μm - 250 μm.

[0020] In the embodiments of this application, when the thickness of the separator functional coating is set to less than 0.1 μm, this thickness is set to be relatively thin, which relatively worsens the ability of the entire separator member to retain electrolyte. This makes it difficult to replenish the electrolyte in the battery cell in a timely manner when there is too little electrolyte or when the electrolyte is depleted, affecting the cycle life of the battery cell. When the thickness of the separator functional coating is set to be greater than 250 μm, this thickness is set to be relatively thick, which increases the ion transport pathway in the battery cell, further increases the liquid phase impedance of the battery cell, affects the gram capacity of the battery cell, and reduces the energy density of the battery cell. At the same time, due to the space limitations inside the battery cell, there is a certain upper limit to the thickness of this separator functional coating. By setting the thickness of this separator functional coating between 0.1 μm and 250 μm, it is possible to balance the internal space of the battery cell with the ability to retain electrolyte, thereby improving the cycle life of the battery cell.

[0021] In some implementations, the thickness of this separator functional coating is 0.5 μm to 50 μm, preferably 2 μm to 20 μm. This allows for a better balance between the internal space of the battery cell and the ability to store the electrolyte, thereby improving the cycle life of the battery cell.

[0022] In some implementations, this separator functional coating is a hollow, resilient structure.

[0023] In the embodiments of this application, by providing a hollow, resilient structure in the separator functional coating of the separator member, on the one hand, the hollow structure allows for the storage of a relatively large amount of electrolyte, thereby enabling timely replenishment of the electrolyte when the electrolyte level in the battery cell is relatively low or depleted, effectively reducing the degradation of the battery cell's performance and improving the battery cell's cycle life. On the other hand, the hollow, resilient structure of this separator functional coating can act as a buffer against the volume expansion of the electrode plates during the charging and discharging process of the battery cell, simultaneously reducing the risk of electrolyte drying out and bridge breakage due to the volume expansion of the electrode plates.

[0024] In some implementations, this hollow, resilient structure includes an open, porous structure.

[0025] In the embodiments of this application, the separator functional coating is set as a hollow, resilient structure, and this hollow, resilient structure includes an open, porous structure. During the charging and discharging process of the battery cell, when the volume of the electrode plates expands and presses against this hollow, resilient structure, the electrolyte inside this hollow, resilient structure is discharged through the open, porous structure, allowing for timely replenishment of the electrolyte to the battery cell. This reduces the risk of electrolyte drying out and bridge breakage, thereby improving the cycle life of the battery cell.

[0026] In some implementations, at least one opening in this pore structure faces the negative electrode plate.

[0027] In the embodiments of this application, at least one opening of the porous structure faces the negative electrode plate, and during the charging and discharging process of the battery, if volume expansion occurs in the negative electrode plate and presses against the hollow, resilient structure, causing a decrease or depletion of the electrolyte between the separator member and the negative electrode plate, the electrolyte stored in the hollow, resilient structure can be discharged through at least one opening on the porous structure, thereby replenishing the electrolyte between the separator member and the negative electrode plate, effectively reducing the risk of electrolyte depletion and bridge breakage between the separator member and the negative electrode plate, and improving the cycle life of the battery cell.

[0028] In some implementations, this hollow resilient structure includes a plurality of unsealed hollow resilient balls arranged along the surface of the separator body. Thus, in embodiments of this application, the hollow resilient structure can store electrolyte by a plurality of unsealed hollow resilient balls arranged along the surface of the separator body, on the one hand, by storing electrolyte by a plurality of unsealed hollow resilient balls, the electrolyte can be replenished in a timely manner when the electrolyte in the battery cell is relatively low or depleted, effectively reducing the degradation of battery performance and improving the cycle life of the battery cell, on the other hand, during the charging and discharging process of the battery cell, the volume of the negative electrode plate expands... When the hollow, resilient structure is pressed, the hollow, resilient ball can act as a buffer against the negative electrode plate. At the same time, as the volume of the negative electrode plate expands and presses against the separator member, causing the electrolyte between the negative electrode plate and the separator member to decrease or dry out, the electrolyte stored in the hollow, resilient ball is pressed and discharged by the negative electrode plate, allowing for timely replenishment of the electrolyte between the separator member and the negative electrode plate. This effectively reduces the risk of electrolyte drying out and bridge breakage between the separator member and the negative electrode plate.

[0029] In some implementation methods, the specific surface area of ​​this pore structure is 0.5 m². 2 / g-10m 2 It is / g.

[0030] In the embodiments of this application, the specific surface of the pore structure product 0.5m 2 If the value is less than / g, the material has relatively few pores, resulting in relatively poor adsorption capacity and difficulty in adsorbing electrolyte, thus making it difficult to store electrolyte through this pore structure. Specific surface of the pore structure product 10m 2 If the value is greater than / g, the difficulty of processing this pore structure becomes relatively high, and manufacturing costs increase. Thus, the specific surface area of ​​this pore structure is 0.5m². 2 / g-10m 2 By setting the value to / g, this pore structure is given good electrolyte storage capacity. At the same time, during the charging and discharging process of the battery cell, when the volume of the electrode plates expands and presses against this hollow, resilient structure, the electrolyte inside this hollow, resilient structure is smoothly discharged through this open pore structure. This allows for timely replenishment of electrolyte to the battery cell, thereby reducing the risk of electrolyte drying out and bridge breakage, and improving the cycle life of the battery cell.

[0031] In some implementations, the compression percentage of this separator member is 8%-95%.

[0032] In the embodiments of this application, by setting the compression percentage of the separator member to 8%-95%, the separator member can act as a buffer against the electrode plates that undergo volume expansion during the charging and discharging process of the battery cell, thereby improving the operating performance of the battery cell.

[0033] In some implementations, the compression percentage of this separator component is 20%-80%. In this way, during the charging and discharging process of the battery cell, this separator component can provide good buffering to the electrode plates that undergo volume expansion, thereby improving the operating performance of the battery cell.

[0034] In some implementations, the pressure-bearing strength range of this separator member is 0.05 MPa to 10 MPa.

[0035] In the embodiments of this application, if the pressure-receiving strength range of the separator member is less than 0.05 MPa, that is, when the electrode plate presses against the separator member after volume expansion occurs during the charging and discharging process of the battery cell, deformation and breakage of the separator member are likely to occur. If the pressure-receiving strength range of the separator member is greater than 10 MPa, that is, the pressure-receiving strength of the separator member is relatively large, making it difficult to generate a buffering effect against the electrode plate after volume expansion during the charging and discharging process of the battery cell, affecting the operating performance of the battery cell and reducing the cycle life of the battery cell. By setting the pressure-receiving strength range of the separator member to 0.05 MPa-10 MPa, the separator member can perform a buffering effect against the electrode plate after volume expansion occurs during the charging and discharging process of the battery cell.

[0036] In some implementations, the pressure-receiving strength of this separator component is in the range of 0.05 MPa to 3 MPa. In this way, during the charging and discharging process of the battery cell, this separator component can provide good buffering to the electrode plates after volume expansion has occurred.

[0037] In some implementations, this battery cell is a sodium-based secondary battery without a negative electrode.

[0038] In some implementations, the negative electrode plate includes a negative electrode current collector and a negative electrode functional coating applied to the surface of the negative electrode current collector, the negative electrode functional coating being applied to one or both sides of the negative electrode current collector.

[0039] In the embodiments of this application, by providing a negative electrode functional coating on one or both surfaces of the negative electrode current collector of the negative electrode plate, the ability of the negative electrode plate to retain electrolyte can be improved. This allows for timely replenishment of electrolyte when the electrolyte level in the battery cell is relatively low or depleted, effectively reducing the degradation of battery cell performance and improving the battery cell's cycle life.

[0040] In some implementations, the material of this negative electrode functional coating is a porous carbon material, preferably, this porous carbon material includes at least one of carbon nanotubes, Super-P, KS-6, mesocarbon microbeads, hard carbon, and graphite.

[0041] In some implementations, the material of the negative electrode functional coating on the negative electrode plate in a battery cell is set to a porous carbon material. For example, this porous carbon material includes at least one of carbon nanotubes, Super-P, KS-6, mesocarbon microbeads, hard carbon, and graphite. This improves the ability of the negative electrode plate to adsorb the electrolyte, i.e., improves the ability of the negative electrode functional coating on the negative electrode plate to retain the electrolyte, thereby reducing the risk of electrolyte drying out and bridge breakage, and thus improving the cycle life of the battery cell.

[0042] In some implementations, the thickness of this negative electrode current collector is between 3 μm and 250 μm.

[0043] In the embodiments of this application, when the thickness of the negative electrode current collector is set to less than 3 μm, that is, the thickness of the negative electrode current collector is relatively thin, making it prone to localized short-circuit melting phenomena, and at the same time the strength value of the negative electrode current collector decreases, affecting the safety performance of the battery cell. When the thickness of the negative electrode current collector is set to more than 250 μm, that is, the thickness of the negative electrode current collector is relatively thick, increasing processing costs, and there is a certain upper limit to the thickness of the negative electrode current collector due to space limitations inside the battery cell. By setting the thickness of the negative electrode current collector to 3 μm-250 μm, the battery cell This allows for improved battery cell performance while maintaining both internal space and electrolyte storage performance of the negative electrode plate.

[0044] In some implementations, the thickness of this negative electrode current collector is 4 μm to 30 μm. This allows for a better balance between the internal space of the battery cell and the electrolyte storage performance of the negative electrode plate, thereby improving the usability of the battery cell.

[0045] In some implementation methods, the thickness of this negative electrode functional coating is between 0.2 μm and 50 μm.

[0046] In the embodiments of this application, when the thickness of the negative electrode functional coating is set to less than 0.2 μm, i.e., when the thickness of the negative electrode functional coating is set to be relatively thin, the ability of the negative electrode plate to retain electrolyte becomes relatively poor, making it difficult to replenish the electrolyte in the battery cell when there is too little or the electrolyte is depleted, thus affecting the cycle life of the battery cell. When the thickness of the negative electrode functional coating is set to more than 50 μm, i.e., when the thickness of the negative electrode functional coating is set to be relatively thick, it increases the ion transport pathway in the battery cell, further increases the liquid phase impedance of the battery cell, affects the gram capacity of the battery cell, and reduces the energy density of the battery cell. At the same time, due to the space limitations inside the battery cell, there is a certain upper limit to the thickness of the negative electrode functional coating. By setting the thickness of the negative electrode functional coating to 0.2 μm-50 μm, it is possible to balance the internal space of the battery cell with the ability of the negative electrode plate to retain electrolyte, effectively mitigate the deterioration of the battery cell's performance, and improve the cycle life of the battery cell.

[0047] In some implementations, the thickness of this negative electrode functional coating is 0.5 μm to 30 μm, preferably 2 μm to 20 μm. This better balances the internal space of the battery cell with the ability to store the electrolyte, reducing the problem of battery performance degradation due to relatively low electrolyte levels or electrolyte depletion in the battery cell, and improving the cycle life of the battery cell.

[0048] According to a second embodiment, a battery is provided that includes a battery cell as described in any one of the above implementation methods.

[0049] According to a third embodiment, a power-consuming device is provided, the power-consuming device includes a battery as described in any one of the above implementation methods, and the battery is used to provide electrical energy to the power-consuming device.

[0050] In some implementations, this power-consuming device may be a vehicle, ship, or aerospace vehicle.

[0051] To more clearly illustrate the technical concept of the embodiments of this application, the following briefly introduces the drawings that may be used in the embodiments of this application. It is obvious that the drawings in the following description are only a few of the embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without expending any creative effort. [Brief explanation of the drawing]

[0052] [Figure 1] This is a schematic diagram of the structure of a vehicle according to one embodiment of this application. [Figure 2] This is a schematic diagram of the structure of an example battery according to one embodiment of this application. [Figure 3] This is a schematic diagram of the structure of an example battery cell according to one embodiment of this application. [Figure 4] This is a schematic cross-sectional view of the local structure of an example battery cell according to one embodiment of this application. [Figure 5] This is a schematic cross-sectional view of the local structure of another example of a battery cell according to one embodiment of this application. [Figure 6] This is a schematic cross-sectional view of the local structure of another example of a battery cell according to one embodiment of this application. [Modes for carrying out the invention]

[0053] In drawings, the drawings are not drawn to the actual scale.

[0054] The embodiments of this application will be described in more detail below, linking them with the drawings and examples. The detailed descriptions and drawings of the embodiments below are for illustrative purposes to illustrate the principles of the embodiments of this application, but are not intended to limit the scope of the embodiments of this application; that is, the embodiments of this application are not limited to those described.

[0055] Unless otherwise defined, all technical and scientific terms used in the embodiments of this application have the same meaning as that generally understood by those skilled in the art, and the terms used in the specification of this application are solely for the purpose of describing specific embodiments and are not intended to limit the embodiments of this application, and the terms “including” and “having” and any variations thereof in this specification, the claims and the description of the drawings are intentionally intended to cover the non-exclusive “including”.

[0056] In the descriptions of the embodiments of this application, technical terms such as "first," "second," etc., are used solely to distinguish different subjects and should not be understood as indicating or implying relative importance, or implicitly indicating the number, specific order, or hierarchical relationship of the indicated technical features. In the descriptions of the embodiments of this application, unless specifically defined, "plural" means two or more.

[0057] The “Examples” as used in this application mean that certain features, structures, or characteristics described in conjunction with the Examples may be included in at least one Example of this application. The appearance of this phrase in each location in the specification does not necessarily refer to the same Example, nor does it mean that each Example is mutually exclusive or alternative to the others. Those skilled in the art will understand, both explicitly and implicitly, that the Examples described in this application may be combined with other Examples.

[0058] In the description of the embodiments of this application, the term "and / or" merely describes a relationship between related objects, indicating that three relationships may exist. For example, A and / or B may represent three cases: A alone, a combination of A and B, or B alone. In this specification, the letter " / " generally indicates that the preceding and succeeding related objects are in an "or" relationship.

[0059] It should be understood that, in the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more sets (including two sets), and "multiple sheets" refers to two or more sheets (including two sheets).

[0060] In the description of the embodiments of this application, the orientations or positional relationships indicated by technical terms such as "center," "vertical direction," "horizontal direction," "length," "width," "thickness," "top," "bottom," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," "axial direction," "radial direction," and "circumferential direction" are orientations or positional relationships shown based on the drawings and are merely for the purpose of facilitating and simplifying the description of the embodiments of this application. They do not indicate or imply that the mentioned devices or elements have a specific orientation or must be configured and operated in a specific orientation, and therefore should not be understood as limitations on the embodiments of this application.

[0061] In the description of the embodiments of this application, unless otherwise explicitly defined or limited, technical terms such as “attachment,” “connection,” “connection,” and “fixing” should be understood in a broad sense. For example, these may be fixed connections, removable connections, integral connections, mechanical connections, electrical connections, direct connections, indirect connections via an intermediate medium, internal communication between two elements, or interaction relationships between two elements. Those skilled in the art may understand the specific meaning of these terms in the embodiments of this application depending on the specific circumstances.

[0062] In the embodiments of this application, a battery refers to a physical module containing one or more battery cells to provide electrical energy. For example, a battery as referred to in this application may include a battery module or a battery pack. A battery generally includes a housing for packaging one or more battery cells. The housing can reduce the influence of liquids or other foreign matter on the charging or discharging of the battery cells.

[0063] It should be understood that the battery cells in the embodiments of this application include, but are not limited to, lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0064] In some implementations, the battery cell in the embodiment of this application may be a metal battery, and specifically, this metal battery may include a lithium metal secondary battery, a sodium metal battery, or a magnesium metal battery, etc.

[0065] In some implementations, a battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator member. During charging and discharging of the battery cell, active ions (e.g., lithium ions) intermittently

[0066] In some implementations, the positive electrode may be a positive electrode plate, and the positive electrode plate may include a positive electrode current collector and a positive electrode active material placed on at least one surface of the positive electrode current collector.

[0067] For example, a positive electrode current collector has two opposing surfaces in the direction of its own thickness, and the positive electrode active material is placed on one or both of the two opposing surfaces of the positive electrode current collector.

[0068] As an example, the positive electrode current collector may employ a metal foil sheet or a composite current collector. For example, as the metal foil sheet, aluminum surface-treated with silver or is stainless steel, copper, aluminum ,mosquito -bon electrodes, carbon, nickel, titanium, etc. may also be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material substrate (such as substrates of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0069] As an example, the positive electrode active material may include at least one of a lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds. In some implementation manners, other conventional materials that can be used as the battery positive electrode active material may also be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of the lithium-containing phosphate may include, but are not limited to, at least one of lithium iron phosphate (for example, LiFePO4 (which may be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (for example, LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0070] As an example, the positive electrode active material may include at least one of a sodium transition metal oxide, a polyanionic type compound, and a Prussian blue-based compound.

[0071] In some implementation manners, the chemical formula of the sodium transition metal oxide can satisfy Na x MO2, where M includes at least one of Ti, V, Mn, Co, Ni, Fe, Zn, V, Zr, Ce, Cr, and Cu, and 0 < x ≦ 1. As an example, Na xIn MO2, x may be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.

[0072] In some implementations, the sodium transition metal oxide may be a doped and modified sodium transition metal oxide, and the doping modification of the sodium transition metal oxide may include at least one of sodium site doping modification, oxygen site doping modification, transition metal site doping modification, and surface coating modification.

[0073] In some implementations, the positive electrode may be made of foamed metal. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon. When foamed metal is used as the positive electrode, the positive electrode active material may or may not be placed on the surface of the foamed metal. For example, a lithium source material, potassium metal, or sodium metal may be filled and / or deposited within the foamed metal, and the lithium source material is lithium metal and / or a lithium-rich material.

[0074] In some implementations, the negative electrode may be a negative electrode plate, and the negative electrode plate may include a negative electrode current collector.

[0075] For example, the negative electrode current collector may be a metal foil sheet, foamed metal, or a composite current collector. For example, as a metal foil sheet, silver-surface-treated aluminum or is Stainless steel, copper, aluminum ,mosquito A carbon electrode, carbon, nickel, or titanium may be used. The composite current collector may include a polymer material base layer and a metal layer. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material substrate (for example, a substrate such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, or polyethylene).

[0076] In some implementations, the battery cell in the embodiment of this application may be a sodium secondary battery without a negative electrode.

[0077] A sodium secondary battery without a negative electrode refers to a battery cell in which a negative electrode active material layer is not spontaneously installed on the negative electrode side during the manufacturing process. For example, a sodium metal or carbonaceous active material layer is not formed on the negative electrode by processes such as coating or deposition during the manufacturing process of the battery cell. During the initial charge, sodium ions gain electrons on the anode side and deposit on the surface of the current collector to form a sodium metallic phase. During discharge, the metallic sodium can be converted back into sodium ions and return to the positive electrode, enabling cycle charging and discharging. Compared to other sodium secondary batteries, a sodium secondary battery without a negative electrode... The pond Because there is no negative electrode active material layer, a higher energy density can be obtained.

[0078] In some implementations, to improve the performance of the battery cell, several functional coatings such as carbonaceous materials, metal oxides, and alloys can be applied to the negative electrode side of a sodium secondary battery without a negative electrode to improve the conductivity of the negative electrode current collector and to improve the uniformity of the deposited sodium metal.

[0079] In some implementation methods, the CB value of a sodium secondary battery without a negative electrode is 0.1 or less.

[0080] Specifically, the CB value is the capacity per unit area of ​​the negative electrode plate in a secondary battery divided by the capacity per unit area of ​​the positive electrode plate. Batteries without a negative electrode contain little to no functional coating, resulting in a relatively small capacity per unit area of ​​the negative electrode plate, and thus a CB value of 0.1 or less for secondary batteries.

[0081] In some implementations, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0082] In some implementations, the electrode assembly further includes a separator member placed between the positive and negative electrodes.

[0083] In some implementations, the separator member is a separator. The embodiments of this application are not particularly limited to the type of separator, and any known porous separator having good chemical and mechanical stability may be selected.

[0084] For example, the main material of the separator may be at least one selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic.

[0085] In some implementations, the separator component is a solid electrolyte. The solid electrolyte is placed between the positive and negative electrodes and serves to facilitate ion transmission and isolate the positive and negative electrodes.

[0086] In some implementations, the battery cell further includes an electrolyte that plays a role in conducting ions between the positive and negative electrodes. The embodiments of this application are not specifically limited to the type of electrolyte, which can be selected according to the requirements. The electrolyte may be liquid, gel-like, or solid.

[0087] In some implementations, the electrode assembly may be a wound structure. The positive and negative plates are wound into a wound structure.

[0088] In some implementations, the electrode assembly has a layered structure. For example, multiple positive and negative electrodes can be installed, and these multiple positive and negative electrodes are stacked alternately.

[0089] For example, multiple positive electrodes may be installed, and the negative electrodes may be folded and stacked to form multiple folded segments, with one positive electrode sandwiched between adjacent folded segments.

[0090] For example, both the positive and negative electrode plates are folded and stacked to form multiple folded segments.

[0091] For example, multiple separator members may be installed, each placed between any adjacent positive or negative electrode plates.

[0092] For example, the separator members may be installed continuously, or they may be installed between any adjacent positive or negative plates by folding or winding them.

[0093] In some implementations, the shape of the electrode assembly may be cylindrical, flattened, or polygonal prism-shaped.

[0094] In some implementations, the electrode assembly is provided with tabs from which current can be drawn. These tabs include a positive electrode tab and a negative electrode tab.

[0095] In some implementations, the battery cell may include a housing. The housing may be used to package components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (e.g., polypropylene), composite metal (e.g., copper-aluminum composite housing), or aluminum-plastic film.

[0096] For example, the battery cell may be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shape. The prismatic battery cell includes prismatic battery cells, blade-shaped battery cells, and polygonal prismatic batteries, and polygonal prismatic batteries are, for example, hexagonal prismatic batteries.

[0097] To meet various power demands, the battery in the embodiment of this application may include multiple battery cells, which may be connected in series, in parallel, or in series-parallel, with series-parallel being a combination of series and parallel connections. Selectively, multiple battery cells may be connected in series, in parallel, or in series-parallel to form a battery module, and then multiple battery modules may be connected in series, in parallel, or in series-parallel to form a battery. In other words, multiple battery cells may directly form a battery, or they may form a battery module first, and then the battery module may form a battery. The battery is further installed in a power-consuming device and provides electrical energy to the power-consuming device.

[0098] Currently, during the charge-discharge cycle of batteries, for example, in metal batteries, the thickness of the negative electrode plate is generally set to be relatively thin, resulting in a relatively poor ability to retain electrolyte on the negative electrode side. During the charge-discharge cycle, the electrolyte is continuously consumed, leading to localized depletion of the electrolyte, which causes a decrease in battery performance and further affects the battery's cycle life. At the same time, during the charge-discharge cycle, the negative electrode plate partially expands and presses against the electrolyte between the negative electrode plate and the separator material, creating a risk of drying out and depletion of the electrolyte on the negative electrode side, as well as bridge breakage. If the electrolyte in the battery is not replenished in a timely manner, it further affects the battery's cycle life and deteriorates the battery's performance.

[0099] In view of this, embodiments of the present application provide a battery cell, a battery and a power consuming device, the battery cell including an electrode assembly, the electrode assembly including a negative electrode plate, a positive electrode plate and a separator member for separating the negative electrode plate and the positive electrode plate, wherein the ratio of the thickness H1 of the separator member to the thickness H2 of the negative electrode plate is 0.07 or more. In embodiments of the present application, by setting the ratio of the thickness H1 of the separator member to the thickness H2 of the negative electrode plate to 0.07 or more, a relatively large amount of electrolyte can be accommodated by increasing the thickness H2 of the separator member, thereby mitigating the problem of performance degradation of the battery cell due to a relatively small amount of electrolyte or depletion of the electrolyte in the battery cell, and improving the cycle life of the battery cell.

[0100] The technical solutions described in the embodiments of this application are all suitable for various power-consuming devices that use batteries.

[0101] Power-consuming devices may include vehicles, mobile phones, portable devices, laptop computers, steamships, aerospace vehicles, electric toys, and power tools. Vehicles may be fuel-oil vehicles, gas vehicles, or new energy vehicles, and new energy vehicles may be pure electric vehicles, hybrid vehicles, or range-extender vehicles. Aerospace vehicles include airplanes, rockets, space shuttles, and spacecraft. Electric toys include stationary or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric airplane toys. Power tools include metal cutting tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, electric impact drills, concrete vibrators, and electric planers.

[0102] It should be understood that the technical solutions described in the embodiments of this application are applicable not only to the power-consuming devices described above, but to all devices that use batteries. However, for the sake of brevity, the embodiments described below will be explained in detail using a vehicle as an example of the power-consuming device.

[0103] For example, as shown in Figure 1, this is a schematic diagram of the structure of a vehicle 1 according to an embodiment of the present application. The vehicle 1 may be a fuel oil vehicle, a gas vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or a range extender vehicle. A motor 40, a controller 30, and a battery 10 may be installed inside the vehicle 1, and the controller 30 is used to control the power supply of the motor 40 by the battery 10. For example, the battery 10 may be installed at the bottom, front, or rear of the vehicle 1. The battery 10 can be used to supply power to the vehicle 1, for example, as an operating power source for the vehicle 1, it can be used for the operating power consumption needs of the vehicle 1's circuit system, such as starting the vehicle 1, navigation, and operation. In another implementation of the present application, the battery 10 can provide driving power to the vehicle 1 not only as an operating power source for the vehicle 1, but also as a driving power source for the vehicle 1, in place of or in place of fuel oil or natural gas.

[0104] To meet different power consumption demands, the battery 10 in the embodiments of this application may be a group of battery cells or a battery pack. The battery 10 may include at least one group of battery cells, and the group of battery cells may include a plurality of battery cells, where the plurality of battery cells may be electrically connected in series, parallel, or series-parallel to form the battery 10, where series-parallel is a mixture of series and parallel connections. The battery 10 may also be called a battery pack. For example, a plurality of battery cells may first be connected in series, parallel, or series-parallel to form a battery module, and the plurality of battery modules may be further connected in series, parallel, or series-parallel to form the battery 10. In other words, a plurality of battery cells may directly form the battery 10, or they may first form a battery module, and then the battery module may form the battery 10.

[0105] In some implementations, the battery 10 may include multiple battery cells. For example, as shown in Figure 2, a schematic diagram of the structure of a battery 10 according to one embodiment of this application, the battery 10 may include multiple battery cells 20. The battery 10 may further include a housing 11, the housing 11 having a hollow structure inside, and the multiple battery cells 20 are housed within the housing 11. For example, the multiple battery cells 20 are connected in parallel, in series, or in series-parallel and then placed inside the housing 11.

[0106] In some implementations, the battery 10 may further include other structures, which are not described here individually. For example, the battery 10 may further include busbar members for realizing electrical connections between multiple battery cells 20, such as parallel, series, or series-parallel connections. Specifically, the busbar members may realize electrical connections between the battery cells 20 by connecting the electrode terminals of the battery cells 20. Furthermore, the busbar members may be fixed to the electrode terminals of the battery cells 20 by welding. The electrical energy of the multiple battery cells 20 may further be derived through the housing via a conductive mechanism. Selectively, the conductive mechanism may also belong to the busbar members.

[0107] In the embodiments of this application, the number of battery cells 20 may be set to any number depending on different power demands. To achieve a relatively large capacity or power, multiple battery cells 20 may be connected in series, parallel, or series-parallel configurations. Since each battery 10 may contain a relatively large number of battery cells 20, to facilitate installation, the battery cells 20 may be grouped together and installed, with each group of battery cells 20 constituting a battery module. The number of battery cells 20 included in a battery module is not limited and may be set according to demand. The battery 10 may include multiple battery modules, and these battery modules may be connected in series, parallel, or series-parallel configurations.

[0108] As shown in Figure 3, this is a schematic diagram of the structure of a battery cell 20 of one embodiment of the present application, the battery cell 20 comprising one or more electrode assemblies 22, a case 211, and a cover plate 212. The case 211 and the cover plate 212 form a housing or battery box 21. The walls of the case 211 and the walls of the cover plate 212 are both referred to as the walls of the battery cell 20, where, for a rectangular parallelepiped battery cell 20, the walls of the case 211 include a bottom wall and four side walls. The shape of the case 211 is determined according to the shape after one or more electrode assemblies 22 are combined, for example, the case 211 may be a hollow rectangular parallelepiped, a straight parallelepiped, or a cylinder, and one of the faces of the case 211 has an opening so that one or more electrode assemblies 22 can be easily placed inside the case 211. For example, if case 211 is a hollow rectangular or square parallelepiped, one of its planes is an opening, that is, this plane allows communication between the inside and outside of case 211 without a wall. If case 211 is a hollow cylindrical body, one of its end faces is an opening, that is, this end face allows communication between the inside and outside of case 211 without a wall. The cover plate 212 covers the opening and is connected to case 211 to form a sealed cavity in which the electrode assembly 22 is placed. The case 211 is filled with an electrolyte, such as an electrolyte solution.

[0109] The battery cell 20 may further include two electrode terminals 214, which may be mounted on a cover plate 212. The cover plate 212 is generally flat, and the two electrode terminals 214 are fixed to the flat surface of the cover plate 212, with the two electrode terminals 214 being the positive electrode terminal 214a and the negative electrode terminal 214b, respectively. A connecting component (or current collector component) is provided corresponding to each electrode terminal 214, and it is located between the cover plate 212 and the electrode assembly 22 to provide an electrical connection between the electrode assembly 22 and the electrode terminal 214.

[0110] As shown in Figure 3, each electrode assembly 22 has a first tab 221a and a second tab 222a. The polarities of the first tab 221a and the second tab 222a are opposite. For example, if the first tab 221a is the positive electrode tab, then the second tab 222a is the negative electrode tab.

[0111] In this battery cell 20, depending on the actual usage requirements, the electrode assembly 22 may be set to one or more, and as shown in Figure 3, four independent electrode assemblies 22 are installed inside the battery cell 20.

[0112] A pressure relief mechanism 213 may be installed in the battery cell 20. The pressure relief mechanism 213 is used to release the internal pressure or temperature of the battery cell 20 when the internal pressure or temperature reaches a threshold.

[0113] The pressure release mechanism 213 may have various possible pressure release structures. For example, the pressure release mechanism 213 may be a temperature-sensitive pressure release mechanism, which is configured to melt when the internal temperature of the battery cell 20 on which the pressure release mechanism 213 is provided reaches a threshold, and / or the pressure release mechanism 213 may be a pressure-sensitive pressure release mechanism, which is configured to rupture when the internal pressure of the battery cell 20 on which the pressure release mechanism 213 is provided reaches a threshold.

[0114] Figure 4 is a schematic cross-sectional view of the local structure of a battery cell 20 according to one embodiment of the present application. As shown in Figure 4, the battery cell 20 includes a separator member 50, a negative electrode plate 60, and a positive electrode plate 70. An electrolyte is filled between the positive electrode plate 70 and the separator member 50, and between the negative electrode plate 60 and the separator member 50.

[0115] In some implementations, the battery cell 20 includes an electrode assembly 22, which includes a negative electrode plate 60, a positive electrode plate 70, and a separator member 50 for separating the negative electrode plate 60 from the positive electrode plate 70, wherein the ratio of the thickness H1 of the separator member 50 to the thickness H2 of the negative electrode plate 60 is 0.07 or greater.

[0116] In the embodiments of this application, the thickness H2 of the negative electrode plate 60 affects the formation of a surface passivation film on the negative electrode plate 60. When the thickness H2 of the negative electrode plate 60 is relatively thick, the initial charge capacity of the battery 10 decreases, affecting the charge and discharge efficiency of the negative electrode plate 60 and reducing the energy density of the battery 10. Therefore, the thickness H2 of the negative electrode plate 60 is generally set within an appropriate range. When the ratio of the thickness H1 of the separator member 50 to the thickness H2 of the negative electrode plate 60 is set to 0.07 or more, increasing the thickness H1 of the separator member 50 allows for the storage of a relatively large amount of electrolyte, mitigating the problem of performance degradation of the battery 10 due to a relatively small amount of electrolyte or depletion of electrolyte, and improving the cycle life of the battery 10.

[0117] In some implementations, the thickness H1 of the separator member 50 and the thickness H2 of the negative electrode plate 60 satisfy 0.07 ≤ H1 / H2 ≤ 241.18, and preferably, the thickness H1 of the separator member 50 and the thickness H2 of the negative electrode plate 60 satisfy 0.15 ≤ H1 / H2 ≤ 220.59.

[0118] In the embodiments of this application, when H1 / H2 < 0.07, if the thickness H1 of the separator member 50 is set to be relatively thin, the ability of the separator member 50 to store electrolyte becomes relatively poor, which can easily lead to insufficient electrolyte in the battery 10 or depletion of electrolyte, causing a decrease in the operating performance of the battery 10 and affecting the cycle life of the battery 10. When H1 / H2 > 241.18, if the thickness H1 of the separator member 50 is set to be relatively thick, it increases the ion transport path in the battery cell 20, further increases the liquid phase impedance of the battery cell 20, affects the gram capacity of the battery cell 20, and reduces the energy density of the battery cell 20. At the same time, due to the space limitations inside the battery cell 20, there is a certain upper limit to the thickness H1 of the separator member 50. Therefore, by setting the ratio of the thickness H1 of the separator member 50 and the thickness H2 of the negative electrode plate 60 in the battery cell 20 to 0.07 ≤ H1 / H2 ≤ 241.18, or further setting the ratio of the thickness H1 of the separator member 50 and the thickness H2 of the negative electrode plate 60 in the battery cell 20 to 0.15 ≤ H1 / H2 ≤ 220.59, it is possible to balance the internal space of the battery cell 20 with the ability to store electrolyte, while effectively reducing the problem of reduced performance of the battery cell 20 due to relatively little electrolyte or depletion of electrolyte, thereby improving the cycle life of the battery cell 20 and improving the gram capacity of the battery cell 20.

[0119] In light of this, the H1 / H2 values ​​in the embodiments of this application should not be set to be excessively large or small. Exemplary examples of H1 / H2 values ​​in the embodiments of this application include 0.07, 0.09, 0.10, 0.15, 0.20, 0.30, 0.31, 0.36, 0.40, 0.44, 0.60, 0.71, 0.80, and 0. 86, 0.89, 1.00, 1.14, 1.16, 1.20, 1.25, 1.33, 1.43, 1.50, 1.67, 1.90, 2.00, 2.14, 2.50, 2.86, 3.00, 3.50, 3.57, 3.75, 4.00, 4.29, 4.50, 5.00, 5.50, 6.00, 6.50, 7.00, 7.50, 8.00, 8.50, 9.00, 9.50, 10.00, 20.00, 21.43, 26.79, 30.00, 37.50, 40.00, 50.00, 60.00, 70.00, 75.00, 80.00, 90.00, 100.00, 110.00, 120.00, 130.00, 140.00, The value may be 150.00, 160.00, 170.00, 180.00, 190.00, 200.00, 210.00, 220.00, 220.59, 230.00, 235.29, 240.00, 241.18, etc., or the value may be within the range obtained by combining any two of the above values.

[0120] In some implementations, the thickness H1 of the separator member 50 and the thickness H2 of the negative electrode plate 60 satisfy 1.16 ≤ H1 / H2 ≤ 75, and preferably, the thickness H1 of the separator member 50 and the thickness H2 of the negative electrode plate 60 satisfy 1.16 ≤ H1 / H2 ≤ 21.43.

[0121] In the embodiments of this application, by setting the thickness H1 of the separator member 50 and the thickness H2 of the negative electrode plate 60 in the battery cell 20 to 1.16 ≤ H1 / H2 ≤ 75, or by setting the thickness H1 of the separator member 50 and the thickness H2 of the negative electrode plate 60 in the battery cell 20 to 1.16 ≤ H1 / H2 ≤ 21.43, a better balance is achieved between the internal space of the battery cell 20 and the ability of the battery cell 20 to store electrolyte, thereby effectively reducing the problem of performance degradation of the battery cell 20 due to relatively little electrolyte or depletion of electrolyte, and improving the cycle life of the battery cell 20.

[0122] In some implementations, the ratio of the thickness H1 of the separator member 50 to the thickness H2 of the negative electrode plate 60 satisfies 1.20 ≤ H1 / H2 ≤ 10. Thus, in the embodiments of this application, by setting the thickness H1 of the separator member 50 and the thickness H2 of the negative electrode plate 60 to 1.20 ≤ H1 / H2 ≤ 10, a better balance is achieved between the space inside the battery cell 20 and the ability of the battery cell 20 to store electrolyte. This effectively reduces the problem of performance degradation of the battery cell 20 due to relatively little electrolyte or depletion of electrolyte, and further improves the cycle life of the battery cell 20.

[0123] It should be understood that, in some implementations, the thickness H1 of the separator member 50 should not be set too large or too small in the embodiments of this application. In some implementations, the range of values ​​for the thickness H1 of the separator member 50 is [3 μm, 750 μm]. If the thickness H1 of the separator member 50 is less than 3 μm, i.e., if the thickness H1 of the separator member 50 is set relatively thin, the ability of the separator member 50 to store electrolyte will be relatively poor, and if there is too little electrolyte in the battery cell 20 or if the electrolyte is depleted, the battery Cell 20 It becomes difficult to replenish the electrolyte in a timely manner, which affects the cycle life of the battery cell 20. If the thickness H1 of this separator member 50 is greater than 750 μm, that is, if the thickness H1 of this separator member 50 is set to be relatively thick, it increases the ion transport path in the battery cell 20, further increases the liquid phase impedance of the battery cell 20, affects the gram capacity of the battery cell 20, and reduces the energy density of the battery cell 20. At the same time, due to the space limitations inside the battery cell 20, there is a certain upper limit to the thickness H1 of this separator member 50. By setting the thickness H1 of this separator member 50 to [3 μm, 750 μm], it is possible to balance the internal space of the battery cell 20 with the ability to store electrolyte, and improve the cycle life of the battery cell 20.

[0124] In view of this, the thickness H1 of the separator member 50 in the embodiment of this application may be set to a value within the range of 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, 500μm, 550μm, 600μm, 650μm, 700μm, 750μm, or any two of the above values ​​combined.

[0125] In some implementations, the range of the thickness H1 of the separator member 50 may be set to [5 μm, 150 μm], for example.

[0126] It should be understood that, in some implementations, the thickness H2 of the negative electrode plate 60 should not be set too large or too small in the embodiments of this application. In some implementations, the range of values ​​for the thickness H2 of the negative electrode plate 60 is [3 μm, 150 μm]. If the thickness H2 of the negative electrode plate 60 is less than 3 μm, i.e., if the thickness H2 of the negative electrode plate 60 is set to be relatively thin, the ability of the negative electrode plate 60 to store electrolyte will be relatively poor, making it difficult to replenish the electrolyte in the battery cell 20 in a timely manner if there is too little electrolyte or if the electrolyte is depleted, thus affecting the cycle life of the battery cell 20. If the thickness H2 of the negative electrode plate 60 is greater than 150 μm, that is, if the thickness H2 of the negative electrode plate 60 is set to be relatively thick, it increases the ion transport path in the battery cell 20, further increases the liquid phase impedance of the battery cell 20, affects the gram capacity of the battery cell 20, and decreases the energy density of the battery cell 20. At the same time, due to the space limitations inside the battery cell 20, there is a certain upper limit to the thickness H2 of the negative electrode plate 60. By setting the thickness H2 of the negative electrode plate 60 to [3 μm, 150 μm], it is possible to balance the internal space of the battery cell 20 with the ability to store the electrolyte, and improve the cycle life of the battery cell 20.

[0127] In view of this, the thickness H2 of the negative electrode plate 60 in the embodiment of this application may be set to a value within the range of 3 μm, 7 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, or any two of the above values ​​combined.

[0128] In some implementations, the range of values ​​for the thickness H2 of the negative electrode plate 60 may be set to [4 μm, 90 μm], for example.

[0129] Figure 5 shows a schematic cross-sectional view of the local structure of a battery cell 20 in another example according to the embodiments of this application. In some implementations, the separator member 50 includes a separator body 51 and a separator functional coating 52 installed on the surface of the separator body 51, wherein the separator functional coating 52 is installed on one or both sides of the surface of the separator body 51. Exemplarily, as shown in Figure 5, the separator functional coating 52 in the separator member 50 is installed on both sides of the surface of the separator body 51.

[0130] In the embodiments of this application, by providing a separator functional coating 52 on one or both sides of the separator body 51 of the separator member 50, the ability of the separator member 50 to store electrolyte can be improved by the installed separator functional coating 52. This allows for timely replenishment of electrolyte in the battery cell 20 when the electrolyte level is relatively low or when the electrolyte is depleted, effectively reducing the deterioration of the battery cell 20's performance and improving the battery cell 20's cycle life.

[0131] In some implementations, the material of the separator functional coating 52 in the embodiments of this application includes at least one of the following: polyvinylidene fluoride copolymer, sodium carboxymethylcellulose, polystyrene-butadiene copolymer, styrene-butadiene block copolymer, styrene-isoprene block copolymer, ethylene-butene copolymer, polypropylene-octene thermoplastic elastomer, ethylene-octene thermoplastic elastomer, and propylene-ethylene copolymer.

[0132] In the embodiments of this application, the material of the separator functional coating 52 of the separator member 50 in the battery cell 20 is set to at least one of polyvinylidene fluoride copolymer, sodium carboxymethylcellulose, polystyrene butadiene copolymer, styrene-butadiene block copolymer, styrene-isoprene block copolymer, ethylene-butene copolymer, polypropylene-octene thermoplastic elastomer, ethylene-octene thermoplastic elastomer, and propylene-ethylene copolymer. This improves the reversible compressibility of the separator functional coating 52 of the separator member 50, allowing it to act as a buffer against the volume expansion of the negative electrode plate 60 during the charging and discharging process of the battery cell 20, thereby mitigating the performance degradation of the battery cell 20.

[0133] In the embodiments of this application, the thickness H3 of the separator body 51 in the separator member 50 should not be set to be excessively large or small. Specifically, the thickness H3 of the separator body 51 may be set according to the actual application.

[0134] In some implementations, the range of the thickness H3 of the separator body 51 is [3 μm, 250 μm]. In the embodiments of this application, if the thickness H3 of the separator body 51 is set to less than 3 μm, that is, if the thickness H3 of the separator body 51 is set to be relatively thin, the ability of the separator member 50 to store electrolyte in the whole becomes relatively poor, making it difficult to replenish the electrolyte in the battery cell 20 if there is too little electrolyte or if the electrolyte is depleted, affecting the cycle life of the battery cell 20. If the thickness H3 of the separator body 51 is set to more than 250 μm, that is, if the thickness H3 of the separator body 51 is set to be relatively thick, it increases the ion transport path in the battery cell 20, further increases the liquid phase impedance of the battery cell 20, affects the gram capacity of the battery cell 20, and reduces the energy density of the battery cell 20. At the same time, due to the space limitations inside the battery cell 20, there is a certain upper limit to the thickness H3 of the separator body 51. By setting the thickness H3 of the separator body 51 to 3μm-250μm, it is possible to balance the internal space of the battery cell 20 with the ability to store the electrolyte, while effectively reducing the degradation of the battery cell 20's performance and improving the battery cell 20's cycle life.

[0135] For example, the thickness H3 of the separator body 51 in the separator member 50 in the embodiment of this application may be set to a value within the range of 3 μm, 5 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 15 μm, 20 μm, 25 μm, 30 μm, 50 μm, 70 μm, 90 μm, 110 μm, 130 μm, 150 μm, 170 μm, 190 μm, 210 μm, 230 μm, 250 μm, or any two of the above values ​​combined.

[0136] In some implementations, the range of the thickness H3 of the separator body 51 is, for example, [5 μm, 50 μm].

[0137] Accordingly, in the embodiments of this application, the thickness H4 of the separator functional coating 52 on the separator member 50 should not be set to be excessively large or small, and the thickness H4 of the separator functional coating 52 may be set according to the actual application.

[0138] In some implementations, the thickness H4 of the separator functional coating 52 is [0.1 μm, 250 μm]. When the thickness H4 of the separator functional coating 52 is set to less than 0.1 μm, that is, when the thickness H4 of the separator functional coating 52 is set to be relatively thin, the ability of the entire separator member 50 to store electrolyte becomes relatively poor, and if there is too little electrolyte in the battery cell 20 or if the electrolyte is depleted, the battery Cell 20 It becomes difficult to replenish the electrolyte in a timely manner, affecting the cycle life of the battery cell 20. If the thickness H4 of this separator functional coating 52 is set to be greater than 250 μm, that is, if the thickness H4 of the separator functional coating 52 is set to be relatively thick, it increases the ion transport pathway in the battery cell 20, further increases the liquid phase impedance of the battery cell 20, affects the gram capacity of the battery cell 20, and reduces the energy density of the battery cell 20. At the same time, due to the space limitations inside the battery cell 20, there is a certain upper limit to the thickness H4 of this separator functional coating 52. By setting the thickness H4 of this separator functional coating 52 to 0.1 μm-250 μm, it is possible to balance the internal space of the battery cell 20 with the ability to store electrolyte, and improve the cycle life of the battery cell 20.

[0139] For example, the thickness H4 of the separator functional coating 52 on the separator member 50 in the embodiments of this application may be set to 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.7 μm, 0.9 μm, 1 μm, 2 μm, 3 μm, 5 μm, 6 μm, 7 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 50 μm, 70 μm, 90 μm, 110 μm, 130 μm, 150 μm, 170 μm, 190 μm, 210 μm, 230 μm, or 250 μm, or the value may be within the range obtained by combining any two of the above values.

[0140] In some implementations, the thickness H4 of the separator functional coating 52 is [0.5 μm, 50 μm], and preferably, the thickness H4 of the separator functional coating 52 is [2 μm, 20 μm]. Thus, the embodiments of this application better balance the internal space of the battery cell 20 with the ability to store the electrolyte, thereby improving the cycle life of the battery cell 20.

[0141] In some implementations, the separator functional coating 52 in the embodiments of this application is a hollow, resilient structure. It should be understood that the hollow, resilient structure in the embodiments of this application can be compressed under external pressure, but after this pressure is removed, the hollow, resilient structure can return to its initial uncompressed state.

[0142] In the embodiments of this application, by providing a hollow, resilient structure in the separator functional coating 52 of the separator member 50, on the one hand, the hollow structure allows for the storage of a relatively large amount of electrolyte, thereby enabling timely replenishment of electrolyte when the electrolyte level in the battery cell 20 is relatively low or depleted, effectively reducing the deterioration of the battery cell 20's performance and improving its cycle life. On the other hand, the hollow, resilient structure of the separator functional coating 52 provides a buffering effect against the volume expansion of the electrode plates during the charging and discharging process of the battery cell 20, simultaneously reducing the risk of electrolyte drying out and bridge breakage due to the volume expansion of the electrode plates.

[0143] In some implementations, the hollow resilient structure in the embodiments of this application includes an open-pore structure. Thus, in the embodiments of this application, the separator functional coating 52 is set as a hollow resilient structure, and this hollow resilient structure includes an open-pore structure. When the volume of the electrode plates expands during the charging and discharging process of the battery cell 20 and presses against this hollow resilient structure, the electrolyte inside the hollow resilient structure is discharged through this open-pore structure, allowing for timely replenishment of the electrolyte to the battery cell 20. This reduces the risk of electrolyte drying out and bridge breakage, thereby improving the cycle life of the battery cell 20.

[0144] In some implementations, at least one opening of the porous structure faces the negative electrode plate 60. Thus, in the embodiments of this application, at least one opening of the porous structure faces the negative electrode plate 60, and during the charging and discharging process of the battery cell 20, if volume expansion occurs in the negative electrode plate 60 and presses against the hollow, resilient structure, causing a decrease or depletion of the electrolyte between the separator member 50 and the negative electrode plate 60, the electrolyte stored in the hollow, resilient structure can be discharged through at least one opening in the porous structure, thereby replenishing the electrolyte between the separator member 50 and the negative electrode plate 60, effectively reducing the risk of electrolyte depletion and bridge breakage between the separator member 50 and the negative electrode plate 60, and improving the cycle life of the battery cell 20.

[0145] FIG. 6 shows a schematic cross-sectional view of the local structure of another example of the battery cell 20 according to an embodiment of the present application. In some implementation manners, as shown in FIG. 6, the hollow and resilient structure in the embodiment of the present application includes a plurality of unsealed hollow and resilient balls 80 arranged along the surface of the separator body 51. Thus, in the embodiment of the present application, the hollow and resilient structure can store the electrolyte by means of the plurality of unsealed hollow and resilient balls 80 arranged along the surface of the separator body 51. On the one hand, by storing the electrolyte with the plurality of unsealed hollow and resilient balls 80, when the electrolyte in the battery cell 20 is relatively less or the electrolyte is depleted, the electrolyte can be replenished in a timely manner, effectively reducing the decrease in the performance of the battery cell 20 and improving the cycle life of the battery cell 20. On the other hand, during the charge and discharge process of the battery cell 20, when the volume of the negative electrode plate 60 expands and presses the hollow and resilient structure, the hollow and resilient ball 80 can exert a buffering effect on the negative electrode plate 60. At the same time, when the volume of the negative electrode plate 60 expands and presses the separator member, resulting in a decrease or dry depletion of the electrolyte between the negative electrode plate 60 and the separator member 50, the electrolyte stored in the hollow and resilient ball 80 is pressed and discharged by the negative electrode plate 60, so as to replenish the electrolyte between the separator member 50 and the negative electrode plate 60 in a timely manner, effectively reducing the risk of dry depletion and bridge disconnection of the electrolyte between the separator member 50 and the negative electrode plate 60.

[0146] In some implementation manners, the diameters of the plurality of unsealed hollow and resilient balls 80 arranged along the surface of the separator body 51 in the embodiment of the present application may be set to [1 μm, 50 μm], and the wall thickness of the hollow and resilient ball 80 may be set to [50 nm, 2 μm]. Specifically, the diameter or wall thickness of the hollow and resilient ball 80 may be set according to actual requirements.

[0147] In some implementation manners, the specific surface area of the pore structure in the embodiment of the present application is 0.5 m 2 / g - 10 m 2 / g. Thus, in the embodiments of this application, the specific surface of the pore structure product 0.5m 2 If the value is less than / g, the material has relatively few pores, resulting in relatively poor adsorption capacity and difficulty in adsorbing electrolyte, thus making it difficult to store electrolyte through this pore structure. Specific surface of the pore structure product 10m 2 If the value is greater than / g, the difficulty of processing this pore structure becomes relatively high, and manufacturing costs increase. Thus, the specific surface area of ​​this pore structure is 0.5m². 2 / g-10m 2 By setting the value to / g, this pore structure is given good electrolyte storage capacity. At the same time, during the charging and discharging process of the battery cell 20, when the volume of the electrode plates expands and presses against this hollow, resilient structure, the electrolyte inside this hollow, resilient structure is smoothly discharged through this open pore structure. This allows for timely replenishment of electrolyte to the battery cell 20, thereby reducing the risk of electrolyte drying out and bridge breakage, and improving the cycle life of the battery cell 20.

[0148] It should be understood that, in the embodiments of this application, the specific surface area of ​​the pore structure should not be set to be excessively large or small, and the specific surface area of ​​the pore structure may be set according to the actual application. Exemplaryly, the specific surface area of ​​the pore structure in the embodiments of this application is 0.5 m². 2 / g, 1m 2 / g, 1.5m 2 / g, 2m 2 / g, 2.5m 2 / g, 3m 2 / g, 3.5m 2 / g, 4m 2 / g, 4.5m 2 / g, 5m 2 / g, 5.5m 2 / g, 6.5m 2 / g, 7m 2 / g, 7.5m 2 / g, 8m 2 / g, 8.5m 2 / g, 9m 2 / g, 9.5m 2 / g, 10m2 The value may be set to / g, or to a value within the range obtained by combining any two of the above values.

[0149] In some implementations, the compression percentage of the separator member 50 in the embodiment of this application is [8%, 95%]. Thus, in the embodiment of this application, by setting the compression percentage of the separator member 50 to 8%-95%, the separator member 50 can act as a buffer against the electrode plates that undergo volume expansion during the charging and discharging process of the battery cell 20, thereby improving the operating performance of the battery cell 20.

[0150] Specifically, the compression percentage of the separator member 50 in the embodiment of this application may be 8%, 10%, 12%, 14%, 16%, 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, or the value may be within the range obtained by combining any two of the above values.

[0151] In some implementations, for example, the compression percentage of the separator member 50 in the embodiment of this application is [20%, 80%].

[0152] In some implementations, the pressure-receiving strength range of the separator member 50 in the embodiment of this application is [0.05 MPa, 10 MPa]. Thus, in the embodiment of this application, if the pressure-receiving strength range of the separator member 50 is less than 0.05 MPa, that is, when the electrode plate presses against the separator member 50 after volume expansion occurs during the charging and discharging process of the battery cell 20, it is likely to cause deformation and breakage of the separator member 50. If the pressure-receiving strength range of the separator member 50 is greater than 10 MPa, that is, the pressure-receiving strength of the separator member 50 is relatively large, making it difficult to generate a buffering effect against the electrode plate after volume expansion during the charging and discharging process of the battery cell 20, affecting the operating performance of the battery cell 20 and reducing the cycle life of the battery cell 20. By setting the pressure-receiving strength range of the separator member 50 to 0.05 MPa-10 MPa, the separator member 50 can perform a buffering effect against the electrode plate after volume expansion occurs during the charging and discharging process of the battery cell 20.

[0153] Specifically, in the embodiments of this application, when measuring the pressure-receiving strength of the separator member 50, it can be tested using a universal testing machine (e.g., MDTC-EQ-M12-01), and the specific steps are as follows: 1. Select a plurality of separator member 50 test samples, and control the thickness of these selected test samples within a certain error range, the thickness of each of these selected test samples being 1 mm or more; 2. Set an initial pressure value, and obtain the initial pressurized thickness by performing a pressurization experiment on each test sample at this constant pressure, for example, setting this initial pressure value to 0.05 MPa; 3. Continue pressurizing these plurality of test samples, increasing the pressure at a constant rate until the thickness value of the test samples stops changing, obtain the pressure output from the universal testing machine and pressure data, and obtain the range of pressure-receiving strength of these test samples by analysis.

[0154] For example, the pressure-receiving strength of the separator member 50 in the embodiment of this application may be a value within the range of 0.05 MPa, 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, or any combination of any two of the above values.

[0155] In some implementations, the pressure-receiving strength of the separator member 50 in the embodiment of this application is, for example, range The pressure may be [0.05 MPa, 3 MPa].

[0156] In some implementations, the negative electrode plate 60 includes a negative electrode current collector 61 and a negative electrode functional coating 62 installed on the surface of the negative electrode current collector 61, wherein the negative electrode functional coating 62 is installed on one or both sides of the negative electrode current collector 61. Exemplarily, as shown in Figures 5 and 6, the negative electrode functional coating 62 on the negative electrode plate 60 may be installed on both sides of the negative electrode current collector 61.

[0157] In the embodiments of this application, by providing a negative electrode functional coating 62 on one or both sides of the negative electrode current collector 61 of the negative electrode plate 60, the ability of the negative electrode plate 60 to retain electrolyte can be improved. This allows for timely replenishment of electrolyte in the battery cell 20 when the electrolyte level is relatively low or when the electrolyte is depleted, effectively reducing the deterioration of the battery cell 20's performance and improving the battery cell 20's cycle life.

[0158] In some implementations, the material of the negative electrode functional coating 62 is a porous carbon material, preferably comprising at least one of carbon nanotubes, Super-P, KS-6, mesocarbon microbeads, hard carbon, and graphite. Thus, in the embodiments of this application, by setting the material of the negative electrode functional coating 62 of the negative electrode plate 60 in the battery cell 20 to a porous carbon material, for example, this porous carbon material may be set to at least one of nanocarbon tubes, Super-P, KS-6, mesocarbon microbeads, hard carbon, and graphite, the ability of the negative electrode plate 60 to adsorb electrolyte can be improved, that is, the ability of the negative electrode functional coating 62 to retain electrolyte can be improved, reducing the risk of electrolyte drying out and bridge breakage, and further improving the cycle life of the battery cell 20.

[0159] In the embodiments of this application, the thickness H5 of the negative electrode current collector 61 in the negative electrode plate 60 should not be set to be excessively large or small, and the thickness H5 of the negative electrode current collector 61 may be set according to the actual requirements.

[0160] It should be understood that, in the embodiments of this application, during the initial charge-discharge process, the electrode material and electrolyte of the battery cell 20 react at the solid-liquid interface to form a passivation layer covering the surface of the electrode material. This passivation layer may also be called an interface layer. As the passivation layer on the surface of the negative electrode material increases, the electrode impedance increases, further affecting the charge-discharge efficiency of the negative electrode plate 60 and reducing the energy density of the battery cell 20. Therefore, the thickness H2 of the negative electrode plate 60 should be set within an appropriate range. The ranges of the thickness H5 of the negative electrode current collector 61 and the thickness H6 of the negative electrode functional coating 62 in the negative electrode plate 60 will be described in detail below.

[0161] In some implementations, the thickness H5 of the negative electrode current collector 61 is [3 μm, 250 μm]. Thus, in the embodiments of this application, if the thickness H5 of the negative electrode current collector 61 is set to less than 3 μm, that is, the thickness H5 of the negative electrode current collector 61 is relatively thin, making it easy for localized short-circuit melting to occur, and at the same time the strength value of the negative electrode current collector 61 decreases, affecting the operating performance of the battery 10. If the thickness H5 of the negative electrode current collector 61 is set to more than 250 μm, that is, the thickness H5 of the negative electrode current collector 61 is relatively thick, increasing the processing cost of the battery 10, and there is a certain upper limit to the thickness H5 of the negative electrode current collector 61 due to the space limitations inside the battery cell 20. By setting the thickness H5 of the negative electrode current collector 61 to 3 μm-250 μm, it is possible to improve the operating performance of the battery cell 20 while balancing the internal space of the battery cell 20 and the fluid retention performance of the negative electrode plate 60.

[0162] For example, the thickness H5 of the negative electrode current collector 61 in the negative electrode plate 60 in the embodiment of this application may be set to a value within the range of 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 50 μm, 70 μm, 90 μm, 110 μm, 130 μm, 150 μm, 170 μm, 190 μm, 210 μm, 230 μm, 250 μm, or any two of the above values ​​combined.

[0163] In some implementations, the range of values ​​for the thickness H5 of the negative electrode current collector 61 is, for example, [4 μm, 30 μm].

[0164] In some implementations, the thickness H6 of the negative electrode functional coating 62 is [0.2 μm, 50 μm]. Thus, in the embodiments of this application, if the thickness H6 of the negative electrode functional coating 62 is set to less than 0.2 μm, that is, if the thickness H6 of the negative electrode functional coating 62 is set to be relatively thin, the ability of the negative electrode plate 60 to store electrolyte becomes relatively poor, making it difficult to replenish the electrolyte in the battery cell 20 when there is too little electrolyte or the electrolyte is depleted in the battery 10, affecting the cycle life of the battery cell 20. If the thickness H6 of the negative electrode functional coating 62 is set to more than 50 μm, that is, if the thickness H6 of the negative electrode functional coating 62 is set to be relatively thick, it increases the ion transport pathway in the battery cell 20, further increases the liquid phase impedance of the battery cell 20, affects the gram capacity of the battery cell 20, and reduces the energy density of the battery cell 20. At the same time, due to the space limitations inside the battery cell 20, there is a certain upper limit to the thickness H6 of the negative electrode functional coating 62. By setting the thickness H6 of this negative electrode functional coating 62 to 0.2 μm-50 μm, it is possible to balance the internal space of the battery cell 20 with the ability of the negative electrode plate 60 to preserve the electrolyte, while effectively reducing the degradation of the battery cell 20's performance and improving the battery cell 20's cycle life.

[0165] For example, the thickness H6 of the negative electrode functional coating 62 in the negative electrode plate 60 in the embodiments of this application may be set to 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 70 μm, 90 μm, 110 μm, 130 μm, 150 μm, 170 μm, 190 μm, 210 μm, 230 μm, or 250 μm, or the value may be within the range obtained by combining any two of the above values.

[0166] In some implementations, the thickness H6 of the negative electrode functional coating 62 is [0.5 μm, 30 μm], and preferably, the thickness H6 of the negative electrode functional coating 62 is [2 μm, 20 μm]. Thus, in the embodiments of this application, the internal space of the battery cell 20 and the ability of the negative electrode plate 60 to store electrolyte are better balanced, effectively reducing the degradation of the performance of the battery cell 20 and improving the cycle life of the battery cell 20.

[0167] The following describes embodiments of this application. The embodiments described below are illustrative and intended to interpret this application and should not be construed as limitations thereon. Where no specific technical or condition is described in the embodiments of this application, the technical or condition or product specifications described in the literature in the art shall apply. Where the manufacturer of the reagents or equipment used is not specified, they are all commonly available commercial products.

[0168] The results obtained by performing liquid retention performance tests and electrical performance tests on the battery cell 20 according to the embodiment of this application are shown in Table 1 below.

[0169] [Table 1] JPEG2026517358000011.jpg182170

[0170] As shown in Table 1 above, H1 in Table 1 represents the thickness of the separator member 50 in the embodiment of this application, and exemplary the separator member 50 may include a separator body 51 and a separator functional coating 52 installed on both sides of the separator body 51. H2 in Table 1 represents the thickness of the negative electrode plate 60 in the embodiment of this application, and exemplary the negative electrode plate 60 includes a negative electrode current collector 61 and a negative electrode functional coating 62 installed on both sides of the negative electrode current collector 61. The electrolyte retention performance in Table 1 indicates the electrolyte storage performance of the separator member 50 in the embodiment of this application. The electrical performance in Table 1 represents the initial efficiency of the battery cell 20, which is the ratio of the initial discharge capacity to the initial charge capacity of the battery cell 20, and it should be understood that in the embodiment of this application, this initial efficiency may also be called the initial effect.

[0171] It should be understood that, in the embodiments of this application, the fluid retention performance of the battery cell 20 can be characterized by the fluid retention performance of the separator member 50. Specifically, when testing the fluid retention performance of the separator member 50, it is necessary to first disassemble a fully-capacity battery cell 20 and obtain different numbers of separator members 50 as experimental samples. These separator members 50 may be circular sheets with a diameter of 10 mm to 20 mm, and each is placed in a different centrifugal tube. For example, the capacity of this centrifuge tube may be selected as 50 ml, where the experimental sample should occupy 2 / 3 of the total volume of the centrifuge tube. The centrifuge tube is then sealed, placed in a centrifuge, and operated at a rotation speed of 300 r / min for 30 minutes. After removing the experimental sample, the electrolyte remaining in the centrifuge tube is weighed, and the mass of this remaining electrolyte is then divided by the corresponding surface area of ​​the experimental sample, i.e., the separator member 50, to obtain the amount of electrolyte retained per unit area of ​​the separator member 50, thereby characterizing the ability of the battery cell 20 to store electrolyte.

[0172] Furthermore, it should be understood that in the embodiments of this application, when performing electrical performance tests on the battery cell 20 in the embodiments of this application, specifically when performing an initial charge capacity test, first, multiple battery cells 20 are obtained as experimental samples (for example, there may be five), and they are charged at 0.1C with constant current and constant voltage up to the nominal upper voltage limit (for example, this nominal upper voltage limit may be 3.65V), and left to stand for 10 minutes. Subsequently, the initial charge capacity of these five experimental samples is measured, the highest and lowest values ​​are removed, and the average value of the remaining three initial charge capacities is calculated to determine the initial charge capacity of the battery cell 20. When conducting the initial discharge capacity test, several experimental samples of battery cells 20 (for example, five) are obtained, and they are discharged at 0.1C with constant current and constant voltage until the nominal lower limit voltage is reached. For example, this nominal lower limit voltage may be 2.5V, and the cells are left standing for 10 minutes. Subsequently, the initial discharge capacity of these five experimental samples is measured, the highest and lowest values ​​are removed, and the average value of the remaining three initial discharge capacities is calculated to determine the initial discharge capacity of the battery cell 20. Next, the ratio of the average initial charge capacity to the average initial discharge capacity obtained above is calculated as the initial efficiency of the battery cell 20, which corresponds to the electrical performance in Table 1.

[0173] In some implementation methods, in order to ensure the normal use of the battery cell 20, that is, to ensure the fluid retention performance of the battery cell 20, the fluid retention performance value of the separator member 50 in the battery cell 20 is generally set to 0.08 or higher. When the fluid retention performance value of this separator member 50 is 0.08 or higher, the battery cell 20 is considered to have relatively good fluid retention performance, which allows the electrode plates to be moistened, resulting in relatively good ion transport capability in the battery cell 20 and facilitating the performance of electrical functions. As shown in Table 1 above, when H1 / H2 is 0.07 or higher, the fluid retention performance value of this separator member 50 is 0.08 or higher in all cases, meaning that in this case the battery cell 20 has relatively good fluid retention performance.

[0174] As shown in Table 1 above, the value of the fluid retention performance increased with increasing H1 / H2. For example, as the thickness H1 of the separator member 50 increases, the value of H1 / H2 also increases, and correspondingly, the fluid retention performance of the battery cell 20 also increases. However, at the same time, an excessively thick separator member 50 thickness H1 increases the ion transport pathway in the battery cell 20, further increases the liquid phase impedance of the battery cell 20, affects the gram capacity of the battery cell 20, reduces the energy density of the battery cell 20, and further degrades the electrical performance of the battery cell 20, making it difficult to meet the basic usage needs of the user. In some implementations, in order to meet the basic electrical performance requirements of the battery cell 20, the initial efficiency of the battery cell 20, i.e., the value of electrical performance in Table 1 above, is generally set to 80% or higher. As shown in Table 1 above, when 0.07 ≤ H1 / H2 ≤ 241.18, the initial efficiency of this battery cell 20 is 80% or higher in all cases, meaning that in this case the battery cell 20 can meet the user's basic usage needs.

[0175] In some other implementations, the initial efficiency of the battery cell 20 may be set to 85% or higher, or to 90% or higher, in order to meet the actual demand for the electrical performance of the battery cell 20 in this field today. For example, as shown in Table 1 above, when 0.15 ≤ H1 / H2 ≤ 220.59, the initial efficiency of the battery cell 20 is 85% or higher in all cases, meaning that in this case the battery cell 20 has relatively good fluid retention and relatively good electrical performance. Also, for example, as shown in Table 1 above, when 1.16 ≤ H1 / H2 ≤ 75, the initial efficiency of the battery cell 20 is 90% or higher in all cases, meaning that in this case the battery cell 20 has relatively good fluid retention and relatively good electrical performance.

[0176] In some other implementations, the initial efficiency of the battery cell 20 may be set to 92% or higher, or to 93% or higher, in order to further meet the actual demand for the electrical performance of the battery cell 20 in this field. For example, as shown in Table 1 above, when 1.16 ≤ H1 / H2 ≤ 21.43, the initial efficiency of the battery cell 20 is 92% or higher in all cases, meaning that in this case the battery cell 20 has relatively good fluid retention performance and relatively excellent electrical performance. Also, for example, as shown in Table 1 above, when 1.20 ≤ H1 / H2 ≤ 10, the initial efficiency of the battery cell 20 is 93% or higher in all cases, meaning that in this case the battery cell 20 has relatively good fluid retention performance and optimal electrical performance.

[0177] This application has been described with reference to the above embodiments, but is subject to various modifications and the replacement of components with equivalents, without departing from the scope of this application. In particular, unless there is a structural conflict, each technical feature referred to in each embodiment may be combined in any manner. This application is not limited to the specific embodiments disclosed in the specification, but includes all technical ideas that fall within the scope of the claims.

Claims

1. It is a battery cell, The electrode assembly includes a negative electrode plate, a positive electrode plate, and a separator member for separating the negative electrode plate and the positive electrode plate. Here, the thickness H of the separator member １ and the thickness H of the negative electrode plate ２ A battery cell characterized in that its ratio to is 0.07 or greater.

2. The thickness H of the separator member １ and the thickness H of the negative electrode plate ２ satisfy 0.07 ≦ H １ / H ２ ≦ 241.18, and preferably, the thickness H of the separator member １ and the thickness H of the negative electrode plate ２ satisfy 0.15 ≦ H １ / H ２ ≦ 220.59, The battery cell according to claim 1, characterized by this.

3. The thickness H of the separator member １ and the thickness H of the negative electrode plate ２ H is 1.16 ≤ H １ / H ２ The thickness H of the separator member satisfies ≤ 75, preferably. １ and the thickness H of the negative electrode plate ２ H is 1.16 ≤ H １ / H ２ A battery cell according to claim 1 or 2, characterized in that it satisfies ≤ 21.

43.

4. The thickness H of the separator member １ and the thickness H of the negative electrode plate ２ H is 1.20 ≤ H １ / H ２ A battery cell according to any one of claims 1 to 3, characterized in that it satisfies ≤ 10.

5. The battery cell according to any one of claims 1 to 4, wherein the separator member includes a separator body and a separator functional coating installed on the surface of the separator body, and the separator functional coating is installed on one or both surfaces of the separator body.

6. The battery cell according to claim 5, characterized in that the material of the separator functional coating comprises at least one of the following: polyvinylidene fluoride copolymer, sodium carboxymethylcellulose, polystyrene-butadiene copolymer, styrene-hydrogenated butadiene block copolymer, styrene-hydrogenated isoprene block copolymer, ethylene-butene copolymer, polypropylene-octene thermoplastic elastomer, ethylene-octene thermoplastic elastomer, and propylene-ethylene copolymer.

7. The battery cell according to claim 5 or 6, characterized in that the thickness of the separator body is 3 μm to 250 μm.

8. The battery cell according to any one of claims 5 to 7, characterized in that the thickness of the separator body is 5 μm to 50 μm.

9. The battery cell according to any one of claims 5 to 8, characterized in that the thickness of the separator functional coating is 0.1 μm to 250 μm.

10. The battery cell according to any one of claims 5 to 9, characterized in that the thickness of the separator functional coating is 0.5 μm to 50 μm, and preferably the thickness of the separator functional coating is 2 μm to 20 μm.

11. The battery cell according to any one of claims 5 to 10, characterized in that the separator functional coating has a hollow, resilient structure.

12. The battery cell according to claim 11, characterized in that the hollow, resilient structure includes an unsealed pore structure.

13. The battery cell according to claim 12, characterized in that at least one opening of the pore structure faces the negative electrode plate.

14. The battery cell according to claim 12 or 13, characterized in that the hollow resilient structure includes a plurality of unsealed hollow resilient balls arranged along the surface of the separator body.

15. The specific surface area of ​​the aforementioned pore structure is 0.5 m². ２ / g-10m ２ The battery cell according to claim 13 or 14, characterized in that it is / g.

16. The battery cell according to any one of claims 1 to 15, characterized in that the compression percentage of the separator member is 8% to 95%.

17. The battery cell according to any one of claims 1 to 16, characterized in that the compression percentage of the separator member is 20% to 80%.

18. The battery cell according to any one of claims 1 to 17, characterized in that the pressure-receiving strength range of the separator member is 0.05 MPa to 10 MPa.

19. The battery cell according to any one of claims 1 to 18, characterized in that the pressure-receiving strength range of the separator member is 0.05 MPa to 3 MPa.

20. The battery cell according to any one of claims 1 to 19, characterized in that the battery cell is a sodium secondary battery without a negative electrode.

21. The battery cell according to any one of claims 1 to 20, wherein the negative electrode plate includes a negative electrode current collector and a negative electrode functional coating installed on the surface of the negative electrode current collector, and the negative electrode functional coating is installed on one or both sides of the negative electrode current collector.

22. The material of the aforementioned negative electrode functional coating is a porous carbon material. Preferably, the porous carbon material comprises at least one of carbon nanotubes, Super-P, KS-6, mesocarbon microbeads, hard carbon, and graphite, as described in claim 21.

23. The battery cell according to claim 21 or 22, characterized in that the thickness of the negative electrode current collector is 3 μm to 50 μm.

24. The battery cell according to any one of claims 21 to 23, characterized in that the thickness of the negative electrode current collector is 4 μm to 30 μm.

25. The battery cell according to any one of claims 21 to 24, characterized in that the thickness of the negative electrode functional coating is 0.2 μm to 50 μm.

26. The battery cell according to any one of claims 21 to 25, characterized in that the thickness of the negative electrode functional coating is 0.5 μm to 30 μm, and preferably the thickness of the negative electrode functional coating is 2 μm to 20 μm.

27. A battery characterized by including a battery cell according to any one of claims 1 to 26.

28. A power-consuming device comprising the battery described in claim 27, wherein the battery is used to provide electrical energy to the power-consuming device.

Images