A lithium-rich cobalt-free high-entropy doped positive electrode material, a preparation method and application thereof

Abstract

This invention belongs to the field of lithium-ion battery technology, and relates to a lithium-rich, cobalt-free, high-entropy doped cathode material, its preparation method, and its application. Addressing the problems of complex processes, high costs, and limited improvement effects of existing cathode materials, this invention provides a lithium-rich, cobalt-free, high-entropy doped cathode material with the chemical formula Li[Li] x Ni y Mn z A 1‑x‑y‑z O2; wherein, 0.1≤x≤0.25, 0.15≤y≤0.25, 0.45≤z≤0.58, 0.04≤1-x-y-z≤0.15; wherein A is at least 4 of Mg, Al, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Zr, Nb, Mo, Ru, Sn, Sb, Te, La, Ta, and W; the content of each A element subscript is between 0.01 and 0.02 and the amount of each A element is equal.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a lithium-rich, cobalt-free, high-entropy doped cathode material, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries dominate the secondary battery market due to their high energy density and long cycle life. However, with the rapid development of mobile device power supplies, electric vehicles, and energy storage grids, current commercial lithium-ion batteries can no longer meet the growing consumer demand in terms of energy density and power density. Cathode materials are a key factor in improving lithium-ion battery performance. Meanwhile, the significant increase in cobalt prices has increased battery costs, making a transition to cobalt-free cathodes essential. Therefore, there is an urgent need to develop low-cost, high-energy-density cobalt-free cathode materials.

[0003] Traditional layered LiCoO2 cathodes, ternary cathodes, olivine-like LiFePO4 cathodes, and spinel-like LiMn2O4 cathodes, while exhibiting good cycle life and rate performance, have relatively low actual specific capacity (≤190 mAh g⁻¹). -1 However, these methods are insufficient to meet the current societal demand for high-energy-density lithium-ion batteries. In contrast, lithium-rich manganese-based cathode materials, due to their high specific capacity (≥240 mAh g⁻¹), are less suitable. -1 The characteristics of lithium-rich cathode materials, such as low cost (low Ni, low Co, or no Co), have attracted widespread attention from researchers. However, the redox reaction of anions in lithium-rich cathode materials leads to oxygen loss, causing irreversible structural changes and voltage decay during cycling, which affects their further commercialization. Currently, methods such as coating, doping, and surface modification are mainly used to improve their electrochemical performance, and some progress has been made. However, problems such as complex processes, high costs, and limited improvement effects still exist. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a lithium-rich, cobalt-free, high-entropy doped cathode material, its preparation method, and its applications. By increasing the intralayer configuration entropy of the material, increasing the diversity of the local environment, stabilizing lattice oxygen, suppressing capacity and voltage decay, and promoting the commercial application of low-cost, high-energy-density lithium-rich cathode materials.

[0005] On one hand, the present invention provides a lithium-rich, cobalt-free, high-entropy doped cathode material, wherein the chemical formula of the lithium-rich, cobalt-free, high-entropy doped cathode material is Li[Li x Ni y Mn z A 1-x-y-zO2; wherein, 0.1≤x≤0.25, 0.15≤y≤0.25, 0.45≤z≤0.58, 0.04≤1-xyz≤0.15; wherein A is at least 4 of Mg, Al, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Zr, Nb, Mo, Ru, Sn, Sb, Te, La, Ta, and W; the content of each A element subscript is between 0.01 and 0.02 and the amount of each A element is equal.

[0006] The preferred values ​​are 0.15≤x≤0.20, 0.18≤y≤0.22, and 0.52≤z≤0.57.

[0007] Preferably, A is a combination of Mo, Al, Nb, and Fe;

[0008] A is a combination of Mo, Al, Nb, Fe, and Ti;

[0009] Alternatively, A can be a combination of Mo, Al, Nb, Fe, Ti, and Cr.

[0010] Preferably, the crystal structure is composed of both the R-3m space group and the C2 / m space group, with lithium layers and transition metal layers arranged alternately, and excess lithium occupying the octahedral sites of the transition metal layers.

[0011] Secondly, the present invention provides a method for preparing a lithium-rich, cobalt-free, high-entropy doped cathode material, comprising:

[0012] (1) Soluble compounds containing Li, soluble compounds containing Ni, soluble compounds containing Mn, and soluble compounds containing A are classified according to the chemical formula Li[Li x Ni y Mn z A 1-x-y-z The stoichiometric ratio of O2 is dissolved in deionized water to obtain solution 1;

[0013] (2) Dissolve citric acid, which has a molar number 1 to 2 times that of the metal element, in deionized water to obtain solution 2;

[0014] (3) Add solution 2 to solution 1, adjust the pH of the mixture to 6-8, and then stir magnetically at 70℃-90℃ until a gel is formed;

[0015] (4) The gel is dried, ground and calcined to obtain the lithium-rich cobalt-free high-entropy doped cathode material.

[0016] Preferably, in step (1): the soluble compound of Li is selected from at least one of the carbonates, acetates, nitrates and halides of Li;

[0017] The soluble compounds of Ni are selected from at least one of Ni acetate, nitrate, sulfate, and halide.

[0018] The soluble compounds of Mn are selected from at least one of the acetates, nitrates, sulfates, and halides of Mn;

[0019] The soluble compound of A is selected from at least one of the following: acetate of A, oxalate of A, nitrate of A, sulfate of A, and halide of A, wherein A is at least four of the following: Mg, Al, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Zr, Nb, Mo, Ru, Sn, Sb, Te, La, Ta, and W.

[0020] Preferably, in step (4): the drying parameters include: drying at 100-140°C for 6-12 hours;

[0021] The calcination parameters include: pre-calcination at 400-500℃ for 4-8 hours, followed by calcination at 850-950℃ for 8-16 hours.

[0022] Thirdly, the present invention provides an electrode comprising: a current collector and an electrode layer coated on the surface of the current collector; the electrode layer comprises a lithium-rich, cobalt-free, high-entropy doped cathode material.

[0023] Preferably, the electrode layer comprises a lithium-rich, cobalt-free, high-entropy doped cathode material, a conductive agent, and a binder; preferably, the mass ratio of the lithium-rich, cobalt-free, high-entropy doped cathode material, the conductive agent, and the binder is (7-8):(2-1):1.

[0024] Fourthly, the present invention provides a high-energy-density battery, comprising: a positive electrode, a negative electrode, a separator, and an electrolyte; wherein the positive electrode comprises a lithium-rich, cobalt-free, high-entropy doped positive electrode material.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] This invention increases the intralayer configuration entropy of the lithium-rich cobalt-free cathode material, thereby increasing the diversity of oxygen coordination environments within the material, suppressing oxygen evolution, and reducing spinel phase transitions caused by transition metal migration. Compared to traditional cathode materials, the aforementioned high-entropy doped cathode material exhibits high discharge specific capacity while showing minimal capacity and voltage decay during cycling, making it possible to apply cobalt-free high-capacity cathode materials to high-energy-density, long-cycle lithium-ion battery systems. Furthermore, the preparation method provided by this invention is simple, with easily controllable conditions, and can yield stable products, demonstrating broad application prospects. Attached Figure Description

[0027] Figure 1 This is a scanning electron microscope image of the high-entropy doped cathode material in Example 1;

[0028] Figure 2 The X-ray powder diffraction pattern of the high-entropy doped cathode material in Example 1 is shown below.

[0029] Figure 3 This is the first charge-discharge curve of the high-entropy doped cathode material in Example 1;

[0030] Figure 4 The graph shows the cycling performance of the high-entropy doped cathode material in Example 1.

[0031] Figure 5 This is a scanning electron microscope image of the conventional lithium-rich manganese-based cathode material in Comparative Example 1;

[0032] Figure 6 The X-ray powder diffraction pattern of the conventional lithium-rich manganese-based cathode material in Comparative Example 1 is shown.

[0033] Figure 7 This is a first-cycle charge-discharge curve of the conventional lithium-rich manganese-based cathode material in Comparative Example 1.

[0034] Figure 8 The graph shows the cycle performance of the conventional lithium-rich manganese-based cathode material in Comparative Example 1. Detailed Implementation

[0035] The present invention will be further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0036] In this disclosure, the chemical formula of the lithium-rich, cobalt-free, high-entropy doped cathode material is Li[Li x Ni y Mn z A 1-x-y-z O2, wherein 0.1≤x≤0.25, 0.15≤y≤0.25, 0.45≤z≤0.58; wherein A is at least four of Mg, Al, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Zr, Nb, Mo, Ru, Sn, Sb, Te, La, Ta, and W.

[0037] In this invention, by increasing the intralayer configuration entropy of the lithium-rich cobalt-free cathode material, the diversity of oxygen coordination environments in the material is increased, thereby suppressing oxygen evolution and transition metal migration. Compared with traditional cathode materials, the above-mentioned high-entropy doped cathode material has a high discharge specific capacity, while exhibiting minimal capacity and voltage decay during cycling, making it possible to apply cobalt-free high-capacity cathode materials to high-energy-density, long-cycle lithium-ion battery systems.

[0038] In an optional implementation, the amount of each element A is equal, and the subscript of each element A is 0.01-0.02. If the subscript of each element A is too low, the beneficial effect of high-entropy doping cannot be achieved. If the subscript of each element A is too high, it will lead to the formation of impurity phases.

[0039] Preferably, A can be a combination of Mo, Al, Nb, and Fe; a combination of Mo, Al, Nb, Fe, and Ti; a combination of Mo, Al, Nb, Fe, Ti, and Cr, etc.

[0040] In this invention, the crystal structure of the high-entropy doped cathode material is composed of both the R-3m space group and the C2 / m space group. In the structure, lithium layers and transition metal layers are arranged alternately, and excess lithium occupies the octahedral sites of the transition metal layers.

[0041] The following example illustrates the preparation method of high-entropy doped cathode materials.

[0042] Soluble compounds containing Li, Ni, Mn, and A are classified according to the chemical formula Li[Li]. x Ni y Mn z A 1-x-y-z The stoichiometric ratio of O2 is dissolved in an appropriate amount of deionized water to obtain solution 1.

[0043] Citric acid was dissolved in deionized water to obtain solution 2. The molar amount of citric acid in solution 2 was 1 to 2 times the total molar amount of the metal elements (Li, Ni, Mn, and A).

[0044] Add solution 2 to solution 1 and adjust the pH of the mixed solution to 6–8 to promote sol formation and stability. Then, magnetically stir at 70–90°C until a gel forms.

[0045] The gel is placed in an oven to dry, thereby removing the solvent and obtaining a powder. For example, it is dried at 100–140°C for 6–12 hours.

[0046] The dried gel was ground evenly and then calcined in a muffle furnace to obtain the target high-entropy doped cathode material.

[0047] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0048] Example 1

[0049] Sol-gel method for synthesis of lithium-rich, cobalt-free, high-entropy doped cathode material Li[Li 0.2 Ni 0.2 Mn 0.54 Mo 0.015 Al 0.015 Nb 0.015 Fe 0.015 O2 is prepared through the following steps:

[0050] a) Weigh lithium acetate, nickel acetate tetrahydrate, manganese acetate tetrahydrate, ammonium molybdate tetrahydrate, aluminum nitrate nonhydrate, niobium oxalate hydrate, and ferric nitrate nonhydrate according to the molar ratio shown in the chemical formula, dissolve them in deionized water, and mix them evenly to obtain solution 1.

[0051] b) Weigh a certain amount of citric acid monohydrate and dissolve it in deionized water to obtain solution 2, wherein the molar amount of citric acid monohydrate used is twice the total molar amount of the metal elements.

[0052] c) Add solution 2 to solution 1, adjust the pH to 7 with ammonia, and magnetically stir at 80°C until the solution forms a gel;

[0053] d) Place the gel in an oven and dry at 120°C for 12 hours;

[0054] e) Grind the dried gel evenly and place it in a muffle furnace for pre-calcination at 450°C for 6 hours, followed by calcination at 900°C for 12 hours to obtain the target high-entropy doped cathode material.

[0055] Electrode preparation: The high-entropy doped cathode material prepared above was used as the active material and mixed with Super C65 and PVDF (polyvinylidene fluoride) at a mass ratio of 8:1:1. The mixture was magnetically stirred with N-methylpyrrolidone as the solvent to form a slurry. The slurry was coated onto aluminum foil with a scraper and dried in a forced-air drying oven at 70°C for 1 hour, followed by drying in a vacuum drying oven at 100°C for 12 hours. The slurry was then cut into circular electrode sheets.

[0056] Battery assembly: In an argon-filled glove box, the obtained circular electrode sheet was used as the positive electrode, and the lithium disc was used as the negative electrode. The battery casing was a CR2032 button cell, the separator was made of Whatman glass fiber, and the electrolyte was a solution prepared with ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:1 as solvents and 1 mol / L LiPF6 as solute. The button cell was assembled in an argon-filled glove box and tested on a LAND testing system at a temperature of 25°C.

[0057] Figure 1 The image shows a scanning electron microscope (SEM) image of the prepared high-entropy doped cathode material. The sample particles are uniformly distributed and have a small particle size, which is beneficial for the rapid insertion and extraction of lithium ions. Figure 2 The XRD pattern of this layered high-entropy doped cathode material is shown. Figure 3 The graph shows the first charge-discharge curve of the high-entropy doped cathode material at a current density of 25 mA / g. Figure 4 The figure shows the cycling stability of this high-entropy doped cathode material at a current density of 25 mA / g.

[0058] Tests showed that the material had an initial discharge capacity of 245 mAh / g and a reversible discharge capacity of 237 mAh / g at the 100th cycle when tested at a voltage range of 2.0 to 4.8 V and a current density of 25 mA / g, with a capacity retention of approximately 97% and a voltage decay of less than 100 mV.

[0059] Example 2

[0060] Sol-gel method for synthesis of lithium-rich, cobalt-free, high-entropy doped cathode material Li[Li 0.2 Ni 0.2 Mn 0.55 Mo 0.01 Al 0.01 Nb 0.01 Fe 0.01 Ti 0.01 O2 is prepared through the following steps:

[0061] a) Weigh lithium acetate, nickel acetate tetrahydrate, manganese acetate tetrahydrate, ammonium molybdate tetrahydrate, aluminum nitrate nonhydrate, niobium oxalate hydrate, ferric nitrate nonhydrate, and titanium tetrachloride according to the molar ratio shown in the chemical formula, dissolve them in deionized water, and mix them evenly to obtain solution 1.

[0062] b) Weigh a certain amount of citric acid monohydrate and dissolve it in deionized water to obtain solution 2, wherein the molar amount of citric acid monohydrate used is twice the total molar amount of the metal elements.

[0063] c) Add solution 2 to solution 1, adjust the pH to 7 with ammonia, and magnetically stir at 80°C until the solution forms a gel;

[0064] d) Place the gel in an oven and dry at 120°C for 12 hours;

[0065] e) Grind the dried gel evenly and place it in a muffle furnace for pre-calcination at 450°C for 6 hours, followed by calcination at 925°C for 12 hours to obtain the target high-entropy doped cathode material.

[0066] Electrode preparation: The high-entropy doped cathode material prepared above was used as the active material and mixed with Super C65 and PVDF (polyvinylidene fluoride) at a mass ratio of 8:1:1. The mixture was magnetically stirred with N-methylpyrrolidone as the solvent to form a slurry. The slurry was coated onto aluminum foil with a scraper and dried in a forced-air drying oven at 70°C for 1 hour, followed by drying in a vacuum drying oven at 100°C for 12 hours. The slurry was then cut into circular electrode sheets.

[0067] Battery assembly: In an argon-filled glove box, the obtained circular electrode sheet was used as the positive electrode, and the lithium disc was used as the negative electrode. The battery casing was a CR2032 button cell, the separator was made of Whatman glass fiber, and the electrolyte was a solution prepared with ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:1 as solvents and 1 mol / L LiPF6 as solute. The button cell was assembled in an argon-filled glove box and tested on a LAND testing system at a temperature of 25°C.

[0068] Tests showed that the material had an initial discharge capacity of 241 mAh / g and a reversible discharge capacity of 237 mAh / g at the 100th cycle when tested at a voltage range of 2.0 to 4.8 V and a current density of 25 mA / g, with a capacity retention of approximately 98% and a voltage decay of less than 100 mV.

[0069] Example 3

[0070] Sol-gel method for synthesis of lithium-rich, cobalt-free, high-entropy doped cathode material Li[Li 0.2 Ni 0.2 Mn 0.54 Mo 0.01 Al 0.01 Nb 0.01 Fe 0.01 Ti 0.01 Cr 0.01 O2 is prepared through the following steps:

[0071] a) Weigh lithium acetate, nickel acetate tetrahydrate, manganese acetate tetrahydrate, ammonium molybdate tetrahydrate, aluminum nitrate nonhydrate, niobium oxalate hydrate, ferric nitrate nonhydrate, titanium tetrachloride, and chromium nitrate nonhydrate according to the molar ratio shown in the chemical formula, dissolve them in deionized water, and mix them evenly to obtain solution 1.

[0072] b) Weigh a certain amount of citric acid monohydrate and dissolve it in deionized water to obtain solution 2, wherein the molar amount of citric acid monohydrate used is twice the total molar amount of the metal elements.

[0073] c) Add solution 2 to solution 1, adjust the pH to 7 with ammonia, and magnetically stir at 80°C until the solution forms a gel;

[0074] d) Place the gel in an oven and dry at 120°C for 12 hours;

[0075] e) Grind the dried gel evenly and place it in a muffle furnace for pre-calcination at 450°C for 6 hours, followed by calcination at 950°C for 12 hours to obtain the target high-entropy doped cathode material.

[0076] Electrode preparation: The high-entropy doped cathode material prepared above was used as the active material and mixed with Super C65 and PVDF (polyvinylidene fluoride) at a mass ratio of 8:1:1. The mixture was magnetically stirred with N-methylpyrrolidone as the solvent to form a slurry. The slurry was coated onto aluminum foil with a scraper and dried in a forced-air drying oven at 70°C for 1 hour, followed by drying in a vacuum drying oven at 100°C for 12 hours. The slurry was then cut into circular electrode sheets.

[0077] Battery assembly: In an argon-filled glove box, the obtained circular electrode sheet was used as the positive electrode, and the lithium disc was used as the negative electrode. The battery casing was a CR2032 button cell, the separator was made of Whatman glass fiber, and the electrolyte was a solution prepared with ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:1 as solvents and 1 mol / L LiPF6 as solute. The button cell was assembled in an argon-filled glove box and tested on a LAND testing system at a temperature of 25°C.

[0078] Tests showed that the material had an initial discharge capacity of 248 mAh / g and a reversible discharge capacity of 236 mAh / g at the 100th cycle when tested at a voltage range of 2.0 to 4.8 V and a current density of 25 mA / g, with a capacity retention of approximately 95% and a voltage decay of less than 120 mV.

[0079] Example 4

[0080] In Example 4, the lithium-rich, cobalt-free, high-entropy doped cathode material Li[Li] was synthesized using the sol-gel method. 0.2 Ni 0.2 Mn 0.525 Mo 0.015 Al 0.015 Nb 0.015 Fe 0.015 Ti 0.015 For details on O2, please refer to Example 2.

[0081] Comparative Example 1

[0082] Sol-gel method for synthesizing conventional lithium-rich manganese-based cathode material Li[Li 0.2 Ni 0.2 Mn 0.6 O2 is prepared through the following steps:

[0083] a) Weigh lithium acetate, nickel acetate tetrahydrate, and manganese acetate tetrahydrate according to the molar ratio shown in the chemical formula, dissolve them in deionized water, and mix them evenly to obtain solution 1.

[0084] b) Weigh a certain amount of citric acid monohydrate and dissolve it in deionized water to obtain solution 2, wherein the molar amount of citric acid monohydrate used is twice the total molar amount of the metal elements.

[0085] c) Add solution 2 to solution 1, adjust the pH to 7 with ammonia, and magnetically stir at 80°C until the solution forms a gel;

[0086] d) Place the gel in an oven and dry at 120°C for 12 hours;

[0087] e) Grind the dried gel evenly and place it in a muffle furnace for pre-calcination at 450°C for 6 hours, followed by calcination at 900°C for 12 hours to obtain the target high-entropy doped cathode material.

[0088] Electrode preparation: The high-entropy doped cathode material prepared above was used as the active material and mixed with Super C65 and PVDF (polyvinylidene fluoride) at a mass ratio of 8:1:1. The mixture was magnetically stirred with N-methylpyrrolidone as the solvent to form a slurry. The slurry was coated onto aluminum foil with a scraper and dried in a forced-air drying oven at 70°C for 1 hour, followed by drying in a vacuum drying oven at 100°C for 12 hours. The slurry was then cut into circular electrode sheets.

[0089] Battery assembly: In an argon-filled glove box, the obtained circular electrode sheet was used as the positive electrode, and the lithium disc was used as the negative electrode. The battery casing was a CR2032 button cell, the separator was made of Whatman glass fiber, and the electrolyte was a solution prepared with ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:1 as solvents and 1 mol / L LiPF6 as solute. The button cell was assembled in an argon-filled glove box and tested on a LAND testing system at a temperature of 25°C.

[0090] Figure 5 The image shows a scanning electron microscope (SEM) image of the prepared conventional lithium-rich manganese-based cathode material. Figure 6 The XRD pattern of this layered conventional lithium-rich manganese-based cathode material is shown. Figure 7 The graph shows the first charge-discharge curve of the high-entropy doped cathode material at a current density of 25 mA / g. Figure 8The figure shows the cycling stability of this high-entropy doped cathode material at a current density of 25 mA / g.

[0091] Tests showed that the material had an initial discharge capacity of 240 mAh / g and a reversible discharge capacity of 211 mAh / g at the 100th cycle when tested at a voltage range of 2.0 to 4.8 V and a current density of 25 mA / g. The capacity retention rate was less than 90%, and the voltage decay was greater than 150 mV.

[0092] Comparative Example 2

[0093] In Comparative Example 2, the lithium-rich, cobalt-free, high-entropy doped cathode material Li[Li] was synthesized using the sol-gel method. 0.2 Ni 0.2 Mn 0.575 Mo 0.005 Al 0.005 Nb 0.005 Fe 0.005 Ti 0.005 For details on O2, please refer to Example 2.

[0094] Comparative Example 3

[0095] In Comparative Example 3, the lithium-rich, cobalt-free, high-entropy doped cathode material Li[Li] was synthesized using the sol-gel method. 0.2 Ni 0.2 Mn 0.475 Mo 0.025 Al 0.025 Nb 0.025 Fe 0.025 Ti 0.025 For details on O2, please refer to Example 2.

[0096] Table 1:

[0097] A1 A2 A3 A4 A5 A6 x y z Subscript A Example 1 Mo Al Nb Fe - - 0.2 0.2 0.54 0.015 Example 2 Mo Al Nb Fe Ti - 0.2 0.2 0.55 0.01 Example 3 Mo Al Nb Fe Ti Cr 0.2 0.2 0.54 0.01 Example 4 Mo Al Nb Fe Ti - 0.2 0.2 0.525 0.015 Comparative Example 1 - - - - - - 0.2 0.2 0.6 0 Comparative Example 2 Mo Al Nb Fe Ti - 0.2 0.2 0.575 0.005 Comparative Example 3 Mo Al Nb Fe Ti - 0.2 0.2 0.475 0.025 .

[0098] Table 2:

[0099] Initial discharge capacity 100-cycle reversible discharge capacity 100-cycle retention rate / % Voltage attenuation Example 1 245mAh / g 237mAh / g 97％ <100mV Example 2 241mAh / g 237mAh / g 98％ <100mV Example 3 248mAh / g 236mAh / g 95％ <120mV Example 4 244mAh / g 234mAh / g 96％ <120mV Comparative Example 1 240mAh / g 211mAh / g 88％ >150mV Comparative Example 2 238mAh / g 217mAh / g 91％ >130mV Comparative Example 3 247mAh / g 230mAh / g 93％ >130mV .

Claims

1. A lithium-rich, cobalt-free, high-entropy doped cathode material, characterized in that, The chemical formula of the lithium-rich, cobalt-free, high-entropy doped cathode material is Li[Li x Ni y Mn z A 1-x-y-z O2; wherein, 0.1≤x≤0.25, 0.15≤y≤0.25, 0.45≤z≤0.58, 0.04≤1-xyz≤0.15; the A is at least 4 of Mg, Al, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Zr, Nb, Mo, Ru, Sn, Sb, Te, La, Ta, and W; the content of each A element subscript is between 0.01 and 0.02 and the amount of each A element is equal; the crystal structure of the lithium-rich cobalt-free high-entropy doped cathode material is composed of both R-3m space group and C2 / m space group, in which lithium layers and transition metal layers are arranged alternately, and excess lithium occupies the octahedral sites of the transition metal layer.

2. The lithium-rich, cobalt-free, high-entropy doped cathode material according to claim 1, characterized in that, 0.15≤x≤0.20, 0.18≤y≤0.22, 0.52≤z≤0.

57.

3. The lithium-rich, cobalt-free, high-entropy doped cathode material according to claim 1 or 2, characterized in that, A is a combination of Mo, Al, Nb, and Fe; Alternatively, A can be a combination of Mo, Al, Nb, Fe, and Ti; Alternatively, A can be a combination of Mo, Al, Nb, Fe, Ti, and Cr.

4. A method for preparing a lithium-rich, cobalt-free, high-entropy doped cathode material according to any one of claims 1-3, characterized in that, include: (1) Soluble compounds containing Li, soluble compounds containing Ni, soluble compounds containing Mn, and soluble compounds containing A are classified according to the chemical formula Li[Li x Ni y Mn z A 1-x-y-z The stoichiometric ratio of O2 is dissolved in deionized water to obtain solution 1; (2) Dissolve citric acid, which has a molar number 1 to 2 times that of the metal element, in deionized water to obtain solution 2; (3) Add solution 2 to solution 1, adjust the pH of the mixture to 6-8, and then stir magnetically at 70℃-90℃ until a gel is formed; (4) The gel is dried, ground and calcined to obtain the lithium-rich cobalt-free high-entropy doped cathode material.

5. The preparation method according to claim 4, characterized in that, In step (1): the Li-containing soluble compound is selected from at least one of Li carbonates, acetates, nitrates, and halides; The Ni-containing soluble compound is selected from at least one of Ni acetate, nitrate, sulfate, and halide. The Mn-containing soluble compound is selected from at least one of the following: Mn acetate, nitrate, sulfate, and halide. The soluble compound containing A is selected from at least one of the following: acetate of A, oxalate of A, nitrate of A, sulfate of A, and halide of A, wherein A is at least four of the following: Mg, Al, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Zr, Nb, Mo, Ru, Sn, Sb, Te, La, Ta, and W.

6. The preparation method according to claim 4, characterized in that, In step (4): the drying parameters include: drying at 100-140℃ for 6-12 hours; The calcination parameters include: pre-calcination at 400-500℃ for 4-8 hours, followed by calcination at 850-950℃ for 8-16 hours.

7. An electrode, characterized in that, include: A current collector and an electrode layer coated on the surface of the current collector; the composition of the electrode layer comprises the lithium-rich, cobalt-free, high-entropy doped cathode material as described in any one of claims 1-3.

8. The electrode according to claim 7, characterized in that, The electrode layer comprises a lithium-rich, cobalt-free, high-entropy doped cathode material, a conductive agent, and a binder; the mass ratio of the lithium-rich, cobalt-free, high-entropy doped cathode material, the conductive agent, and the binder is (7-8):(2-1):

1.

9. A high-energy-density battery, characterized in that, include: A positive electrode, a negative electrode, a separator, and an electrolyte; wherein the positive electrode comprises the lithium-rich, cobalt-free, high-entropy doped positive electrode material according to any one of claims 1-3.

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