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US-20260125276-A1 - POSITIVE ELECTRODE ACTIVE MATERIAL AND PREPARATION METHOD THEREOF, POSITIVE ELECTRODE SHEET, AND SODIUM-ION BATTERY

US20260125276A1US 20260125276 A1US20260125276 A1US 20260125276A1US-20260125276-A1

Abstract

A positive electrode active material has a chemical formula of Na x A y Ni a Fe b Mn c Cu d A e O n , where A is selected from at least one of Zn, Mg, Ca, K, and Li, and the following conditions are satisfied: (1) 0.67≤x≤0.85, 0.01≤y≤0.2, and x+y≤1; (2) 0.11≤a≤0.33, 0.11≤b≤0.33, 0.33≤c≤0.66, 0.11≤d≤0.33, 0≤e≤0.1, and a+b+c+d=1; (3) n satisfies that an algebraic sum of positive and negative valences in the chemical formula equals zero; under same values of x, a, b, c, d, and n, a sodium layer spacing in an unit cell of the positive electrode active material is reduced by 0.005 Å-0.115 Å compared to that of Na x Ni a Fe b Mn c Cu d O n .

Inventors

  • Zhigao XUE
  • Zengxue WU
  • Weili SUN
  • Zunzhi WANG
  • Rui Liu
  • Jonghee Lee

Assignees

  • NINGBO RONBAY NEW ENERGY TECHNOLOGY Co.,Ltd.

Dates

Publication Date
20260507
Application Date
20251226
Priority Date
20230706

Claims (18)

  1. 1 . A positive electrode active material, wherein a chemical formula of the positive electrode active material is Na x A y Ni a Fe b Mn c Cu d A e O n , wherein A is selected from at least one of Zn, Mg, Ca, K, and Li, and the following conditions are satisfied: 0 . 6 ⁢ 7 ≤ x ≤ 0 . 8 ⁢ 5 , 0 . 0 ⁢ 1 ≤ y ≤ 0.2 , and ⁢ x + y ≤ 1 ; ( 1 ) 0.11 ≤ a ≤ 0 . 3 ⁢ 3 , 0 . 1 ⁢ 1 ≤ b ≤ 0 . 3 ⁢ 3 , 0.33 ≤ c ≤ 0 . 6 ⁢ 6 , 0 . 1 ⁢ 1 ≤ d ≤ 0 . 3 ⁢ 3 , ( 2 ) 0 ≤ e ≤ 0.1 , and ⁢ a + b + c + d = 1 ; (3) n satisfies that an algebraic sum of positive and negative valences in the chemical formula equals zero; under same values of x, a, b, c, d, and n, a sodium layer spacing in a unit cell of the positive electrode active material is reduced by 0.005 Å-0.115 Å compared to that of Na x Ni a Fe b Mn c Cu d O n .
  2. 2 . The positive electrode active material according to claim 1 , wherein 0.001≤e≤0.1.
  3. 3 . The positive electrode active material according to claim 1 , wherein y>e.
  4. 4 . The positive electrode active material according to claim 1 , wherein the sodium layer spacing in the unit cell of the positive electrode active material is 3.20 Å-3.45 Å.
  5. 5 . The positive electrode active material according to claim 1 , wherein a transition-metal layer spacing in the unit cell of the positive electrode active material is 2.03 Å-2.10 Å.
  6. 6 . The positive electrode active material according to claim 1 , wherein an absolute value of a volume change ratio of the unit cell of the positive electrode active material is less than or equal to 2.5% within a voltage condition of less than or equal to 4.4 V.
  7. 7 . The positive electrode active material according to claim 1 , wherein the positive electrode active material is a single crystal or a secondary particle.
  8. 8 . A preparation method for the positive electrode active material according to claim 1 , comprising the following steps: preparing a nickel-manganese-iron-copper oxide in a molar ratio of Ni:Fe:Mn:Cu=a:b:c:d, wherein 0.11≤a≤0.33, 0.11≤b≤0.33, 0.33≤c≤0.66, 0.11≤d≤0.33, and a+b+c+d=1; subjecting the nickel-manganese-iron-copper oxide, a sodium source, and a doping source to mixing based on Na x A y Ni a Fe b Mn c Cu d A e O n , 0.67≤x≤0.85, 0.01≤y≤0.2, 0≤e≤0.1, and x+y≤1, and then sintering to obtain the positive electrode active material, wherein the doping source is selected from at least one of a zinc source, a magnesium source, a calcium source, a potassium source, and a lithium source.
  9. 9 . The preparation method for the positive electrode material according to claim 8 , wherein 0.001≤e≤0.1.
  10. 10 . The preparation method for the positive electrode material according to claim 8 , wherein y>e.
  11. 11 . The preparation method for the positive electrode material according to claim 8 , wherein the sodium layer spacing in the unit cell of the positive electrode active material is 3.20 Å-3.45 Å.
  12. 12 . The preparation method for the positive electrode material according to claim 8 , wherein a transition-metal layer spacing in the unit cell of the positive electrode active material is 2.03 Å-2.10 Å.
  13. 13 . The preparation method for the positive electrode material according to claim 8 , wherein an absolute value of a volume change ratio of the unit cell of the positive electrode active material is less than or equal to 2.5% within a voltage condition of less than or equal to 4.4 V.
  14. 14 . The preparation method for the positive electrode material according to claim 8 , wherein the positive electrode active material is a single crystal or a secondary particle.
  15. 15 . The preparation method for the positive electrode material according to claim 8 , wherein the sodium source is selected from at least one of sodium carbonate, sodium bicarbonate, and sodium hydroxide; and/or the zinc source is zinc oxide; and/or the magnesium source is selected from at least one of magnesium oxide and magnesium hydroxide; and/or the calcium source is selected from at least one of calcium oxide and calcium carbonate; and/or the potassium source is selected from at least one of potassium oxide, potassium carbonate, potassium hydroxide, and potassium bicarbonate; and/or the lithium source is selected from at least one of lithium oxide, lithium hydroxide, and lithium carbonate.
  16. 16 . The preparation method for the positive electrode material according to claim 8 , wherein in the step of the subjecting the nickel-manganese-iron-copper oxide, the sodium source, and the doping source to the mixing and then the sintering, sintering temperature is 800° C.-1200° C., heating rate is 1° C./min-5° C./min, and sintering time is 8 h-16 h.
  17. 17 . A positive electrode sheet, comprising a positive current collector and a positive electrode active layer provided on a surface of the positive current collector, and the positive electrode active layer comprises the positive electrode material according to claim 1 .
  18. 18 . A sodium-ion battery, comprising the positive electrode sheet according to claim 17 .

Description

This application is a continuation of International Application No. PCT/CN2024/101459, filed on Jun. 25, 2024, which claims priority to Chinese patent application No. 202310825219.4, filed on Jul. 6, 2023, both of which are hereby incorporated by reference in their entireties. TECHNICAL FIELD This present disclosure relates to the technology field of sodium-ion batteries and, in particular, to a positive electrode active material and a preparation method thereof, a positive electrode sheet, and a sodium-ion battery. BACKGROUND Sodium-ion batteries are gradually applied in commercial fields based on their low cost and considerable capacity. In particular, positive electrode active materials, as core components of batteries, determine both cost and electrochemical performance of batteries. Similar to lithium-ion batteries, positive electrode active materials for sodium-ion batteries mainly include layered oxides and polyanions. Among them, layered oxides are considered as preferred positive electrode active materials for sodium-ion batteries due to their high specific capacity, low preparation cost, and high production yield. However, in sodium-ion batteries, sodium layered oxides, due to their low structural stability, are prone to sodium ion deintercalation and subsequent deposition, resulting in lattice distortion or collapse during long cycling. This significantly affects the stability of sodium-ion batteries. Therefore, it is necessary to seek a positive electrode active material for sodium-ion batteries that can enhance structural stability and improve performance. SUMMARY In view of the above, it is necessary to provide a positive electrode active material and a preparation method thereof, a positive electrode sheet, and a sodium-ion battery to address the above problems. The positive electrode active material exhibits high-rate performance, excellent cycling stability, and high-voltage durability, etc., and thus a resulting sodium-ion battery has excellent performance. A positive electrode active material is provided, which has a chemical formula of NaxAyNiaFebMncCudAeOn, where A is selected from at least one of Zn, Mg, Ca, K, and Li, and the following conditions are satisfied: (1) 0.67≤x≤0.85, 0.01≤y≤0.2, and x+y≤1; (2) 0.11≤a≤0.33, 0.11≤b≤0.33, 0.33≤c≤0.66, 0.11≤d≤0.33, 0≤e≤0.1, and a+b+c+d=1; (3) n satisfies that an algebraic sum of positive and negative valences in the chemical formula equals zero; under same values of x, a, b, c, d, and n, a sodium layer spacing in an unit cell of the positive electrode active material is reduced by 0.005 Å-0.115 Å compared to that of NaxNiaFebMncCudOn. In one embodiment, 0.001≤e≤0.1. In one embodiment, y>e. In one embodiment, the sodium layer spacing in the unit cell of the positive electrode active material is 3.20 Å-3.45 Å. In one embodiment, a transition-metal layer spacing in the unit cell of the positive electrode active material is 2.03 Å-2.10 Å. In one embodiment, an absolute value of a volume change ratio of the unit cell of the positive electrode active material is less than or equal to 2.5% within a voltage condition of less than or equal to 4.4 V. In one embodiment, the positive electrode active material is a single crystal or a secondary particle. A method for preparing the positive electrode active material as described above includes the following steps: preparing a nickel-manganese-iron-copper oxide in a molar ratio of Ni:Fe:Mn:Cu=a:b:c:d, where 0.11≤a≤0.33, 0.11≤b≤0.33, 0.33≤c≤0.66, 0.11≤d≤0.33, and a+b+c+d=1; subjecting the nickel-manganese-iron-copper oxide, a sodium source, and a doping source to mixing based on NaxAyNiaFebMncCudAeOn, 0.67≤x≤0.85, 0.01≤y≤0.2, 0≤e≤0.1, and x+y≤1 and then sintering to obtain the positive electrode active material, where the doping source is selected from at least one of a zinc source, a magnesium source, a calcium source, a potassium source, and a lithium source. In one embodiment, the sodium source is selected from at least one of sodium carbonate, sodium bicarbonate, and sodium hydroxide; and/or the zinc source is zinc oxide; and/or the magnesium source is selected from at least one of magnesium oxide and magnesium hydroxide; and/or the calcium source is selected from at least one of calcium oxide and calcium carbonate; and/or the potassium source is selected from at least one of potassium oxide, potassium carbonate, potassium hydroxide, and potassium bicarbonate; and/or the lithium source is selected from at least one of lithium oxide, lithium hydroxide, and lithium carbonate. In one embodiment, in the step of the subjecting the nickel-manganese-iron-copper oxide, the sodium source, and the doping source to the mixing and then the sintering, sintering temperature is 800° C.-1200° C., heating rate is 1° C./min-5° C./min, and sintering time is 8 hours-16 hours. A positive electrode sheet is provided, including a positive current collector and a positive electrode material layer provided on a surface of the posi