Coating, coating composition, secondary battery and electronic device

Abstract

A coating, a coating composition, a secondary battery, and an electronic device. The coating composition comprises a melamine compound and a binder. The melamine compound comprises a melamine cyanurate, and simultaneously satisfies relational expressions: 1.8≤K1 / K2≤3, 0.18≤K2 / K3≤0.5, and K3≥K1≥K2, where K1 is the highest peak intensity of a melamine compound 110 crystal plane, K2 is the peak intensity of a melamine compound 200 crystal plane, and K3 is the peak intensity of a melamine compound 202 crystal plane.

Description

Coatings, coating compositions, secondary batteries and electronic devices

[0001] This application claims priority to Chinese Patent Application No. 202411484011.1, filed on October 23, 2024, entitled "Coating, Coating Composition, Secondary Battery and Electronic Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of electrochemical energy storage, and more particularly to a coating, a coating composition, a secondary battery, and an electronic device. Background Technology

[0003] In existing technologies, materials such as alumina, boehmite, barium sulfate, and magnesium oxide are commonly used to make the coating of the separator. However, these materials are all inactive materials, which have poor ability to stabilize the battery cell, resulting in poor thermal stability and cycle stability of the battery cell. Summary of the Invention

[0004] In view of this, this application provides a coating, a coating composition, a secondary battery, and an electronic device.

[0005] The first aspect of this application provides a coating composition comprising a melamine compound, the melamine compound comprising melamine cyanurate, the melamine compound simultaneously satisfying the following relationships: 1.8≤K1 / K2≤3.0, 0.18≤K2 / K3≤0.5, K3≥K1≥K2.

[0006] In the X-ray diffraction pattern of the melamine compound, K1 is the peak intensity of the melamine compound 110 crystal plane, K2 is the peak intensity of the melamine compound 200 crystal plane, and K3 is the peak intensity of the melamine compound 202 crystal plane.

[0007] This application controls the relationship between the peak intensity K1 of melamine compound 110, the peak intensity K2 of melamine compound 200, and the peak intensity K3 of melamine compound 202, giving the melamine compounds a special crystal orientation characteristic. Using these melamine compounds to create coatings can reduce the thermal shrinkage of the separator at high temperatures and lower the impedance of the secondary battery. When the relationship between K1, K2, and K3 satisfies 1.8≤K1 / K2≤3.0, 0.18≤K2 / K3≤0.5, and K3≥K1≥K2, the morphology of the melamine compounds tends towards a plate-like crystal structure. The melamine compounds have small particle size, large specific surface area, and large thermally stable area, which is beneficial for improving the thermal shrinkage resistance of the separator or electrode and reducing the impedance of the secondary battery, thereby improving the high-temperature storage performance, thermal stability, and cycle performance of the secondary battery.

[0008] Based on the first aspect, in some embodiments, the melamine compound satisfies 1.9 ≤ K1 / K2 ≤ 2.7. Satisfying this condition is beneficial for further improving the heat shrinkage resistance of the separator or electrode and reducing the impedance of the secondary battery, thereby further improving the high-temperature storage performance, thermal stability and cycle performance of the secondary battery.

[0009] Based on the first aspect, in some embodiments, the melamine compound satisfies 0.2 ≤ K2 / K3 ≤ 0.5. Meeting this condition is beneficial for further improving the heat shrinkage resistance of the separator or electrode and reducing the impedance of the secondary battery, thereby further improving the high-temperature storage performance, thermal stability, and cycle performance of the secondary battery.

[0010] Based on the first aspect, in some embodiments, K1-D is the lowest peak of the melamine compound 110 crystal plane in the X-ray diffraction pattern, the peak shape of K1-D is lattice distorted, the 2θ diffraction angle of K1-D is 10.5°±0.5°, the 2θ diffraction angle of the peak corresponding to K1 is 10.9°±0.5°, the 2θ diffraction angle of the peak corresponding to K2 is 11.8°±0.5°, and the 2θ diffraction angle of the peak corresponding to K3 is 28.0°±0.5°.

[0011] Based on the first aspect, in some embodiments, the residual amount of melamine monomer W1 in the melamine compound is ≤1 wt%, the residual amount of cyanuric acid monomer W2 in the melamine compound is ≤1 wt%, and the residual amounts of melamine monomer W1 and cyanuric acid monomer W2 in the melamine compound are not simultaneously 0. Controlling the residual amounts of melamine monomer and cyanuric acid monomer in the melamine compound within the above range can improve the adhesion of the coating and improve the cycle performance of the secondary battery.

[0012] Based on the first aspect, in some embodiments, the pH of the aqueous solution of the melamine compound is 5 ≤ ​​pH ≤ 6.5, wherein the water content in the aqueous solution of the melamine compound is 90 wt%, and the melamine compound content is 10 wt%. Controlling the pH of the aqueous solution of the melamine compound within the above range can improve the adhesion of the coating and enhance the cycle performance of the secondary battery.

[0013] Based on the first aspect, in some embodiments, the primary particle size D50 of the melamine compound is 0.3–1.5 μm. Controlling the primary particle size D50 of the melamine compound within this range reduces the likelihood of the melamine compound clogging the gaps in the separator, thereby reducing the degradation of the secondary battery's impedance and improving the secondary battery's high-temperature storage performance, thermal stability, and cycle performance.

[0014] Based on the first aspect, in some embodiments, the primary particle size D50 of the melamine compound is 0.4–1.0 μm. Meeting this condition can further improve the impedance of the secondary battery, as well as its high-temperature storage performance, thermal stability, and cycle performance.

[0015] Based on the first aspect, in some embodiments, the primary particle size D90 of the melamine compound is 0.6–3 μm. A primary particle size D90 within this range allows for controlled coating thickness and uniform application, reducing the impedance of the secondary battery and thereby improving its high-temperature storage performance, thermal stability, and cycle performance.

[0016] Based on the first aspect, in some embodiments, the mass ratio of melamine compound to binder is (90-95):(5-10). Controlling the mass ratio of melamine compound to binder within this range effectively ensures the adhesion of the coating while reducing the impedance of the secondary battery, thereby improving the thermal stability and cycle performance of the secondary battery.

[0017] A second aspect of this application provides a coating comprising the coating composition described above.

[0018] Based on the second aspect, in some embodiments, the coating thickness is 0.8–3.5 μm. A coating thickness within this range is beneficial for reducing the impedance of the secondary battery, thereby improving its thermal stability and cycle performance.

[0019] Based on the second aspect, in some embodiments, the coating thickness is 1.0–3 μm. A coating thickness within this range is beneficial for further reducing the impedance of the secondary battery, thereby further improving the thermal stability and cycle performance of the secondary battery.

[0020] A third aspect of this application provides a secondary battery, including the above-described coating, positive electrode, separator, and electrolyte, wherein the coating is disposed on at least one surface of the positive electrode or separator.

[0021] Based on the third aspect, in some embodiments, the electrolyte contains 1,3-propanesulfonate lactone and fluoroethylene carbonate. The presence of 1,3-propanesulfonate lactone and fluoroethylene carbonate in the electrolyte can synergistically stabilize the anode of the secondary battery, reduce the impedance of the secondary battery, and thus improve the thermal stability and cycle performance of the secondary battery.

[0022] Based on the third aspect, in some embodiments, the sum of the percentages of 1,3-propanesulfonate lactone and fluoroethylene carbonate in the electrolyte is 0.1% to 5% of the total mass of the electrolyte. Controlling the sum of the percentages of 1,3-propanesulfonate lactone and fluoroethylene carbonate within this range helps to reduce impedance and improve the thermal stability and cycle performance of the secondary battery.

[0023] A fourth aspect of this application provides an electronic device including the aforementioned secondary battery. The secondary battery powers the electronic device and exhibits good thermal stability and cycling performance after high-temperature storage performance testing, high-temperature cycling performance testing, and hot box testing. Attached Figure Description

[0024] Figure 1 is an X-ray diffraction pattern of melamine cyanurate provided in Examples 1-3 of this application.

[0025] Figure 2 is an X-ray diffraction pattern of melamine cyanurate provided in Comparative Examples 1-2 of this application. Detailed Implementation

[0026] The embodiments of this application are described in detail below. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. The reagents and materials used in the following embodiments are all commercially available.

[0027] As used in this application, the terms “comprising,” “containing,” and “including” are used in their open, non-restrictive sense.

[0028] Additionally, quantities, ratios, and other numerical values ​​are sometimes presented in range format in this document. It should be understood that such range format is for convenience and brevity and should be interpreted flexibly to include not only the numerical values ​​explicitly specified as range limits, but also all individual numerical values ​​or subranges covered within the range, as if each numerical value and subrange were explicitly specified.

[0029] In the detailed description and claims, a list of items connected by the terms "one or more of," "one or more of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A or B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, or C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0030] This application provides a coating composition comprising a melamine compound and an adhesive. The melamine compound includes melamine cyanurate, and the melamine compound simultaneously satisfies the following relationships: 1.8 ≤ K1 / K2 ≤ 3.0, 0.18 ≤ K2 / K3 ≤ 0.5, K3 ≥ K1 ≥ K2.

[0031] In the X-ray diffraction pattern of the melamine compound, K1 is the peak intensity of the melamine compound 110 crystal plane, K2 is the peak intensity of the melamine compound 200 crystal plane, and K3 is the peak intensity of the melamine compound 202 crystal plane.

[0032] This application controls the relationship between the peak intensity K1 of melamine compound 110, the peak intensity K2 of melamine compound 200, and the peak intensity K3 of melamine compound 202, giving the melamine compounds a special crystal orientation characteristic. Using these melamine compounds to create coatings can reduce the thermal shrinkage of the separator at high temperatures and lower the impedance of the secondary battery. When the relationship between K1, K2, and K3 satisfies 1.8≤K1 / K2≤3.0, 0.18≤K2 / K3≤0.5, and K3≥K1≥K2, the morphology of the melamine compounds tends towards a plate-like crystal structure. The melamine compounds have small particle size, large specific surface area, and large thermally stable area, which is beneficial for improving the thermal shrinkage resistance of the separator or electrode and reducing the impedance of the secondary battery, thereby improving the high-temperature storage performance, thermal stability, and cycle performance of the secondary battery. If the relationship between K1, K2, and K3 does not satisfy 1.8≤K1 / K2≤3.0, 0.18≤K2 / K3≤0.5, and K3≥K1≥K2, the morphology of the melamine compound will be rod-shaped or irregular granular, instead of plate-shaped crystals. Using this morphology of melamine compound to prepare coatings will result in poor coating uniformity, which will have a negative impact on the high-temperature storage performance, thermal stability, and cycle performance of secondary batteries.

[0033] In some embodiments, the value of K1 / K2 can be 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, or any value within the range of any two of the above values. The value of K2 / K3 can be 0.18, 0.20, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, or any value within the range of any two of the above values.

[0034] In some embodiments, the melamine compound satisfies 1.9 ≤ K1 / K2 ≤ 2.7. For example, the value of K1 / K2 can be 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, or any value within the range of any two of the above values. Meeting this condition is beneficial for further improving the heat shrinkage resistance of the separator or electrode and reducing the impedance of the secondary battery, thereby further improving the high-temperature storage performance, thermal stability, and cycle performance of the secondary battery.

[0035] In some embodiments, the melamine compound satisfies 0.2 ≤ K2 / K3 ≤ 0.5. For example, the value of K2 / K3 can be 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, or any value within the range of any two of the above values. Meeting this condition is beneficial for further improving the heat shrinkage resistance of the separator or electrode and reducing the impedance of the secondary battery, thereby further improving the high-temperature storage performance, thermal stability, and cycle performance of the secondary battery.

[0036] Based on the first aspect, in some embodiments, K1-D is the lowest peak of the melamine compound 110 crystal plane in the X-ray diffraction pattern. The peak shape of K1-D undergoes lattice distortion deformation. The 2θ diffraction angle of K1-D is located at 10.5°±0.5°, the 2θ diffraction angle of the peak corresponding to K1 is located at 10.9°±0.5°, the 2θ diffraction angle of the peak corresponding to K2 is located at 11.8°±0.5°, and the 2θ diffraction peak of the peak corresponding to K3 is located at 28.0°±0.5°.

[0037] In some embodiments, the residual amount of melamine monomer W1 in the melamine compound is ≤1 wt%, the residual amount of cyanuric acid monomer W2 in the melamine compound is ≤1 wt%, and the residual amounts of melamine monomer W1 and cyanuric acid monomer W2 in the melamine compound are not simultaneously 0. Controlling the residual amounts of melamine monomer and cyanuric acid monomer in the melamine compound within the above range can improve the adhesion of the coating and improve the cycle performance of the secondary battery.

[0038] In some embodiments, the residual amount W1 of melamine monomer in the melamine compound can be 0 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, or any value within the range of any two of the above values. The residual amount W2 of cyanuric acid monomer in the melamine compound can be 0 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, or any value within the range of any two of the above values. However, the residual amount W1 of melamine monomer and the residual amount W2 of cyanuric acid monomer in the melamine compound are not both 0.

[0039] In some embodiments, the pH of the aqueous solution of the melamine compound is 5 ≤ ​​pH ≤ 6.5. For example, the pH of the aqueous solution of the melamine compound is 5, 5.3, 5.5, 5.8, 6.0, 6.3, 6.5, or any value within the range of any two of the above values. The aqueous solution of the melamine compound contains 90 wt% water and 10 wt% melamine compound. Controlling the pH of the aqueous solution of the melamine compound within the above range can improve the adhesion of the coating and enhance the cycle performance of the secondary battery.

[0040] In some embodiments, the primary particle size D50 of the melamine compound is 0.3–1.5 μm, for example, the primary particle size D50 of the melamine compound is 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, or any value within the range of any two of the above values. Controlling the primary particle size D50 of the melamine compound within this range makes it less likely for the melamine compound to clog the pores of the separator or positive electrode, thereby reducing the degradation of the secondary battery's impedance and improving the high-temperature storage performance, thermal stability, and cycle performance of the secondary battery.

[0041] In this application, "primary particle size D50" refers to the particle size of the melamine compound when the cumulative particle size distribution percentage reaches 50% before the particles agglomerate. The primary particle size D50 of the melamine compound in aqueous solution is measured using a laser particle size analyzer.

[0042] In some embodiments, the primary particle size D50 of the melamine compound is 0.4–1.0 μm, for example, the primary particle size D50 of the melamine compound is 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, or any value within the range of any two of the above values. Meeting this condition can further improve the impedance of the secondary battery, thereby improving the high-temperature storage performance, thermal stability, and cycle stability of the secondary battery.

[0043] In some embodiments, the primary particle size D90 of the melamine compound is 0.6–3 μm, for example, 0.6 μm, 0.8 μm, 1.0 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3 μm, or any value within the range of any two of the above values. Controlling the primary particle size D90 of the melamine compound within this range allows for controlled coating thickness and uniform application, reducing the impedance of the secondary battery and thereby improving its high-temperature storage performance, thermal stability, and cycle performance.

[0044] In this application, "primary particle size D90" refers to the particle size of the melamine compound when the cumulative particle size distribution percentage reaches 90% before the particles agglomerate. The primary particle size D90 of the melamine compound in aqueous solution is measured using a laser particle size analyzer.

[0045] In some embodiments, the mass ratio of melamine compound to binder is (90-95):(5-10), for example, 90:10, 91:9, 92:8, 93:7, 94:6, 95:5, or any value within the range of any two of the above values. Controlling the mass ratio of melamine compound to binder within this range effectively ensures the adhesion of the coating while reducing the impedance of the secondary battery, thereby improving the thermal stability and cycle performance of the secondary battery.

[0046] In some embodiments, the type of adhesive includes, but is not limited to, at least one of styrene-butadiene rubber, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, styrene-acrylate copolymer, styrene-butadiene copolymer, polyamide, polyacrylonitrile, polystyrene, polyvinyl alcohol, polyhexanediol, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinyl acetate, polyvinylpyrrolidone, polyvinyl ether, polytetrafluoroethylene, or polyhexafluoropropylene.

[0047] This application also provides a coating comprising the above-described coating composition. The coating can be formed by applying and drying the coating composition.

[0048] In some embodiments, the coating thickness is 0.8–3.5 μm, for example, a coating thickness of 0.8 μm, 1.0 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2.0 μm, 2.2 μm, 2.4 μm, 2.8 μm, 3.0 μm, 3.2 μm, 3.4 μm, 3.5 μm, or any value within the range of any two of the above values. A coating thickness within this range is beneficial for reducing the impedance of the secondary battery, thereby improving the thermal stability and cycle performance of the secondary battery.

[0049] In some embodiments, the coating thickness is 1.0–3.0 μm, for example, 1.0 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2.0 μm, 2.2 μm, 2.4 μm, 2.8 μm, 3.0 μm, or any value within the range of any two of the above values. A coating thickness within this range is beneficial for further reducing the impedance of the secondary battery, thereby further improving the thermal stability and cycle performance of the secondary battery.

[0050] This application also provides a secondary battery, including the above-described coating, positive electrode, separator, and electrolyte, wherein the coating is disposed on at least one surface of the positive electrode or separator.

[0051] In some embodiments, the positive electrode includes a positive current collector and a positive active material layer disposed on the positive current collector. The positive active material layer may include a positive active material (positive electrode material) and may be located on one surface or two opposing surfaces of the positive current collector. In some embodiments, the positive current collector may be aluminum foil, or other positive current collectors commonly used in the art may be used. In some embodiments, the thickness of the positive current collector may be from 1 μm to 200 μm. In some embodiments, the positive active material layer may be coated only on a portion of the positive current collector. In some embodiments, the thickness of the positive active material layer may be from 10 μm to 500 μm. It should be understood that these are merely exemplary, and other suitable thicknesses may be used.

[0052] In some embodiments, the coating is located on one surface or two opposing surfaces of the positive electrode. In some embodiments, the coating is located on the surface of the positive electrode active material layer opposite to the positive electrode current collector.

[0053] In some embodiments, the positive electrode active material layer includes a positive electrode active material. In some embodiments, the positive electrode active material may include at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or lithium nickel manganese oxide, and the above positive electrode active materials may be doped and / or coated.

[0054] In some embodiments, the positive electrode active material layer further includes a positive electrode binder and a positive electrode conductive agent. In some embodiments, the positive electrode binder may include at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, styrene-acrylate copolymer, styrene-butadiene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinyl acetate, polyvinylpyrrolidone, polyvinyl ether, polytetrafluoroethylene, or polyhexafluoropropylene. In some embodiments, the positive electrode conductive agent may include at least one of conductive carbon black, acetylene black, Ketjen black, graphene, carbon nanotubes, or carbon fibers.

[0055] The material and shape of the separator used in the secondary battery of this application are not particularly limited, and can be any technology disclosed in the prior art. In some embodiments, the separator comprises a polymer or inorganic material formed of a material stable to the electrolyte of this application.

[0056] In some embodiments, the separator may include a substrate layer and a surface treatment layer. The substrate layer is a nonwoven fabric, membrane, or composite membrane with a porous structure, and the material of the substrate layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate, and polyimide. Specifically, a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite membrane may be selected.

[0057] A surface treatment layer is disposed on at least one surface of the substrate layer. The surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by a mixture of polymer and inorganic material. The inorganic layer includes inorganic particles and a binder. The inorganic particles are selected from at least one of alumina, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate. The binder is selected from at least one of polyvinylidene fluoride, a copolymer of polyvinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl alkoxy, polymethyl methacrylate, polytetrafluoroethylene, and polyhexafluoropropylene. The polymer layer contains a polymer, and the polymer material is selected from at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl alkoxy, polyvinylidene fluoride, and poly(vinylidene fluoride-hexafluoropropylene).

[0058] In some embodiments, the coating is located on one surface or two opposing surfaces of the release membrane. In some embodiments, the coating is located on the surface of the surface treatment layer opposite to the substrate layer.

[0059] In some embodiments, the electrolyte of the secondary battery includes a lithium salt and a non-aqueous solvent. This application does not impose any particular limitation on the lithium salt, as long as it achieves the purpose of this application. For example, the lithium salt may include, but is not limited to, at least one of LiPF6, LiBF4, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, Li2SiF6, lithium bis(oxalato)borate (LiBOB), or lithium difluoroborate. This application does not impose any particular limitation on the content of the lithium salt in the electrolyte, as long as it achieves the purpose of this application. For example, based on the mass of the electrolyte, the mass percentage of the lithium salt is 5% to 23%, for example, the concentration of the lithium salt in the electrolyte may be 5%, 8%, 12%, 16%, 20%, 23%, or a range consisting of any two of the above values.

[0060] In some embodiments, the electrolyte includes 1,3-propanesulfonate lactone and fluoroethylene carbonate. The presence of 1,3-propanesulfonate lactone and fluoroethylene carbonate in the electrolyte can synergistically stabilize the anode of the secondary battery, reduce the impedance of the secondary battery, and thus improve the thermal stability and cycle performance of the secondary battery.

[0061] In some embodiments, the sum of the percentages of 1,3-propanesulfonate lactone and fluoroethylene carbonate in the electrolyte is 0.1% to 5% of the total mass of the electrolyte. For example, it can be a range consisting of any two of the above values: 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5%. Controlling the sum of the percentages of 1,3-propanesulfonate lactone and fluoroethylene carbonate within this range helps to reduce impedance and improve the thermal stability and cycle performance of the secondary battery.

[0062] In some embodiments, the secondary battery further includes a negative electrode sheet, which includes a negative current collector and a negative electrode material layer disposed on the negative current collector. The negative electrode material layer includes at least one of natural graphite, artificial graphite, or a silicon-based material. In some embodiments, the silicon-based material includes at least one of silicon, silicon oxide, silicon carbide, or silicon alloy.

[0063] The negative electrode current collector can be at least one of copper foil, nickel foil, stainless steel foil, titanium foil or carbon-based current collector, or any composite current collector disclosed in the prior art, or a current collector formed by combining the aforementioned conductive foil and polymer substrate in some optional embodiments, but not limited to.

[0064] The negative electrode material layer also includes a binder to bond the negative electrode active material particles, thereby facilitating the formation of the film layer and improving the bonding force between the negative electrode material layer and the negative electrode current collector. In some embodiments, the binder may include, but is not limited to, polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, or nylon, etc.

[0065] The negative electrode material layer may further include a conductive material, which includes, but is not limited to, carbon-based materials, metal-based materials, conductive polymers, or any combination thereof. In some embodiments, carbon-based materials may include, but are not limited to, natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof. In some embodiments, metal-based materials may include, but are not limited to, metal powder or metal fibers, and in some optional embodiments, copper, nickel, aluminum, or silver. In some embodiments, the conductive polymer may be a polyphenylene derivative.

[0066] The negative electrode material layer may also include a dispersant, which may include at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, carboxymethyl cellulose, lithium hydroxypropyl carboxymethyl cellulose, sodium hydroxypropyl carboxymethyl cellulose, lithium hydroxyethyl carboxymethyl cellulose, sodium hydroxyethyl carboxymethyl cellulose, or hydroxyethyl carboxymethyl cellulose.

[0067] In some embodiments, the secondary battery is a lithium-ion battery, but this application is not limited thereto.

[0068] In some embodiments of this application, taking a lithium-ion battery as an example, the positive electrode sheet, the separator, and the negative electrode sheet are wound or stacked in sequence to form an electrode assembly, which is then encapsulated in a housing such as an aluminum-plastic film, injected with electrolyte, formed, and encapsulated to produce a lithium-ion battery.

[0069] Embodiments of this application also provide electronic devices including the aforementioned secondary batteries. The secondary batteries power the electronic devices and exhibit good high-temperature storage performance, thermal stability, and cycle performance after high-temperature storage performance testing, high-temperature cycling performance testing, and hot box testing. The electronic devices may include, but are not limited to, laptops, pen-based computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and lithium-ion capacitors, etc.

[0070] The present application will be described below through specific embodiments and comparative examples. Those skilled in the art should understand that the preparation methods described in this application are merely examples, and any other suitable preparation methods are within the scope of this application.

[0071] Preparation of melamine compounds

[0072] The preparation methods of the melamine compounds in Examples 1-2 to 1-14 are as follows: based on the preparation method of the melamine compound in Example 1-1, the amounts of crystal growth factor and cyanuric acid are adjusted. Examples 1-2 to 1-7 are based on Example 1-1, with adjustments made to the amount of crystal growth factor, ranging from 0.05 to 0.5 parts. Examples 1-8 to 1-14 are based on adjusting the amount of cyanuric acid added in the third batch, ranging from 1.01 to 1.1 parts.

[0073] The preparation method of the melamine compound in Comparative Example 1-1 is as follows: Based on the preparation method of Example 1-1, the amount of crystal growth factor used is 0.6 parts.

[0074] The preparation methods of the melamine compounds in Comparative Examples 1-2 are as follows:

[0075] Based on the preparation method in Example 1-1, the amount of crystal growth factor used was 0 parts.

[0076] The preparation methods of the melamine compounds in Comparative Examples 1-3 are as follows:

[0077] Based on the preparation method in Example 1-1, the amount of crystal growth factor used is 0.03 parts.

[0078] Comparative Examples 1-4 used alumina instead of melamine compounds.

[0079] Example 1-1

[0080] Preparation of melamine compounds

[0081] Five parts of the 1,3,5-triazine-2,4,6-triamine compound were placed in a 5-liter stirrer equipped with a mechanical stirrer, thermometer, and cooler. 20 parts of water were added, the stirrer was started, and the mixture was heated to 90°C and stirred at 300 rpm for 2 hours to obtain a 1,3,5-triazine-2,4,6-triamine solution. The pH of the 1,3,5-triazine-2,4,6-triamine solution was adjusted to 9–10 using sodium hydroxide. Then, 0.1 parts of crystal growth factor (referring to melamine cyanurate seed crystals with a particle size of 1–40 nanometers) were added to the 1,3,5-triazine-2,4,6-triamine solution.

[0082] The mixture was stirred at 500 rpm for 10 minutes. Then, cyanuric acid was added in three batches to the 1,3,5-triazine-2,4,6-triamine solution in the following order: 2 parts cyanuric acid, 2 parts cyanuric acid, and 1.1 parts cyanuric acid. The temperature was maintained at 110°C, and the mixture was stirred continuously for 2 hours to obtain a viscous white paste. This paste was then vacuum filtered, washed, and dried. Finally, the product was subjected to ultrafine pulverization to obtain melamine cyanurate.

[0083] Preparation of lithium-ion batteries

[0084] (1) Preparation of positive electrode sheet

[0085] Lithium cobalt oxide (positive electrode active material), conductive carbon black (conductive agent), and polyvinylidene fluoride (binder) were added to N-methylpyrrolidone in a weight ratio of 96:2.5:1.5 and stirred evenly to form a positive electrode slurry. The positive electrode slurry was uniformly coated on one side of the aluminum foil of the positive electrode current collector and dried. The above steps were repeated on the other side of the aluminum foil to obtain a positive electrode sheet with a positive electrode active layer on both sides. After cold pressing and cutting, the positive electrode sheet was obtained.

[0086] (2) Preparation of negative electrode sheet

[0087] Artificial graphite (anode active material), sodium carboxymethyl cellulose (dispersant), and styrene-butadiene rubber (binder) are added to deionized water in a weight ratio of 96:2:2 and stirred evenly to form a negative electrode slurry. The negative electrode slurry is then uniformly coated onto one side of a copper foil current collector and dried. The above steps are repeated on the other side of the copper foil to obtain a negative electrode sheet with a negative electrode active layer on both sides. After cold pressing and cutting, the negative electrode sheet is obtained.

[0088] (3) Preparation of composite separator membrane

[0089] A polyethylene porous membrane with a thickness of 5μm and a porosity of 55% was selected as the substrate layer of the composite isolation membrane.

[0090] The prepared melamine cyanurate was tested, and the residual amounts of melamine monomer (W1) and cyanurate monomer (W2) were measured to be 0.1. The pH of its aqueous solution was measured to be 5.5. The residual amounts of melamine monomer (W1), cyanurate monomer (W2), and its aqueous solution pH are affected by the ratio of 1,3,5-triazine-2,4,6-triamine compound and cyanuric acid. By adjusting the ratio of melamine monomer and cyanuric acid, different residual amounts of melamine monomer (W1), cyanurate monomer (W2), and their aqueous solutions pH can be obtained.

[0091] In a dispersion tank, melamine cyanurate and styrene-butadiene rubber binder were added at a mass ratio of 93 parts:7 parts, followed by 400 parts of deionized water. The mixture was dispersed and mixed evenly to obtain a coating slurry. The coating slurry was then applied to one surface of the substrate layer using a gravure roller transfer coating method. After drying in an oven, the coating composition on the substrate layer had a coating thickness of 2 μm. The film was then wound up to obtain a composite release film.

[0092] (4) Preparation of electrolyte

[0093] In an argon-filled glove box, first add 3.5% succinate and 85% chain carbonate (EP:EMC:DEC:PP mass ratio of 15:20:20:45) of the total electrolyte. In addition, weigh out 0.15% 1,3-propanesulfonate lactone and fluoroethylene carbonate, with the remainder being lithium salt LiPF6.

[0094] (5) Assembly

[0095] The prepared positive electrode, composite separator, and negative electrode are stacked in sequence, with the composite separator positioned between the positive and negative electrode to obtain a stacked electrode assembly. After welding the tabs, the electrode assembly is placed in an aluminum-plastic film packaging bag, heat-sealed around the perimeter, leaving an injection port for the electrolyte. The electrolyte is then injected, and after vacuum sealing, settling, formation, and degassing processes, a lithium-ion battery is obtained.

[0096] Coating composition characteristic testing

[0097] (1) Values ​​of K1, K2, and K3

[0098] Equal amounts of melamine compounds from each example and comparative example were placed in an X-ray powder diffractometer (DBAdvance 250 in-situ X-ray powder diffractometer) and scanned to obtain X-ray diffraction patterns. In the X-ray diffraction patterns, K1 is the peak intensity of the melamine compound 110 crystal plane, K2 is the peak intensity of the melamine compound 200 crystal plane, and K3 is the peak intensity of the melamine compound 202 crystal plane. The values ​​of K1, K2, and K3 were read from the X-ray diffraction patterns, and the values ​​of K1 / K2 and K2 / K3 were calculated.

[0099] (2) The residual amounts of melamine monomer W1 and cyanuric acid monomer W2 in melamine compounds

[0100] The precipitation method was used to test the melamine compound M1. A certain mass of melamine compound M1 was dispersed in water, filtered to obtain a solution, cyanuric acid solution was added, and the mixture was heated to react and generate a poorly soluble melamine precipitate. The precipitate was filtered, dried, and weighed as M2. W1 = (M1-M2) / M1×100%.

[0101] The precipitation method was used to test the melamine compound M1. A certain mass of melamine compound M1 was dispersed in water, filtered to obtain a solution, melamine solution was added, and the reaction was heated to generate a poorly soluble melamine precipitate. The precipitate was obtained by suction filtration, dried and weighed as M3. W2 = (M1-M3) / M1×100%.

[0102] (3) pH of melamine compound aqueous solution

[0103] The aqueous solution of melamine compound contained 90 wt% water and 10 wt% melamine compound. The pH value of the aqueous solution of melamine compound was measured using a pH meter.

[0104] (4) Primary particle size D50, primary particle size D90

[0105] Take 1g of melamine compound sample and disperse it in 40g of aqueous solution. Add 1-2 drops of 0.5wt% sodium hexametaphosphate dispersant, sonicate for 10min, and then place it in a laser particle size analyzer to test the values ​​of the first particle size D50 and the first particle size D90.

[0106] Coating performance test

[0107] (1) Resistance to heat shrinkage

[0108] The composite separator was cut into square pieces and precisely measured using a microscope. The length of the stretched separator in the MD (longitudinal) direction was A0, and the length of the stretched separator in the TD (transverse) direction was B0, where both A0 and B0 were 30 mm long. The composite separator was then placed in a 130°C constant temperature chamber for 1 hour. The length A1 and width B1 of the separator were then measured using a microscope. The heat shrinkage resistance of the composite separator was obtained using the following formula: Heat shrinkage resistance = (A1 / A0 + B1 / B0) / 2 * 100%.

[0109] (2) Adhesion test

[0110] Disassemble a fully charged lithium-ion battery, remove the composite structure of coating plus base film or coating plus positive electrode, cut it into strips 5cm long and 15mm wide, and test the tensile force in a universal tensile testing machine using a 180° method. Test the tensile force of 3 strips in each test group, and then take the average value of the three test data.

[0111] Lithium-ion battery performance testing

[0112] (1) Impedance

[0113] The lithium-ion battery was placed in a 25°C constant temperature chamber and left to stand for 10 minutes. It was then charged at a constant current rate of 1C to 4.5V, and charged at a constant voltage of 4.5V to 0.05C. After standing for 10 minutes, the DC impedance of the lithium-ion battery under full charge was measured.

[0114] (2) Thickness expansion rate at 85℃

[0115] A lithium-ion battery was charged at 25°C to 4.5V. The thickness of the battery was then measured using a panel pressure gap (PPG) thickness gauge. This initial thickness, H0, was defined as the initial thickness of the lithium-ion battery. The battery was then stored in an 85°C constant temperature chamber for 24 hours, and the thickness was measured again using the same method. This final thickness, H1, was defined as the thickness of the battery after storage. The thickness expansion rate at 85°C was calculated as (H1 - H0) / H0 × 100%.

[0116] The lower the thickness expansion rate at 85℃, the better the high-temperature storage performance of the battery.

[0117] (3) Hot box pass rate test

[0118] The lithium-ion batteries in each embodiment and comparative example were charged at room temperature with a constant current at a 1C rate to a full charge voltage of 4.5V. They were then charged further at a constant voltage of 4.5V until a cutoff current of 0.05C was reached, ensuring they were fully charged. The appearance was inspected to ensure the lithium-ion batteries were in normal working order. The fully charged lithium-ion batteries were then placed in an oven and heated at a rate of 5°C / min until the designated oven test temperature was reached. This temperature was maintained for one hour, during which time the state of the lithium-ion batteries was observed.

[0119] Judgment criteria: The battery does not catch fire or explode, meaning the battery passes the test temperature.

[0120] Increase the temperature by 1°C from the initial test temperature, obtain a new lithium-ion battery, and repeat the test until the lithium-ion battery can no longer pass the test temperature. This gives the highest acceptable thermal chamber test temperature for a fully charged battery. The higher the acceptable thermal chamber test temperature, the better the battery's thermal stability.

[0121] (4) Capacity retention rate during 45℃ cycling

[0122] First, in an environment of 45℃, the initial charge and discharge were performed. First, a constant current charge of 1C was used to charge to 4.5V, followed by a constant voltage charge to 0.05C. Then, a constant current discharge was performed at 0.5C to 3.0V. This charge-discharge cycle was repeated, and the discharge capacity of the 3rd cycle and the 400th cycle were recorded.

[0123] 45℃ cycle capacity retention rate = (discharge capacity of the 400th cycle / discharge capacity of the 3rd cycle) × 100%.

[0124] A higher 45℃ cycle capacity retention rate indicates better cycle performance of the battery.

[0125] Test results:

[0126] Figure 1 shows the X-ray diffraction patterns of melamine cyanurate provided in Examples 1-3. From Figure 1, it can be seen that the K1 value of melamine cyanurate prepared in Examples 1-3 is 19700, the K2 value is 7000, and the K3 value is 30500. At the 110 crystal plane, there is also a low peak K1-D, the 2θ diffraction angle of which is 10.5°. The 2θ diffraction angle of the peak corresponding to K1 is 10.9°, the 2θ diffraction angle of the peak corresponding to K2 is 11.8°, and the 2θ diffraction angle of the peak corresponding to K3 is 28.0°.

[0127] The X-ray diffraction patterns of the melamine compounds in the other embodiments are similar to those in Figure 1. The 2θ diffraction angles of the peaks corresponding to K1 are all at 10.9°, those corresponding to K2 are all at 11.8°, and those corresponding to K3 are all at 28.0°. There is also a K1-D peak on the 110 crystal plane, but the peak height of the K1-D peak is lower than that of the peak corresponding to K1. The peak shape of the K1-D peak is lattice-distorted, and the 2θ diffraction angle of the K1-D peak is all at 10.5°.

[0128] Figure 2 shows the X-ray diffraction patterns of melamine cyanurate provided in Comparative Examples 1-2. As can be seen from Figure 2, the K1 value of melamine cyanurate in Comparative Examples 1-2 is 49000, the K2 value is 30000, and the K3 value is 37500. Furthermore, its X-ray diffraction pattern shows no K1-D peaks on the 110 crystal plane.

[0129] Examples 1-3

[0130] The only difference between the preparation methods of Examples 1-3 and Example 1-1 is that the amount of crystal growth factor used in the preparation method of the melamine compound in Examples 1-3 is 0.08 parts, and the rest is the same as in Example 1-1.

[0131] Examples 1-2, Examples 1-4 to Examples 1-7

[0132] The amount of crystal growth factor was adjusted to adjust the K1, K2, K3, D50 and D90 of the corresponding melamine compound, and the relevant parameters in Tables 1 and 2 were obtained. The rest were the same as in Examples 1-3.

[0133] Comparative Examples 1-1 to 1-3

[0134] The amount of crystal growth factor was adjusted to adjust the K1, K2, K3, D50 and D90 of the corresponding melamine compound, and the relevant parameters in Tables 1 and 2 were obtained. The rest were the same as in Examples 1-3.

[0135] Comparative Examples 1-4

[0136] The melamine compound in Example 1-1 was replaced with alumina, and the rest was the same as in Example 1-1.

[0137] Examples 1-8 to Examples 1-14

[0138] The amount of cyanuric acid was adjusted to adjust the residual amount of melamine monomer W1, the residual amount of cyanuric acid monomer W2, and the pH of the aqueous solution of the corresponding melamine compound, and the relevant parameters in Table 3 were obtained. The rest were the same as in Examples 1-3.

[0139] Examples 1-15 to Examples 1-22

[0140] The coating thickness of the coating composition on the substrate layer was adjusted to obtain the relevant parameters in Table 4. The rest were the same as in Examples 1-3.

[0141] Examples 1-23 to 1-26 adjusted the mass ratio of melamine compound and adhesive to obtain the relevant parameters in Table 5, and the rest were the same as in Examples 1-3.

[0142] Example 2-1

[0143] The difference between Example 2-1 and Example 1-3 is that the coating composition of Example 2-1 is coated on one surface of the positive electrode, and the total percentage of 1,3-propanesulfonate lactone and fluoroethylene carbonate in the electrolyte of Example 2-1 is 0.1 wt%.

[0144] Examples 2-2 to 2-8

[0145] The combined percentage of 1,3-propanesulfonate lactone and fluoroethylene carbonate in the electrolyte was adjusted to obtain the relevant parameters in Table 6. The rest were the same as in Examples 1-3.

[0146] Comparative Example 2-1

[0147] The only difference between Comparative Example 2-1 and Examples 1-3 is that no coating composition was applied to the substrate layer of Comparative Example 2-1, while the rest was the same as Examples 1-3.

[0148] Table 1

[0149] Table 2

[0150] In Tables 1 and 2 above, compared to Comparative Examples 1-1 to 1-3, in Examples 1-1 to 1-7, when the K1 / K2, K2 / K3, D50, and D90 values ​​of the melamine compound are within a suitable range, the heat shrinkage resistance of the separator is improved, the impedance of the lithium-ion battery is reduced, and consequently, the thickness expansion rate of the lithium-ion battery at 85°C is reduced, the hot box test pass temperature is improved, and the 45°C cycle capacity retention rate is increased. Therefore, the high-temperature storage performance, thermal stability, and high-temperature cycle performance of the lithium-ion battery are improved. In particular, when 1.9 ≤ K1 / K2 ≤ 2.7 and / or 0.2 ≤ K2 / K3 ≤ 0.5, the impedance of the lithium-ion battery is further reduced, and the heat shrinkage resistance of the separator of the lithium-ion battery is improved. Consequently, the high-temperature storage performance, thermal stability, and cycle performance of the lithium-ion battery are further improved.

[0151] Table 3

[0152] In Table 3 above, in Examples 1-3 and Examples 1-8 to Examples 1-14, when the residual amount of melamine monomer W1, the residual amount of cyanuric acid monomer W2 and / or the pH of the aqueous solution of melamine compound are within a suitable range, it is beneficial to improve the adhesion of the coating and the capacity retention rate during 45°C cycling.

[0153] Table 4

[0154] In Table 4 above, in Examples 1-3 and Examples 1-15 to Examples 1-22, the thickness of the coating was adjusted. When the thickness of the coating is within a suitable range, it is beneficial to improve the thermal box test pass temperature and the 45°C cycle capacity retention rate of the lithium-ion battery, that is, to improve the thermal stability and cycle stability of the lithium-ion battery.

[0155] Table 5

[0156] In Table 5 above, in Examples 1-3 and Examples 1-22 to 1-26, the mass ratio of melamine compound to binder was adjusted. When the mass ratio of melamine compound to binder is within a suitable range, it is beneficial to improve the adhesion of the coating, reduce the impedance of the lithium-ion battery, and improve the thermal stability and cycle performance of the lithium-ion battery.

[0157] Table 6

[0158] In Table 6 above, in Examples 1-3 and Examples 2-1 to 2-8, adjusting the sum of the percentages of 1,3-propanesulfonate lactone and fluoroethylene carbonate helps to reduce the impedance of lithium-ion batteries and improve their thermal stability and cycle stability.

[0159] Compared with Example 2-3, the lithium-ion battery with the coating composition coated on the separator surface of Comparative Example 2-1 has lower impedance, better thermal stability and cycle stability.

[0160] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. A coating composition, characterized in that, Including melamine compounds and adhesives, The melamine compound includes melamine cyanurate. The melamine compound simultaneously satisfies the following relationship: 1.8≤K1 / K2≤3.0 0.18≤K2 / K3≤0.5 K3≥K1≥K2, In the X-ray diffraction pattern of the melamine compound, K1 is the peak intensity of the melamine compound 110 crystal plane, K2 is the peak intensity of the melamine compound 200 crystal plane, and K3 is the peak intensity of the melamine compound 202 crystal plane.

2. The coating composition according to claim 1, characterized in that, The melamine compound satisfies at least one of the following conditions: (1) 1.9 ≤ K1 / K2 ≤ 2.7; (2) 0.2 ≤ K2 / K3 ≤ 0.5; (3) K1-D is the lowest peak of the melamine compound 110 crystal plane. The peak shape of K1-D is lattice distorted. The 2θ diffraction angle of K1-D is 10.5°±0.5°. The 2θ diffraction angle of the peak corresponding to K1 is 10.9°±0.5°. The 2θ diffraction angle of the peak corresponding to K2 is 11.8°±0.5°. The 2θ diffraction angle of the peak corresponding to K3 is 28.0°±0.5°.

3. The coating composition according to claim 1 or 2, characterized in that, The residual amount of melamine monomer W1 in the melamine compound is ≤1 wt%, the residual amount of cyanuric acid monomer W2 in the melamine compound is ≤1 wt%, and the residual amounts of melamine monomer W1 and cyanuric acid monomer W2 in the melamine compound are not both 0.

4. The coating composition according to any one of claims 1-3, characterized in that, The aqueous solution of the melamine compound has a pH of 5 ≤ pH ≤ 6.5, wherein the aqueous solution of the melamine compound contains 90 wt% water and 10 wt% melamine compound.

5. The coating composition according to any one of claims 1-4, characterized in that, The primary particle size D50 of the melamine compound is 0.3–1.5 μm.

6. The coating composition according to any one of claims 1-5, characterized in that, The primary particle size D50 of the melamine compound is 0.4–1.0 μm.

7. The coating composition according to any one of claims 1-6, characterized in that, The primary particle size D90 of the melamine compound is 0.6–3.0 μm.

8. The coating composition according to any one of claims 1-7, characterized in that, The mass ratio of the melamine compound to the adhesive is (90-95):(5-10).

9. A coating, characterized in that, The coating comprises the coating composition according to any one of claims 1-8.

10. The coating as claimed in claim 9, characterized in that, The thickness of the coating is 0.8 to 3.5 μm.

11. The coating as claimed in claim 9 or 10, characterized in that, The thickness of the coating is 1.0 to 3.0 μm.

12. A secondary battery, characterized in that, The secondary battery includes the coating, positive electrode, separator, and electrolyte as described in claim 9, wherein the coating is disposed on at least one surface of the positive electrode or the separator.

13. The secondary battery according to claim 12, characterized in that, The electrolyte contains 1,3-propanesulfonate lactone and fluoroethylene carbonate.

14. The secondary battery according to claim 12 or 13, characterized in that, The sum of the percentages of 1,3-propanesulfonate lactone and fluoroethylene carbonate in the electrolyte is 0.1% to 5% of the total mass of the electrolyte.

15. An electronic device comprising the secondary battery as described in any one of claims 12-14.

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