High entropy layered oxide sodium ion battery cathode material, preparation method and application

Abstract

The present invention belongs to the technical field of sodium ion batteries, and specifically relates to a high entropy layered oxide sodium ion battery positive electrode material, a preparation method and an application thereof. The steps include: mixing a nickel source, a manganese source, a titanium source and a zirconium source, adding a sodium source, ball milling and vacuum drying, and then calcining at a high temperature to obtain an O3 phase layered high entropy oxide material NaNi 0.45 Mn 0.3 Ti 0.2 Zr 0.05 O2 (abbreviated as NaNMTZ positive electrode material); NaNMTZ material, a carbon source, an inorganic substance, and an organic solvent are mixed, magnetically stirred, and then the organic solvent is removed by rotary evaporation. The resulting mixture is heat-treated to remove inorganic substances, centrifuged, and vacuum-dried to obtain a nitrogen-doped NaNMTZ / C composite material. The cathode material prepared by this invention has a regular surface, high crystallinity, uniform dispersion, and excellent conductivity. This structure exhibits a considerable wide potential window reversible capacity, excellent rate capability, and a stable cycle life.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium ion batteries, and in particular relates to a high-entropy layered oxide sodium ion battery positive electrode material, a preparation method and an application thereof. Background Art

[0002] With the rapid development of information technology, energy production and utilization play a vital role in maintaining the normal operation of modern society. With the continuous depletion of fossil fuels and the increasing environmental problems, the demand for renewable clean energy such as wind, solar, and tidal power is rapidly increasing. To integrate these intermittent and regional energy sources into a practical large-scale power grid, inexpensive and efficient energy storage systems are crucial for fully storing energy during peak and valley periods and releasing it during peak periods. However, limited lithium resources have restricted the further development of lithium-ion batteries. Compared to lithium, the abundance of sodium in the Earth's crust makes sodium-based raw materials inexpensive. Their similar physicochemical properties to lithium and their similar "rocking chair" operating principle to lithium-ion batteries allow sodium-ion batteries to fully leverage the established methods and processes of lithium-ion batteries. Currently, the specific capacity, energy density, and rate performance of sodium-ion batteries are primarily limited by the cathode material. The development of low-cost, high-energy-density, and high-power-density sodium-ion cathode materials remains a major challenge.

[0003] High-entropy oxides (HEOs), first proposed in 2015, are typically composed of five or more elements in equiatomic or near-equiatomic ratios. These elements share common atomic sites to form a unified lattice, exhibiting a disordered arrangement within the crystal. This disordered distribution, coupled with the interactions between different metal ions, results in a high mixing entropy, effectively suppressing the formation of intermetallic compounds or complex phases, thereby favoring a single-phase solid solution structure. Due to the thermodynamic high-entropy effect, kinetic hysteresis diffusion, structural lattice distortion, and "cocktail" effects similar to those observed in high-entropy alloys, HEOs exhibit properties far superior to those of traditional oxides, including extremely high structural stability, exceptional dielectric constants, and ultrahigh lithium-ion and sodium-ion conductivity. These properties have spurred interest in HEOs among energy storage researchers. However, as cathode materials for sodium-ion batteries, these materials still suffer from low ionic and electronic conductivity, high charge transfer resistance, and poor rate capability. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides a high entropy layered oxide sodium ion battery cathode material and a preparation method and application thereof. The material is an O3 type nitrogen-doped layered material NaNi with a stable phase structure. 0.45 Mn 0.3 T i0.2 Zr0.05 O2(NaNMTZ), a hierarchical structure of nitrogen-doped carbon with excellent conductivity, boasts structural advantages such as uniform dispersion, good crystallinity, and small and uniform particle size, providing a good foundation for its excellent electrochemical performance. Furthermore, through the rational design of the incorporated transition metal elements and nitrogen-doped carbon, the overall conductivity of the material is enhanced, effectively increasing the ion diffusion rate of the high-entropy oxide as a cathode material for sodium-ion batteries, improving electronic conductivity, and enhancing its rate performance.

[0005] The method for preparing a high entropy layered oxide sodium ion battery cathode material of the present invention comprises the following steps:

[0006] (1) uniformly mixing a nickel source, a manganese source, a titanium source, and a zirconium source to prepare a material A;

[0007] (2) mixing material A with a sodium source and ball milling to obtain a fully mixed slurry, and then drying the slurry to prepare precursor B;

[0008] (3) heating the precursor B, then cooling it to room temperature, grinding and sieving it to obtain NaNMTZ layered high entropy oxide sodium ion battery cathode material;

[0009] (4) mixing a NaNMTZ layered high entropy oxide sodium ion battery cathode material, a carbon source, and an inorganic substance, adding an organic solvent, and performing ultrasonic stirring to obtain a mixture;

[0010] (5) The mixture in the above step (4) is heated under a mixed atmosphere, cooled to room temperature, washed by centrifugation with hydrochloric acid, and dried to obtain a high entropy layered oxide sodium ion battery positive electrode material.

[0011] The molar ratio of the nickel source, manganese source, titanium source and zirconium source in step (1) is (9-10): (5-6): 4: 1;

[0012] The molar ratio of material A to the sodium source in step (2) is 1:1; the sodium source is a mixture of sodium carbonate, sodium oxalate and sodium hydroxide, and the molar ratio of the mixture of sodium carbonate, sodium oxalate and sodium hydroxide is (9-10):0.65:0.35; the ball milling is specifically performed in a planetary ball mill for 9-10 hours, and the speed of the planetary ball mill is 300r / min; the grinding is performed in an agate mortar;

[0013] The drying in step (2) is specifically drying in a vacuum drying oven at 70-80° C. for 10-12 h;

[0014] The heating in step (3) is specifically to raise the temperature to 900-950°C at a heating rate of (4.5-5)°C / min in an air atmosphere and keep the temperature for 10-12 hours; the grinding is performed in an agate mortar; and the sieving is performed using a 200-mesh sieve (pore size 0.074 mm);

[0015] The carbon source described in step (4) is a mixture of petroleum asphalt, high-temperature coal tar pitch and urea, and the mass ratio of petroleum asphalt, high-temperature coal tar pitch and urea is 3:(3-4):3; the inorganic substance described in step (4) is a mixture of NaCl and nano-MgO, and the mass ratio of NaCl and nano-MgO is 4:(1-1.5); the organic solvent in step (4) is a mixture of toluene, ethylene glycol and anhydrous ethanol, and the volume ratio of toluene, ethylene glycol and anhydrous ethanol is (4-6):3:(1-1.5);

[0016] The mass ratio of the NaNMTZ layered high entropy oxide sodium ion battery positive electrode material, the carbon source and the inorganic substance in step (4) is 1:10:(200-250); the amount of the organic solvent added is (18-23) mL of organic solvent per gram of carbon source;

[0017] The ultrasonic stirring in step (4) is specifically to perform ultrasonic dispersion for 1-1.5 hours and then to perform strong magnetic stirring for 10-12 hours to remove the organic solvent;

[0018] The mixed atmosphere in step (5) is a mixed gas of NH3 and N2, and the volume ratio of NH3 to N2 is 5:(90-95);

[0019] The heating in step (5) is to raise the temperature to 600-800°C and keep it warm for 1-2 hours;

[0020] The concentration of the hydrochloric acid in step (5) is (0.9-1.2) mol / L; the drying is vacuum drying, and the drying time is 10-12 hours.

[0021] The application of the high entropy layered oxide sodium ion battery positive electrode material comprises the following steps:

[0022] The nitrogen-doped NaNMTZ / C composite material obtained in the above steps was used as the research electrode and a sodium metal sheet as the counter electrode in an argon-filled glove box to construct a CR2025 button-type sodium-ion battery. Charge and discharge cycles were performed in the potential range of 2-4.0 V. At a current of 0.5 C, the initial reversible specific capacity ranged from 81.73 to 104.58 mAh / g, and after 100 cycles, the capacity retention reached 61.2% to 68.8%, demonstrating excellent charge-discharge performance and cycling stability.

[0023] Compared with the prior art, the preparation method and application of the high entropy layered oxide sodium ion battery positive electrode material of the present invention have the following beneficial effects:

[0024] 1. The transition metal element doping selected in the present invention not only helps to improve the crystallinity of the layered oxide, but also effectively reduces the impedance of the positive electrode material, improves the stability of the sodium ion channel and the reversibility of the sodium ion cyclic deintercalation, and ensures that the battery has a high specific capacity after multiple cycles, thereby improving the performance of the electrode material and improving the performance of the sodium ion battery.

[0025] 2. The layered high entropy oxide sodium ion battery positive electrode material prepared by the present invention has structural advantages such as regular surface, high crystallinity, and uniform distribution, which is beneficial to improving the electrochemical performance of the material.

[0026] 3. NaNi prepared by the present invention 0.45 Mn 0.3 Ti 0.2 Zr 0.05 O2 / C layered high entropy oxide sodium ion battery positive electrode material has a high electron and ion transfer rate, excellent performance, and has a high reversible charge and discharge capacity and cycle performance.

[0027] 4. The preparation method of the present invention has the characteristics of low equipment requirements, strong controllability, short production cycle, low raw material cost and easy industrial production. It can effectively meet the actual needs of various applications of sodium ion batteries and has important social and economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the cycle performance curve of the layered high entropy oxide sodium ion battery positive electrode material obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] Example 1

[0030] A method for preparing a layered high entropy oxide sodium ion battery positive electrode material comprises the following steps:

[0031] 0.03 mol of nickel oxide, 0.015 mol of nickel hydroxide, 0.02 mol of manganese dioxide, 0.01 mol of manganese (IV) hydroxide, 0.018 mol of titanium dioxide, 0.002 mol of titanic acid, 0.0045 mol of zirconium dioxide and 0.0005 mol of zirconium hydroxide were prepared into powders and mixed evenly to obtain material A; material A was mixed with 0.09 mol of sodium carbonate, 0.0065 mol of sodium oxalate and 0.0035 mol of sodium hydroxide, and ball-milled for 10 hours to obtain a fully mixed slurry, which was then vacuum-dried at 80°C for 12 hours to obtain precursor B; precursor B was heated to 950°C in an air atmosphere at a heating rate of 5°C / min, kept warm for 12 hours, cooled to room temperature with the furnace, and then placed in an agate mortar for grinding and sieved to obtain NaNMTZ layered material.

[0032] A mixture of 0.1g NaNMTZ, 0.3g petroleum asphalt, 0.4g high-temperature coal tar, 0.3g urea, 20g NaCl, and nano-MgO (in a mass ratio of 4:1) and 20mL of a mixture of toluene, ethylene glycol, and anhydrous ethanol (in a volume ratio of 6:3:1) were added to a 50mL round-bottom flask. After ultrasonic dispersion for 1.5h, the mixture was subjected to strong magnetic stirring for 12h. The toluene, ethylene glycol, and anhydrous ethanol were removed by rotary evaporation. The mixture, after removal of toluene, ethylene glycol, and anhydrous ethanol, was transferred to a tube furnace and heated to 700°C in a mixed gas of NH3 and N2 (in a volume ratio of 5:95) for 1.5h. After cooling to room temperature, the NaCl and nano-MgO in the mixture were removed with 1mol / L hydrochloric acid. After centrifugal washing, the mixture was vacuum dried for 12h to obtain the nitrogen-doped NaNMTZ / C composite. The resulting product was used as the research electrode and a sodium metal sheet as the counter electrode to assemble a CR2025 button-type sodium-ion battery in an argon-filled glove box. Charge and discharge cycles were performed in the potential range of 2-4.0 V. At a current of 0.5C, the initial reversible specific capacity was 104.58 mAh / g, and the capacity retention rate reached 65.2% after 100 cycles, demonstrating excellent charge and discharge performance and cycle stability. The cycle performance curve of the layered high-entropy oxide sodium-ion battery positive electrode material is shown in the figure below. Figure 1 shown.

[0033] Example 2

[0034] A method for preparing a layered high entropy oxide sodium ion battery positive electrode material comprises the following steps:

[0035] 0.03 mol of nickel oxide, 0.015 mol of nickel hydroxide, 0.02 mol of manganese dioxide, 0.01 mol of manganese (IV) hydroxide, 0.018 mol of titanium dioxide, 0.002 mol of titanic acid, 0.0044 mol of zirconium dioxide and 0.0006 mol of zirconium hydroxide were prepared into powders and mixed evenly to obtain material A; material A was mixed with 0.09 mol of sodium carbonate, 0.0065 mol of sodium oxalate and 0.0035 mol of sodium hydroxide, and ball milled for 10 hours to obtain a fully mixed slurry, which was then vacuum dried at 80°C for 10 hours to obtain precursor B; precursor B was heated to 950°C in an air atmosphere at a heating rate of 4.5°C / min, kept warm for 12 hours, cooled to room temperature with the furnace, and then placed in an agate mortar for grinding and sieved to obtain NaNMTZ layered material.

[0036] A mixture of 0.1g NaNMTZ, 0.33g petroleum asphalt, 0.34g high-temperature coal tar, 0.33g urea, 20g NaCl, and nano-MgO (in a mass ratio of 4:1) was added to a 50mL round-bottom flask along with 20mL of a mixture of toluene, ethylene glycol, and anhydrous ethanol (in a volume ratio of 4:3:1). The mixture was ultrasonically dispersed for 1.5h and then magnetically stirred for 12h. The toluene, ethylene glycol, and anhydrous ethanol were then removed by rotary evaporation. The mixture, after removal of toluene, ethylene glycol, and anhydrous ethanol, was then heated to 700°C in a tube furnace under a mixture of NH3 and N2 (in a volume ratio of 5:95) and held at that temperature for 1.5h. After cooling to room temperature, the NaCl and nano-MgO were removed from the mixture using 0.9mol / L hydrochloric acid. The mixture was then centrifuged and dried in vacuo for 12h to yield the nitrogen-doped NaNMTZ / C composite. The resulting product was used as the research electrode and a sodium metal sheet as the counter electrode in an argon-filled glove box to construct a CR2025 button-type sodium-ion battery. Charge and discharge cycles were performed within the potential range of 2-4.0 V. At a current of 0.5 C, the initial reversible specific capacity was 81.73 mAh / g, and after 100 cycles, the capacity retention reached 68.8%, demonstrating excellent charge-discharge performance and cycling stability.

[0037] Example 3

[0038] A method for preparing a layered high entropy oxide sodium ion battery positive electrode material comprises the following steps:

[0039] 0.03 mol of nickel oxide, 0.015 mol of nickel hydroxide, 0.0225 mol of manganese dioxide, 0.0075 mol of manganese (IV) hydroxide, 0.0179 mol of titanium dioxide, 0.0021 mol of titanic acid, 0.0045 mol of zirconium dioxide and 0.0005 mol of zirconium hydroxide were prepared into powders and mixed evenly to obtain material A; material A was mixed with 0.0909 mol of sodium carbonate, 0.0059 mol of sodium oxalate and 0.0032 mol of sodium hydroxide, and ball-milled for 10 hours to obtain a fully mixed slurry, which was then vacuum-dried at 80°C for 10 hours to obtain precursor B; precursor B was heated to 950°C in an air atmosphere at a heating rate of 5°C / min, kept warm for 12 hours, cooled to room temperature with the furnace, and then placed in an agate mortar for grinding and sieved to obtain NaNMTZ layered material.

[0040] A mixture of 0.1g NaNMTZ, 0.32g petroleum asphalt, 0.36g high-temperature coal tar, 0.32g urea, 25g NaCl, and nano-MgO (in a mass ratio of 4:1.5) was added to a 50mL round-bottom flask along with 23mL of a mixture of toluene, ethylene glycol, and anhydrous ethanol (in a volume ratio of 6:3:1.5). The mixture was ultrasonically dispersed for 1.5h and then subjected to strong magnetic stirring for 12h. The toluene, ethylene glycol, and anhydrous ethanol were then removed by rotary evaporation. The mixture, after removal of toluene, ethylene glycol, and anhydrous ethanol, was then heated to 700°C in a tube furnace under a mixture of NH3 and N2 (in a volume ratio of 5:95) and held at that temperature for 1.5h. After cooling to room temperature, the NaCl and nano-MgO were removed from the mixture using 0.9mol / L hydrochloric acid. The mixture was then centrifuged and dried in vacuo for 12h to yield the nitrogen-doped NaNMTZ / C composite. The resulting product was used as the research electrode and a sodium metal sheet as the counter electrode in an argon-filled glove box to form a CR2025 button-type sodium-ion battery. Charge and discharge cycles were performed in the potential range of 2-4.0 V. At a current of 0.5 C, the initial reversible specific capacity was 95.38 mAh / g, and after 100 cycles, the capacity retention reached 62.2%, demonstrating excellent charge-discharge performance and cycling stability.

[0041] Example 4

[0042] A method for preparing a layered high entropy oxide sodium ion battery positive electrode material comprises the following steps:

[0043] 0.03 mol of nickel oxide, 0.015 mol of nickel hydroxide, 0.0225 mol of manganese dioxide, 0.0075 mol of manganese (IV) hydroxide, 0.0179 mol of titanium dioxide, 0.0021 mol of titanic acid, 0.0044 mol of zirconium dioxide and 0.0006 mol of zirconium hydroxide were prepared into powders and mixed evenly to obtain material A; material A was mixed with 0.09 mol of sodium carbonate, 0.0065 mol of sodium oxalate and 0.0035 mol of sodium hydroxide, and ball milled for 10 hours to obtain a fully mixed slurry, which was then vacuum dried at 80°C for 12 hours to obtain precursor B; precursor B was heated to 950°C in an air atmosphere at a heating rate of 5°C / min, kept warm for 12 hours, cooled to room temperature with the furnace, and then placed in an agate mortar for grinding and sieved to obtain NaNMTZ layered material.

[0044] A mixture of 0.1g NaNMTZ, 0.33g petroleum asphalt, 0.34g high-temperature coal tar, 0.33g urea, 20g NaCl, and nano-MgO (in a mass ratio of 4:1.2) and 20mL of a mixture of toluene, ethylene glycol, and anhydrous ethanol (in a volume ratio of 6:3:1) were added to a 50mL round-bottom flask. After ultrasonic dispersion for 1.5h, the mixture was subjected to strong magnetic stirring for 12h. The toluene, ethylene glycol, and anhydrous ethanol were removed by rotary evaporation. The mixture, after removal of toluene, ethylene glycol, and anhydrous ethanol, was transferred to a tube furnace and heated to 700°C in a mixed gas of NH3 and N2 (in a volume ratio of 5:95) for 1.5h. After cooling to room temperature, the NaCl and nano-MgO in the mixture were removed with 1.2mol / L hydrochloric acid. After centrifugal washing, the mixture was vacuum dried for 12h to obtain the nitrogen-doped NaNMTZ / C composite. The resulting product was used as the research electrode and a sodium metal sheet as the counter electrode in an argon-filled glove box to form a CR2025 button-type sodium-ion battery. Charge and discharge cycles were performed in the potential range of 2-4.0 V. At a current of 0.5 C, the initial reversible specific capacity was 88.93 mAh / g, and after 100 cycles, the capacity retention reached 66.2%, demonstrating excellent charge-discharge performance and cycling stability.

[0045] Example 5

[0046] A method for preparing a layered high entropy oxide sodium ion battery positive electrode material comprises the following steps:

[0047] 0.027 mol of nickel oxide, 0.018 mol of nickel hydroxide, 0.02 mol of manganese dioxide, 0.01 mol of manganese (IV) hydroxide, 0.0179 mol of titanium dioxide, 0.0021 mol of titanic acid, 0.0045 mol of zirconium dioxide and 0.0005 mol of zirconium hydroxide were prepared into powders and mixed evenly to obtain material A; material A was mixed with 0.0909 mol of sodium carbonate, 0.0059 mol of sodium oxalate and 0.0032 mol of sodium hydroxide, and ball milled for 10 hours to obtain a fully mixed slurry, which was then vacuum dried at 70°C for 12 hours to obtain precursor B; precursor B was heated to 950°C in an air atmosphere at a heating rate of 4.5°C / min, kept warm for 12 hours, cooled to room temperature with the furnace, and then placed in an agate mortar for grinding and sieved to obtain NaNMTZ layered material.

[0048] A mixture of 0.1g NaNMTZ, 0.32g petroleum asphalt, 0.36g high-temperature coal tar, 0.32g urea, 25g NaCl, and nano-MgO (in a mass ratio of 4:1) was added to a 50mL round-bottom flask along with 20mL of a mixture of toluene, ethylene glycol, and anhydrous ethanol (in a volume ratio of 6:3:1.5). The mixture was ultrasonically dispersed for 1.5h and then subjected to strong magnetic stirring for 12h. The toluene, ethylene glycol, and anhydrous ethanol were then removed by rotary evaporation. The mixture, after removal of toluene, ethylene glycol, and anhydrous ethanol, was then heated to 700°C in a tube furnace under a mixture of NH3 and N2 (in a volume ratio of 5:90) and held at that temperature for 1.5h. After cooling to room temperature, the NaCl and nano-MgO were removed from the mixture using 1mol / L hydrochloric acid. The mixture was then centrifuged and washed and then vacuum dried for 12h to obtain the nitrogen-doped NaNMTZ / C composite. The resulting product was used as the research electrode and a sodium metal sheet as the counter electrode in an argon-filled glove box to form a CR2025 button-type sodium-ion battery. Charge and discharge cycles were performed in the potential range of 2-4.0 V. At a current of 0.5 C, the initial reversible specific capacity was 91.55 mAh / g, and after 100 cycles, the capacity retention reached 65.1%, demonstrating excellent charge-discharge performance and cycling stability.

[0049] Example 6

[0050] A method for preparing a layered high entropy oxide sodium ion battery positive electrode material comprises the following steps:

[0051] 0.027 mol of nickel oxide, 0.018 mol of nickel hydroxide, 0.02 mol of manganese dioxide, 0.01 mol of manganese (IV) hydroxide, 0.0179 mol of titanium dioxide, 0.0021 mol of titanic acid, 0.0044 mol of zirconium dioxide and 0.0006 mol of zirconium hydroxide were prepared into powders and mixed evenly to obtain material A; material A was mixed with 0.0909 mol of sodium carbonate, 0.0059 mol of sodium oxalate and 0.0032 mol of sodium hydroxide, and ball-milled for 9 hours to obtain a fully mixed slurry, which was then vacuum-dried at 70°C for 10 hours to obtain precursor B; precursor B was heated to 950°C in an air atmosphere at a heating rate of 5°C / min, kept warm for 12 hours, cooled to room temperature with the furnace, and then placed in an agate mortar for grinding and sieved to obtain NaNMTZ layered material.

[0052] A mixture of 0.1g NaNMTZ, 0.33g petroleum asphalt, 0.34g high-temperature coal tar, 0.33g urea, 20g NaCl, and nano-MgO (in a mass ratio of 4:1) was added to a 50mL round-bottom flask along with 20mL of a mixture of toluene, ethylene glycol, and anhydrous ethanol (in a volume ratio of 5:3:1). The mixture was ultrasonically dispersed for 1.5h and then subjected to strong magnetic stirring for 12h. The toluene, ethylene glycol, and anhydrous ethanol were then removed by rotary evaporation. The mixture, after removal of toluene, ethylene glycol, and anhydrous ethanol, was then heated to 700°C in a tube furnace under a mixture of NH3 and N2 (in a volume ratio of 3:95) and held at that temperature for 1.5h. After cooling to room temperature, the NaCl and nano-MgO were removed from the mixture using 1mol / L hydrochloric acid. The mixture was then centrifuged and washed and then vacuum dried for 12h to obtain the nitrogen-doped NaNMTZ / C composite. The resulting product was used as the research electrode and a sodium metal sheet as the counter electrode in an argon-filled glove box to form a CR2025 button-type sodium-ion battery. Charge and discharge cycles were performed in the potential range of 2-4.0 V. At a current of 0.5 C, the initial reversible specific capacity was 92.45 mAh / g, and after 100 cycles, the capacity retention reached 64.4%, demonstrating excellent charge-discharge performance and cycling stability.

[0053] Example 7

[0054] A method for preparing a layered high entropy oxide sodium ion battery positive electrode material comprises the following steps:

[0055] 0.027 mol of nickel oxide, 0.018 mol of nickel hydroxide, 0.0225 mol of manganese dioxide, 0.0075 mol of manganese (IV) hydroxide, 0.018 mol of titanium dioxide, 0.002 mol of titanic acid, 0.0045 mol of zirconium dioxide and 0.0005 mol of zirconium hydroxide were prepared into powders and mixed evenly to obtain material A; material A was mixed with 0.09 mol of sodium carbonate, 0.0065 mol of sodium oxalate and 0.0035 mol of sodium hydroxide, and ball-milled for 9 hours to obtain a fully mixed slurry, which was then vacuum-dried at 70°C for 10 hours to obtain precursor B; precursor B was heated to 950°C in an air atmosphere at a heating rate of 5°C / min, kept warm for 12 hours, cooled to room temperature with the furnace, and then placed in an agate mortar for grinding and sieved to obtain NaNMTZ layered material.

[0056] A mixture of 0.1g NaNMTZ, 0.33g petroleum asphalt, 0.34g high-temperature coal tar, 0.33g urea, 20g NaCl, and nano-MgO (in a mass ratio of 4:1) was added to a 50mL round-bottom flask along with 20mL of a mixture of toluene, ethylene glycol, and anhydrous ethanol (in a volume ratio of 6:3:1). The mixture was ultrasonically dispersed for 1.5h and then subjected to strong magnetic stirring for 12h. The toluene, ethylene glycol, and anhydrous ethanol were then removed by rotary evaporation. The mixture, after removal of toluene, ethylene glycol, and anhydrous ethanol, was then heated to 700°C in a tube furnace under a mixture of NH3 and N2 (in a volume ratio of 5:95) and held at that temperature for 1.5h. After cooling to room temperature, the NaCl and nano-MgO were removed from the mixture using 1mol / L hydrochloric acid. The mixture was then centrifuged and washed and then vacuum dried for 12h to obtain the nitrogen-doped NaNMTZ / C composite. The resulting product was used as the research electrode and a sodium metal sheet as the counter electrode in an argon-filled glove box to construct a CR2025 button-type sodium-ion battery. Charge and discharge cycles were performed within the potential range of 2-4.0 V. At a current of 0.5 C, the initial reversible specific capacity was 84.58 mAh / g, and after 100 cycles, the capacity retention reached 66.2%, demonstrating excellent charge-discharge performance and cycling stability.

[0057] Example 8

[0058] A method for preparing a layered high entropy oxide sodium ion battery positive electrode material comprises the following steps:

[0059] 0.027 mol of nickel oxide, 0.018 mol of nickel hydroxide, 0.0225 mol of manganese dioxide, 0.0075 mol of manganese (IV) hydroxide, 0.018 mol of titanium dioxide, 0.002 mol of titanic acid, 0.0044 mol of zirconium dioxide and 0.0006 mol of zirconium hydroxide were prepared into powders and mixed evenly to obtain material A; material A was mixed with 0.0909 mol of sodium carbonate, 0.0059 mol of sodium oxalate and 0.0032 mol of sodium hydroxide, and ball-milled for 9 hours to obtain a fully mixed slurry, which was then vacuum-dried at 70°C for 12 hours to obtain precursor B; precursor B was heated to 950°C in an air atmosphere at a heating rate of 5°C / min, kept warm for 12 hours, cooled to room temperature with the furnace, and then placed in an agate mortar for grinding and sieved to obtain NaNMTZ layered material.

[0060] A mixture of 0.1g NaNMTZ, 0.3g petroleum asphalt, 0.4g high-temperature coal tar, 0.3g urea, 20g NaCl, and nano-MgO (in a mass ratio of 4:1) and 18mL of a mixture of toluene, ethylene glycol, and anhydrous ethanol (in a volume ratio of 6:3:1) were added to a 50mL round-bottom flask. The mixture was ultrasonically dispersed for 1.5h and then magnetically stirred for 12h. The toluene, ethylene glycol, and anhydrous ethanol were removed by rotary evaporation. The mixture, after removal of toluene, ethylene glycol, and anhydrous ethanol, was transferred to a tube furnace and heated to 700°C in a mixed gas of NH3 and N2 (in a volume ratio of 5:95) for 1.5h. After cooling to room temperature, the NaCl and nano-MgO in the mixture were removed with 1.2mol / L hydrochloric acid. After centrifugation and washing, it was vacuum-dried for 12h to obtain the nitrogen-doped NaNMTZ / C composite. The resulting product was used as the research electrode and a sodium metal sheet as the counter electrode in an argon-filled glove box to form a CR2025 button-type sodium-ion battery. Charge and discharge cycles were performed in the potential range of 2-4.0 V. At a current of 0.5 C, the initial reversible specific capacity was 86.58 mAh / g, and after 100 cycles, the capacity retention reached 61.2%, demonstrating excellent charge-discharge performance and cycling stability.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a high entropy layered oxide sodium ion battery cathode material, characterized in that: The following steps are involved: (1) uniformly mixing a nickel source, a manganese source, a titanium source, and a zirconium source to prepare a material A; the molar ratio of the nickel source, the manganese source, the titanium source, and the zirconium source is (9-10): (5-6): 4:1; (2) mixing material A with a sodium source and ball milling to obtain a fully mixed slurry, and then drying the slurry to prepare a precursor B; the molar ratio of material A to the sodium source is 1:1; (3) Precursor B is heated to 900-950°C, kept warm for 10-12 hours, then cooled to room temperature, ground and sieved to obtain NaNMTZ layered high entropy oxide sodium ion battery cathode material; (4) Mixing NaNMTZ layered high entropy oxide sodium ion battery positive electrode material, carbon source and inorganic matter, adding an organic solvent, and ultrasonically stirring to obtain a mixture; the mass ratio of the NaNMTZ layered high entropy oxide sodium ion battery positive electrode material, carbon source and inorganic matter is 1:10:(200-250); the carbon source is a mixture of petroleum asphalt, high-temperature coal tar pitch and urea, and the mass ratio of the petroleum asphalt, high-temperature coal tar pitch and urea is 3:(3-4):3; the inorganic matter is a mixture of NaCl and nano-MgO, and the mass ratio of NaCl to nano-MgO is 4:(1-1.5); (5) heating the mixture in step (4) to 600-800°C under a mixed atmosphere and keeping the temperature for 1-2 hours; The mixed atmosphere is a mixed gas of NH3 and N2, and the volume ratio of NH3 to N2 is 5:(90-95); cooling to room temperature, centrifugation washing with hydrochloric acid, and drying to obtain a high-entropy layered oxide sodium ion battery positive electrode material.

2. The method for preparing a high entropy layered oxide sodium ion battery cathode material according to claim 1, wherein: The sodium source in step (2) is a mixture of sodium carbonate, sodium oxalate and sodium hydroxide, and the molar ratio of the mixture of sodium carbonate, sodium oxalate and sodium hydroxide is (9-10):0.65:0.35; the ball milling is specifically performed in a planetary ball mill for 9-10 hours, and the rotation speed of the planetary ball mill is 300r / min.

3. The method for preparing a high entropy layered oxide sodium ion battery cathode material according to claim 1, wherein: The drying in step (2) is specifically drying in a vacuum drying oven at 70-80°C for 10-12 hours.

4. The method for preparing a high entropy layered oxide sodium ion battery cathode material according to claim 1, wherein: The heating in step (3) is specifically to heat the material to 900-950°C at a heating rate of 4.5-5°C / min in an air atmosphere; the grinding is performed in an agate mortar; and the screening is performed using a 200-mesh sieve with a pore size of 0.074 mm.

5. The method for preparing a high entropy layered oxide sodium ion battery cathode material according to claim 1, wherein: The organic solvent described in step (4) is a mixture of toluene, ethylene glycol and anhydrous ethanol, and the volume ratio of toluene, ethylene glycol and anhydrous ethanol is (4-6):3:(1-1.5).

6. The method for preparing a high entropy layered oxide sodium ion battery cathode material according to claim 1, wherein: The amount of organic solvent added in step (4) is 18-23 mL of organic solvent per gram of carbon source; the ultrasonic stirring is specifically, ultrasonic dispersion for 1-1.5 hours and then strong magnetic stirring for 10-12 hours to remove the organic solvent.

7. The method for preparing a high entropy layered oxide sodium ion battery cathode material according to claim 1, wherein: The concentration of the hydrochloric acid in step (5) is 0.9-1.2 mol / L; the drying is vacuum drying, and the drying time is 10-12 h.

8. The high entropy layered oxide sodium ion battery cathode material prepared by any one of claims 1 to 7, characterized in that: The raw materials of the high-entropy layered oxide sodium ion battery positive electrode material include a nickel source, a manganese source, a titanium source and a zirconium source, and the molar ratio of the nickel source, manganese source, titanium source and zirconium source is (9-10): (5-6): 4:

1.

9. The high entropy layered oxide sodium ion battery cathode material according to claim 8, characterized in that The nickel source is a mixture of nickel oxide and nickel hydroxide, and the molar ratio of nickel oxide to nickel hydroxide is (1.5-2):1; the manganese source is a mixture of manganese dioxide and manganese (IV) hydroxide, and the molar ratio of manganese dioxide to manganese (IV) hydroxide is (2-3):1; the titanium source is a mixture of titanium dioxide and titanic acid, and the molar ratio of titanium dioxide to titanic acid is (8.5-9):1; the zirconium source is a mixture of zirconium dioxide and zirconium hydroxide, and the molar ratio of zirconium dioxide to zirconium hydroxide is (8-9):

1.

10. The high entropy layered oxide sodium ion battery cathode material according to claim 8, wherein The high-entropy layered oxide sodium ion battery positive electrode material is subjected to charge and discharge cycles in the potential range of 2-4.0 V and a current of 0.5C. The initial reversible specific capacity is 81.73-104.58 mAh / g, and the capacity retention rate reaches 61.2%-68.8% after 100 cycles.

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