A transition metal-doped mixed ionic / electronic conductor interface layer-coated high-nickel cobalt-free cathode material

Abstract

A high-nickel, cobalt-free cathode material coated with a transition metal-doped mixed ionic / electronic conductor interface layer, wherein the chemical formula of the transition metal-doped mixed ionic / electronic conductor interface layer is Li. a M b N c O d Where M is one of V, Fe, Ni, Co, and Cu, N is one of Al, Zr, Sn, and Si, and the value of a is 1 or 2, 0 < b ≤ 0.5, 0.5 ≤ c < 1, and 2 ≤ d ≤ 3. This invention reduces the formation of residual lithium on the surface of high-nickel cobalt-free materials. It solves the problems of structural collapse and rapid capacity decay that occur in high-nickel cobalt-free cathode materials during electrochemical processes, and the resulting cathode material has good cycle stability and high reversible capacity.

Description

Technical Field

[0001] This invention relates to a high-nickel cathode material coated with a mixed ion / electron conductor interface layer, specifically a high-nickel cathode material coated with a transition metal-doped mixed ion / electron conductor interface layer. Background Technology

[0002] In recent years, with the rapid development of the new energy vehicle industry, high-energy-density lithium-ion batteries have become a key research focus for power batteries, and the key to improving energy density lies in the development of cathode materials. Currently, the most widely researched cathode materials are ternary materials. Based on different proportions of nickel salts, cobalt salts, and manganese (aluminum) salts, they are mainly divided into models such as NCM333, NCM523, NCM622, NCM811, and NCA. Cobalt accounts for a large proportion of the cost of ternary materials. To reduce the cost of lithium batteries, cathode materials will develop towards high-nickel, low-cobalt, or cobalt-free directions. Taking current market products as an example, from NCM523 and NCM622 to NCM811 and the 9-series ternary materials currently under development, the nickel content has been continuously increasing, while the cobalt content has been decreasing. This effectively reduces the dependence of ternary materials on cobalt metal while improving the energy density of lithium batteries, meeting the needs of reducing lithium battery costs and achieving long driving ranges for new energy vehicles. High-nickel, cobalt-free materials themselves have poor structural stability, requiring synergistic composite or doping surface modification technologies to solve problems related to capacity, structure, and cycle life. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a high-nickel cobalt-free cathode material with a transition metal doped mixed ion / electron conductor interface layer with good cycle stability.

[0004] The technical solution adopted by this invention to solve its technical problem is as follows: a high-nickel, cobalt-free cathode material coated with a transition metal-doped mixed ion / electron conductor interface layer, wherein the chemical formula of the transition metal-doped mixed ion / electron conductor interface layer is Li. a M b N c O d Where M is one of V, Fe, Ni, Co, and Cu, N is one of Al, Zr, Sn, and Si, a is 1 or 2, 0 < b ≤ 0.5, 0.5 ≤ c < 1, and 2 ≤ d ≤ 3.

[0005] By adopting the above technical solution, a high-nickel cobalt-free cathode material with coating modification was obtained.

[0006] Preferably, the chemical formula of the high-nickel cobalt-free cathode material is LiNi. x X 1-xO2, where X is one or both of Mn and Fe, and the range of x is 0.8≤x≤0.98.

[0007] By adopting the above technical solution, a high-nickel cobalt-free cathode material with coating modification was obtained.

[0008] Preferably, the molar ratio of the transition metal-doped mixed ionic / electronic conductor interface layer to the high-nickel cobalt-free cathode material is 0.01-0.08:1.

[0009] By adopting the above technical solution, a high-nickel cobalt-free cathode material with coating modification was obtained.

[0010] Preferably, the preparation method of the high-nickel cobalt-free cathode material coated with the transition metal-doped mixed ion / electron conductor interface layer includes the following steps:

[0011] (1) The lithium source, M source, and N source are reacted under high temperature and high pressure conditions to obtain Li a M b N c O d Material;

[0012] (2) The Li under the high temperature and high pressure conditions described in step (1) a M b N c O d The material is sprayed onto a high-nickel cobalt-free cathode material precursor and mixed evenly to obtain a composite material.

[0013] (3) The composite is mixed with a lithium source and sintered to obtain a high-nickel cobalt-free cathode material with a transition metal-doped mixed ion / electron conductor interface layer.

[0014] To ensure that the Li used for spraying in step (2) a M b N c O d The conditions of the materials are consistent with the reaction conditions in step (1). The reaction in step (1) can be carried out in a high-temperature and high-pressure reactor with a spray outlet at the bottom. After the reaction is completed, spraying can be achieved directly through the spray outlet; other conditions that can ensure Li a M b N c O d The way the material is situated in the environment is also feasible.

[0015] The above-mentioned technical solution employs a spray-reactive melting infiltration technology, which introduces composite components onto the surface of primary particles of the host material. The modified layer reacts with the substrate material through the reactive melting infiltration process, achieving strong bonding through chemical bonds, and combining with the spraying process to achieve optimal composite effect. The spray-reactive melting infiltration technology enables chemical bonding between the surface coating layer and the substrate material, greatly increasing the stability of the coating layer. Furthermore, the high-temperature melting infiltration technology successfully achieves coating of high-nickel, cobalt-free primary particles, resulting in a more complete coating surface and better coating effect. This method has a simple preparation process, a short flow, readily available raw materials, and produces no toxic or harmful substances, making it easy to scale up production.

[0016] By adopting the above technical solution, a high-nickel cobalt-free cathode material with coating modification was obtained through spray-reactive melting infiltration technology.

[0017] Preferably, in step (1), the lithium source is one or more of lithium oxide, lithium hydroxide, lithium nitrate, and lithium carbonate.

[0018] By adopting the above technical solution, it is possible to prepare Li a M b N c O d The material provides a suitable lithium source.

[0019] Preferably, in step (1), the M source is one or more of oxides, nitrates, carbonates, and acetates containing V, Fe, Ni, Co, and Cu.

[0020] By adopting the above technical solution, it is possible to prepare Li a M b N c O d The material provides a suitable M source.

[0021] Preferably, in step (1), the N source is one or more of the following: oxides, nitrates, carbonates, and acetates containing Al, Zr, Sn, and Si.

[0022] By adopting the above technical solution, it is possible to prepare Li a M b N c O d The material provides a suitable N source.

[0023] Preferably, in step (1), the high temperature and high pressure conditions are a temperature of 1200-1800℃ and a pressure of 1-2MPa.

[0024] By adopting the above technical solution, Li can be produced. a M b N cO d Material.

[0025] Preferably, in step (1), the reaction time is 1-5 hours.

[0026] By adopting the above technical solution, Li can be produced. a M b N c O d Material.

[0027] Preferably, in step (2), the spraying rate is 0.1-0.5 L / s.

[0028] The spraying process allows Li, which was originally under high temperature and high pressure conditions, to... a M b N c O d When the material enters a normal environment, a suitable rate allows Li a M b N c O d The material is in a suitable state when it is being coated.

[0029] Preferably, in step (3), the lithium source is one or more of lithium carbonate, lithium oxide, and lithium acetate.

[0030] By adopting the above technical solution, it is possible to prepare LiNi x X 1-x O2 materials provide a suitable lithium source.

[0031] Preferably, in step (3), the molar ratio of the lithium source to the high-nickel cobalt-free cathode material precursor is 1.02-1.06:1.

[0032] By adopting the above technical solution, it is possible to prepare LiNi x X 1-x O2 materials provide a suitable lithium source.

[0033] Preferably, in step (3), the sintering temperature is 900-1200℃ and the sintering time is 10-24h.

[0034] By adopting the above technical solution, the high-nickel cobalt-free cathode material precursor can be converted into a high-nickel cobalt-free cathode material.

[0035] Preferably, the high-nickel cobalt-free cathode material precursor is Ni. x X 1-x (OH)2.

[0036] By adopting the above technical solution, high-nickel cobalt-free cathode materials can be obtained after lithium mixing and sintering.

[0037] More preferably, the high-nickel cobalt-free cathode material precursor is prepared by co-precipitation reaction using a metal ion solution containing nickel and element X under an inert atmosphere.

[0038] By adopting the above technical solution, a suitable precursor Ni can be obtained. x X 1-x (OH)2, other substances that can produce the precursor Ni x X 1-x The (OH)2 method is also feasible.

[0039] More preferably, the nickel source used is one or more of nickel nitrate, nickel sulfate, and nickel acetate.

[0040] By adopting the above technical solution, it is possible to prepare Ni precursor. x X 1-x (OH)2 provides a suitable nickel source.

[0041] More preferably, the X source used is one or more of manganese nitrate, manganese sulfate, manganese acetate, ferrous nitrate, ferrous sulfate, and ferrous acetate.

[0042] By adopting the above technical solution, it is possible to prepare Ni precursor. x X 1-x (OH)2 provides a suitable source of X.

[0043] More preferably, the complexing agent is ammonia.

[0044] By adopting the above technical solution, it is possible to prepare Ni precursor. x X 1-x (OH)2 provides a suitable coprecipitation environment.

[0045] More preferably, the precipitant is a sodium hydroxide solution.

[0046] By adopting the above technical solution, metal ions can be co-precipitated.

[0047] More preferably, the concentration of the metal ion solution is 1-3 mol / L.

[0048] By adopting the above technical solution, a good co-precipitation effect is achieved.

[0049] More preferably, the concentration of the complexing agent is 15-25 wt%.

[0050] By adopting the above technical solution, it is possible to prepare Ni precursor. x X 1-x (OH)2 provides a suitable coprecipitation environment.

[0051] More preferably, the concentration of the precipitant is 4-6 mol / L.

[0052] By adopting the above technical solution, a good co-precipitation effect is achieved.

[0053] More preferably, the pH of the coprecipitation reaction solution is 10-12.

[0054] By adopting the above technical solution, a good co-precipitation effect is achieved.

[0055] More preferably, the coprecipitation reaction time is 30-60 hours.

[0056] By adopting the above technical solution, a good co-precipitation effect is achieved.

[0057] Beneficial effects of this invention:

[0058] The coating layer of this invention is a transition metal-doped mixed ionic / electronic conductor material. This material is a lithium-containing composite salt that promotes ion conduction and electron transfer, thereby effectively improving the rate performance and ion diffusion rate of high-nickel cobalt-free materials. Simultaneously, this lithium-containing composite layer can form chemical bonds with the high-nickel cobalt-free precursor, thereby enhancing the composite stability of the surface coating layer and the host material, while ensuring lithium uniformity during subsequent lithiation sintering and reducing the formation of residual lithium on the surface of the high-nickel cobalt-free material. This solves the problems of structural collapse and rapid capacity decay that occur in high-nickel cobalt-free cathode materials during electrochemical processes, resulting in a cathode material with good cycle stability and high reversible capacity. Attached Figure Description

[0059] Figure 1 This is a SEM image of the high-nickel, cobalt-free cathode material coated with a transition metal-doped mixed ion / electron conductor interface layer in Example 1 of the present invention. Detailed Implementation

[0060] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0061] The raw materials used in the embodiments of the present invention are all obtained through conventional commercial channels. Example 1

[0062] The high-nickel, cobalt-free cathode material in this embodiment, coated with a transition metal-doped mixed ion / electron conductor interface layer, has the chemical formula of the transition metal-doped mixed ion / electron conductor interface layer as LiAl. 0.9 V 0.1 O2. The chemical formula of the high-nickel, cobalt-free cathode material is LiNi. 0.85 Mn 0.15 O2. The molar ratio of the transition metal-doped mixed ion / electron conductor interface layer to the high-nickel cobalt-free cathode material is 0.05:1. An electron micrograph of the high-nickel cobalt-free cathode material coated with the transition metal-doped mixed ion / electron conductor interface layer is shown below. Figure 1As shown in the figure, the high-nickel cobalt-free material is in the form of micron-sized blocks with a smooth surface.

[0063] The preparation method of the high-nickel cobalt-free cathode material coated with the transition metal-doped mixed ion / electron conductor interface layer includes the following steps:

[0064] (1) Weigh 5 mol lithium hydroxide, 0.5 mol vanadium nitrate, and 4.5 mol aluminum oxide, transfer them to a high-temperature and high-pressure reactor, and react them at 1500℃ and 1 MPa for 1 h to obtain LiAl. 0.9 V 0.1 O2 materials;

[0065] (2) Maintain the environmental conditions in the high-temperature and high-pressure reactor, and then prepare the LiAl. 0.9 V 0.1 O2 material is sprayed through a spray device at the bottom of a high-temperature, high-pressure reactor onto 0.1 mol Ni. 0.85 Mn 0.15 The (OH)2 precursor was subjected to spray coating treatment at a spray rate of 0.2 L / s and a spray volume of 5 mmol to obtain the complex.

[0066] (3) The composite was mixed with 0.104 mol of LiOH in a solid state and then sintered at high temperature in a muffle furnace at 950°C for 10 h to obtain a high-nickel cobalt-free cathode material LiAl with a transition metal-doped mixed ion / electron conductor interface layer. 0.9 V 0.1 O2@LiNi 0.85 Mn 0.15 O2.

[0067] The high-nickel cobalt-free cathode material precursor Ni 0.85 Mn 0.15 The preparation method of (OH)2 includes the following steps:

[0068] Dissolve 0.085 mol NiSO4·7H2O and 0.015 mol MnSO4·H2O in deionized water to prepare a 2 mol L solution. -1 A metal ion solution was prepared and then added to a continuous stirred tank reactor under a nitrogen atmosphere, with 4 mol / L of the solution added. -1 After adding NaOH precipitant and 20 wt% NH3·H2O complexing agent, the pH of the solution was maintained in the range of 10-11, and the reaction was allowed to proceed for 60 hours. After washing and drying, Ni was obtained. 0.85 Mn 0.15 (OH)2 precursor. Example 2

[0069] The high-nickel, cobalt-free cathode material in this embodiment is coated with a transition metal-doped mixed ion / electron conductor interface layer, the chemical formula of which is Li₂Zr. 0.9 Ni 0.1 O3. The chemical formula of the high-nickel, cobalt-free cathode material is LiNi. 0.85 Mn 0.15 O2. The molar ratio of the transition metal-doped mixed ionic / electronic conductor interface layer to the high-nickel cobalt-free cathode material is 0.05:1.

[0070] The preparation method of the high-nickel cobalt-free cathode material coated with the transition metal-doped mixed ion / electron conductor interface layer includes the following steps:

[0071] (1) Weigh 5 mol lithium hydroxide, 0.5 mol nickel nitrate and 4.5 mol zirconium oxide, transfer them to a high temperature and high pressure reactor, and react at 1500℃ and 1 MPa for 1 h to obtain Li2Zr. 0.9 Ni 0.1 O3 materials;

[0072] (2) Maintain the environmental conditions in the high-temperature and high-pressure reactor, and then prepare the Li2Zr. 0.9 Ni 0.1 O3 material is sprayed through a spray device at the bottom of a high-temperature, high-pressure reactor onto 0.1 mol Ni. 0.85 Mn 0.15 The (OH)2 precursor was subjected to spray coating treatment at a spray rate of 0.2 L / s and a spray volume of 5 mmol to obtain the complex.

[0073] (3) The composite was mixed with 0.104 mol of LiOH in a solid state and then sintered at high temperature in a muffle furnace at 950°C for 10 h to obtain a high-nickel cobalt-free cathode material Li2Zr with a transition metal-doped mixed ion / electron conductor interface layer. 0.9 Ni 0.1 O3@LiNi 0.85 Mn 0.15 O2.

[0074] The high-nickel cobalt-free cathode material precursor Ni 0.85 Mn 0.15 The preparation method of (OH)2 includes the following steps:

[0075] Dissolve 0.085 mol NiSO4·7H2O and 0.015 mol MnSO4·H2O in deionized water to prepare a 2 mol L solution. -1 A metal ion solution was prepared and then added to a continuous stirred tank reactor under a nitrogen atmosphere, with 4 mol / L of the solution added. -1After adding NaOH precipitant and 20 wt% NH3·H2O complexing agent, the pH of the solution was maintained in the range of 10-11, and the reaction was allowed to proceed for 60 hours. After washing and drying, Ni was obtained. 0.85 Mn 0.15 (OH)2 precursor. Example 3

[0076] The high-nickel, cobalt-free cathode material in this embodiment is coated with a transition metal-doped mixed ion / electron conductor interface layer, the chemical formula of which is Li₂Zr. 0.9 Fe 0.1 O3. The chemical formula of the high-nickel, cobalt-free cathode material is LiNi. 0.85 Mn 0.15 O2. The molar ratio of the transition metal-doped mixed ionic / electronic conductor interface layer to the high-nickel cobalt-free cathode material is 0.05:1.

[0077] The preparation method of the high-nickel cobalt-free cathode material coated with the transition metal-doped mixed ion / electron conductor interface layer includes the following steps:

[0078] (1) Weigh 5 mol lithium hydroxide, 0.5 mol ferric nitrate and 4.5 mol zirconium oxide, transfer them to a high temperature and high pressure reactor, and react at 1500℃ and 1 MPa for 1 h to obtain Li2Zr. 0.9 Fe 0.1 O3 materials;

[0079] (2) Maintain the environmental conditions in the high-temperature and high-pressure reactor, and then prepare the Li2Zr. 0.9 Fe 0.1 O3 material is sprayed through a spray device at the bottom of a high-temperature, high-pressure reactor onto 0.1 mol Ni. 0.85 Mn 0.15 The (OH)2 precursor was subjected to spray coating treatment at a spray rate of 0.2 L / s and a spray volume of 5 mmol to obtain the complex.

[0080] (3) The composite was mixed with 0.104 mol of LiOH in a solid state and then sintered at high temperature in a muffle furnace at 950°C for 10 h to obtain a high-nickel cobalt-free cathode material Li2Zr with a transition metal-doped mixed ion / electron conductor interface layer. 0.9 Fe 0.1 O3@LiNi 0.85 Mn 0.15 O2.

[0081] The high-nickel cobalt-free cathode material precursor Ni 0.85 Mn 0.15 The preparation method of (OH)2 includes the following steps:

[0082] Dissolve 0.085 mol NiSO4·7H2O and 0.015 mol MnSO4·H2O in deionized water to prepare a 2 mol L solution. -1 A metal ion solution was prepared and then added to a continuous stirred tank reactor under a nitrogen atmosphere, with 4 mol / L of the solution added. -1 After adding NaOH precipitant and 20 wt% NH3·H2O complexing agent, the pH of the solution was maintained in the range of 10-11, and the reaction was allowed to proceed for 60 hours. After washing and drying, Ni was obtained. 0.85 Mn 0.15 (OH)2 precursor. Example 4

[0083] The high-nickel, cobalt-free cathode material in this embodiment is coated with a transition metal-doped mixed ion / electron conductor interface layer, the chemical formula of which is Li₂Zr. 0.9 Ni 0.1 O3. The chemical formula of the high-nickel, cobalt-free cathode material is LiNi. 0.92 Mn 0.08 O2. The molar ratio of the transition metal-doped mixed ionic / electronic conductor interface layer to the high-nickel cobalt-free cathode material is 0.05:1.

[0084] The preparation method of the high-nickel cobalt-free cathode material coated with the transition metal-doped mixed ion / electron conductor interface layer includes the following steps:

[0085] (1) Weigh 5 mol lithium hydroxide, 0.5 mol nickel nitrate and 4.5 mol zirconium oxide, transfer them to a high temperature and high pressure reactor, and react at 1500℃ and 1 MPa for 1 h to obtain Li2Zr. 0.9 Ni 0.1 O3 materials;

[0086] (2) Maintain the environmental conditions in the high-temperature and high-pressure reactor, and then prepare the Li2Zr. 0.9 Ni 0.1 O3 material is sprayed through a spray device at the bottom of a high-temperature, high-pressure reactor onto 0.1 mol Ni. 0.92 Mn 0.08 The (OH)2 precursor was subjected to spray coating treatment at a spray rate of 0.2 L / s and a spray volume of 5 mmol to obtain the complex.

[0087] (3) The composite was mixed with 0.104 mol of LiOH in a solid state and then sintered at high temperature in a muffle furnace at 950°C for 10 h to obtain a high-nickel cobalt-free cathode material Li2Zr with a transition metal-doped mixed ion / electron conductor interface layer. 0.9 Ni0.1 O3@LiNi 0.92 Mn 0.08 O2.

[0088] The high-nickel cobalt-free cathode material precursor Ni 0.92 Mn 0.08 The preparation method of (OH)2 includes the following steps: dissolving 0.092 mol NiSO4·7H2O and 0.008 mol MnSO4·H2O in deionized water to prepare a 2 mol L... -1 A metal ion solution was prepared and then added to a continuous stirred tank reactor under a nitrogen atmosphere, with 4 mol L⁻¹ added. -1 After adding NaOH precipitant and 20 wt% NH3·H2O complexing agent, the pH of the solution was maintained in the range of 10-11, and the reaction was allowed to proceed for 60 hours. After washing and drying, Ni was obtained. 0.85 Mn 0.15 (OH)2 precursor. Example 5

[0089] In this embodiment, a conventional coating method is used, employing LiAl. 0.9 V 0.1 O2 material coated with high-nickel cobalt-free cathode material LiNi 0.85 Mn 0.15 O2.

[0090] The preparation method includes the following steps:

[0091] (1) Weigh 5 mol lithium hydroxide, 0.5 mol vanadium nitrate, and 4.5 mol aluminum oxide, transfer them to a high-temperature and high-pressure reactor, and react them at 1500℃ and 1 MPa for 1 h to obtain LiAl. 0.9 V 0.1 O2 materials;

[0092] (2) 5 mmol of the prepared LiAl 0.9 V 0.1 O2 material and 0.1 mol Ni 0.85 Mn 0.15 The (OH)₂ precursor and 0.104 mol of LiOH were mixed in a solid phase and then sintered at 950°C for 10 h in a muffle furnace to obtain LiAl. 0.9 V 0.1 O2@LiNi 0.85 Mn 0.15 O2.

[0093] The high-nickel cobalt-free cathode material precursor Ni 0.85 Mn 0.15 The preparation method of (OH)2 is the same as that in Example 1.

[0094] Battery assembly is completed using the following method:

[0095] High-nickel, cobalt-free coated material was used as the positive electrode active material, and mixed with conductive agent acetylene black (AB) and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) was used as the solvent, and the mixture was stirred at 800 rpm for 2 hours in a small beaker to obtain a slurry. The slurry was coated onto current collector aluminum foil using an automatic coating machine, laid flat on tempered glass, and dried in a vacuum drying oven at 85°C for 4 hours. After die-cutting to prepare 12mm diameter electrode sheets, the sheets were dried in a vacuum drying oven at 105°C for 4 hours. The sheets were then placed in a glove box filled with argon atmosphere (moisture and oxygen content both below 0.1 ppm) for 4 hours to reduce moisture adsorbed during transfer. Finally, the sheets were assembled into CR2032 coin cells in the glove box. The battery uses a 1 mol / L NaClO4 solution as the electrolyte, a pure lithium metal sheet with a diameter of 16 mm and a thickness of 0.5 mm as the negative electrode, and a porous polyethylene membrane of model Celgard2300 with a diameter of 18 mm as the separator.

[0096] After the battery assembly was completed and aged for 12 hours, charge and discharge tests were conducted at different potentials.

[0097] The discharge specific capacity of the battery was tested after 200 cycles at a voltage of 3-4.5V and a current density of 1C. The results are shown in Table 1.

[0098] Table 1. Electrical performance test results of batteries assembled from the materials obtained in Examples 1-5.

[0099] Source of cathode materials <![CDATA[Discharge specific capacity / mAh g -1 > Capacity retention rate / % Example 1 178.8 93.5 Example 2 180.5 94.5 Example 3 173.1 90.6 Example 4 186.9 97.8 Example 5 163.2 85.4

[0100] As shown in Table 1, the cathode materials of Examples 1-5 still maintain a high discharge specific capacity and capacity retention rate after 200 cycles; the cathode materials of Examples 1-4 prepared by spray-reactive melting infiltration technology perform better.

[0101] The above description is merely a basic explanation of the concept of this invention, and any equivalent modifications made based on the technical solution of this invention shall fall within the protection scope of this invention.

Claims

1. A high-nickel, cobalt-free cathode material coated with a transition metal-doped mixed ionic / electronic conductor interface layer, characterized in that, The chemical formula of the transition metal-doped mixed ion / electron conductor interface layer is Li. a M b N c O d Where M is one of V, Fe, Co, and Cu, N is one of Al, Zr, Sn, and Si, and the value of a is 1 or 2, 0 < b ≤ 0.5, 0.5 ≤ c < 1, and 2 ≤ d ≤ 3; The chemical formula of the high-nickel cobalt-free cathode material is LiNi. x X 1-x O2, wherein X is one or both of Mn and Fe, and the range of x is 0.8≤x≤0.98; the molar ratio of the transition metal-doped mixed ion / electron conductor interface layer to the high-nickel cobalt-free cathode material is 0.01-0.08:1; The preparation method of the high-nickel cobalt-free cathode material coated with the transition metal-doped mixed ion / electron conductor interface layer includes the following steps: (1) The lithium source, M source, and N source are reacted under high temperature and high pressure conditions to obtain Li a M b N c O d Material; The high temperature and high pressure conditions are a temperature of 1200-1800℃ and a pressure of 1-2MPa. (2) The Li under the high temperature and high pressure conditions described in step (1) a M b N c O d The material is sprayed onto a high-nickel cobalt-free cathode material precursor and mixed evenly to obtain a composite material. The reaction in step (1) was carried out in a high-temperature and high-pressure reactor with a spray outlet at the bottom. After the reaction was completed, the spray was directly applied through the spray outlet. (3) The composite is mixed with a lithium source and sintered to obtain a high-nickel cobalt-free cathode material with a transition metal-doped mixed ion / electron conductor interface layer. The spray-reactive melting infiltration technology can introduce composite components onto the primary particle surface of the host material. The modified layer can react with the substrate material through the reactive melting infiltration process, achieving strong composite through chemical bonds, and combined with the spray process to achieve the optimal composite effect.

2. The high-nickel, cobalt-free cathode material coated with a transition metal-doped mixed ion / electron conductor interface layer according to claim 1, characterized in that, In step (1), the lithium source is one or more of lithium oxide, lithium hydroxide, lithium nitrate, and lithium carbonate; the M source is one or more of oxides, nitrates, carbonates, and acetates containing V, Fe, Co, and Cu; the N source is one or more of oxides, nitrates, carbonates, and acetates containing Al, Zr, Sn, and Si; and the reaction time is 1-5 h.

3. The high-nickel, cobalt-free cathode material coated with a transition metal-doped mixed ion / electron conductor interface layer according to claim 1 or 2, characterized in that, In step (2), the spraying rate is 0.1-0.5 L / s.

4. The high-nickel, cobalt-free cathode material coated with a transition metal-doped mixed ion / electron conductor interface layer according to claim 1 or 2, characterized in that, In step (3), the lithium source is one or more of lithium carbonate, lithium oxide, and lithium acetate; the molar ratio of the lithium source to the high-nickel cobalt-free cathode material precursor is 1.02-1.06:1; the sintering temperature is 900-1200℃ and the sintering time is 10-24h.

5. The high-nickel, cobalt-free cathode material coated with a transition metal-doped mixed ion / electron conductor interface layer according to claim 1 or 2, characterized in that, The high-nickel, cobalt-free cathode material precursor is Ni. x X 1-x (OH)2.

6. The high-nickel, cobalt-free cathode material coated with a transition metal-doped mixed ion / electron conductor interface layer according to claim 5, characterized in that, The high-nickel, cobalt-free cathode material precursor is prepared by co-precipitation reaction using a solution of metal ions containing nickel and element X under an inert atmosphere.

7. The high-nickel, cobalt-free cathode material coated with a transition metal-doped mixed ion / electron conductor interface layer according to claim 6, characterized in that, In the coprecipitation reaction, the nickel source used is one or more of nickel nitrate, nickel sulfate, and nickel acetate; the X source used is one or more of manganese nitrate, manganese sulfate, manganese acetate, ferrous nitrate, ferrous sulfate, and ferrous acetate; the complexing agent is ammonia; and the precipitant is sodium hydroxide solution.

8. The high-nickel, cobalt-free cathode material coated with a transition metal-doped mixed ionic / electronic conductor interface layer according to claim 7, characterized in that, In the coprecipitation reaction, the concentration of the metal ion solution is 1-3 mol / L; the concentration of the complexing agent is 15-25 wt%; the concentration of the precipitant is 4-6 mol / L; the pH value of the coprecipitation reaction solution is 10-12; and the coprecipitation reaction time is 30-60 h.

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