Positive electrode material and preparation method and application thereof

Abstract

The invention belongs to the technical field of batteries, and particularly relates to a positive electrode material and a preparation method and application thereof. The positive electrode material comprises the following raw materials in parts by mass: 100 parts of a positive electrode active material, 0.1-60 parts of a fluorine source and 0.1-60 parts of a boron source. The positive electrode material has the beneficial effects that the interface compatibility of the positive electrode material and the sulfide electrolyte under a high-voltage condition is improved, the oxygenolysis of the sulfide electrolyte is inhibited, and the advantage of high specific energy of the high-voltage positive electrode material in the sulfide solid-state battery is fully exerted.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and in particular relates to a positive electrode material and a preparation method and application thereof. Background Art

[0002] Sulfide solid-state batteries are regarded as an important direction for the development of next-generation high-energy-density secondary batteries due to their advantages such as high ionic conductivity, high energy density, high safety, and long life. The positive electrode material is a key component that determines the energy of the battery. Promoting the application of high-voltage positive electrode materials in sulfide solid-state batteries is of great significance for the development of high-energy-density solid-state batteries. However, the serious interfacial side reactions between sulfide electrolytes and high-voltage positive electrode materials are the decisive factors restricting the development of high-voltage sulfide solid-state batteries. Therefore, the development of a positive electrode coating that can achieve interface compatibility between high-voltage positive electrode materials and sulfide electrolytes is an urgent need to promote the large-scale development of high-voltage solid-state batteries.

[0003] The prior art discloses a sulfide all-solid-state battery based on positive electrode coating and a preparation method thereof, which uses B2O3, H2BO3 or boron powder to mechanically mix and heat-treat the ternary positive electrode NCM811 to obtain a surface boron-coated NCM811 positive electrode material, effectively inhibiting the interface reaction between the positive electrode material and the sulfide electrolyte, and significantly improving its first coulomb efficiency and cycle life in the sulfide solid-state battery. However, in the preparation method, the boron source and the positive electrode material are both in the solid phase, and the uniform dispersion and full contact of the boron source and the positive electrode material cannot be guaranteed; the applicable positive electrode material is single and has poor universality; in addition, high-energy mechanical ball milling and heat treatment are required during preparation, and ball milling may cause particle crushing of commercial polycrystalline positive electrode materials; because its heat treatment temperature is as high as 500°C, it may cause an increase in cation mixing in the NCM811 material; the preparation method does not pay attention to the interface compatibility and reversible capacity of the boron-coated NCM811 positive electrode when matching the sulfide solid electrolyte under high voltage conditions above 4.2V. The prior art also discloses a ternary composite positive electrode material, a preparation method thereof, and an application in solid-state batteries. A layer of polymer and nano-oxide particles are coated on the surface of the ternary positive electrode by a liquid phase method, which effectively enhances the interfacial stability between the ternary positive electrode and the sulfide electrolyte, and inhibits the contact failure between the positive electrode / electrolyte caused by the volume deformation of the positive electrode. However, the preparation method is relatively complicated and not easy to scale up. The organic solvent used is not recycled, resulting in waste liquid. Its universality also needs to be further verified. In addition, the preparation method does not pay attention to the applicability of the polymer and nano-oxide particle coating layer in high-voltage solid-state batteries above 4.3V.

[0004] The existing positive electrode material surface coating technology has the following shortcomings: cumbersome preparation process, uncontrollable coating uniformity, single applicable positive electrode material type, high voltage sulfide solid-state battery performance needs to be investigated, heat treatment conditions may destroy the positive electrode material structure or the preparation method is not environmentally friendly, which greatly limits the large-scale application of high voltage positive electrode materials in sulfide solid-state batteries. Therefore, developing a green and environmentally friendly positive electrode material modification method with simple preparation process, strong universality, and enhanced high voltage performance of sulfide solid-state batteries is of great significance to accelerate the development of the next generation of high specific energy sulfide solid-state batteries. Summary of the invention

[0005] The present application provides a positive electrode material and a preparation method and application thereof, aiming to solve the problems of the prior art positive electrode material surface coating process being cumbersome, the coating layer uniformity being uncontrollable, the coating method having relatively single applicability and environmental problems.

[0006] In a first aspect, the present application provides a positive electrode material, comprising the following raw materials in parts by mass: 100 parts of positive electrode active material, 0.1-60 parts of fluorine source, and 0.1-60 parts of boron source.

[0007] According to some embodiments of the positive electrode material described in the present application, the chemical formula of the positive electrode active material includes Li x M y O2, Na a M b O2 and MF c One or more of; wherein, 0<x<2, 0<y≤1, 0<a<2, 0<b≤1, 1≤c≤7, M includes but is not limited to one or more of Co, Mn, Ni, Nb, Fe, Li, Cu and Bi.

[0008] According to some embodiments of the positive electrode material described in the present application, the positive electrode active material is not limited to LiCoO2, LiMn2O4, LiMn 1.5 Ni 0.5 O4, LiNiO2, LiNi 0.9 Mn 0.05 Co 0.05 O2、LiNi 0.8 Mn 0.1 Co 0.1 O2、LiNi 1 / 3Mn 1 / 3 Co 1 / 3 O2, Li2MnO3, Li 1.2 Mn 0.6 Ni 0.2 O2、Li 1.2 Mn 0.6 Nb 0.2 O2、NaNi 0.5 Mn0.5 O2、NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2、Na 0.75 [Li 0.25 Mn 0.75 ]O2、Na 0.67 Mn 0.67 Ni 0.33 O2、Na 0.6 [Li 0.2 Mn 0.8 ]One or more of ]O2, Na2Mn3O7, CuF3, FeF3, NiF2, BiF3 and CoF3.

[0009] According to some embodiments of the positive electrode material described in the present application, the fluorine source includes but is not limited to one or more of lithium difluorophosphate, sodium difluorophosphate, lithium hexafluorophosphate, sodium hexafluorophosphate, lithium difluorooxalatoborate, sodium difluorooxalatoborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate, sodium trifluoromethanesulfonate, lithium difluorobis(oxalatophosphate) and sodium bis(trifluoromethylsulfonyl)imide.

[0010] According to some embodiments of the positive electrode material described in the present application, the boron source includes but is not limited to one or more of lithium bis(oxalatoborate), sodium bis(oxalatoborate), lithium tetrafluoroborate, sodium tetrafluoroborate, lithium difluorooxalatoborate and sodium difluorooxalatoborate.

[0011] According to some embodiments of the positive electrode material described in the present application, the positive electrode material includes the following raw materials in parts by mass: 100 parts of positive electrode active material, 0.5-10 parts of fluorine source, and 0.5-10 parts of boron source.

[0012] According to some embodiments of the positive electrode material described in the present application, the molar ratio of the fluorine source to the boron source is 100:(1-95); preferably, the molar ratio of the fluorine source to the boron source is 100:(30-60).

[0013] The present application also provides a method for preparing the positive electrode material according to the first aspect of the present application, comprising the following steps:

[0014] (1) mixing a fluorine source, a boron source, a positive electrode active material and an organic solvent to obtain a mixed solution;

[0015] (2) distilling the mixed solution to remove the organic solvent to obtain a positive electrode material precursor;

[0016] (3) heat-treating the positive electrode material precursor to obtain the positive electrode material.

[0017] According to some embodiments of the positive electrode material preparation method described in the present application, the organic solvent includes but is not limited to one or more of ethanol, ethylene glycol, isopropanol, n-butanol, n-hexanol, ethyl acetate, butyl acetate, propyl propionate, dimethyl carbonate, propylene carbonate and diphenyl carbonate.

[0018] According to some embodiments of the positive electrode material preparation method described in the present application, the mass ratio of the organic solvent to the positive electrode active material is (1-50):1.

[0019] According to some embodiments of the positive electrode material preparation method described in the present application, the temperature of the heat treatment is 50-500° C., and the time of the heat treatment is 0.5 h-10 h.

[0020] According to some embodiments of the method for preparing the positive electrode material described in the present application, the temperature of the heat treatment is 80-200°C.

[0021] According to some embodiments of the method for preparing the positive electrode material described in the present application, the heat treatment is performed under an inert or vacuum atmosphere.

[0022] The third aspect of the present application provides a composite positive electrode material, including the positive electrode material described in the first aspect of the present application or the positive electrode material obtained by the preparation method described in the second aspect of the present application.

[0023] According to some embodiments of the composite cathode material described in the present application, the composite cathode material further includes a solid electrolyte and a conductive agent.

[0024] According to some embodiments of the composite cathode material described in the present application, the solid electrolyte includes a sulfide electrolyte.

[0025] According to some embodiments of the composite cathode material described in the present application, the chemical formula of the solid electrolyte includes Li x N y S z and / or Na x N y S z , wherein the relationship between x, y and z satisfies x+ny-2z=0, n is the valence state of N, and N includes but is not limited to one or more of P, Cl, Br, I, Mn, Mo, Si, Ge, Sn, Al, As, C, B, O, H and Sb.

[0026] According to some embodiments of the composite cathode material described in the present application, the solid electrolyte includes Li6PS5Cl, Li6PS5Br, Li6PS5I, Li7P3S 11 、Li7P 2.9 Mn 0.1 S 10.7 I 0.3、Li7P 2.9 S 10.85 Mo 0.01 , Li 6.35 P 0.65 Si 0.35 S5Br、Li 6.35 P 0.65 Si 0.35 S5Br、Li 6.6 P 0.4 Ge 0.6 S5I、Li 3.25 Ge 0.25 P 0.75 S4, Li7PS6, Li7Ge3PS 12 、Li4GeS4、Li4SnS4、Li 11 AlP2S 12 , Li 3.833 Sn 0.833 As 0.166 S4, Li 10 GeP2S 12 , Li 10 SnP2S 12 , Li 10 SiP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , 80Li2S·20P2S5, 75Li2S·25P2S5, 70Li2S·30P2S5, 60Li2S·40P2S5, 67Li2S·33P2S5, 55(66Li2S·33P2S5)·45LiI, 95(60Li2S·40SiS2)·5Li3BO3(Li3AlO3), 77(75Li2S·25P2S5)·33LiBH4, 40Li2S·28SiS2·30LiI, 30Li2S·26B2S3·33LiI, β-Li3PS4–LZNO, β-Li3PS4–Al2O3, β-Li3PS4–SiO2, β-Li3PS4–LLZO, Na3PS4, Na3BS3 and Na3SbS4.

[0027] According to some embodiments of the composite positive electrode material described in the present application, the conductive agent includes one or more of Supper P, carbon fiber conductive agent VGCF, carbon nanotube conductive agent and Ketjen black.

[0028] The fourth aspect of the present application provides a battery, comprising the composite positive electrode material described in the third aspect of the present application.

[0029] According to some embodiments of the battery described in the present application, the battery includes a sulfide solid-state lithium battery or a sulfide solid-state sodium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The first charge and discharge specific capacity-voltage curve of the solid-state lithium battery assembled with the positive electrode materials described in Example 3 and Comparative Example 4 of the present application;

[0031] Figure 2 The first charge and discharge specific capacity-voltage curve of the solid-state lithium battery assembled with the positive electrode material described in Example 14 of the present application;

[0032] Figure 3 The first charge and discharge specific capacity-voltage curve of the solid-state lithium battery assembled with the positive electrode material described in Example 15 of the present application;

[0033] Figure 4 This is a graph showing the first charge and discharge specific capacity-voltage curve of a solid-state lithium battery assembled from the positive electrode material described in Example 16 of the present application. DETAILED DESCRIPTION

[0034] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0035] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0036] The embodiment of the present application provides a positive electrode material, comprising the following raw materials in parts by mass: 100 parts of positive electrode active material, 0.1-60 parts of fluorine source, and 0.1-60 parts of boron source.

[0037] The dual modification of the positive electrode surface with fluorine and boron significantly enhances the interfacial stability between high-voltage positive electrode materials (such as layered high-nickel ternary, lithium cobalt oxide, lithium-rich manganese-based, sodium nickel manganese oxygen positive electrodes) and sulfide solid electrolytes, allowing the high specific energy advantage of high-voltage positive electrode materials to be fully utilized in sulfide solid-state batteries.

[0038] The positive electrode material described in the present application improves the interfacial compatibility between the positive electrode material and the sulfide electrolyte under high voltage conditions, inhibits the oxidative decomposition of the sulfide electrolyte, and gives full play to the high specific energy advantage of the high voltage positive electrode material in the sulfide solid-state battery.

[0039] In some embodiments of the present application, the positive electrode material includes the following raw materials in parts by mass: 100 parts of positive electrode active material, 1-50 parts of fluorine source, and 0.8-55 parts of boron source.

[0040] In some embodiments of the present application, the positive electrode material includes the following raw materials in parts by mass: 100 parts of positive electrode active material, 5-30 parts of fluorine source, and 5-30 parts of boron source.

[0041] In some embodiments of the present application, the positive electrode material includes the following raw materials in parts by mass: 100 parts of positive electrode active material, 10-20 parts of fluorine source, and 10-20 parts of boron source.

[0042] In some embodiments of the present application, the chemical formula of the positive electrode active material includes Li x M y O2, Na a M b O2 and MF c One or more of; wherein, 0<x<2, 0<y≤1, 0<a<2, 0<b≤1, 1≤c≤7, M includes but is not limited to one or more of Co, Mn, Ni, Nb, Fe, Li, Cu and Bi.

[0043] In some embodiments of the present application, the positive electrode active material includes but is not limited to LiCoO2, LiMn2O4, LiMn 1.5 Ni 0.5 O4, LiNiO2, LiNi 0.9 Mn 0.05 Co 0.05 O2、LiNi 0.8 Mn 0.1 Co 0.1 O2、LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, Li2MnO3, Li 1.2 Mn 0.6 Ni 0.2 O2、Li 1.2 Mn 0.6 Nb 0.2 O2、NaNi 0.5 Mn 0.5 O2、NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2、Na 0.75 [Li0.25 Mn 0.75 ]O2、Na 0.67 Mn 0.67 Ni 0.33 O2、Na 0.6 [Li 0.2 Mn 0.8 ]One or more of ]O2, Na2Mn3O7, CuF3, FeF3, NiF2, BiF3 and CoF3.

[0044] In some embodiments of the present application, the fluorine source includes but is not limited to one or more of lithium difluorophosphate, sodium difluorophosphate, lithium hexafluorophosphate, sodium hexafluorophosphate, lithium difluorooxalate borate, sodium difluorooxalate borate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate, sodium trifluoromethanesulfonate, lithium difluorobis(oxalate phosphate) and sodium bis(trifluoromethanesulfonyl)imide. The fluorine source described in the present application is easily soluble in an organic solvent and can be directly purchased from the market or synthesized using a disclosed preparation method.

[0045] In some embodiments of the present application, the boron source includes but is not limited to one or more of lithium bis(oxalatoborate), sodium bis(oxalatoborate), lithium tetrafluoroborate, sodium tetrafluoroborate, lithium difluorooxalatoborate and sodium difluorooxalatoborate.

[0046] In some embodiments of the present application, the positive electrode material includes the following raw materials in parts by mass: 100 parts of positive electrode active material, 0.5-10 parts of fluorine source, and 0.5-10 parts of boron source. Within this ratio range, the thickness of the surface modification layer of the obtained positive electrode material is appropriate, and the electrochemical performance of the obtained solid-state battery is optimal.

[0047] In some embodiments of the present application, the molar ratio of the fluorine source to the boron source is 100:(1-95), for example, 100:1, 100:5, 100:10, 100:30, 100:50, 100:65, 100:80, 100:90, 100:95, etc.

[0048] In some embodiments of the present application, the molar ratio of the fluorine source to the boron source is 100:(30-60).

[0049] The present application also provides a method for preparing the positive electrode material according to the first aspect of the present application, comprising the following steps:

[0050] (1) mixing a fluorine source, a boron source, a positive electrode active material and an organic solvent to obtain a mixed solution;

[0051] (2) distilling the mixed solution to remove the organic solvent to obtain a positive electrode material precursor;

[0052] (3) heat-treating the positive electrode material precursor to obtain the positive electrode material.

[0053] The preparation method described in this application uses a liquid phase method to double-coat the surface of the high-voltage positive electrode material with fluorine and boron, achieving uniform dispersion of the fluorine source and the boron source on the surface of the high-voltage positive electrode material; the distillation process is introduced to achieve effective recovery and recycling of the organic solvent. The preparation method described in this application overcomes the problems of uneven coating thickness, poor universality, and generation of waste liquid and waste gas in the previous technology, and has the advantages of uniform and controllable coating thickness, good universality, simple process, easy large-scale production, and green environmental protection.

[0054] In addition, during the mixing and stirring process of the fluorine source, boron source, positive electrode active material and organic solvent using the preparation method described in the present application, the fluorine source and boron source may induce the shedding of residual alkali on the surface of the positive electrode material, thereby reducing the interfacial charge transfer impedance when the positive electrode material is composited with the sulfide electrolyte, thereby accelerating the interfacial carrier transport; during heat treatment, fluorine atoms and boron atoms are doped into the surface lattice of the positive electrode material, and fluorine atoms form strong chemical bonds with transition metals, which can inhibit the degradation of the positive electrode surface structure; boron atoms have a riveting effect on the lattice oxygen on the surface of the positive electrode material, hindering the interfacial side reactions between the high-voltage positive electrode material and the sulfide electrolyte and the decomposition of the sulfide electrolyte caused by oxygen evolution at the positive electrode.

[0055] During the charge and discharge process of solid-state batteries, the fluorine source forms an interfacial passivation film rich in lithium fluoride (or sodium fluoride) on the surface of the positive electrode material, which can improve the interfacial stability between the high-voltage positive electrode material and the sulfide electrolyte; the boron source may decompose on the surface of the positive electrode material to produce boron-containing organic matter, which is helpful to alleviate the volume change of the positive electrode particles during the lithium extraction process. The positive electrode / electrolyte interface contact failure caused by the volume change. Therefore, when the surface fluorine-boron double-coated positive electrode material is matched with the sulfide electrolyte, it shows excellent interfacial compatibility at a high charge cutoff voltage, and the high capacity advantage is fully utilized in room temperature solid-state batteries.

[0056] In some embodiments of the present application, the organic solvent includes one or more of ethanol, ethylene glycol, isopropanol, n-butanol, n-hexanol, ethyl acetate, butyl acetate, propyl propionate, dimethyl carbonate, propylene carbonate and diphenyl carbonate.

[0057] In some embodiments of the present application, the mass ratio of the organic solvent to the positive electrode active material is (1-50):1, for example, 1:1, 2:1, 5:1, 10:1, 15:1, 20:1, 26:1, 30:1, 35:1, 40:1, 43:1, 50:1, etc.

[0058] In some embodiments of the present application, the temperature of the heat treatment is 50-500°C, for example, 50°C, 100°C, 120°C, 150°C, 180°C, 220°C, 260°C, 300°C, 360°C, 400°C, 430°C, 500°C, etc., and the time of the heat treatment is 0.5h-10h.

[0059] In some embodiments of the present application, the heat treatment temperature is 80-200°C; within this treatment temperature range, the uniform distribution of the fluorine source and the boron source on the positive electrode surface and the sufficient volatilization of the residual solvent can be ensured, and the loss of the fluorine source and the boron source due to thermal decomposition can be reduced.

[0060] In some embodiments of the present application, the heat treatment is performed under an inert or vacuum atmosphere.

[0061] An embodiment of the present application also provides a composite positive electrode material, including the positive electrode material described in the first aspect of the present application or the positive electrode material obtained by the preparation method described in the second aspect of the present application.

[0062] The composite positive electrode material described in the present application has good interface compatibility with the sulfide electrolyte, can significantly inhibit the oxidative decomposition of the sulfide electrolyte under high voltage, and has a high electrochemical reversible capacity.

[0063] In some embodiments of the present application, the composite positive electrode material also includes a solid electrolyte and a conductive agent.

[0064] In some embodiments of the present application, the solid electrolyte includes a sulfide electrolyte; further preferably, the chemical formula of the solid electrolyte includes Li x N y S z and / or Na x N y S z , wherein the relationship between x, y and z satisfies x+ny-2z=0, n is the valence state of N, and N includes but is not limited to one or more of P, Cl, Br, I, Mn, Mo, Si, Ge, Sn, Al, As, C, B, O, H and Sb.

[0065] In some embodiments of the present application, the solid electrolyte includes Li6PS5Cl, Li6PS5Br, Li6PS5I, Li7P3S 11 、Li7P 2.9 Mn 0.1 S 10.7 I 0.3 、Li7P 2.9 S 10.85 Mo 0.01 , Li 6.35 P 0.65 Si 0.35S5Br、Li 6.35 P 0.65 Si 0.35 S5Br、Li 6.6 P 0.4 Ge 0.6 S5I、Li 3.25 Ge 0.25 P 0.75 S4, Li7PS6, Li7Ge3PS 12 、Li4GeS4、Li4SnS4、Li 11 AlP2S 12 , Li 3.833 Sn 0.833 As 0.166 S4, Li 10 GeP2S 12 , Li 10 SnP2S 12 , Li 10 SiP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , 80Li2S·20P2S5, 75Li2S·25P2S5, 70Li2S·30P2S5, 60Li2S·40P2S5, 67Li2S·33P2S5, 55(66Li2S·33P2S5)·45LiI, 95(60Li2S·40SiS2)·5Li3BO3(Li3AlO3), 77(75Li2S·25P2S5)·33LiBH4, 40Li2S·28SiS2·30LiI, 30Li2S·26B2S3·33LiI, β-Li3PS4–LZNO, β-Li3PS4–Al2O3, β-Li3PS4–SiO2, β-Li3PS4–LLZO, Na3PS4, Na3BS3 and Na3SbS4.

[0066] In some embodiments of the present application, the conductive agent includes one or more of Supper P, carbon fiber conductive agent VGCF, carbon nanotube conductive agent and Ketjen black.

[0067] An embodiment of the present application also provides a battery, comprising the composite positive electrode material described in the third aspect of the present application.

[0068] The battery described in the present application has the characteristics of high capacity, high operating voltage, high energy density, and good rate performance, and has good positive electrode / electrolyte interface stability in the high voltage region above 4.5V.

[0069] In some embodiments of the present application, the battery includes a sulfide solid-state lithium battery or a sulfide solid-state sodium battery.

[0070] The technical solution of this application will be further explained below in conjunction with specific implementation cases and drawings.

[0071] Example 1

[0072] A method for preparing a positive electrode material comprises the following steps:

[0073] 0.1g lithium hexafluorophosphate and 0.3g lithium bis(oxalatoborate) were dissolved in 1000g ethanol to obtain a fluorine-boron solution. 100g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a rotation speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 80°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0074] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0075] Example 2

[0076] The positive electrode material described in Example 2 is different from that in Example 1 only in that the amounts of fluorine source and boron source added during the preparation of the positive electrode material described in Example 2 are different from those in Example 1.

[0077] The specific steps include:

[0078] 0.5 g of lithium hexafluorophosphate and 1.5 g of lithium bis(oxalatoborate) were dissolved in 1000 g of ethanol to obtain a fluorine-boron solution. 100 g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a rotation speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 80°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0079] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0080] Example 3

[0081] The positive electrode material described in Example 3 is different from that in Example 1 only in that the amounts of fluorine source and boron source added during the preparation of the positive electrode material described in Example 3 are different from those in Example 1.

[0082] The specific steps include:

[0083] 1.0g lithium hexafluorophosphate and 3.0g lithium bis(oxalatoborate) were dissolved in 1000g ethanol to obtain a fluorine-boron solution. 100g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a rotation speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 80°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0084] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0085] Example 4

[0086] The positive electrode material described in Example 4 is different from that in Example 1 only in that the amounts of fluorine source and boron source added during the preparation of the positive electrode material described in Example 4 are different from those in Example 1.

[0087] The specific steps include:

[0088] 5g of lithium hexafluorophosphate and 15g of lithium bis(oxalatoborate) were dissolved in 1000g of ethanol to obtain a fluorine-boron solution. 100g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a rotation speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 80°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0089] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0090] Example 5

[0091] The positive electrode material described in Example 5 is different from that in Example 1 only in that the amounts of fluorine source and boron source added during the preparation of the positive electrode material described in Example 5 are different from those in Example 1.

[0092] The specific steps include:

[0093] Dissolve 10g lithium hexafluorophosphate and 30g lithium bis(oxalatoborate) in 1000g ethanol to obtain a fluorine-boron solution. Then weigh 100g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a rotation speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 80°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0094] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0095] Example 6

[0096] The positive electrode material described in Example 6 is different from that in Example 3 only in that the molar ratio of the fluorine source to the boron source in the preparation process of the positive electrode material described in Example 6 is different from the molar ratio of the fluorine source to the boron source in Example 3.

[0097] The specific steps include:

[0098] 2.0 g of lithium hexafluorophosphate and 2.0 g of lithium bis(oxalatoborate) were dissolved in 1000 g of ethanol to obtain a fluorine-boron solution. 100 g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a rotation speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 80°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0099] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0100] Example 7

[0101] The positive electrode material described in Example 7 is different from that in Example 3 only in that the molar ratio of the fluorine source to the boron source in the preparation process of the positive electrode material described in Example 7 is different from the molar ratio of the fluorine source to the boron source in Example 3.

[0102] The specific steps include:

[0103] 1.33g lithium hexafluorophosphate and 2.67g lithium bis(oxalatoborate) were dissolved in 1000g ethanol to obtain a fluorine-boron solution. 100g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a rotation speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 80°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0104] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0105] Example 8

[0106] The positive electrode material described in Example 8 is different from that in Example 3 only in that the molar ratio of the fluorine source to the boron source in the preparation process of the positive electrode material described in Example 8 is different from the molar ratio of the fluorine source to the boron source in Example 3.

[0107] The specific steps include:

[0108] 0.89g lithium hexafluorophosphate and 3.11g lithium bis(oxalatoborate) were dissolved in 1000g ethanol to obtain a fluorine-boron solution. 100g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a rotation speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 80°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0109] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0110] Example 9

[0111] The positive electrode material described in Example 9 is different from that in Example 3 only in that the molar ratio of the fluorine source to the boron source in the preparation process of the positive electrode material described in Example 9 is different from the molar ratio of the fluorine source to the boron source in Example 3.

[0112] The specific steps include:

[0113] 0.8g lithium hexafluorophosphate and 3.2g lithium bis(oxalatoborate) were dissolved in 1000g ethanol to obtain a fluorine-boron solution. 100g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a rotation speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 80°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0114] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0115] Example 10

[0116] The positive electrode material described in Example 10 is different from that in Example 3 only in that the molar ratio of the fluorine source to the boron source in the preparation process of the positive electrode material described in Example 10 is different from the molar ratio of the fluorine source to the boron source in Example 3.

[0117] The specific steps include:

[0118] 0.57g lithium hexafluorophosphate and 3.43g lithium bis(oxalatoborate) were dissolved in 1000g ethanol to obtain a fluorine-boron solution. 100g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a rotation speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 80°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0119] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0120] Embodiment 11

[0121] The positive electrode material described in Example 11 is different from that in Example 3 only in that the temperature of heat treatment during the preparation process of the positive electrode material described in Example 11 is different from that in Example 3.

[0122] The specific steps include:

[0123] 1.0g lithium hexafluorophosphate and 3.0g lithium bis(oxalatoborate) were dissolved in 1000g ethanol to obtain a fluorine-boron solution. 100g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 50°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0124] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0125] Example 12

[0126] The positive electrode material described in Example 12 is different from that in Example 3 only in that the temperature of heat treatment during the preparation process of the positive electrode material described in Example 12 is different from that in Example 3.

[0127] The specific steps include:

[0128] 1.0g lithium hexafluorophosphate and 3.0g lithium bis(oxalatoborate) were dissolved in 1000g ethanol to obtain a fluorine-boron solution. 100g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a rotation speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 160°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0129] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0130] Embodiment 13

[0131] The positive electrode material described in Example 13 is different from that in Example 3 only in that the temperature of heat treatment during the preparation process of the positive electrode material described in Example 13 is different from that in Example 3.

[0132] The specific steps include:

[0133] 1.0g lithium hexafluorophosphate and 3.0g lithium bis(oxalatoborate) were dissolved in 1000g ethanol to obtain a fluorine-boron solution. 100g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 300°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0134] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0135] Embodiment 14

[0136] The difference between Example 14 and Example 3 is that the positive electrode active material selected in the positive electrode material preparation process of Example 14 is LiNi 0.8 Mn 0.1 Co 0.1 O2, and the rest of the operations are the same as in Example 3.

[0137] Embodiment 15

[0138] The difference between Example 15 and Example 1 is that the positive electrode active material selected in the positive electrode material preparation process of Example 15 is Li 1.2 Mn 0.56 Ni 0.16 Co 0.08 O2, and the rest of the operations are the same as in Example 3.

[0139] Example 16

[0140] The only difference between Example 16 and Example 3 is that the positive electrode active material selected in the positive electrode material preparation process of Example 16 is LiCoO2, and no conductive agent is required. The rest of the operations are the same as in Example 3.

[0141] Embodiment 17

[0142] The difference between Example 17 and Example 3 is that the positive electrode active material selected in the positive electrode material preparation process of Example 17 is NaNi 0.5 Mn 0.5 O2, and the sulfide electrolyte is replaced by Li6PS5Cl to Na3PS4, and the rest of the operations are the same as those in Example 3.

[0143] Comparative Example 1

[0144] The only difference between Comparative Example 1 and Example 3 is that no fluorine source is added during the preparation of the positive electrode material described in Comparative Example 1.

[0145] The specific steps include:

[0146] Dissolve 3.0g of lithium bis(oxalatoborate) in 1000g of ethanol to obtain a fluorine-boron solution, then weigh 100g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a rotation speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 80°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0147] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0148] Comparative Example 2

[0149] The only difference between Comparative Example 2 and Example 3 is that no boron source is added during the preparation of the positive electrode material described in Comparative Example 2.

[0150] The specific steps include:

[0151] 1.0g lithium hexafluorophosphate was dissolved in 1000g ethanol to obtain a fluorine-boron solution, and then 100g of high-voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is uniformly dispersed in the fluorine-boron solution, and a mixed solution is obtained by stirring at a rotation speed of 900 rpm for 4 hours; the mixed solution is distilled at 78°C (stirring speed is 550 rpm) to recover ethanol, and the mixed solution is heat-treated at 80°C in an argon atmosphere in a tubular furnace for 6 hours and crushed to obtain a high-voltage solid-state lithium battery coated positive electrode material.

[0152] Weigh 0.7 g of the above-obtained coated positive electrode material, 0.3 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0153] Comparative Example 3

[0154] Weigh 1.0g lithium hexafluorophosphate, 3.0g lithium bis(oxalatoborate), 100g high voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder is added into a mortar and manually ground and mixed thoroughly to obtain a coated positive electrode material.

[0155] Weigh 0.6 g of the above-obtained coated positive electrode material, 0.4 g of sulfide electrolyte Li6PS5Cl, and 0.03 g of conductive agent VGCF, add them into a mortar, and grind and mix them manually to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0156] Comparative Example 4

[0157] Weigh 0.6g of high voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 powder, 0.4g sulfide electrolyte Li6PS5Cl, and 0.03g conductive agent VGCF were added into a mortar and manually ground and mixed thoroughly to obtain a high-voltage solid-state lithium battery composite positive electrode material.

[0158] Performance study of the positive electrode materials described in Examples 1-13 and Comparative Examples 1-4 of the present application

[0159] Solid-state lithium / sodium battery assembly and electrochemical performance testing:

[0160] Solid-state battery assembly was performed in a glove box with a high-purity argon atmosphere (water content ≤ 0.1ppm, oxygen content ≤ 0.1ppm): 80mg of Li6PS5Cl sulfide electrolyte powder was weighed and placed in the inner cavity of the solid-state battery mold, and the electrolyte layer was obtained by cold pressing at a pressure of 350Mpa once; then, 10mg of the composite positive electrode materials obtained in the above-mentioned Examples 1-13 and Comparative Examples 1-3 were weighed and evenly spread on one side of the electrolyte layer in the solid-state battery mold, and the composite positive electrode layer was obtained by cold pressing at a pressure of 600Mpa once. Finally, a φ10 indium sheet (thickness of 100μm), a φ3 lithium sheet (thickness of 50μm), and a φ10 copper foam (thickness of 300μm) were placed in turn on the other side of the electrolyte layer in the solid-state lithium battery mold, and after sealing, a solid-state lithium battery was obtained by cold pressing at a pressure of 200Mpa once, and then the Wuhan Blue Electric Test System was used to perform electrochemical charge and discharge tests on it.

[0161] 40 mg Na was placed on the other side of the electrolyte layer in the solid-state sodium battery mold. 15 Sn4 alloy, after sealing, was cold pressed once with a pressure of 200Mpa to obtain a solid-state sodium battery. The solid-state lithium / sodium battery obtained above was placed in a 30°C constant temperature box for 3 hours, and then subjected to electrochemical charge and discharge tests using the Wuhan Blue Electric test system.

[0162] High voltage lithium battery positive electrode material Li 1.2 Mn 0.6 Ni 0.2 O2 was charged and discharged at 0.1C (1C = 200 mA / g) in the voltage range of 2.0 to 4.7 V (vs. Li+ / Li).

[0163] High voltage lithium battery positive electrode material LiNi 0.8 Mn 0.1 Co 0.1 O2 (Example 14) was subjected to 0.1C (1C=200mA / g) charge and discharge test in the voltage range of 2.7-4.7V (vs.Li+ / Li).

[0164] High voltage lithium battery positive electrode material Li 1.2 Mn 0.56 Ni 0.16 Co 0.08 O2 (Example 15) was subjected to 0.1C (1C=200mA / g) charge and discharge test in the voltage range of 2.0 to 4.7V (vs.Li+ / Li).

[0165] The high voltage lithium battery positive electrode material LiCoO2 (Example 16) was subjected to 0.1C (1C=140mA / g) charge and discharge test in the voltage range of 2.8-4.6V (vs.Li+ / Li).

[0166] High voltage sodium battery cathode material NaNi 0.5 Mn 0.5 O2 (Example 17) was subjected to 0.1C (1C=240mA / g) charge and discharge test in the voltage range of 2.0 to 4.3V (vs.Na+ / Na).

[0167] The test results are shown in Table 1:

[0168] Table 1

[0169]

[0170]

[0171] It can be seen from Table 1 that after the surface fluorine-boron modification of the high-voltage positive electrode material by the distillation-assisted liquid phase coating method proposed in the present invention, the battery polarization caused by the positive electrode / electrolyte interface side reaction and electrolyte decomposition in the high voltage region can be significantly reduced, thereby greatly improving the reversible specific capacity and first coulombic efficiency of the high-voltage positive electrode material in the sulfide solid-state battery, and having good universality.

[0172] The first charge and discharge specific capacity-voltage curve of the solid-state lithium battery obtained by assembling the positive electrode materials described in Example 3 and Comparative Example 4 of the present application is as follows: Figure 1 As shown;

[0173] from Figure 1 It can be seen that the high-voltage oxygen reaction platform of Comparative Example 4 is significantly suppressed, the charge and discharge capacity is extremely low, and the voltage at the start of discharge is lower than 4.3V, and the battery polarization is large; in contrast, Example 3 exhibits a significant anion oxygen oxidation platform in the high voltage region above 4.4V, thereby releasing a high charge and discharge capacity and showing extremely low battery polarization.

[0174] The first charge and discharge specific capacity-voltage curves of the solid-state lithium battery obtained by assembling the positive electrode materials described in Examples 14-16 of the present application are shown in Figures 14-16 and 14-16, respectively. Figure 2 , Figure 3 and Figure 4 As shown;

[0175] from Figure 2-Figure 4 It can be seen that the high-voltage high-nickel ternary, lithium-rich manganese-based and lithium cobalt oxide positive electrodes prepared by the preparation method of the present application all exhibit high reversible capacity in sulfide solid-state lithium batteries and show excellent universality.

[0176] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A positive electrode material, characterized in that: The invention comprises the following raw materials in parts by mass: 100 parts of positive electrode active material, 0.1-60 parts of fluorine source and 0.1-60 parts of boron source.

2. The positive electrode material according to claim 1, characterized in that The chemical formula of the positive electrode active material includes Li x M y O2, Na a M b One or more of O2 and MFc; wherein 0<x<2, 0<y≤1, 0<a<2, 0<b≤1, 1≤c≤7, M is but not limited to one or more of Co, Mn, Ni, Nb, Fe, Li, Cu and Bi; Preferably, the positive electrode active material includes but is not limited to LiCoO2, LiMn2O4, LiMn 1.5 Ni 0.5 O4, LiNiO2, LiNi 0.9 Mn 0.05 Co 0.05 O2、LiNi 0.8 Mn 0.1 Co 0.1 O2、LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, Li2MnO3, Li 1.2 Mn 0.6 Ni 0.2 O2、Li 1.2 Mn 0.6 Nb 0.2 O2、NaNi 0.5 Mn 0.5 O2、NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2、Na 0.75 [Li 0.25 Mn 0.75 ]O2、Na 0.67 Mn 0.67 Ni 0.33 O2、Na 0.6 [Li 0.2 Mn 0.8 ]One or more of O2, Na2Mn3O7, CuF3, FeF3, NiF2, BiF3 and CoF3.

3. The positive electrode material according to claim 1, characterized in that The fluorine source includes, but is not limited to, one or more of lithium difluorophosphate, sodium difluorophosphate, lithium hexafluorophosphate, sodium hexafluorophosphate, lithium difluorooxalatoborate, sodium difluorooxalatoborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate, sodium trifluoromethanesulfonate, lithium difluorobis(oxalatophosphate) and sodium bis(trifluoromethylsulfonyl)imide.

4. The positive electrode material according to claim 1, characterized in that The boron source includes, but is not limited to, one or more of lithium bisoxalatoborate, sodium bisoxalatoborate, lithium tetrafluoroborate, sodium tetrafluoroborate, lithium difluorooxalatoborate and sodium difluorooxalatoborate.

5. The positive electrode material according to claim 1, characterized in that The positive electrode material comprises the following raw materials in parts by mass: 100 parts of positive electrode active material, 0.5-10 parts of fluorine source, and 0.5-10 parts of boron source; And / or, the molar ratio of the fluorine source to the boron source is 100:(1-95); preferably, the molar ratio of the fluorine source to the boron source is 100:(30-60).

6. The method for preparing the positive electrode material according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) mixing a fluorine source, a boron source, a positive electrode active material and an organic solvent to obtain a mixed solution; (2) distilling the mixed solution to remove the organic solvent to obtain a positive electrode material precursor; (3) heat-treating the positive electrode material precursor to obtain the positive electrode material.

7. The method for preparing the positive electrode material according to claim 6, characterized in that: The organic solvent is, but is not limited to, one or more of ethanol, ethylene glycol, isopropanol, n-butanol, n-hexanol, ethyl acetate, butyl acetate, propyl propionate, dimethyl carbonate, propylene carbonate and diphenyl carbonate; And / or, the mass ratio of the organic solvent to the positive electrode active material is (1-50):

1.

8. The method for preparing the positive electrode material according to claim 6, characterized in that: The heat treatment temperature is 50-500°C, and the heat treatment time is 0.5h-10h; Preferably, the temperature of the heat treatment is 80-200°C; And / or, the heat treatment is performed under an inert or vacuum atmosphere.

9. A composite positive electrode material, characterized in that: A positive electrode material comprising the positive electrode material according to any one of claims 1 to 5 or the positive electrode material obtained by the preparation method according to any one of claims 6 to 8; Preferably, the composite cathode material further comprises a solid electrolyte and a conductive agent; More preferably, the solid electrolyte comprises a sulfide electrolyte; further preferably, the chemical formula of the solid electrolyte comprises Li x N y S z and / or Na x N y S z , wherein the relationship between x, y and z satisfies x+ny-2z=0, n is the valence state of N, and N includes but is not limited to one or more of P, Cl, Br, I, Mn, Mo, Si, Ge, Sn, Al, As, C, B, O, H and Sb; More preferably, the solid electrolyte includes Li6PS5Cl, Li6PS5Br, Li6PS5I, Li7P3S 11 、Li7P 2.9 Mn 0.1 S 10.7 I 0.3 、Li7P 2.9 S 10.85 Mo 0.01 , Li 6.35 P 0.65 Si 0.35 S5Br、Li 6.35 P 0.65 Si 0.35 S5Br、Li 6.6 P 0.4 Ge 0.6 S5I、Li 3.25 Ge 0.25 P 0.75 S4, Li7PS6, Li7Ge3PS 12 、Li4GeS4、Li4SnS4、Li 11 AlP2S 12 , Li 3.833 Sn 0.833 As 0.166 S4, Li 10 GeP2S 12 , Li 10 SnP2S 12 , Li 10 SiP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , 80Li2S·20P2S5, 75Li2S·25P2S5, 70Li2S·30P2S5, 60Li2S·40P2S5, 67Li2S·33P2S5, 55(66Li2S·33P2S5)·45LiI, 95(60Li2S·40SiS2)·5Li3BO3(Li3AlO3), 77(75Li2S·25P2S5)·33LiBH4, 40Li2S·28SiS2·30LiI, 30Li2S·26B2S3·33LiI, β-Li3PS4–LZNO, β-Li3PS4–Al2O3, β-Li3PS4–SiO2, β-Li3PS4–LLZO, Na3PS4, Na3BS3 and Na3SbS4; Preferably, the conductive agent includes one or more of Supper P, carbon fiber conductive agent VGCF, carbon nanotube conductive agent and Ketjen black.

10. A battery, characterized in that: Comprising the composite positive electrode material according to claim 9; Preferably, the battery comprises a sulfide solid-state lithium battery or a sulfide solid-state sodium battery.

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