Current collector, secondary battery, battery module, battery pack, and power consumption device

Abstract

The present application provides a current collector, a secondary battery, a battery module, a battery pack, and a power consumption device. One side of the current collector is coated with a coating including an interface protection layer. The interface protection layer is advantageous in reducing the contact area between the metal and the electrolyte, thereby reducing the occurrence of side reactions between the metal and the electrolyte, and effectively improving the battery's coulombic efficiency and capacity retention rate after 100 cycles.

Description

[Technical Field]

[0001] The present application relates to the field of secondary battery technology, and in particular to current collectors, secondary batteries, battery modules, battery packs, and power consuming devices. [Background technology]

[0002] In recent years, secondary batteries have been widely used in energy storage power systems such as hydroelectric, thermal, wind and solar power plants, as well as in multiple fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace.

[0003] Interfacial stability is an important index for evaluating secondary batteries. Side reactions between metals and electrolytes have a serious impact on interfacial stability, resulting in a deterioration of the electrochemical performance and safety of the battery, making it impossible to meet the application demands of next-generation electrochemical systems. Summary of the Invention

[0004] The present application has been made in view of the above-mentioned problems, and an object of the present application is to provide a current collector having a coating that is advantageous for reducing contact between a metal deposited on the current collector and an electrolyte, thereby reducing side reactions between the metal and the electrolyte and improving the coulombic efficiency and cycle performance of a battery.

[0005] According to a first aspect of the present application, there is provided a current collector having a coating, the coating including at least an interface protection layer, and the coating being formed on at least one side of the current collector.

[0006] During charge and discharge, metal ions can pass freely through the interfacial protective layer and be deposited on the current collector, or the metal on the current collector can be detached and pass through the interfacial protective layer in the form of metal ions. In other words, during charge and discharge, the interfacial protective layer is located between the metal phase and the electrolyte, which is advantageous in reducing contact between the metal and the electrolyte, thereby reducing the occurrence of side reactions between the metal and the electrolyte, and effectively improving the coulombic efficiency and cycle capacity retention rate of the battery.

[0007] In either embodiment, the coating further comprises an induction deposition layer, the induction deposition layer and the interface protection layer being disposed in that order in a direction from the side closest to the current collector to the side away from the current collector.

[0008] An induced deposition layer and an interface protection layer are sequentially formed on one side of the current collector, which can reduce the nucleation overpotential of metal ions, induce uniform deposition of metal ions, adjust the deposition behavior of metal ions, inhibit dendrites, and reduce contact between the metal and the electrolyte, thereby reducing the occurrence of side reactions between the metal and the electrolyte and effectively improving the coulomb efficiency and cycle capacity retention rate of the battery.

[0009] In either embodiment, the induction deposition layer is in direct contact with the current collector surface.

[0010] In either embodiment, the interface protection layer is in direct contact with the surface of the guided deposition layer.

[0011] By forming an induced deposition layer on the surface of the current collector and forming an interface protection layer on the surface of the induced deposition layer, the nucleation overpotential of metal ions can be reduced and the contact between the metal and the electrolyte can be reduced, thereby effectively improving the performance of the battery.

[0012] In any embodiment, the interface protection layer comprises one or more of polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene copolymer, polyacrylic acid, and polyimide, and optionally one or more of polyvinylidene fluoride and carboxymethyl cellulose.

[0013] The interfacial protection layer includes one or more of polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene copolymer, polyacrylic acid, and polyimide, which are advantageous for improving the battery's coulombic efficiency and cycle capacity retention rate. The interfacial protection layer includes one or more of polyvinylidene fluoride and carboxymethyl cellulose, which significantly reduces the metal ion nucleation overpotential, further improving the battery's coulombic efficiency and cycle capacity retention rate.

[0014] In any embodiment, the thickness of the interface protection layer is 15 nm to 1500 nm, and optionally 50 nm to 500 nm.

[0015] The thickness of the interface protection layer is controlled to 15-1500 nm, which is advantageous for improving the battery's Coulombic efficiency and cycle capacity retention rate or reducing the metal ion nucleation overvoltage, providing effective protection while avoiding the increase in battery internal resistance and the reduction in battery cycle performance and energy density that would otherwise be caused by an excessively thick layer.The thickness of the interface protection layer is controlled to 50-500 nm, which is advantageous for further improving the battery's Coulombic efficiency and cycle capacity retention rate or more significantly reducing the metal ion nucleation overvoltage.

[0016] In either embodiment, the induction deposition layer comprises a conductive material including a carbon material and / or a metallic material.

[0017] The guided deposition layer containing the conductive material is advantageous in reducing the nucleation overpotential of metal ions and improving the coulombic efficiency and cycle capacity retention of the battery.

[0018] In any embodiment, the conductive material comprises one or more of Super P, carbon nanotubes, hard carbon, two-dimensional graphene, graphene quantum dots, gold, silver, copper, aluminum, iron, and nickel, and optionally one or more of Super P, carbon nanotubes, hard carbon, two-dimensional graphene, and graphene quantum dots.

[0019] The guided deposition layer containing the above material is advantageous in reducing the nucleation overpotential of metal ions and improving the battery's coulombic efficiency and cycle capacity retention rate. Compared to the guided deposition layer containing a metal material, the guided deposition layer containing a carbon material has a lower metal ion nucleation overpotential and a higher battery coulombic efficiency and cycle capacity retention rate.

[0020] In any embodiment, the thickness of the guided deposition layer is between 50 nm and 2000 nm, and optionally between 200 nm and 1000 nm.

[0021] Controlling the thickness of the induced deposition layer between 50nm and 2000nm can provide sufficient nucleation sites, reducing the nucleation overpotential of metal ions and improving the battery's coulombic efficiency and cycle capacity retention rate, while avoiding the reduction in battery energy density due to increased side reactions caused by an excessively thick layer. Controlling the thickness of the induced deposition layer between 200nm and 1000nm can more significantly reduce the nucleation overpotential of metal ions and further improve the battery's coulombic efficiency and cycle capacity retention rate.

[0022] In either embodiment, the induction deposition layer further comprises an adhesive comprising one or more selected from polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene copolymer, polyacrylic acid, and sodium alginate.

[0023] The adhesive provides high adhesive strength between the induction deposition layer and the current collector, preventing the current collector from being detached, and is also advantageous for uniform distribution of the conductive carbon material in the induction deposition layer.

[0024] In either embodiment, the adhesive material in the induction deposition layer is at least partially the same as the material of the interface protection layer.

[0025] Controlling the adhesive material in the induction deposition layer and the material of the interface protection layer to be at least partially the same is advantageous in increasing the compatibility between the interface protection layer and the induction deposition layer, reducing the nucleation overpotential of metal ions, and improving the coulombic efficiency and cycle capacity retention rate of the battery.

[0026] In any embodiment, the current collector comprises at least one of a metal foil material, a metal foam current collector, a metal mesh current collector, a carbon felt current collector, a carbon cloth current collector, a carbon paper current collector, and a composite current collector.

[0027] The current collector has excellent tensile strength and ductility, which is advantageous for the stability and safety of the battery.

[0028] According to a second aspect of the present application, there is provided a secondary battery including an electrolyte and a negative electrode plate, the negative electrode plate including the current collector according to any of the embodiments.

[0029] This secondary battery has excellent cycle performance.

[0030] In any of the embodiments, the secondary battery includes at least one of a lithium battery and a sodium battery.

[0031] In any of the embodiments, the secondary battery is a sodium battery without an anode, which can have a high energy density.

[0032] In any of the embodiments, the electrolyte solution includes an ether-based solvent, and the ether-based solvent includes one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, crown ether, and optionally one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and diethylene glycol dimethyl ether.

[0033] The electrolytes containing the above solvents are advantageous in reducing the overvoltage of sodium ions and improving the coulombic efficiency and cycle capacity retention of the battery. The solvent may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and diethylene glycol dimethyl ether, which is advantageous in further improving the coulombic efficiency and cycle capacity retention of the battery.

[0034] In any embodiment, the electrolyte further comprises a sodium borate-based additive.

[0035] Sodium borate additives can react with metals to generate boron-rich inorganic compounds, thereby forming an interfacial protective layer and an organic / inorganic composite protective layer, which is beneficial for improving the cycle performance of batteries. At the same time, when SEI film damage occurs during battery cycling, sodium borate additives can continuously generate boron-rich inorganic compounds, repair the SEI film damage, and further improve the cycle performance of batteries.

[0036] In any embodiment, the sodium borate additive includes one or more of sodium difluoro(oxalato)borate, sodium tetrafluoroborate, sodium bis(oxalato)borate, sodium tetraphenylborate, and optionally one or more of sodium difluoro(oxalato)borate, sodium bis(oxalato)borate.

[0037] The electrolyte solution containing the sodium borate-based additive is advantageous in improving the coulomb efficiency and cycle capacity retention rate of the battery.

[0038] In any embodiment, the mass content of the sodium borate-based additive is 0.01% to 1.8%, and optionally 0.1% to 1.0%, based on the total mass of the electrolyte.

[0039] Controlling the mass content of the sodium borate-based additive to 0.01% to 1.8% is advantageous for improving the battery's coulombic efficiency and cycle capacity retention rate. Controlling the mass content of the sodium borate-based additive to 0.1% to 1.0% can further improve the battery's coulombic efficiency and cycle capacity retention rate.

[0040] According to a third aspect of the present application, there is provided a battery module, which includes the secondary battery of the second aspect of the present application.

[0041] According to a fourth aspect of the present application, there is provided a battery pack, which includes the secondary battery according to the second aspect of the present application or the battery module according to the third aspect of the present application.

[0042] According to a fifth aspect of the present application, there is provided a power consumption device, which includes at least one of the secondary battery of the second aspect of the present application, the battery module of the third aspect of the present application, and the battery pack of the fourth aspect of the present application. [Brief explanation of the drawings]

[0043] [Figure 1]1 is a schematic diagram of a secondary battery according to an embodiment of the present application; [Figure 2] FIG. 2 is an exploded view of the secondary battery shown in FIG. 1 according to the embodiment of the present application. [Figure 3] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 4] 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Figure 5] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application. [Figure 6] 1 is a schematic diagram of a power consumption device powered by a secondary battery according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0044] Hereinafter, embodiments specifically disclosing the current collector, secondary battery, battery module, battery pack, and power consumption device of the present application will be described in detail with appropriate reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or repeated description of structures that are actually the same may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0045] The "ranges" disclosed in this application are defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive, and any combination is possible; i.e., any lower limit may be combined with any upper limit to form a single range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, these ranges are intended to be understood as 60 to 110 and 80 to 120, respectively. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all possible. In this application, unless otherwise specified, the numerical range "ab" is a shorthand notation for any combination of real numbers a to b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have already been listed in this specification, and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0046] Unless otherwise stated, all embodiments and optional embodiments in this application can be combined with each other to form a new technical solution.

[0047] Unless otherwise stated, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0048] Unless otherwise specified, all steps in this application may be performed in order or randomly, and are preferably performed in order. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, when the method mentioned above may further include step (c), it means that step (c) may be added to the method in any order, and for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0049] Unless otherwise specified, the terms "comprise" and "comprises" used in this application may be open ended or closed ended. For example, the terms "comprise" and "comprises" may indicate that other components not listed may be further included or included, or that only the listed components may be included or included.

[0050] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, "A or B" is satisfied when A is true (or exists) and B is false (or does not exist), when A is false (or does not exist) but B is true (or exists), or when both A and B are true (or exist).

[0051] Metal secondary batteries are secondary batteries that use a metal material (e.g., lithium, sodium, magnesium, potassium, etc.) as the negative electrode. The metal material on the negative electrode current collector may be pre-deposited on the current collector surface as a negative electrode active material, or may be deposited on the current collector surface in situ during the charge / discharge process. That is, metal secondary batteries include not only sodium batteries, lithium batteries, magnesium batteries, potassium batteries, etc., which have a negative electrode active material, but also batteries without a negative electrode. In a negative electrode-less battery, the negative electrode plate uses a negative electrode current collector but does not contain a negative electrode active material, and metal ions are deposited on the negative electrode current collector in situ during the initial charge / discharge process.

[0052] Currently, metal batteries have many problems. For example, in the case of sodium batteries without a negative electrode, side reactions are likely to occur between metallic sodium and the electrolyte during the charge and discharge process, consuming a large amount of sodium element and reducing the coulomb efficiency and cycle performance of the battery.

[0053] [Current collector] Based on this, the present application provides a current collector having a coating, the coating including at least an interface protection layer, and the coating being formed on at least one side of the current collector.

[0054] The interfacial protective layer reduces contact between the metal and the electrolyte, thereby reducing side reactions between the metal and the electrolyte and providing protection for the metal. The interfacial protective layer is located between the current collector and the electrolyte and allows metal ions to pass freely through the interfacial protective layer. During charging, metal ions pass through the interfacial protective layer from the electrolyte and deposit on the current collector. During discharging, electrons lost by the metal desorb from the current collector in the form of metal ions and diffuse through the interfacial protective layer into the electrolyte.

[0055] As used herein, the term "at least one side of the current collector" refers to at least one surface of the current collector.

[0056] In some embodiments, the interface protection layer is a polymer layer.

[0057] In some embodiments, the current collector is a negative electrode current collector of a secondary battery.

[0058] In some embodiments, the current collector is a negative electrode current collector in a battery without a negative electrode, and the interfacial protection layer is in direct contact with the current collector surface.

[0059] In some embodiments, the current collector is a negative electrode current collector of a metal battery, and the interfacial protection layer has a metal phase between it and the current collector.

[0060] The interface protection layer is advantageous in reducing contact between the metal and the electrolyte, thereby reducing the occurrence of side reactions between the metal and the electrolyte, and effectively improving the coulombic efficiency of the battery and the capacity retention rate after 100 cycles.

[0061] In this specification, the coulombic efficiency refers to the first coulombic efficiency, which is mainly used to characterize the ratio of the discharge capacity to the charge capacity of the battery during the first cycle, and can reflect the consumption degree of metal ions, which can be tested by any known method.

[0062] In this specification, the capacity retention rate after 100 cycles is mainly used to characterize the cycle usage performance of a battery, and can reflect the cycle performance of a battery, and can be tested by any known method.

[0063] In some embodiments, the coating further comprises an induction deposition layer, with the induction deposition layer and the interface protection layer disposed in that order in a direction from the side closest to the current collector to the side away from the current collector.

[0064] Herein, the guided deposition layer guides uniform deposition of metal by providing sufficient nucleation sites, which is beneficial in suppressing metal dendrites.

[0065] Some embodiments have one or more coatings between the dielectric deposition layer and the current collector.

[0066] In some embodiments, a deposition layer is present between the induction deposition layer and the interfacial protection layer. The deposition layer may be a metal phase that has been previously deposited between the current collector and the interfacial protection layer. The deposition layer may be a metal phase that is deposited on the current collector by passing metal ions through the interfacial protection layer.

[0067] The current collector is sequentially provided with an induced deposition layer and an interface protection layer, which can reduce the nucleation overpotential of metal ions, induce uniform deposition of metal ions, adjust the deposition behavior of metal ions, suppress dendrites, and reduce contact between the metal and the electrolyte, thereby reducing the occurrence of side reactions between the metal and the electrolyte and effectively improving the coulombic efficiency and cycle capacity retention of the battery. As used herein, the term "nucleation overpotential" refers to the potential required for metal ions to gain electrons at the negative electrode to form and deposit metal atoms.

[0068] Nucleation overpotential is used herein primarily to characterize the potential required for metal ion deposition and can characterize the uniformity of metal ion deposition, which can be tested by any known method.

[0069] In some embodiments, the induction deposition layer is in direct contact with the current collector surface.

[0070] In some embodiments, the interface protection layer is in direct contact with the guided deposition layer surface.

[0071] By forming an induced deposition layer on the surface of the current collector and forming an interface protection layer on the surface of the induced deposition layer, the nucleation overpotential of metal ions can be reduced and the contact between the metal and the electrolyte can be reduced, thereby effectively improving the performance of the battery.

[0072] In some embodiments, the interface protection layer comprises one or more of polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene copolymer, polyacrylic acid, polyimide, and optionally one or more of polyvinylidene fluoride, carboxymethyl cellulose.

[0073] The interfacial protection layer includes one or more of polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene copolymer, polyacrylic acid, and polyimide, which is advantageous for improving the battery's coulombic efficiency and capacity retention rate after 100 cycles. The interfacial protection layer includes one or more of polyvinylidene fluoride and carboxymethyl cellulose, which can significantly reduce the nucleation overpotential of metal ions, further improving the battery's coulombic efficiency and capacity retention rate after 100 cycles.

[0074] In some embodiments, the thickness of the interface protection layer is 15 nm to 1500 nm, and optionally 50 nm to 500 nm. In some embodiments, the thickness of the interface protection layer is optionally 15 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm, 1400 nm, or 1500 nm.

[0075] Controlling the thickness of the interface protection layer between 15 nm and 1500 nm is beneficial for improving the battery's Coulombic efficiency and capacity retention rate after 100 cycles or reducing the metal ion nucleation overvoltage, providing effective protection while avoiding an increase in battery internal resistance and a decrease in battery cycle performance and energy density due to an excessively thick layer. Controlling the thickness of the interface protection layer between 50 nm and 500 nm is beneficial for further improving the battery's Coulombic efficiency and capacity retention rate after 100 cycles or more significantly reducing the metal ion nucleation overvoltage.

[0076] In some embodiments, the induction deposition layer comprises a conductive material including a carbon material and / or a metallic material.

[0077] As used herein, the term "carbon material" refers to a material that includes carbon. Exemplary carbon materials include, but are not limited to, Super P, carbon nanotubes, hard carbon, two-dimensional graphene, or graphene quantum dots.

[0078] In some embodiments, the conductive material comprises a carbon material.

[0079] In some embodiments, the conductive material comprises a metallic material.

[0080] In some embodiments, the conductive material includes a carbon material and a metallic material.

[0081] The induced deposition layer containing the conductive material has good conductivity, which reduces excessive local current density, lowers the nucleation overpotential of metal ions, and is advantageous in improving the coulombic efficiency of the battery and the capacity retention rate after 100 cycles.

[0082] In some embodiments, the carbon material comprises a carbon nanomaterial.

[0083] As used herein, the term "carbon nanomaterial" refers to a carbon material having at least one dimension in three-dimensional space that is nano-sized (1 nm to 100 nm) or that is composed of basic units that are nano-sized, which corresponds to a scale where approximately 10 to 1000 atoms are closely arranged.

[0084] Carbon nanomaterials are easy to induce the deposition of metal ions on the undercoating surface through adsorption, and their nanoscale structure and arrangement improve the uniformity of the distribution of nucleation sites, which is advantageous for more uniform deposition of metal ions.

[0085] In some embodiments, the conductive material comprises one or more of Super P, carbon nanotubes, hard carbon, two-dimensional graphene, graphene quantum dots, gold, silver, copper, aluminum, iron, nickel, and optionally one or more of Super P, carbon nanotubes, hard carbon, two-dimensional graphene, graphene quantum dots.

[0086] As used herein, the term "Super P" refers to carbon black that has interparticle agglomerations forming spherules.

[0087] As used herein, the term "carbon nanotube" refers to a seamless hollow cylinder formed by rolling up single- or multi-layer graphene, with a tube diameter less than 100 nm and a tube length greater than 100 nm. By way of example, carbon nanotubes include, but are not limited to, single-walled carbon nanotubes and / or multi-walled carbon nanotubes.

[0088] As used herein, the term "hard carbon" refers to carbon that is difficult to graphitize.

[0089] In some embodiments, two-dimensional graphene refers to graphene that exhibits a sheet-like structure having nanoscale (less than 100 nm) dimensions in the thickness direction and dimensions greater than 100 nm in other directions, and may include single-layer graphene and / or multi-layer graphene.

[0090] As used herein, the term "single-layer graphene" refers to a single-layer sheet-like structure in which carbon atoms are tightly and periodically arranged in a hexagonal honeycomb structure. For example, the thickness of single-layer graphene is only 0.3 nm to 0.4 nm.

[0091] As used herein, the term "multilayer graphene" refers to a graphene produced by stacking 2 to 10 single-layer graphene layers together to a total thickness of less than 100 nm.

[0092] As used herein, the term "graphene quantum dots" refers to graphene nanoparticles whose graphene size is within 100 nm in each dimension.

[0093] The induction deposition layer containing the above material is advantageous in reducing the nucleation overpotential of metal ions and improving the battery's coulombic efficiency and cycle capacity retention. Compared to induction deposition layers containing metal materials, induction deposition layers containing carbon materials have a lower protective ion nucleation overpotential and higher battery coulombic efficiency and cycle capacity retention.

[0094] In some embodiments, the thickness of the induction deposition layer is 50 nm to 2000 nm, optionally 200 nm to 1000 nm, hi some embodiments, the thickness of the induction deposition layer is optionally 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm, 1400 nm, 1500 nm, 1600 nm, 1700 nm, 1800 nm, 1900 nm, or 2000 nm.

[0095] Controlling the thickness of the induced deposition layer between 50 nm and 2000 nm can provide sufficient nucleation sites, reducing the nucleation overpotential of metal ions and improving the battery's coulombic efficiency and cycle capacity retention rate, while avoiding the reduction in battery energy density due to increased side reactions caused by an excessively thick layer. Controlling the thickness of the induced deposition layer between 200 nm and 1000 nm can more significantly reduce the nucleation overpotential of metal ions and further improve the battery's coulombic efficiency and capacity retention rate after 100 cycles.

[0096] As used herein, the term "nucleation site" refers to the location where metal ions gain electrons at the negative electrode to form metal atoms and deposit.

[0097] In some embodiments, the induction deposition layer further comprises an adhesive comprising one or more selected from polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene copolymer, polyacrylic acid, sodium alginate.

[0098] The adhesive provides high adhesive strength between the induction deposition layer and the current collector, preventing the current collector from being detached, and is also advantageous for uniform distribution of the conductive carbon material in the induction deposition layer.

[0099] In some embodiments, the adhesive material in the induction deposition layer is at least partially the same as the material of the interface protection layer.

[0100] In some embodiments, the adhesive material in the induction deposition layer is exactly the same as the material of the interface protection layer, for example, the adhesive contains only carboxymethyl cellulose, and the interface protection layer contains only carboxymethyl cellulose.

[0101] In some embodiments, the adhesive material in the induction deposition layer is partially the same as the material of the interface protection layer. For example, the adhesive comprises a mixture of carboxymethyl cellulose and styrene-butadiene copolymer, and the interface protection layer comprises only carboxymethyl cellulose.

[0102] Controlling the adhesive material in the induction deposition layer and the material of the interface protection layer to be at least partially the same is advantageous in increasing the compatibility between the interface protection layer and the induction deposition layer, reducing the nucleation overpotential of metal ions, and improving the battery's coulombic efficiency and capacity retention rate after 100 cycles.

[0103] In some embodiments, the current collector comprises at least one of a metal foil material, a metal foam current collector, a metal mesh current collector, a carbon felt current collector, a carbon cloth current collector, a carbon paper current collector, and a composite current collector.

[0104] In some embodiments, the metal foil material is optionally copper foil, aluminum foil, stainless steel foil, iron foil, zinc foil, or titanium foil, and the metal foam current collector is optionally copper foam, aluminum foam, or zinc foam. The metal mesh current collector is optionally copper mesh or aluminum mesh. The composite current collector includes a polymer base film and metal foil materials formed on both sides of the polymer base film. The composite current collector may have a "sandwich" structure, with a polymer base film positioned in the middle and metal foil materials on both sides. The polymer base film is optionally one of polyamide, polyterephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, poly-p-phenylene terephthamide, polypropylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, and polycarbonate.

[0105] The current collector has excellent tensile strength and ductility, which is advantageous for the stability and safety of the battery.

[0106] [Positive electrode plate] The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer formed on at least a portion of the surface of the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material, which may include at least one of a layered transition metal oxide, a polyanion-type compound, and a Prussian blue-based compound.

[0107] The transition metal in the layered transition metal oxide may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Optionally, the layered transition metal oxide may be, for example, NaxMO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu, and 0 <x≦1である。

[0108] Polyanionic compounds include metal ions, transition metal ions, and tetrahedral (YO4) n-anionic units, the metal ion is optionally one of sodium ion, lithium ion, potassium ion, and zinc ion, the transition metal is optionally at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, Y is optionally at least one of P, S, and Si, and n is (YO4) n- represents the valence state of

[0109] The Prussian blue compound may be a type of compound having sodium ions, transition metal ions, and cyano ions (CN-). The transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. The Prussian blue compound may be, for example, Na a Me b Me' c (CN)6, where Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co, and Zn; <a≦2、0<b<1、0<c<1である。

[0110] The positive electrode active material layer may further include a conductive agent to improve the conductive performance of the positive electrode, which may be one or more of Super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers.

[0111] The positive electrode active material layer may further include an adhesive for firmly adhering the positive electrode active material and optional conductive agent to the positive electrode current collector, and the adhesive may be at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyvinyl alcohol (PVA), ethylene-vinyl acetate copolymer (EVA), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), sodium alginate (SA), polymethacrylic acid (PMA), and carboxymethyl chitosan (CMCS).

[0112] The positive electrode current collector may be a conductive carbon sheet, a metal foil, a carbon-coated metal foil, a porous metal plate, or a composite current collector. The conductive carbon material of the conductive carbon sheet may be one or more of Super P, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers. The metal material of the metal foil, the carbon-coated metal foil, and the porous metal plate may each independently be at least one of copper, aluminum, nickel, and stainless steel. The composite current collector may be a composite current collector formed by combining a metal foil with a polymer base film.

[0113] In some embodiments, a positive electrode plate can be manufactured in the following manner: Components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, which is then applied to a positive electrode current collector, dried, cold-pressed, and other processes to obtain a positive electrode plate.

[0114] [Electrolytes] The electrolyte serves to conduct ions between the positive and negative electrodes. The present application does not specifically limit the type of electrolyte, and it may be selected according to needs. For example, the electrolyte may be liquid, gel, or all-solid.

[0115] In some embodiments, the electrolyte is an electrolytic solution, which includes an electrolyte salt and a solvent.

[0116] In some embodiments, the electrolyte salt may be selected from at least one of sodium hexafluorophosphate, sodium bisfluorosulfonylimide, sodium bistrifluoromethanesulfonylimide, sodium trifluoromethanesulfonate, sodium tetrafluoroborate, sodium difluorophosphate, sodium perchlorate, and sodium chloride.

[0117] In some embodiments, the electrolyte solution comprises an ester-based solvent, and the ester-based solvent comprises at least one selected from ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene carbonate, methyl acetate, ethyl propionate, and fluoroethylene carbonate.

[0118] In some embodiments, the electrolyte solution comprises an ether-based solvent, the ether-based solvent comprising one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, crown ether, and optionally one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and diethylene glycol dimethyl ether.

[0119] The electrolytes containing the above ether solvents are advantageous in reducing the overvoltage of sodium ions, inducing uniform deposition of metal ions, and having high anti-reduction properties, which promote the formation of a stable solid electrolyte interface on the protective metal surface, reduce side reactions during cycling, and improve the battery's coulombic efficiency and capacity retention rate after 100 cycles. The solvent may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and diethylene glycol dimethyl ether, which are advantageous in further improving the battery's coulombic efficiency and capacity retention rate after 100 cycles.

[0120] In some embodiments, the electrolyte solution further optionally contains additives. For example, the additives may include a negative electrode film-forming additive, a positive electrode film-forming additive, and may further include additives that can improve some battery performance, such as an additive that improves the overcharge performance of the battery, or an additive that improves the high-temperature or low-temperature performance of the battery.

[0121] In some embodiments, the electrolyte further comprises a sodium borate-based additive.

[0122] In some embodiments, the sodium borate-based additive comprises an ionic compound, the cation of the ionic compound comprises sodium ions, and the anion of the ionic compound comprises borate ions and derivatives thereof.

[0123] Sodium borate additives react with sodium metal to generate boron-rich inorganic compounds, thereby forming an interfacial protective layer and an organic / inorganic composite protective layer, which is beneficial for improving the cycle performance of batteries. At the same time, when SEI film damage occurs during battery cycling, sodium borate additives can continuously generate boron-rich inorganic compounds, repair the SEI film damage, and further improve the cycle performance of batteries.

[0124] In some embodiments, the sodium borate additive comprises one or more of sodium difluoro(oxalato)borate, sodium bis(oxalato)borate, and optionally sodium difluoro(oxalato)borate.

[0125] The electrolyte containing the sodium borate additive is advantageous in improving the battery's coulombic efficiency and capacity retention rate after 100 cycles, while the electrolyte containing sodium difluoro(oxalato)borate further improves the battery's coulombic efficiency and capacity retention rate after 100 cycles.

[0126] In some embodiments, the mass content of the sodium borate-based additive is 0.01% to 1.8%, and optionally 0.1% to 1.0%, based on the total mass of the electrolyte. In some embodiments, the mass content of the sodium borate-based additive is optionally 0.01%, 0.02%, 0.04%, 0.06%, 0.08%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.6%, or 1.8%, based on the total mass of the electrolyte.

[0127] Controlling the mass content of the sodium borate-based additive to 0.01% to 1% is advantageous for improving the battery's coulombic efficiency and capacity retention rate after 100 cycles. Controlling the mass content of the sodium borate-based additive to 0.1% to 0.5% can further improve the battery's coulombic efficiency and capacity retention rate after 100 cycles.

[0128] [Separator] In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of separator, and any known porous separator with good chemical stability and mechanical stability may be selected.

[0129] In some embodiments, the separator may be made of at least one of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, and natural fibers. The separator may be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, and are not particularly limited.

[0130] In some embodiments, the positive electrode plate, the negative electrode plate, and the separator may be wound or stacked to form an electrode assembly.

[0131] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and the electrolyte.

[0132] In some embodiments, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the secondary battery may be a pouch, such as a bag-shaped pouch. The pouch may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0133] [Secondary battery] The secondary battery includes an electrolyte and a negative electrode plate, which in some embodiments includes a current collector.

[0134] The present application does not particularly limit the shape of the secondary battery, which may be cylindrical, rectangular, or any other shape. For example, Figure 1 shows an example of a rectangular secondary battery 5.

[0135] In some embodiments, the secondary battery further comprises a positive electrode plate and a separator.

[0136] In some embodiments, the secondary battery includes at least one of a lithium battery and a sodium battery.

[0137] In some embodiments, the secondary battery includes at least one of a potassium battery, a magnesium battery, and a zinc battery.

[0138] In some embodiments, the secondary battery is a sodium battery without a negative electrode.

[0139] Anode-less sodium batteries contain no anode active material and only anode current collector. During the initial charge, sodium ions gain electrons at the cathode and deposit as metallic sodium on the current collector surface, forming a sodium metal phase. During discharge, the metallic sodium converts back to sodium ions and returns to the cathode, achieving cycle charging and discharging. Compared to sodium-ion secondary batteries and sodium metal batteries, anode-less sodium batteries are not limited by the anode material and can therefore achieve higher energy density.

[0140] In some embodiments, referring to FIG. 2 , the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and side plate together form a surrounding accommodating cavity. The case 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can be installed to cover the opening to seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged within the accommodating cavity. An electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and can be selected by those skilled in the art according to specific actual needs.

[0141] [Battery module] In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0142] Fig. 3 shows an example of a battery module 4. Referring to Fig. 3, in the battery module 4, a plurality of secondary batteries 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fixed by fasteners.

[0143] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of secondary batteries 5 are accommodated in this accommodating space.

[0144] [Battery pack] In some embodiments, the battery modules can be further assembled into a battery pack, and the number of battery modules included in the battery pack can be one or more, and the specific number can be selected by those skilled in the art depending on the application and capacity of the battery pack.

[0145] 4 and 5 show an example of a battery pack 1. Referring to FIGS. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 may be provided with a lid on the lower housing 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0146] [Power consumption equipment] In one embodiment of the present application, there is provided a power consuming device including at least one of the secondary battery of any of the embodiments, the battery module of any of the embodiments, or the battery pack of any of the embodiments.

[0147] The power consuming device includes at least one of a secondary battery, a battery module, or a battery pack according to the present application. The secondary battery, the battery module, or the battery pack may be used as a power source for the power consuming device or as an energy storage unit for the power consuming device. The power consuming 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, satellites, energy storage systems, etc.

[0148] The power consumption device can be selected from a secondary battery, a battery module, or a battery pack depending on its usage needs.

[0149] 6 shows an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the demand for high power output and high energy density of the secondary battery of the power consuming device, a battery pack or battery module can be employed.

[0150] Other examples of the device may include a mobile phone, a tablet computer, a laptop computer, etc. These devices are generally required to be thin and lightweight, and may use a secondary battery as a power source.

[0151] Example The following examples of the present application are described. The examples described below are illustrative and are used only to interpret the present application and should not be understood as limitations on the present application. Unless specific techniques or conditions are specified in the examples, they are carried out according to the techniques or conditions described in literature in the field or according to the product instructions. Unless the manufacturer is specified, the reagents or equipment used are all commercially available products.

[0152] 1. Manufacturing method Example 1 1) Manufacturing of current collectors 5 g of carboxymethyl cellulose (CMC) was weighed and added to deionized water, and the mixture was stirred to dissolve the carboxymethyl cellulose thoroughly. The solution was then applied to the surface of a copper foil, which was then transferred to a vacuum oven and dried completely to produce a current collector with an interface protection layer.

[0153] 2) Manufacturing of positive electrode plates 10 wt% of polyvinylidene fluoride adhesive was thoroughly dissolved in N-methylpyrrolidone (NMP), and 10 wt% of carbon black conductive agent and 80 wt% of positive electrode active material Na4Fe3(PO4)2P2O7 (NFPP) were added and stirred to mix uniformly to obtain positive electrode slurry. The positive electrode slurry was then uniformly applied to the surface of the positive electrode current collector copper foil, followed by drying, cold pressing, and cutting to obtain a positive electrode plate.

[0154] 3) Separator A polypropylene film was used as the separator.

[0155] 4) Electrolyte production In an argon atmosphere glove box (H2O<0.1 ppm, O2<0.1 ppm), sodium salt sodium hexafluorophosphate (NaPF6) was dissolved in ethylene glycol dimethyl ether (DME) organic solvent and stirred uniformly. Then sodium difluoro(oxalato)borate (NaDFOB) additive was added, where the concentration of NaPF6 was 1 mol / L. Calculated based on the total mass of the electrolyte, the weight content of sodium difluoro(oxalato)borate was 0.25%, i.e., the electrolyte solution of Example 1.

[0156] 5) Full battery manufacturing Manufacture of a complete battery without a negative electrode: The positive electrode plate, separator, and current collector are stacked in this order, and the separator is placed between the positive and negative current collectors to act as an insulator, then wound up to obtain a bare cell. Tabs are welded to the bare cell, and the bare cell is placed in an aluminum case and baked at 80°C to remove water. Then, electrolyte is injected and sealed to obtain an uncharged battery. The uncharged battery is then subjected to further processes such as standing, hot pressing, cold pressing, chemical formation, shaping, and capacity testing to obtain a sodium metal battery product without a negative electrode.

[0157] Fabrication of a metal negative electrode full battery: The current collector was placed in a physical vapor deposition apparatus, and a sodium metal phase was pre-deposited on the current collector by ion sputtering to obtain a metal negative electrode plate. The positive electrode plate, separator, and metal negative electrode plate were stacked in this order, with a separator positioned between the positive electrode plate and the metal negative electrode plate to serve as an insulator. Then, the stack was wound to obtain a bare cell. Tabs were welded to the bare cell, and the bare cell was placed in an aluminum case and baked at 80°C to remove water. The electrolyte was then injected and sealed to obtain an uncharged battery. The uncharged battery then underwent further processes, including standing, hot pressing, cold pressing, chemical formation, shaping, and capacity testing, to obtain a sodium metal battery product.

[0158] 6) Manufacture of button-type sodium batteries Manufacture of a button-type sodium battery without a negative electrode: The above current collector, separator, and sodium sheet are stacked in order, and a separator is placed between the negative current collector and the sodium sheet to act as an insulator. Then, electrolyte is injected, and the battery is sealed and assembled into a button-type battery.

[0159] Fabrication of a metal-negative button-type sodium battery: The current collector is placed in a physical vapor deposition device, and a sodium metal phase is pre-deposited on the current collector by ion sputtering to obtain a metal-negative electrode plate. The metal-negative electrode plate, separator, and sodium sheet are stacked in order, and a separator is placed between the metal-negative electrode plate and the sodium sheet to serve as an insulator. Then, the electrolyte is injected, sealed, and assembled into a button-type battery.

[0160] Examples 2 to 7 The batteries of Examples 2 to 7 were manufactured using a method similar to that of Example 1, but the thickness of the interface protection layer was adjusted.

[0161] The battery of Example 8 was manufactured in a similar manner to that of Example 1, but the manufacturing method of the current collector surface coating was adjusted. The specific manufacturing method is as follows:

[0162] 5 g of carboxymethyl cellulose (CMC) was weighed and added to deionized water, and the mixture was stirred to dissolve the carboxymethyl cellulose thoroughly. 5 g of single-walled carbon nanotubes were then added and ultrasonically dispersed to form a slurry. The slurry was then applied to the surface of a copper foil and then transferred to a vacuum oven to completely dry, resulting in a current collector with an inductive deposition layer.

[0163] 5 g of CMC was weighed and added to deionized water, and the mixture was stirred to fully dissolve the CMC. The solution was then applied to the surface of the dielectric deposition layer of the current collector having the dielectric deposition layer, and then transferred to a vacuum oven to completely dry, thereby obtaining a current collector having an interface protection layer and a dielectric deposition layer.

[0164] Examples 9 to 14 The batteries of Examples 9 to 14 were manufactured using a method similar to that of Example 8, but the thickness of the interface protection layer was adjusted.

[0165] Examples 15 to 20 The batteries of Examples 15 to 20 were manufactured in a similar manner to that of Example 8, but the thickness of the induction deposition layer was adjusted, and the specific parameters were as shown in Table 1.

[0166] Examples 21 to 24 The batteries of Examples 21 to 24 were manufactured in a similar manner to that of Example 8, but the types of components in the induction deposition layer were adjusted.

[0167] Examples 25 to 31 The batteries of Examples 25 to 31 were manufactured using a method similar to that of Example 8, but the content of the NaDFOB additive in the electrolyte was adjusted.

[0168] Examples 32 to 35 The batteries of Examples 32 to 35 were manufactured using a method similar to that of Example 8, but the types of components in the interface protective layer were adjusted.

[0169] Example 36 The battery of Example 36 is manufactured in a similar manner to that of Example 8, except that the adhesive of the induction deposition layer is adjusted to polyvinylidene fluoride, and the specific parameters are as shown in Table 1.

[0170] Example 37 The battery of Example 37 is manufactured in a similar manner to that of Example 36, except that the adhesive of the interface protection layer is adjusted to polyvinylidene fluoride, and the specific parameters are as shown in Table 1.

[0171] Example 38 The battery of Example 38 was manufactured in a similar manner to that of Example 8, but the type of additive in the electrolyte was adjusted. The specific parameters are as shown in Table 1.

[0172] Examples 39 to 41 The batteries of Examples 39 to 41 were manufactured using a method similar to that of Example 8, but the type of solvent in the electrolyte was adjusted.

[0173] Example 42 The battery of Example 42 is manufactured in a manner similar to that of Example 1, except that a metal layer is pre-deposited between the current collector and the interface protection layer, and the specific parameters are as shown in Table 1.

[0174] Comparative Example 1 The battery of Comparative Example 1 was manufactured using a method similar to that of Example 1, but no interface protection layer was provided on the current collector surface.

[0175] Comparative Example 2 The battery of Comparative Example 2 was manufactured in a similar manner to that of Comparative Example 1, but no additives were added to the electrolyte. The specific parameters are shown in Table 1.

[0176] Comparative Example 3 The battery of Comparative Example 3 was manufactured in a similar manner to that of Comparative Example 2, except that only an induction deposition layer was formed on the surface of the current collector. The specific parameters are shown in Table 1.

[0177] Comparative Example 4 The battery of Comparative Example 4 was manufactured using a method similar to that of Example 42, but no interface protection layer was provided on the surface. The specific parameters were as shown in Table 1.

[0178] 2. Performance test 1. Battery performance test 1) Overvoltage test The overvoltage test process is as follows: At 25°C, the button cell battery with the prepared negative electrode current collector sodium sheet is charged with 2 mA / cm 2 The battery was discharged to 1 mAh at a constant current of 1000 kJ / s, and the most negative potential obtained during the process was recorded as the overvoltage. The test process for the comparative example and other examples was the same as above.

[0179] 2) Initial coulombic efficiency test The initial coulombic efficiency test process is as follows: At 25°C, the prepared full battery is charged at a constant current of 1 / 3C to 3.7V, then charged at a constant voltage of 3.7V until the current drops to 0.05C to obtain the initial charge capacity (Cc1), and then discharged at a constant current of 1 / 3C to 2.5V to obtain the initial discharge capacity (Cd1), and the battery coulombic efficiency is calculated according to the following formula:

[0180] Coulomb efficiency = initial discharge capacity (Cd1) / initial charge capacity (Cc1) x 100% The test procedures for the comparative example and other examples were the same as those described above.

[0181] 3) Battery cycle capacity retention rate test The battery capacity retention test procedure is as follows: At 25°C, the fabricated full battery was charged at a constant current of 1C to 3.7V, then charged at a constant voltage of 3.7V until the current decreased to 0.05C, and then discharged at 1C to 2.5V. The resulting capacity was designated as the initial capacity (C0). The same battery was repeated, and the discharge capacity (Cn) of the battery after the nth cycle was recorded. The battery capacity retention after each cycle was calculated as Pn = Cn / C0 × 100%, with the 100 points (P1, P2...100) as the ordinate and the corresponding cycle number as the abscissa, to obtain a graph of battery capacity retention versus cycle number. In this test process, the first cycle corresponds to n=1, the second cycle corresponds to n=2, ... the 100th cycle corresponds to n=100, and the battery capacity retention rate data for the Examples or Comparative Examples in Table 2 is the data measured after 100 cycles under the above test conditions, i.e., the P100 value. The test process for the Comparative Examples and other Examples is the same as above.

[0182] 3. Analysis of the test results of each example and comparative example According to the above method, the batteries of each example and comparative example were manufactured, and the performance parameters of each item were measured. The results are shown in Tables 1 and 2 below.

[0183] [Table 1-1] [Table 1-2] [Table 1-3] [Table 1-4] [Table 1-5] [Table 1-6] [Table 1-7] [Table 1-8] [Table 1-9]

[0184] [Table 2-1] [Table 2-2]

[0185] As can be seen from the above results, the coatings in Examples 1 to 42 were formed on at least one side of the current collector and included an interface protection layer. Comparing Examples 1 to 41 with Comparative Examples 1, 42, and 4, it can be seen that the interface protection layer was formed as a coating on one side of the current collector copper foil, and the interface protection layer can reduce contact between sodium metal and the electrolyte, which is advantageous in reducing side reactions between sodium metal and the electrolyte, and effectively improves the coulombic efficiency of the battery and the capacity retention rate after 100 cycles.

[0186] As can be seen from the comparison between Examples 8 to 14 and Examples 1 to 7, compared with the coating containing only a carboxymethyl cellulose (CMC) interfacial protection layer, the coating further contains a carbon nanotube-induced deposition layer, and the carbon nanotube-induced deposition layer is located between the current collector copper foil and the carboxymethyl cellulose (CMC) interfacial protection layer, which is more advantageous in reducing the nucleation overvoltage of sodium ions, further improving the battery's Coulomb efficiency and capacity retention rate after 100 cycles. The reduction in the nucleation overvoltage of sodium ions is more than 90% (reduction = (Examples 1 to 7) and the amplification of the Coulombic efficiency and the capacity retention rate after 100 cycles exceeds 20% (taking the method of calculating the amplification of the Coulombic efficiency as an example: amplification = (minimum Coulombic efficiency in Examples 8 to 14 - maximum Coulombic efficiency in Examples 1 to 7) / (minimum Coulombic efficiency in Examples 1 to 7) × 100%, where the Coulombic efficiency is the same as the method of calculating the amplification of the capacity retention rate after 100 cycles), thereby significantly improving the cycle performance and safety of the battery.

[0187] As can be seen from a comparison of Examples 1, 3 to 6 with Examples 2 and 7, and Examples 8, 10 to 13 with Examples 9 and 14, controlling the thickness of the carboxymethyl cellulose (CMC) interfacial protection layer to 15 to 1500 nm is advantageous in improving the battery's Coulombic efficiency and capacity retention rate after 100 cycles or in reducing the nucleation overvoltage of sodium ions. As can be seen from a comparison of Examples 1, 4 to 5 with Examples 3 and 6, and Examples 8, 11 to 12 with Examples 10 and 13, controlling the thickness of the carboxymethyl cellulose (CMC) interfacial protection layer to 50 to 500 nm is advantageous in further improving the battery's Coulombic efficiency and capacity retention rate after 100 cycles or in reducing the nucleation overvoltage of sodium ions.

[0188] As can be seen from a comparison between Examples 8, 16-19 and Examples 15 and 20, controlling the thickness of the carbon nanotube-induced deposition layer to 50-2000 nm can provide sufficient nucleation sites, which is beneficial for reducing the nucleation overvoltage of sodium ions, improving the battery's Coulombic efficiency and capacity retention rate after 100 cycles, with the reduction in the nucleation overvoltage of sodium ions exceeding 46%. As can be seen from a comparison between Examples 8, 17-18 and Examples 16 and 19, controlling the thickness of the carbon nanotube-induced deposition layer to 200-1000 nm can more significantly reduce the nucleation overvoltage of sodium ions, which is beneficial for further improving the battery's Coulombic efficiency and capacity retention rate after 100 cycles.

[0189] As can be seen from a comparison between Examples 8, 21-24 and Comparative Example 1, the deposition-induced deposition layer containing carbon nanotubes, Super P, graphene, metallic silver, or a Super P-carbon nanotube mixture can effectively reduce the nucleation overpotential of sodium ions and improve the battery's Coulombic efficiency and capacity retention rate after 100 cycles. As can be seen from a comparison between Examples 8, 21-22, and 24 and Example 23, compared with a deposition layer containing only a metal material, the deposition layer containing a carbon material has a lower sodium ion nucleation overpotential and a higher battery Coulombic efficiency and capacity retention rate after 100 cycles. As can be seen from a comparison between Examples 8, 24 and Example 22, compared with a graphene-induced deposition layer, the carbon nanotube-induced deposition layer or Super P-carbon nanotube-induced deposition layer can further reduce the nucleation overpotential of sodium ions and more significantly improve the battery's Coulombic efficiency and capacity retention rate after 100 cycles.

[0190] As can be seen from a comparison between Examples 8, 21 to 24 and Comparative Example 1, the deposition-induced deposition layer contains carbon nanotubes, Super P, graphene, metallic silver, or a Super P-carbon nanotube mixture, and in combination with the addition of sodium difluoro(oxalato)borate (NaDFOB) additive to the electrolyte, this is advantageous in further improving the coulombic efficiency of the battery and the capacity retention rate after 100 cycles.

[0191] As can be seen from a comparison between Examples 8, 26-30 and Examples 25 and 31, controlling the mass content of sodium difluoro(oxalato)borate (NaDFOB) additive in the electrolyte solution to 0.01%-1.8% based on the total mass of the electrolyte is advantageous for improving the capacity retention rate of the battery after 100 cycles. As can be seen from a comparison between Examples 8, 27-28 and Examples 26 and 30, controlling the mass content of sodium difluoro(oxalato)borate (NaDFOB) additive in the electrolyte solution to 0.1%-1.0% based on the total mass of the electrolyte can further improve the coulombic efficiency of the battery and the capacity retention rate after 100 cycles.

[0192] A comparison of Examples 8, 32-35 with Comparative Example 3 shows that an interface protection layer containing carboxymethyl cellulose (CMC), polyacrylic acid (AA), polyvinylidene fluoride (PVDF), styrene-butadiene (SBR), or polyimide (PI) is beneficial in improving the battery's Coulombic efficiency and capacity retention after 100 cycles, with increases in both the battery's Coulombic efficiency and capacity retention after 100 cycles exceeding 63%. A comparison of Examples 8, 33 with Examples 32, 34-35 shows that, compared with an interface protection layer containing polyacrylic acid (AA), styrene-butadiene (SBR), or polyimide (PI), an interface protection layer containing carboxymethyl cellulose (CMC) or polyvinylidene fluoride (PVDF) significantly reduces the nucleation overpotential of sodium ions, further improving the battery's Coulombic efficiency and capacity retention after 100 cycles.

[0193] As can be seen from a comparison of Example 8 with Examples 32 to 35, Example 37 and Example 36, controlling the material of the interface protection layer and the adhesive material in the guided deposition layer to be at least partially the same is advantageous in reducing the nucleation overpotential of sodium ions and improving the battery's coulombic efficiency and capacity retention rate after 100 cycles.

[0194] As can be seen from the comparison between Examples 8 and 38 and Example 25, the electrolyte containing sodium difluoro(oxalato)borate or sodium bis(oxalato)borate is advantageous in improving the battery's coulombic efficiency and capacity retention rate after 100 cycles. As can be seen from the comparison between Examples 8 and 38, compared with the electrolyte containing sodium bis(oxalato)borate, the electrolyte containing sodium difluoro(oxalato)borate has better battery coulombic efficiency and capacity retention rate after 100 cycles.

[0195] As can be seen from a comparison between Examples 8, 39 to 41 and Comparative Example 3, the electrolyte solution containing ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, or tetrahydrofuran is advantageous in reducing the overvoltage of sodium ions and improving the battery's Coulombic efficiency and capacity retention rate after 100 cycles. As can be seen from a comparison between Examples 8, 39 to 40 and Example 41, compared to an electrolyte solution containing tetrahydrofuran, an electrolyte solution containing ethylene glycol dimethyl ether, ethylene glycol diethyl ether, or diethylene glycol dimethyl ether is advantageous in further improving the battery's Coulombic efficiency and capacity retention rate after 100 cycles.

[0196] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea and achieves the same effects within the scope of the technical solution of the present application is included within the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the embodiments without departing from the spirit of the present application, and other methods constructed by combining some of the components of the embodiments, are also included within the scope of the present application. [Explanation of symbols]

[0197] 1: battery pack, 2: upper housing, 3: lower housing, 4: battery module, 5: secondary battery, 51: case, 52: electrode assembly, 53: cover plate.

Claims

1. A current collector having a coating, the coating including at least an interface protection layer, the coating being formed on at least one side of the current collector.

2. 2. The current collector according to claim 1, wherein the coating further comprises an induction deposition layer, and the induction deposition layer and the interface protection layer are disposed in this order in a direction from a side closest to the current collector to a side away from the current collector.

3. 3. The current collector of claim 2, wherein the induction deposition layer is in direct contact with the current collector surface.

4. 4. The current collector according to claim 2, wherein the interface protection layer is in direct contact with the surface of the induction deposition layer.

5. The current collector according to any one of claims 1 to 4, wherein the interface protection layer contains one or more of polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene copolymer, polyacrylic acid, and polyimide, and optionally contains one or more of polyvinylidene fluoride and carboxymethyl cellulose.

6. 6. The current collector according to claim 1, wherein the thickness of the interface protection layer is 15 nm to 1500 nm, and optionally 50 nm to 500 nm.

7. 7. The current collector according to claim 2, wherein the induction deposition layer comprises a conductive material comprising a carbon material and / or a metallic material.

8. 8. The current collector according to claim 2, wherein the conductive material comprises one or more of superconducting carbon black, carbon nanotubes, hard carbon, two-dimensional graphene, graphene quantum dots, gold, silver, copper, aluminum, iron, and nickel, and optionally comprises one or more of Super P, carbon nanotubes, hard carbon, two-dimensional graphene, and graphene quantum dots.

9. 9. The current collector according to claim 2, wherein the thickness of the induction deposition layer is between 50 nm and 2000 nm, and optionally between 200 nm and 1000 nm.

10. 10. The current collector according to claim 2, wherein the induction deposition layer further comprises an adhesive comprising one or more selected from polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene copolymer, polyacrylic acid, and sodium alginate.

11. 11. The current collector according to claim 2, wherein the adhesive material in the induction deposition layer is at least partially the same as the material of the interface protection layer.

12. 12. The current collector according to claim 1, wherein the current collector comprises at least one of a metal foil material, a metal foam current collector, a metal mesh current collector, a carbon felt current collector, a carbon cloth current collector, a carbon paper current collector, and a composite current collector.

13. A secondary battery comprising an electrolyte and a negative electrode plate, the negative electrode plate comprising the current collector according to claim 1 .

14. 14. The secondary battery according to claim 13, wherein the secondary battery includes at least one of a lithium battery and a sodium battery.

15. 15. The secondary battery according to claim 13, wherein the secondary battery is a sodium battery without a negative electrode.

16. 16. The secondary battery according to claim 13, wherein the electrolytic solution contains an ether-based solvent, and the ether-based solvent contains one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, and crown ether, and optionally contains one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and diethylene glycol dimethyl ether.

17. 17. The secondary battery according to claim 13, wherein the electrolyte solution further contains a sodium borate-based additive.

18. 18. The secondary battery of claim 17, wherein the sodium borate-based additive comprises one or more of sodium difluoro(oxalato)borate and sodium bis(oxalato)borate, and optionally comprises sodium difluoro(oxalato)borate.

19. 19. The secondary battery according to claim 17 or 18, wherein the mass content of the sodium borate-based additive is 0.01% to 1.8%, and optionally 0.1% to 1.0%, based on the total mass of the electrolyte solution.

20. A battery module comprising the secondary battery according to any one of claims 13 to 19.

21. A battery pack comprising the secondary battery according to any one of claims 13 to 19 or the battery module according to claim 20.

22. 22. A power consuming device comprising at least one selected from the group consisting of the secondary battery according to claim 13, the battery module according to claim 20, and the battery pack according to claim 21.

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