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CN-122000349-A - Positive electrode active material, preparation method thereof, positive electrode plate, sodium secondary battery and electric equipment

CN122000349ACN 122000349 ACN122000349 ACN 122000349ACN-122000349-A

Abstract

The invention relates to the technical field of secondary batteries, and provides an anode active material, a preparation method thereof, an anode plate, a sodium secondary battery and electric equipment. The chemical formula of the positive electrode active material comprises Na a Ni 1‑b‑c‑d Fe b Mn c M d O 2 , wherein a is more than or equal to 0.95 and less than or equal to 1.10,0.03, b is more than or equal to 0.50,0.03 and less than or equal to 0.50, c is more than or equal to 0.10, d is more than or equal to 0 and is more than or equal to Ta, cr, la, al, ce, Y, mg, sr, zr, ca, zn, B, W, nb, si, mo, F, P, co, li, ti, cu, the microcrystalline boundary density of the positive electrode active material is N, N=K S /K X ,K S is the average value of the subgrain grain size of the positive electrode active material obtained through an EBSD test, K X is the microcrystalline size of the positive electrode active material, and N is more than or equal to 8.0 and less than or equal to 28.0. The battery containing the positive electrode active material has excellent cycle performance and rate performance.

Inventors

  • XU YAWEN
  • GAO DONGLI
  • SONG SHUNLIN
  • WU LIANGCE
  • CHEN YANBIN

Assignees

  • 北京当升材料科技股份有限公司

Dates

Publication Date
20260508
Application Date
20260331

Claims (11)

  1. 1. A positive electrode active material, wherein the positive electrode active material has a chemical formula comprising: Na a Ni 1-b-c-d Fe b Mn c M d O 2 ; Wherein, the a is more than or equal to 0.95 and less than or equal to 1.10,0.03 and b is more than or equal to 0.50,0.03-0.50, 0< d; less than or equal to 0.10, M comprises one or more of Ta, cr, la, al, ce, Y, mg, sr, zr, ca, zn, B, W, nb, si, mo, F, P, co, li, ti, cu; The crystallite boundary density of the positive electrode active material is N, N=K S /K X ,K S is the average value of the subgrain size of the positive electrode active material obtained through an EBSD test, and K X is the crystallite size of the positive electrode active material, wherein N is more than or equal to 8.0 and less than or equal to 28.0.
  2. 2. The positive electrode active material according to claim 1, wherein N is 10.0≤N≤24.5, and/or, B is more than or equal to 0.15 and less than or equal to 0.40; and/or the number of the groups of groups, C is more than or equal to 0.15 and less than or equal to 0.40; and/or the number of the groups of groups, 0<D < 0.06, and/or, M includes one or more of Al, mg, zr, sr, ca, zn, nb, ti, mo.
  3. 3. The positive electrode active material according to claim 1, wherein K S nm or less and 1000nm or less, optionally K S nm or less and/or, K X nm or less than 38nm or less than 59nm, alternatively, K X nm or less than 42nm or less than 55nm.
  4. 4. A positive electrode active material according to any one of claims 1 to 3, wherein the positive electrode active material comprises single crystal particles having a cross section in which the ratio of small angle grain boundaries is G, G≤22%, optionally 12≤G≤18%, and/or, The positive electrode active material includes single crystal particles having a large angle grain boundary of L, a ratio of L≤78% to L≤90%, optionally 82% to L≤88%, and/or, 3.5.Ltoreq.L/G≤9.0, optionally, L/G is more than or equal to 4.5 and less than or equal to 7.3.
  5. 5. The positive electrode active material according to any one of claims 1 to 3, wherein the positive electrode active material has a median particle diameter D 50 ,3.2μm≤D 50 .5 μm or less, optionally 4.0 μm or less D 50 . Ltoreq.7.0 μm, and/or, The positive electrode active material has a specific surface area of S,0.45m 2 /g≤S≤0.90m 2 /g, optionally 0.50m 2 /g≤S≤0.75m 2 /g, and/or, The positive electrode active material has a repose angle α <52.0 °, alternatively α is less than or equal to 47.5 °.
  6. 6. A method of producing the positive electrode active material according to any one of claims 1 to 5, comprising: mixing a nickel source, an iron source, a manganese source, a complexing agent and a precipitator for coprecipitation reaction to obtain slurry, and aging, filtering, washing and drying the slurry to obtain a precursor; and mixing the precursor with a sodium source and an M source, and sintering to obtain the positive electrode active material.
  7. 7. A process according to claim 6, wherein the pH of the coprecipitation reaction is 9.5-12.5, optionally 10-12, and/or, The temperature of the coprecipitation reaction is 40-65 ℃, optionally 45-60 ℃.
  8. 8. The method according to claim 6 or 7, wherein the sintering comprises a constant temperature section 1 and a constant temperature section 2 in sequence, The temperature of the constant temperature section 1 is T1,650 ℃ and T1 and 930 ℃, alternatively 750 ℃ and T1 and 910 ℃ and/or, The constant temperature time of the constant temperature section 1 is t1, t1 is less than or equal to 5h and less than or equal to 10h, optionally, t1 is less than or equal to 6h and less than or equal to 8h, and/or, Heating to a temperature rise rate of V1 of the constant temperature section 1, wherein V1 is less than or equal to 2 ℃ and less than or equal to 8 ℃ and/or less than or equal to 3 ℃ and less than or equal to 6 ℃ and/or, The temperature of the constant temperature section 2 is T2,980 ℃ less than or equal to T2 less than or equal to 1080 ℃, alternatively 1000 ℃ less than or equal to T2 less than or equal to 1040 ℃, and/or, The constant temperature time of the constant temperature section 2 is t2, t2 is less than or equal to 5h and less than or equal to 15h, optionally, t2 is less than or equal to 7h and less than or equal to 12h, and/or, Heating to a temperature of the constant temperature section 2 at a temperature of V2, V2 being 1 ℃ or less and V2 being 5 ℃ or less and/or min, optionally V2 being 1 ℃ or less and V2 being 3 ℃ or less and/or, 1.1.Ltoreq.T2/T1≤1.6, optionally 1.1≤T2/T1≤1.3, and/or, T2/t1 is 0.5 or less and 3.0 or less, alternatively, t2 is 1.1 ∈2-t 1 is less than or equal to 2.0.
  9. 9. A positive electrode sheet comprising the positive electrode active material according to any one of claims 1 to 5, or the positive electrode active material produced by the method according to any one of claims 6 to 8.
  10. 10. A sodium secondary battery comprising the positive electrode sheet according to claim 9.
  11. 11. An electrical device comprising the sodium secondary battery of claim 10.

Description

Positive electrode active material, preparation method thereof, positive electrode plate, sodium secondary battery and electric equipment Technical Field The invention relates to the technical field of secondary batteries, in particular to an anode active material and a preparation method thereof, an anode plate, a sodium secondary battery and electric equipment. Background With the transformation of global energy structures and the vigorous development of new energy automobile industry, the demand for high-performance energy storage technology is increasingly urgent. Among many energy storage schemes, lithium ion batteries are widely focused due to the advantages of high energy density, long cycle life, green safety and the like, and are widely applied to various fields such as large-scale commercial energy storage, electric automobiles, electronic numbers and the like, and the aspects of human production and life are deeply influenced. Then, with the continuous growth of the lithium ion battery market, the problems of shortage of metal elements such as lithium, cobalt and the like in raw materials, price rising and the like are gradually exposed, and the development of the lithium ion battery is seriously hindered. Under the background, the sodium element in the sodium ion battery rapidly draws the wide attention of people due to the advantages of abundant resources, low price, wide distribution and the like, and the sodium ion battery is considered to be a substitute of the lithium ion battery. Therefore, the sodium ion battery also meets the unprecedented development opportunity, and the sodium ion battery industry is gradually moving from a laboratory to large-scale application under the drive of multiple factors such as technical breakthrough, market scale expansion, competition pattern evolution, policy support and the like. However, the existing sodium ion battery still has the problems of poor cycle life, higher impedance, requirement for improvement of rate performance and the like, and needs to be solved. Disclosure of Invention The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, an object of the present invention is to provide a positive electrode active material having excellent cycle performance and rate performance, a method of preparing the same, a positive electrode tab, a sodium secondary battery, and electric devices. Therefore, the first aspect of the invention provides a positive electrode active material, which has a chemical formula of Na aNi1-b-c-dFebMncMdO2, wherein a is more than or equal to 0.95 and less than or equal to 1.10,0.03 and less than or equal to b is more than or equal to 0.50,0.03 and less than or equal to 0.50, d is more than or equal to 0 and less than or equal to 0.10, M comprises one or more of Ta, cr, la, al, ce, Y, mg, sr, zr, ca, zn, B, W, nb, si, mo, F, P, co, li, ti, cu, the microcrystalline boundary density of the positive electrode active material is N, N=K S/KX,KS is the average value of the subgrain size of the positive electrode active material obtained by an EBSD test, K X is the microcrystalline size of the positive electrode active material, and N is more than or equal to 8.0 and less than or equal to 28.0. According to the positive electrode active material provided by the embodiment of the application, the microcrystalline boundary density N of the positive electrode active material is controlled, so that the single diffusion path of sodium ions in crystal grains caused by the fact that the microcrystalline boundary density of the positive electrode active material is too small can be avoided, and the positive electrode active material basically completely depends on bulk diffusion. The method has the advantages of improving the diffusion path of sodium ions in the positive electrode active material, ensuring the positive electrode active material to have excellent multiplying power performance, avoiding the situation that a great number of defects caused by overlarge microcrystalline boundary density of the positive electrode active material occupy sodium sites, causing local irreversible phase change and losing part of capacity, reducing the initial capacity, and avoiding the situation that the high defect density area possibly becomes a starting point of harmful phase change, causing voltage attenuation and capacity reduction and cycle performance deterioration of the positive electrode active material in long-term circulation. In summary, the positive electrode active material provided by the application has excellent cycle performance and rate performance. In some embodiments of the invention, 10.0≤N≤24.5, and/or, 0.15≤b≤0.40, and/or, 0.15≤c≤0.40, and/or 0<d≤0.06, and/or M comprises one or more of Al, mg, zr, sr, ca, zn, nb, ti, mo. In some embodiments of the invention, 500 nm≤K S≤1000 nm, optionally 650 nm≤K S≤900 nm; and/or, 38 nm≤K X≤59 nm, optionally 42 nm≤K X≤55 nm. In som