Battery cell and method of manufacturing the same, composite electrolyte, electric device

Abstract

The application discloses a battery monomer, a preparation method thereof, a composite electrolyte and an electric device. The battery monomer comprises a positive electrode sheet, a negative electrode sheet and a composite electrolyte. The composite electrolyte is arranged between the positive electrode sheet and the negative electrode sheet, and at least partially contacts the positive electrode sheet and the negative electrode sheet. The composite electrolyte comprises a solid-state electrolyte layer and a gel electrolyte, and the gel electrolyte is attached to at least part of the surface of the solid-state electrolyte layer. At least part of the solid-solid contact is changed into gel-solid contact, which is beneficial to increasing the contact area and the ion channel, thereby optimizing the ion conductivity of the electrolyte as a whole in the battery monomer, and further improving the rate performance of the battery monomer.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to battery cells and their preparation methods, composite electrolytes, and electrical devices. Background Technology

[0002] Batteries have been widely used in many fields such as mobile devices and transportation.

[0003] Currently, solid electrolytes can be used in batteries to achieve charge transfer. Solid electrolytes refer to materials that have ionic conductivity in a solid state. However, solid electrolytes have problems such as low ionic conductivity and poor battery rate performance. Summary of the Invention

[0004] This application is made in view of the above-mentioned issues, and its purpose is to provide a battery cell and its preparation method, composite electrolyte, and power device, which aim to improve the ionic conductivity and rate performance of the battery cell.

[0005] In a first aspect, this application provides a battery cell including a positive electrode, a negative electrode, and a composite electrolyte; wherein the composite electrolyte is disposed between the positive electrode and the negative electrode, and the composite electrolyte is at least partially in contact with the positive electrode and the negative electrode; the composite electrolyte includes a solid electrolyte layer and a gel electrolyte, and the gel electrolyte is attached to at least a portion of the surface of the solid electrolyte layer.

[0006] Because the positive electrode, solid electrolyte, and negative electrode in an all-solid-state electrolyte battery are in solid-solid contact, which is a "hard" contact that is difficult to fully adhere, it easily leads to a reduction in ion channels and low ion conductivity. This application addresses this issue by incorporating a composite electrolyte between the positive and negative electrodes. In this composite electrolyte, a gel electrolyte is attached to at least a portion of the surface of the solid electrolyte layer. The use of the gel electrolyte transforms at least a portion of the solid-solid contact into a gel-solid contact, which increases the contact area and ion channels, thereby optimizing the overall ion conductivity of the electrolyte in the battery cell and further improving the rate performance of the battery cell.

[0007] In any embodiment, the solid electrolyte layer is made of inorganic solid electrolyte and / or polymer solid electrolyte.

[0008] In any embodiment, the inorganic solid electrolyte includes at least one of a sulfide electrolyte, a sodium fast ion conductor, and an oxide electrolyte. All of the above materials are ionicly conductive in solid form.

[0009] In any embodiment, the sulfide electrolyte includes glassy Na₂S-P₂S₅, Na₂S₅, etc. 11 Sn2 PnX12 , Na3Pn y Pn′ 1-y X z X′ 4-z One or more of them, where Pn includes at least one of P and Sb, X includes at least one of S and Se, Pn′ includes at least one of Si, Sn, and Ge, X′ includes at least one of F, Br, and Cl, 0 < y ≤ 1, 0 < z ≤ ́4; and / or,

[0010] The sodium fast ion conductor includes Na 3+a M b M′ 2-b Si 2-c P c O 12 , where M and M′ each independently include at least one of Zr, Ca, Mg, Zn, La, Ti, and Nb, 0 ≤ a ≤ 1, 0 < b ≤ 2, 0 ≤ c < 2; and / or,

[0011] The oxide electrolyte includes at least one of Na-β-Al2 O3 and Na-β″-Al2 O3, where the Na-β-Al2O3 includes β-Na2 O·11Al2 O3 and the Na-β″-Al2 O3 includes β″-Na2 O·5Al^2 O3.

[0012] The above inorganic solid electrolytes can all be used as solid electrolytes to achieve charge transfer in sodium ion batteries and have good mechanical properties, which is beneficial to preventing the piercing of dendrites growing on the negative electrode sheet. <00||00095>

[0013] [[ID=3||]]In any embodiment, the polymer solid electrolyte includes a polymer.

[0014] In any embodiment, the polymer includes at least one of polyimide, polyethylene oxide, polyethylene glycol, polyvinyl pyrrolidone, polymethyl methacrylate, polyvinylidene fluoride, poly(vinylidene fluoride - co - hexafluoropropylene), polyvinyl alcohol, polyacrylonitrile, polyvinyl chloride, polyacrylamide, polytrimethylene carbonate, and perfluoropolyether. The above polymers have good mechanical properties, which is beneficial to preventing the piercing of dendrites growing on the negative electrode sheet.

[0015] In any embodiment, the polymer solid electrolyte further includes inorganic fillers, and the inorganic fillers include at least one of TiO2, Al2O3, SiO2, ZrO2, MgO, and CuO. The inorganic fillers are beneficial to improving the mechanical properties of the polymer solid electrolyte and are beneficial to preventing the piercing of dendrites growing on the negative electrode sheet.

[0016] In any embodiment, the polymer solid electrolyte further includes an electrolyte salt, wherein the electrolyte salt includes at least one selected from sodium chloride, sodium bromide, sodium nitrate, sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium tetrafluoroyttrium, sodium acetate, sodium trifluoroacetate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide. The electrolyte salt constitutes 10%-20% of the polymer solid electrolyte by mass.

[0017] Solid electrolytes are formed by mixing electrolyte salts into polymers. The presence of electrolyte salts enables charge transfer in sodium-ion batteries, and when the mass ratio of electrolyte salts is appropriate as described above, polymer solid electrolytes exhibit good ionic conductivity.

[0018] In any embodiment, the thickness of the solid electrolyte layer is 10-30 μm. Within this suitable thickness range, the solid electrolyte layer achieves good mechanical properties, which helps prevent dendrites growing on the negative electrode from piercing through it.

[0019] In any embodiment, the average pore size of the solid electrolyte layer is 5-20 nm. This suitable range of average pore size helps prevent dendrites growing on the negative electrode from piercing the surface.

[0020] In any embodiment, the gel electrolyte comprises a gel polymer and an electrolyte salt.

[0021] In any embodiment, the monomers of the gel polymer include at least one of olefin monomers, ester monomers, ether monomers, nitrile monomers, and natural polymers. Substances containing the above monomers, upon curing, are conducive to forming a gel-state polymer.

[0022] In any embodiment, the olefin monomer includes at least one selected from vinylidene fluoride, hexafluoropropylene, ethylene oxide, and acrylic acid; and / or,

[0023] Ester monomers include at least one of methacrylates, vinylene carbonates, vinyl acetates, and polyethylene glycol methacrylates; and / or,

[0024] Ether monomers include at least one of ethylene oxide, 1,3-dioxolane, and dioxane; and / or,

[0025] Nitrile monomers include acrylonitrile or butyl 2-cyano-2-acrylate; and / or,

[0026] Natural polymers include at least one of starch, cellulose, chitosan, lignin, and chitin.

[0027] Substances containing the above monomers are conducive to forming polymers in a gel state after curing.

[0028] In any embodiment, the electrolyte salt accounts for 10%-20% of the mass of the gel electrolyte. This mass percentage of the electrolyte salt is beneficial for improving the ionic conductivity of the gel electrolyte, thereby further improving the overall ionic conductivity of the electrolyte.

[0029] In any embodiment, the thickness of the gel electrolyte attached to the surface of the solid electrolyte layer is 10-80 μm. A suitable thickness of the gel electrolyte is beneficial for improving the overall ionic conductivity of the electrolyte and for preventing short circuits caused by dendrites piercing the solid electrolyte layer. The gel electrolyte fills the pores of the solid electrolyte layer, and its thickness within these pores is 300-500 nm. The gel electrolyte and the solid electrolyte layer form a tight contact layer at the contact points, which helps improve the overall mechanical strength of the composite electrolyte.

[0030] In any embodiment, the battery cell includes a sodium-ion battery cell without a negative electrode, wherein the negative electrode sheet includes a metal current collector and a conductive agent layer disposed on the surface of the metal current collector.

[0031] In any embodiment, a solid electrolyte layer is disposed on the surface of the conductive agent layer, and the gel electrolyte is disposed between the solid electrolyte layer and the positive electrode sheet.

[0032] For sodium-ion battery cells without a negative electrode, sodium ions released from the positive electrode during charging are reversibly deposited onto the surface of the negative electrode, transforming into metallic sodium. During discharging, the metallic sodium is stripped from the current collector surface. During this process, dendrites are more likely to form. Dendrites not only cause short circuits but also lead to the formation of "dead sodium," meaning that the sodium metal cannot fully participate in the reaction during charging and discharging, resulting in decreased cycle performance. Therefore, this application employs a solid electrolyte layer on the surface of the negative electrode. The good mechanical properties of the solid electrolyte layer help to inhibit dendrite growth. Furthermore, a portion of the gel electrolyte fills the pores of the solid electrolyte layer, which helps to optimize the interface between the solid electrolyte layer and the positive and negative electrodes, thereby improving dendrite formation and further enhancing the battery's cycle performance.

[0033] In any embodiment, the conductive agent layer is made of at least one of carbon nanotubes, conductive carbon black, Sn, Zn, and Mg, and the thickness of the conductive agent layer is 2-5 micrometers.

[0034] In any embodiment, the battery cell further includes a separator, the solid electrolyte layer is disposed on the side of the separator facing the negative electrode, and the gel electrolyte is disposed between the separator and the positive electrode, and between the separator and the negative electrode.

[0035] A solid electrolyte layer is provided on the separator. The good mechanical properties of the solid electrolyte layer are beneficial to blocking the growth of dendrites and preventing the dendrites from piercing the separator. Similarly, when the gel electrolyte is disposed between the separator and the positive electrode plate and between the separator and the negative electrode plate, it is beneficial to optimize the interface between the solid electrolyte layer and the negative electrode plate, thereby facilitating the improvement of dendrite formation and further enhancing the cycle performance of the battery.

[0036] In a second aspect of the present application, a composite electrolyte is provided. The composite electrolyte includes a solid electrolyte layer and a gel electrolyte, and the gel electrolyte is attached to at least a part of the surface of the solid electrolyte layer.

[0037] In the composite electrolyte, the gel electrolyte is attached to at least a part of the surface of the solid electrolyte layer. The use of the gel electrolyte changes at least part of the solid-solid contact into gel-solid contact, which is beneficial to increasing the contact area and ion channels, thereby optimizing the overall ionic conductivity of the electrolyte in the battery cell and further enhancing the rate performance of the battery cell.

[0038] In any implementation manner, the material of the solid electrolyte layer includes an inorganic solid electrolyte and / or a polymer solid electrolyte.

[0039] In any implementation manner, the inorganic solid electrolyte includes at least one of a chalcogenide electrolyte, a sodium fast ion conductor, and an oxide electrolyte. The above materials are all materials having ionic conductivity in a solid state.

[0040] In any implementation manner, the chalcogenide electrolyte includes one or more of vitreous Na2S-P2S5, Na 11 Sn2 PnX 12 、Na3Pn y Pn′ 1-y X z X′ 4-z where Pn includes at least one of P and Sb, X includes at least one of S and Se, Pn′ includes at least one of Si, Sn, and Ge, X′ includes at least one of F, Br, and Cl, 0 < y ≤ 1, 0 < z ≤ 4; and / or,

[0041] The sodium fast ion conductor includes Na 3+a M b M′ 2-b Si 2-c P c O 12 ​​​The oxide electrolyte includes at least one of Na-β-Al2O3 and Na-β″-Al2O3, wherein the Na-β-Al2O3 includes β-Na2O·11Al2O3 and the Na-β″-Al2O3 includes β″-Na2O·5Al2O3.

[0043] All of the above-mentioned inorganic solid electrolytes can be used as solid electrolytes to achieve charge transfer in sodium-ion batteries, and they have good mechanical properties, which helps to prevent dendrites growing on the negative electrode from piercing through.

[0044] In any embodiment, the polymer solid electrolyte comprises a polymer.

[0045] In any embodiment, the polymer includes at least one of polyimide, polyethylene oxide, polyethylene glycol, polyvinylpyrrolidone, polymethyl methacrylate, polyvinylidene fluoride, poly(vinylidene fluoride-copolyhexafluoropropylene), polyvinyl alcohol, polyacrylonitrile, polyvinyl chloride, polyacrylamide, polytrimethylene carbonate, and perfluoropolyether.

[0046] The aforementioned polymer has good mechanical properties, which helps prevent dendrites growing on the negative electrode from piercing through it.

[0047] In any embodiment, the polymer solid electrolyte further includes an inorganic filler, which includes at least one selected from TiO2, Al2O3, SiO2, ZrO2, MgO, and CuO. The inorganic filler helps improve the mechanical properties of the polymer solid electrolyte and helps prevent dendrites growing on the negative electrode from piercing through it.

[0048] In any embodiment, the polymer solid electrolyte further includes an electrolyte salt, wherein the electrolyte salt includes at least one selected from sodium chloride, sodium bromide, sodium nitrate, sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium tetrafluoroyttrium, sodium acetate, sodium trifluoroacetate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide. The electrolyte salt constitutes 10%-20% of the polymer solid electrolyte by mass.

[0049] Solid electrolytes are formed by mixing electrolyte salts into polymers. The presence of electrolyte salts enables charge transfer in sodium-ion batteries, and when the mass ratio of electrolyte salts is appropriate as described above, polymer solid electrolytes exhibit good ionic conductivity.

[0050] In any embodiment, the thickness of the solid electrolyte layer is 10-30 μm. Within this suitable thickness range, the solid electrolyte layer achieves good mechanical properties, which helps prevent dendrites growing on the negative electrode from piercing through it.

[0051] In any embodiment, the average pore size of the solid electrolyte layer is 5-20 nm. This suitable range of average pore size helps prevent dendrites growing on the negative electrode from piercing the surface.

[0052] In any embodiment, the gel electrolyte comprises a gel polymer and an electrolyte salt; the thickness of the gel electrolyte attached to the surface of the solid electrolyte layer is 10-80 μm. A suitable thickness of the gel electrolyte is beneficial for improving the overall ionic conductivity of the electrolyte and for preventing short circuits caused by dendrites piercing the solid electrolyte layer. The gel electrolyte fills the pores of the solid electrolyte layer, and the thickness of the gel electrolyte filling the pores of the solid electrolyte layer is 300-500 nm. The gel electrolyte and the solid electrolyte layer form a tight contact layer at the contact points, which is beneficial for improving the overall mechanical strength of the composite electrolyte.

[0053] In any embodiment, the monomers of the gel polymer include at least one of olefin monomers, ester monomers, ether monomers, nitrile monomers, and natural polymers. Substances containing the above monomers, upon curing, are conducive to forming a gel-state polymer.

[0054] In any embodiment, the olefin monomer includes at least one selected from vinylidene fluoride, hexafluoropropylene, ethylene oxide, and acrylic acid; and / or,

[0055] Ester monomers include at least one of methacrylates, vinylene carbonates, vinyl acetates, and polyethylene glycol methacrylates; and / or,

[0056] Ether monomers include at least one of ethylene oxide, 1,3-dioxolane, and dioxane; and / or,

[0057] Nitrile monomers include acrylonitrile or butyl 2-cyano-2-acrylate; and / or,

[0058] Natural polymers include at least one of starch, cellulose, chitosan, lignin, and chitin.

[0059] Substances containing the above monomers are conducive to forming polymers in a gel state after curing.

[0060] In any embodiment, the electrolyte salt accounts for 10%-20% of the mass of the gel electrolyte. This mass percentage of the electrolyte salt is beneficial for improving the ionic conductivity of the gel electrolyte, thereby further improving the overall ionic conductivity of the electrolyte.

[0061] Thirdly, this application provides a method for preparing a battery cell, comprising the following steps:

[0062] A solid electrolyte layer is placed between the positive electrode and the negative electrode.

[0063] Assemble the positive electrode, the solid electrolyte layer, and the negative electrode;

[0064] A gel electrolyte solution is injected into the gap between the positive and negative electrode plates, and the gel electrolyte solution is solidified so that the solidified gel electrolyte adheres to at least a portion of the surface of the solid electrolyte layer.

[0065] This method has a simple preparation process and is easy to industrialize.

[0066] In any embodiment, the step of injecting a gel electrolyte solution into the gap between the positive and negative electrode plates and solidifying the gel electrolyte solution to allow the solidified gel electrolyte to adhere to at least a portion of the surface of the solid electrolyte layer includes:

[0067] The gel electrolyte solution is injected into the gap between the positive and negative electrode plates at an injection coefficient of 6-7 g / Ah. The solution is left to stand for 12-24 hours to solidify, so that the solidified gel electrolyte adheres to at least a portion of the surface of the solid electrolyte layer.

[0068] By allowing the electrolyte to stand for 12-24 hours after injection, some of the gel electrolyte can fill the pores of the solid electrolyte layer, thereby optimizing the interface between the solid electrolyte layer and the positive and negative electrode plates, which helps to improve dendrite formation and further enhances the cycle performance of the battery.

[0069] Fourthly, this application provides an electrical device including a battery cell according to the first aspect of this application. Attached Figure Description

[0070] Figure 1 This is a schematic diagram of a battery cell according to one embodiment of this application.

[0071] Figure 2 yes Figure 1 An exploded view of a battery cell according to one embodiment of this application is shown.

[0072] Figure 3 This is a schematic diagram of a battery module according to one embodiment of this application.

[0073] Figure 4 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0074] Figure 5 yes Figure 4 An exploded view of a battery pack according to one embodiment of this application is shown.

[0075] Figure 6 This is a schematic diagram of an electrical device in which a single battery cell is used as a power source according to one embodiment of this application.

[0076] Explanation of reference numerals in the attached figures:

[0077] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Top cover assembly. Detailed Implementation

[0078] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the battery cell, its preparation method, composite electrolyte, and power application device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0079] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0080] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0081] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0082] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0083] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0084] While conventional liquid electrolytes are low-cost and have high conductivity, they suffer from problems such as easy leakage and electrode corrosion. In contrast, solid-state electrolytes do not have the potential for liquid leakage. However, solid-state electrolytes have strong intermolecular forces and high ion migration barriers, resulting in low ionic conductivity and consequently poor battery rate performance.

[0085] Based on this, in a first aspect, embodiments of this application provide a battery cell including a positive electrode, a negative electrode, and a composite electrolyte; wherein the composite electrolyte is disposed between the positive electrode and the negative electrode, and the composite electrolyte is at least partially in contact with the positive electrode and the negative electrode; the composite electrolyte includes a solid electrolyte layer and a gel electrolyte, and the gel electrolyte is attached to at least a portion of the surface of the solid electrolyte layer.

[0086] In this article, the solid electrolyte layer can refer to a layer containing materials capable of transporting ions in a solid state. The solid electrolyte layer can be qualitatively or quantitatively detected using equipment and methods known in the art. Relevant detection methods can refer to domestic and international testing standards, domestic and international enterprise standards, etc., and those skilled in the art can also adaptively modify certain detection steps / instrument parameters from the perspective of detection accuracy to obtain more accurate detection results. One detection method can be used for qualitative or quantitative determination, or several detection methods can be used in combination. For example, scanning electron microscopy (SEM), an instrument known in the art, can be used to perform cross-sectional or interface testing on disassembled battery cells.

[0087] In this article, gel electrolyte can refer to a gel-state electrolyte that can transport ions, which is a semi-solid state between liquid and solid.

[0088] Because the positive electrode, solid electrolyte, and negative electrode in an all-solid-state electrolyte battery are in solid-solid contact, which is a "hard" contact that is difficult to fully adhere, it easily leads to a reduction in ion channels and low ion conductivity. This application addresses this issue by incorporating a composite electrolyte between the positive and negative electrodes. In this composite electrolyte, a gel electrolyte is attached to at least a portion of the surface of the solid electrolyte layer. The use of the gel electrolyte transforms at least a portion of the solid-solid contact into a gel-solid contact, which increases the contact area and ion channels, thereby optimizing the overall ion conductivity of the electrolyte in the battery cell and further improving the rate performance of the battery cell.

[0089] In some embodiments, the solid electrolyte layer is made of inorganic solid electrolyte and / or polymer solid electrolyte. That is, in some embodiments, the solid electrolyte layer can be made of both inorganic solid electrolyte and polymer solid electrolyte; in some embodiments, the solid electrolyte layer can be made of inorganic solid electrolyte; and in some embodiments, the solid electrolyte layer can be made of polymer solid electrolyte.

[0090] In some embodiments, the inorganic solid electrolyte includes at least one of a sulfide electrolyte, a sodium fast ion conductor, and an oxide electrolyte. All of the above materials are ionicly conductive in solid form.

[0091] In some embodiments, the sulfide electrolyte includes glassy Na₂S-P₂S₅, Na 11 Sn2 PnX 12 Na3Pn y Pn′ 1-y X z X′ 4-z One or more of the following, wherein Pn includes at least one of P and Sb, X includes at least one of S and Se, Pn′ includes at least one of Si, Sn, and Ge, X′ includes at least one of F, Br, and Cl, and 0 <y≤1,0<z≤4。

[0092] In some implementations, y can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1.

[0093] In some implementations, z can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.5, 1.6, 1.8, 2, 2.2, 2.4, 2.5, 2.6, 2.8, 3, 3.2, 3.4, 3.5, 3.6, 3.8, or 4.

[0094] Sodium fast ion conductors include Na3+a M b M′ 2-b Si 2-c P c O 12 , wherein M and M′ each independently include at least one of Zr, Ca, Mg, Zn, La, Ti, and Nb, 0 ≤ a ≤ 1, 0 < b ≤ 2, 0 ≤ c < 2; the oxide electrolyte includes at least one of Na-β-Al2O3 and Na-β″-Al2O3, wherein the Na-β-Al2O3 includes β-Na2O·11Al2O3, and the Na-β″-Al2O3 includes β″-Na2O·5Al2O3.

[0095] In some embodiments, a can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.

[0096] In some embodiments, b can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or 1.9.

[0097] In some embodiments, c can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or 1.9.

[0098] The above inorganic solid electrolytes can all be used as solid electrolytes to achieve charge transfer in sodium-ion batteries and have good mechanical properties, which is beneficial to preventing the piercing of dendrites growing on the negative electrode sheet.

[0099] In some embodiments, the polymer solid electrolyte includes a polymer.

[0100] In some embodiments, the polymer includes at least one of polyimide, polyethylene oxide, polyethylene glycol, polyvinylpyrrolidone, polymethyl methacrylate, polyvinylidene fluoride, poly(vinylidene fluoride-co-hexafluoropropylene), polyvinyl alcohol, polyacrylonitrile, polyvinyl chloride, polyacrylamide, polytrimethylene carbonate, and perfluoropolyether. The above polymers have good mechanical properties, which is beneficial to preventing the piercing of dendrites growing on the negative electrode sheet.

[0101] In some embodiments, the polymer solid electrolyte further includes inorganic fillers, which include at least one selected from TiO2, Al2O3, SiO2, ZrO2, MgO, and CuO. Inorganic fillers are beneficial for improving the mechanical properties of the polymer solid electrolyte and for preventing dendrites growing on the negative electrode from piercing through it.

[0102] In some embodiments, the polymer solid electrolyte further includes an electrolyte salt, wherein the electrolyte salt includes at least one selected from sodium chloride, sodium bromide, sodium nitrate, sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium tetrafluoroyttrium, sodium acetate, sodium trifluoroacetate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide. The electrolyte salt constitutes 10%-20% of the polymer solid electrolyte by mass. The mass percentage of the electrolyte salt in the polymer solid electrolyte can be any range consisting of 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or more.

[0103] Solid electrolytes are formed by mixing electrolyte salts into polymers. The presence of electrolyte salts enables charge transfer in sodium-ion batteries, and when the mass ratio of electrolyte salts is appropriate as described above, polymer solid electrolytes exhibit good ionic conductivity.

[0104] In some embodiments, the thickness of the solid electrolyte layer is 10-30 μm. Within this suitable thickness range, the solid electrolyte layer achieves good mechanical properties, which helps prevent dendrites growing on the negative electrode from penetrating it. The thickness of the solid electrolyte layer can be measured using a scanning electron microscope (SEM). The thickness of the solid electrolyte layer can be any range of 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, or any of the above values.

[0105] In some embodiments, the average pore size of the solid electrolyte layer is 5-20 nm. This suitable range of average pore size helps prevent dendrites growing on the negative electrode from piercing the surface. The average pore size of the solid electrolyte layer can refer to the average value of all types of pores in the solid electrolyte layer, i.e., the average size of macropores, mesopores, and micropores. The average pore size of the solid electrolyte layer can be measured by nitrogen gas adsorption or small-angle X-ray scattering. The average pore size of the solid electrolyte layer can be any value ranging from 5 nm, 10 nm, 15 nm, 20 nm, or higher.

[0106] In some embodiments, the gel electrolyte comprises a gel polymer and an electrolyte salt.

[0107] In some embodiments, the monomers of the gel polymer include at least one of olefin monomers, ester monomers, ether monomers, nitrile monomers, and natural polymers. Substances containing the above monomers, upon curing, are conducive to forming a gel polymer.

[0108] In some embodiments, the olefin monomers include at least one selected from vinylidene fluoride, hexafluoropropylene, ethylene oxide, and acrylic acid; the ester monomers include at least one selected from methacrylate, vinylene carbonate, vinyl acetate, and polyethylene glycol methacrylate; the ether monomers include at least one selected from ethylene oxide, 1,3-dioxolane, and dioxane; the nitrile monomers include acrylonitrile or butyl 2-cyano-2-acrylate; and the natural polymers include at least one selected from starch, cellulose, chitosan, lignin, and chitin. Substances containing the above monomers, upon curing, are conducive to forming a gel-like polymer.

[0109] In some embodiments, the electrolyte salt constitutes 10%-20% of the gel electrolyte by mass. This mass percentage of the electrolyte salt is beneficial for improving the ionic conductivity of the gel electrolyte, thereby further improving the overall ionic conductivity of the electrolyte. The mass percentage of the electrolyte salt in the gel electrolyte can be any combination of 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or higher.

[0110] In some embodiments, the thickness of the gel electrolyte attached to the surface of the solid electrolyte layer is 10-80 μm. A suitable thickness of the gel electrolyte is beneficial in two ways: firstly, it improves the overall ionic conductivity of the electrolyte; secondly, it helps to prevent short circuits caused by dendrites piercing the solid electrolyte layer. The thickness of the gel electrolyte attached to the surface of the solid electrolyte layer can be any range of 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, or any combination thereof.

[0111] In some embodiments, the gel electrolyte fills the pores of the solid electrolyte layer, and the thickness of the gel electrolyte filling the pores of the solid electrolyte layer is 300-500 nm. The gel electrolyte and the solid electrolyte layer form a tightly contacted layer at the contact points, which is beneficial for improving the overall mechanical strength of the composite electrolyte. The thickness of the gel electrolyte filling the pores of the solid electrolyte layer can be any range of 300 nm, 320 nm, 340 nm, 360 nm, 380 nm, 400 nm, 420 nm, 440 nm, 460 nm, 480 nm, 500 nm, or more.

[0112] If the solid electrolyte is disposed on the electrode plates and there is no separator in the battery, the thickness of the gel electrolyte adhering to the surface of the solid electrolyte layer can be determined by measuring the distance from the surface of the solid electrolyte layer to the other electrode plate. If a separator is provided in the battery, and the solid electrolyte is disposed on one side of the separator surface, with the gel electrolyte disposed between the separator and the two electrodes, the thickness of the gel electrolyte adhering to the surface of the solid electrolyte layer can be determined by measuring the distance between the solid electrolyte and its opposite electrode plate, and the distance between the other side of the separator and its opposite electrode plate. The sum of these two distances is the thickness of the gel electrolyte adhering to the surface of the solid electrolyte layer. The thickness of the gel electrolyte filling the pores of the solid electrolyte layer can be measured cross-sectionally using SEM.

[0113] In some embodiments, the battery cell includes a sodium-ion battery cell without a negative electrode, wherein the negative electrode includes a metal current collector and a conductive agent layer disposed on the surface of the metal current collector.

[0114] In some embodiments, a solid electrolyte layer is disposed on the surface of the conductive agent layer, and the gel electrolyte is disposed between the solid electrolyte layer and the positive electrode.

[0115] For sodium-ion battery cells without a negative electrode, sodium ions released from the positive electrode during charging are reversibly deposited onto the surface of the negative electrode, transforming into metallic sodium. During discharging, the metallic sodium is stripped from the current collector surface. During this process, dendrites are more likely to form. Dendrites not only cause short circuits but also lead to the formation of "dead sodium," meaning that the sodium metal cannot fully participate in the reaction during charging and discharging, resulting in decreased cycle performance. Therefore, this application employs a solid electrolyte layer on the surface of the negative electrode. The good mechanical properties of the solid electrolyte layer help to inhibit dendrite growth. Furthermore, a portion of the gel electrolyte fills the pores of the solid electrolyte layer, which helps to optimize the interface between the solid electrolyte layer and the positive and negative electrodes, thereby improving dendrite formation and further enhancing the battery's cycle performance.

[0116] In some embodiments, the conductive agent layer is made of at least one of carbon nanotubes, conductive carbon black, Sn, Zn, and Mg, and the thickness of the conductive agent layer is 2-5 micrometers. When the conductive agent layer is made of at least one of Sn, Zn, and Mg, for example, the conductive agent layer can be a Sn plating layer, a Zn plating layer, a Mg plating layer, etc., formed by means such as electroplating.

[0117] In some embodiments, the battery cell further includes a separator, the solid electrolyte layer is disposed on the side of the separator facing the negative electrode, and the gel electrolyte is disposed between the separator and the positive electrode, and between the separator and the negative electrode.

[0118] A solid electrolyte layer is placed on the separator. The good mechanical properties of the solid electrolyte layer help to block the growth of dendrites and prevent dendrites from piercing the separator. Similarly, placing a gel electrolyte between the separator and the positive electrode, and between the separator and the negative electrode, helps to optimize the interface between the solid electrolyte layer and the negative electrode, thereby helping to improve the formation of dendrites and further improving the cycle performance of the battery.

[0119] A second aspect of this application provides a composite electrolyte comprising a solid electrolyte layer and a gel electrolyte, wherein the gel electrolyte is attached to at least a portion of the surface of the solid electrolyte layer.

[0120] In the composite electrolyte, the gel electrolyte is attached to at least part of the surface of the solid electrolyte layer. The use of gel electrolyte changes at least part of the solid-solid contact to gel-solid contact, which is beneficial to increase the contact area and increase ion channels, thereby optimizing the overall ionic conductivity of the electrolyte in the battery cell, and further improving the rate performance of the battery cell.

[0121] In some embodiments, the solid electrolyte layer is made of inorganic solid electrolytes and / or polymer solid electrolytes.

[0122] In some embodiments, the inorganic solid electrolyte includes at least one of a sulfide electrolyte, a sodium fast ion conductor, and an oxide electrolyte. All of the above materials are ionicly conductive in solid form.

[0123] In some embodiments, the sulfide electrolyte includes glassy Na₂S-P₂S₅, Na 11 Sn2 PnX 12 Na3Pn y Pn′ 1-y X z X′ 4-zOne or more of them, where Pn includes at least one of P and Sb, X includes at least one of S and Se, Pn′ includes at least one of Si, Sn, and Ge, X′ includes at least one of F, Br, and Cl, 0 < y ≤ 1, 0 < z ≤ 4.

[0124] In some embodiments, y can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.

[0125] In some embodiments, z can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.5, 1.6, 1.8, 2, 2.2, 2.4, 2.5, 2.6, 2.8, 3, 3.2, 3.4, 3.5, 3.6, 3.8, or 4.

[0126] The sodium fast ion conductor includes Na 3+a M b M′ 2-b Si 2-c P c O 12 , where M and M′ each independently include at least one of Zr, Ca, Mg, Zn, La, Ti, and Nb, 0 ≤ a ≤ 1, 0 < b ≤ 2, 0 ≤ c < 2; the oxide electrolyte includes at least one of Na-β-Al2O3 and Na-β″-Al2O3, where the Na-β-Al2O3 includes β-Na2O·11Al2O3, and the Na-β″-Al2O3 includes β″-Na2O·5Al2O3.

[0127] In some embodiments, a can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.

[0128] In some embodiments, b can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or 1.9.

[0129] In some embodiments, c can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or 1.9.

[0130] All of the above inorganic solid electrolytes can be used as solid electrolytes to achieve charge transfer in sodium ion batteries and have good mechanical properties, which is beneficial to preventing the piercing of dendrites growing on the negative electrode sheet.

[0131] In some embodiments, the polymer solid electrolyte comprises a polymer.

[0132] In some embodiments, the polymer includes at least one selected from polyimide, polyethylene oxide, polyethylene glycol, polyvinylpyrrolidone, polymethyl methacrylate, polyvinylidene fluoride, poly(vinylidene fluoride-copolyhexafluoropropylene), polyvinyl alcohol, polyacrylonitrile, polyvinyl chloride, polyacrylamide, polytrimethylene carbonate, and perfluoropolyether.

[0133] The aforementioned polymer has good mechanical properties, which helps prevent dendrites growing on the negative electrode from piercing through it.

[0134] In some embodiments, the polymer solid electrolyte further includes inorganic fillers, which include at least one selected from TiO2, Al2O3, SiO2, ZrO2, MgO, and CuO. Inorganic fillers are beneficial for improving the mechanical properties of the polymer solid electrolyte and for preventing dendrites growing on the negative electrode from piercing through it.

[0135] In some embodiments, the polymer solid electrolyte further includes an electrolyte salt, wherein the electrolyte salt includes at least one selected from sodium chloride, sodium bromide, sodium nitrate, sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium tetrafluoroyttrium, sodium acetate, sodium trifluoroacetate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide. The mass percentage of the electrolyte salt in the polymer solid electrolyte is 10%-20%. The solid electrolyte formed by mixing the electrolyte salt into the polymer allows for charge transfer in the sodium-ion battery, and when the mass percentage of the electrolyte salt is at the aforementioned suitable ratio, the polymer solid electrolyte exhibits good ionic conductivity. The mass percentage of the electrolyte salt in the polymer solid electrolyte can be any value ranging from 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or higher.

[0136] In some embodiments, the thickness of the solid electrolyte layer is 10-30 μm. Within this suitable thickness range, the solid electrolyte layer achieves good mechanical properties, which helps prevent dendrites growing on the negative electrode from penetrating it. The thickness of the solid electrolyte layer can be measured using a scanning electron microscope (SEM). The thickness of the solid electrolyte layer can be any range of 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, or any of the above values.

[0137] In some embodiments, the average pore size of the solid electrolyte layer is 5-20 nm. This suitable range of average pore size helps prevent dendrites growing on the negative electrode from piercing the surface. The average pore size of the solid electrolyte layer can refer to the average value of all types of pores in the solid electrolyte layer, i.e., the average size of macropores, mesopores, and micropores. The average pore size of the solid electrolyte layer can be measured by nitrogen gas adsorption or small-angle X-ray scattering. The average pore size of the solid electrolyte layer can be any value ranging from 5 nm, 10 nm, 15 nm, 20 nm, or higher.

[0138] In some embodiments, the gel electrolyte comprises a gel polymer and an electrolyte salt.

[0139] In some embodiments, the monomers of the gel polymer include at least one of olefin monomers, ester monomers, ether monomers, nitrile monomers, and natural polymers. Substances containing the above monomers, upon curing, are conducive to forming a gel polymer.

[0140] In some embodiments, the olefin monomers include at least one of vinylidene fluoride, hexafluoropropylene, ethylene oxide, and acrylic acid; the ester monomers include at least one of methacrylate, vinylene carbonate, vinyl acetate, and polyethylene glycol methacrylate; the ether monomers include at least one of ethylene oxide, 1,3-dioxolane, and dioxane; the nitrile monomers include acrylonitrile or butyl 2-cyano-2-acrylate; and the natural polymers include at least one of starch, cellulose, chitosan, lignin, and chitin.

[0141] Substances containing the above monomers are conducive to forming polymers in a gel state after curing.

[0142] In some embodiments, the electrolyte salt constitutes 10%-20% of the gel electrolyte by mass. This mass percentage of the electrolyte salt is beneficial for improving the ionic conductivity of the gel electrolyte, thereby further improving the overall ionic conductivity of the electrolyte. The mass percentage of the electrolyte salt in the gel electrolyte can be any combination of 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or higher.

[0143] In some embodiments, the thickness of the gel electrolyte attached to the surface of the solid electrolyte layer is 10-80 μm. A suitable thickness of the gel electrolyte is beneficial in two ways: firstly, it improves the overall ionic conductivity of the electrolyte; secondly, it helps to prevent short circuits caused by dendrites piercing the solid electrolyte layer. The thickness of the gel electrolyte attached to the surface of the solid electrolyte layer can be any range of 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, or any combination thereof.

[0144] In some embodiments, the gel electrolyte fills the pores of the solid electrolyte layer, and the thickness of the gel electrolyte filling the pores of the solid electrolyte layer is 300-500 nm. The gel electrolyte and the solid electrolyte layer form a tightly contacted layer at the contact points, which is beneficial for improving the overall mechanical strength of the composite electrolyte. The thickness of the gel electrolyte filling the pores of the solid electrolyte layer can be any range of 300 nm, 320 nm, 340 nm, 360 nm, 380 nm, 400 nm, 420 nm, 440 nm, 460 nm, 480 nm, 500 nm, or more.

[0145] Thirdly, this application provides a method for preparing a battery cell, comprising the following steps:

[0146] A solid electrolyte layer is placed between the positive electrode and the negative electrode.

[0147] Assemble the positive electrode, the solid electrolyte layer, and the negative electrode;

[0148] A gel electrolyte solution is injected into the gap between the positive and negative electrode plates, and the gel electrolyte solution is solidified so that the solidified gel electrolyte adheres to at least a portion of the surface of the solid electrolyte layer.

[0149] This method has a simple preparation process and is easy to industrialize.

[0150] In some embodiments, the step of injecting a gel electrolyte solution into the gap between the positive and negative electrode plates and solidifying the gel electrolyte solution to allow the solidified gel electrolyte to adhere to at least a portion of the surface of the solid electrolyte layer includes:

[0151] The gel electrolyte solution is injected into the gap between the positive and negative electrode plates at an injection coefficient of 6-7 g / Ah. The solution is left to stand for 12-24 hours to solidify, so that the solidified gel electrolyte adheres to at least a portion of the surface of the solid electrolyte layer.

[0152] By allowing the electrolyte to stand for 12-24 hours after injection, some of the gel electrolyte can fill the pores of the solid electrolyte layer, thereby optimizing the interface between the solid electrolyte layer and the positive and negative electrode plates, which helps to improve dendrite formation and further enhances the cycle performance of the battery.

[0153] Fourthly, this application provides an electrical device including a battery cell according to the first aspect of this application.

[0154] In addition, the battery cell, battery module, battery pack and power device of this application will be described below with appropriate reference to the accompanying drawings.

[0155] [Positive electrode plate]

[0156] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including a positive electrode active material.

[0157] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0158] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0159] In some embodiments, when the battery cell is a sodium-ion battery, the positive electrode active material may further include positive electrode active materials known in the art for use in sodium-ion batteries. For example, the positive electrode active material is selected from one or more of layered transition metal oxides, polyanionic compounds, and Prussian blue analogues.

[0160] In layered transition metal oxides, the transition metal can be at least one selected from Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. For example, Na is a layered transition metal oxide. x MO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, and 0 < x ≤ 1.

[0161] Polyanionic compounds can be those containing sodium ions, transition metal ions, or tetrahedral (YO4) ions. n-A class of compounds with anionic units. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si; n represents (YO4). n- The price state.

[0162] Polyanionic compounds can also contain sodium ions, transition metal ions, or tetrahedral (YO4) ions. n- A class of compounds containing anionic units and halide anions. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si, and n represents (YO4). n- The valence state; the halogen can be at least one of F, Cl and Br.

[0163] Polyanionic compounds can also be sodium ion-containing tetrahedral (YO4) compounds. n- Anionic unit, polyhedral unit (ZO) y ) m+ And a class of compounds with optional halide anions. Y can be at least one of P, S, and Si, and n represents (YO4). n- The valence state; Z represents a transition metal, which can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; m represents (ZO) y ) m+ The valence state; the halogen can be at least one of F, Cl and Br.

[0164] In some embodiments, the polyanionic compound is, for example, NaFePO4, Na3V2(PO4)3, NaM'PO4F (M' being one or more of V, Fe, Mn, and Ni) and Na3(VO y )2(PO4)2F 3-2y At least one of (0≤y≤1).

[0165] In some embodiments, the Prussian blue analogue may be a compound containing sodium ions, transition metal ions, and cyanide ions (CN). - A class of compounds. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Prussian blue analogues include, for example, Na. a Me b Me' c (CN)6, wherein Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co and Zn, 0 < a ≤ 2, 0 < b < 1, 0 < c < 1.

[0166] In some embodiments, the specific positive electrode active material is, for example, NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2, Na4Fe3(PO4)2P2O7, NaFePO4, Na3V2(PO4)3, NaMnFe(CN)6, but there are no particular restrictions, so conventional positive electrode active materials used in sodium-ion batteries can be selected.

[0167] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0168] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0169] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0170] [Negative electrode plate]

[0171] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0172] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0173] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0174] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and sodium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0175] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0176] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0177] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0178] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0179] [Isolation membrane]

[0180] In some embodiments, the battery cell also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0181] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0182] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0183] In some embodiments, the battery cell may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0184] In some embodiments, the outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a flexible package, such as a pouch. The material of the flexible package can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0185] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 The example shown is a square-structured battery cell 5.

[0186] In some implementations, refer to Figure 2 The outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be placed over the opening to close the receiving cavity. The positive electrode sheet, negative electrode sheet, and separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in a single battery cell 5 can be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0187] In some implementations, individual battery cells can be assembled into a battery module. The number of individual battery cells contained in a battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0188] Figure 3 This is battery module 4, used as an example. (See reference...) Figure 3 In battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0189] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0190] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0191] Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0192] Thirdly, embodiments of this application provide an electrical device including a battery cell according to the second aspect of this application.

[0193] In addition, this application also provides an electrical device, which includes at least one of the battery cell, battery module, or battery pack provided in this application. The battery cell, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0194] As the electrical device, a single battery cell, a battery module, or a battery pack can be selected according to its usage requirements.

[0195] Figure 6 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of individual battery cells, a battery pack or battery module can be used.

[0196] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0197] Example

[0198] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0199] Example 1

[0200] Negative electrode plate:

[0201] A negative electrode-free structure is adopted, and a CNT coating is coated on both sides of Cu foil as a Na deposition current collector, with a single-sided coating thickness of 2 μm.

[0202] Solid electrolyte preparation:

[0203] β-Na₂O·11Al₂O₃ powder was ball-milled for 10 hours. Subsequently, the β-Na₂O·11Al₂O₃ powder was mixed with PVDF solvent to form a slurry with a solid content of 30%, which was then spray-dried onto the surface of the negative electrode to prepare a solid electrolyte layer with a thickness of 20 μm. In this embodiment, the average pore size of the solid electrolyte layer was 20 nm.

[0204] Preparation of gel electrolyte polyacrylic acid:

[0205] Sodium hexafluorophosphate was dispersed in ethylene glycol dimethyl ether to form a 1 mol / L solution. Azobisisobutyronitrile (AIBN) was added to the solution and, after complete dissolution, acrylic acid was added to obtain a mixture. The mass of the AIBN was 0.5% of the mixture's mass, and the mass of the acrylic acid was 5% of the mixture's mass. The raw materials were mixed and allowed to stand for 12 hours. Then, the reaction system was placed in an oven and allowed to stand at 60°C for 2 hours to form a pre-gel.

[0206] After the pre-gel is injected into the battery cell (injection coefficient 6.0 g / Ah), it is cured under an oxygen-free atmosphere at a controlled curing temperature of 70°C for 10 hours to obtain the gel electrolyte. In this embodiment, the thickness of the gel electrolyte is 50 μm, and the thickness of the gel electrolyte filling the pores of the solid electrolyte layer is 350 nm.

[0207] Preparation of the positive electrode sheet:

[0208] 93.8 wt% of positive electrode active material, 3.0 wt% of conductive agent (conductive carbon black), 2.5 wt% of binder (polyvinylidene fluoride), 0.3 wt% of dispersant, and 0.4 wt% of residual alkali remover were mixed, and then N-methylpyrrolidone was added and stirred to disperse, thus preparing a positive electrode slurry. After stirring, the viscosity of the prepared oil-based slurry was adjusted to 8000-15000 mPa·s. The prepared slurry did not separate into layers. Then, the slurry was coated onto Al foil using a double-sided double-cavity coating device with the coating weight controlled at 200 mg / 1540.25 cm2. After double-sided coating, the slurry was dried, cold-pressed, slit, and the positive electrode sheet was obtained.

[0209] The preparation methods of Examples 2-10 and Comparative Examples 1-2 in this application are similar to those of Example 1. For the differences, please refer to Table 1.

[0210] In Examples 1-9, the solid electrolyte layer is disposed on the surface of the conductive agent layer of the negative electrode sheet, and the gel electrolyte is disposed between the solid electrolyte layer and the positive electrode sheet.

[0211] In Example 10, a solid electrolyte layer is disposed on the side of the separator facing the negative electrode, and a gel electrolyte is disposed between the separator and the positive electrode, and between the separator and the negative electrode.

[0212] Performance testing:

[0213] 1. Initial DC impedance performance test:

[0214] At 25°C, the batteries of the above embodiments and comparative examples were charged at a constant current of 0.5C to 3.65V, and then charged at a constant voltage to a current of 0.05C. The batteries were then discharged at a constant current of 0.5C for 30 minutes to adjust the batteries to 50% SOC, and the voltage of the batteries at this time was recorded as U1. The batteries were then discharged at a constant current of 4C for 30 seconds, and the voltage at the end of the discharge was recorded as U2, using a sampling time of 0.1 seconds. The initial DCR of the battery is represented by the discharge DCR at 50% SOC, and the initial DCR of the battery is (U1-U2) / 4C.

[0215] 2. Ratio Performance Test:

[0216] The prepared battery was placed in a 25℃ constant temperature chamber and left to stand for 4 hours to reach a constant temperature. The battery that had reached a constant temperature was then charged at 1C constant current to 3.7V / 4V at 25℃, and then discharged at 1C constant current to 2.5V. After 5 cycles, the battery was left to stand for 5 minutes. Then, the battery was charged at 2C constant current to 3.7V / 4V, and after 5 cycles, the battery was left to stand for 5 minutes. Then, the battery was discharged at 2C constant current to 2.5V and left to stand for 5 minutes. The capacity C2 of the 2C discharge was obtained. The charging and discharging current was then increased to nC and the corresponding discharge capacity was recorded as Cn. The charging and discharging current was recorded when the rate R = Cn / C1 × 100% just reached ≤50%.

[0217] 3. Cyclic performance test:

[0218] Under a constant temperature environment of 25℃, the capacitor is charged at a rate of 1C to 4.2V at a voltage range of 2.5-4.43V. Then, it is charged at a constant voltage of 4.2V until the current is ≤0.05C. After resting for 5 minutes, it is discharged at a rate of 1C to 2.8V. The discharge capacity is recorded. The process is repeated to obtain the capacity retention rate after each cycle. The capacity retention rate is calculated as: discharge capacity at the current cycle number / discharge capacity at the first cycle * 100%. The number of cycles corresponding to when the capacity retention rate drops to 80% or below is recorded.

[0219]

[0220] As can be seen from the results in Table 1, compared with Comparative Examples 1 and 2, which only used solid electrolyte layers or gel electrolytes, the battery cells of Examples 1-10 of this application using the composite electrolyte of this application have lower initial DC resistance values, higher rate performance, and more cycles at 80% SOH, indicating that the composite electrolyte used in the embodiments of this application improves the overall ionic conductivity of the electrolyte in the battery cell, thereby further improving the rate performance and cycle performance of the battery cell.

[0221] As can be seen from Examples 1-4, by adjusting the thickness of the solid electrolyte layer, the rate performance and cycle performance of the battery cells can be further improved.

[0222] As can be seen from Examples 1 and 5-6, using solid electrolyte layers or gel electrolytes of different materials can further improve the rate performance and cycle performance of battery cells.

[0223] As can be seen from Examples 1 and 7-9, by adjusting the settling time of the gel electrolyte solution, the rate performance and cycle performance of the battery cells can be further improved.

[0224] As can be seen from Examples 1 and 10, placing the solid electrolyte in different locations can further improve the rate performance and cycle performance of the battery cells.

[0225] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A battery cell, characterized in that, Includes positive electrode, negative electrode, and composite electrolyte; The composite electrolyte is disposed between the positive electrode and the negative electrode, and the composite electrolyte is at least partially in contact with the positive electrode and the negative electrode. The composite electrolyte comprises a solid electrolyte layer and a gel electrolyte, wherein the gel electrolyte is attached to at least a portion of the surface of the solid electrolyte layer.

2. The battery cell according to claim 1, characterized in that, The solid electrolyte layer is made of inorganic solid electrolytes and / or polymer solid electrolytes.

3. The battery cell according to claim 2, characterized in that, The inorganic solid electrolyte includes at least one of sulfide electrolytes, sodium fast ion conductors, and oxide electrolytes.

4. The battery cell according to claim 3, characterized in that, The chalcogen-based electrolyte includes vitreous Na2S-P2S5, Na 11 Sn2 PnX 12 , Na3 Pn y Pn′ 1-y X z X′ 4-z one or more of them, where Pn includes at least one of P and Sb, X includes at least one of S and Se, Pn′ includes at least one of Si, Sn, and Ge, X′ includes at least one of F, Br, and Cl, 0 < y ≤ 1, 0 < z ≤ 4; and / or, The sodium fast ion conductor includes Na 3+a M b M′ 2-b Si 2-c P c O 12 , where M and M′ each independently include at least one of Zr, Ca, Mg, Zn, La, Ti, Nb, 0 ≤ a ≤ 1, 0 < b ≤ 2, 0 ≤ c < 2; and / or, The oxide electrolyte includes at least one of Na-β-Al2O3 and Na-β″-Al2O3, wherein the Na-β-Al2O3 includes β-Na2O·11Al2O3 and the Na-β″-Al2O3 includes β″-Na2O·5Al2O3.

5. The battery cell according to claim 2, characterized in that, The polymer solid electrolyte comprises a polymer, wherein the polymer includes at least one of polyimide, polyethylene oxide, polyethylene glycol, polyvinylpyrrolidone, polymethyl methacrylate, polyvinylidene fluoride, poly(vinylidene fluoride-copolyhexafluoropropylene), polyvinyl alcohol, polyacrylonitrile, polyvinyl chloride, polyacrylamide, polytrimethylene carbonate, and perfluoropolyether.

6. The battery cell according to any one of claims 5, characterized in that, The polymer solid electrolyte further includes inorganic fillers, which include at least one of TiO2, Al2O3, SiO2, ZrO2, MgO and CuO.

7. The battery cell according to any one of claims 2 to 6, characterized in that, The polymer solid electrolyte also includes electrolyte salts. The electrolyte salt includes at least one of sodium chloride, sodium bromide, sodium nitrate, sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium tetrafluoroyttrium, sodium acetate, sodium trifluoroacetate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide; and / or, The electrolyte salt accounts for 10%-20% of the mass of the polymer solid electrolyte.

8. The battery cell according to any one of claims 1 to 7, characterized in that, The thickness of the solid electrolyte layer is 10-30 μm.

9. The battery cell according to any one of claims 1 to 8, characterized in that, The average pore size of the solid electrolyte layer is 5-20 nm.

10. The battery cell according to any one of claims 1 to 9, characterized in that, The gel electrolyte comprises a gel polymer and an electrolyte salt.

11. The battery cell according to claim 10, characterized in that, The monomers of the gel polymer include at least one of olefin monomers, ester monomers, ether monomers, nitrile monomers, and natural polymers.

12. The battery cell according to claim 11, characterized in that, The olefin monomers include at least one selected from vinylidene fluoride, hexafluoropropylene, ethylene oxide, and acrylic acid; and / or, The ester monomers include at least one selected from methacrylate, vinylene carbonate, vinyl acetate, and polyethylene glycol methacrylate; and / or, The ether monomers include at least one of ethylene oxide, 1,3-dioxocyclopentane, and dioxane; and / or, The nitrile monomers include acrylonitrile or butyl 2-cyano-2-acrylate; and / or, The natural polymers include at least one of starch, cellulose, chitosan, lignin, and chitin.

13. The battery cell according to any one of claims 10 to 12, characterized in that, The electrolyte salt constitutes 10%-20% of the mass of the gel electrolyte.

14. The battery cell according to any one of claims 1 to 13, characterized in that, The thickness of the gel electrolyte attached to the surface of the solid electrolyte layer is 10-80 μm, and / or the gel electrolyte fills the pores of the solid electrolyte layer, and the thickness of the gel electrolyte filling the pores of the solid electrolyte layer is 300-500 nm.

15. The battery cell according to any one of claims 1 to 14, characterized in that, The battery cell includes a sodium-free negative electrode battery cell, wherein the negative electrode sheet includes a metal current collector and a conductive agent layer disposed on the surface of the metal current collector.

16. The battery cell according to claim 15, characterized in that, The solid electrolyte layer is disposed on the surface of the conductive agent layer, and the gel electrolyte is disposed between the solid electrolyte layer and the positive electrode sheet; wherein, the material of the conductive agent layer includes at least one of carbon nanotubes, conductive carbon black, Sn, Zn, and Mg, and the thickness of the conductive agent layer is 2-5 micrometers.

17. The battery cell according to any one of claims 1 to 16, characterized in that, The battery cell also includes a separator, the solid electrolyte layer is disposed on the side of the separator facing the negative electrode, and the gel electrolyte is disposed between the separator and the positive electrode, and between the separator and the negative electrode.

18. A composite electrolyte, characterized in that, The composite electrolyte comprises a solid electrolyte layer and a gel electrolyte, wherein the gel electrolyte is attached to at least a portion of the surface of the solid electrolyte layer.

19. The composite electrolyte according to claim 18, characterized in that, The solid electrolyte layer is made of inorganic solid electrolytes and / or polymer solid electrolytes.

20. The composite electrolyte according to claim 19, characterized in that, The inorganic solid electrolyte includes at least one of sulfide electrolytes, sodium fast ion conductors, and oxide electrolytes.

21. The composite electrolyte according to claim 20, characterized in that, The chalcogenide electrolyte includes vitreous Na2S-P2S5, Na 11 Sn2 PnX 12 , Na3 Pn y Pn′ 1-y X z X′ 4-z one or more of them, where Pn includes at least one of P and Sb, X includes at least one of S and Se, Pn′ includes at least one of Si, Sn, and Ge, X′ includes at least one of F, Br, and Cl, 0 < y ≤ 1, 0 < z ≤ 4; and / or, The sodium fast ion conductor comprises Na 3+a M b M′ 2-b Si 2-c P c O 12 , wherein M and M′ each independently comprise at least one of Zr, Ca, Mg, Zn, La, Ti, and Nb, 0 ≤ a ≤ 1, 0 < b ≤ 2, 0 ≤ c < 2; and / or, The oxide electrolyte includes at least one of Na-β-Al2O3 and Na-β″-Al2O3, wherein the Na-β-Al2O3 includes β-Na2O·11Al2O3 and the Na-β″-Al2O3 includes β″-Na2O·5Al2O3.

22. The composite electrolyte according to claim 21, characterized in that, The polymer solid electrolyte comprises a polymer, wherein the polymer includes at least one of polyimide, polyethylene oxide, polyethylene glycol, polyvinylpyrrolidone, polymethyl methacrylate, polyvinylidene fluoride, poly(vinylidene fluoride-copolyhexafluoropropylene), polyvinyl alcohol, polyacrylonitrile, polyvinyl chloride, polyacrylamide, polytrimethylene carbonate, and perfluoropolyether.

23. The composite electrolyte according to claim 19 or 22, characterized in that, The polymer solid electrolyte further includes inorganic fillers, which include at least one of TiO2, Al2O3, SiO2, ZrO2, MgO and CuO.

24. The composite electrolyte according to any one of claims 19 to 23, characterized in that, The polymer solid electrolyte further includes an electrolyte salt, wherein the electrolyte salt comprises at least one selected from sodium chloride, sodium bromide, sodium nitrate, sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium tetrafluoroyttrium, sodium acetate, sodium trifluoroacetate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide. The electrolyte salt constitutes 10%-20% of the polymer solid electrolyte by mass.

25. The composite electrolyte according to any one of claims 18 to 24, characterized in that, The thickness of the solid electrolyte layer is 10-30 μm.

26. The composite electrolyte according to any one of claims 18 to 25, characterized in that, The average pore size of the solid electrolyte layer is 5-20 nm.

27. The composite electrolyte according to claims 18 to 26, characterized in that, The gel electrolyte comprises a gel polymer and an electrolyte salt; and / or, the thickness of the gel electrolyte attached to the surface of the solid electrolyte layer is 10-80 μm; and / or, the gel electrolyte fills the pores of the solid electrolyte layer, and the thickness of the gel electrolyte filling the pores of the solid electrolyte layer is 300-500 nm.

28. The composite electrolyte according to claim 27, characterized in that, The monomers of the gel polymer include at least one of olefin monomers, ester monomers, ether monomers, nitrile monomers, and natural polymers.

29. The composite electrolyte according to claim 28, characterized in that, The olefin monomers include at least one selected from vinylidene fluoride, hexafluoropropylene, ethylene oxide, and acrylic acid; and / or, The ester monomers include at least one selected from methacrylate, vinylene carbonate, vinyl acetate, and polyethylene glycol methacrylate; and / or, The ether monomers include at least one of ethylene oxide, 1,3-dioxocyclopentane, and dioxane; and / or, The nitrile monomers include acrylonitrile or butyl 2-cyano-2-acrylate; and / or, The natural polymers include at least one of starch, cellulose, chitosan, lignin, and chitin.

30. The composite electrolyte according to any one of claims 18 to 29, characterized in that, The electrolyte salt constitutes 10%-20% of the mass of the gel electrolyte.

31. A method for preparing a single battery cell, characterized in that, Includes the following steps: A solid electrolyte layer is placed between the positive electrode and the negative electrode. Assemble the positive electrode, the solid electrolyte layer, and the negative electrode; A gel electrolyte solution is injected into the gap between the positive and negative electrode plates, and the gel electrolyte solution is solidified so that the solidified gel electrolyte adheres to at least a portion of the surface of the solid electrolyte layer.

32. The preparation method according to claim 31, characterized in that, The step of injecting the gel electrolyte solution into the gap between the positive and negative electrode plates and solidifying the gel electrolyte solution to allow the solidified gel electrolyte to adhere to at least a portion of the surface of the solid electrolyte layer includes: The gel electrolyte solution is injected into the gap between the positive and negative electrode plates at an injection coefficient of 6-7 g / Ah. The solution is left to stand for 12-24 hours to solidify, so that the solidified gel electrolyte adheres to at least a portion of the surface of the solid electrolyte layer.

33. An electrical device, characterized in that, Includes the battery cell as described in any one of claims 1 to 17.

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