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US-12620589-B2 - Method for producing positive electrode active material for lithium secondary battery and method for producing positive electrode for lithium secondary battery

US12620589B2US 12620589 B2US12620589 B2US 12620589B2US-12620589-B2

Abstract

A method for producing a positive electrode active material for a lithium secondary battery capable of reducing the amount of the lithium compound to be eluted and improving the cycle characteristic and the discharge rate characteristic of a lithium secondary battery is achieved. According to one embodiment of the present invention, a method for producing a positive electrode active material for a lithium secondary battery includes a step of mixing a powder P2 having a specific molar specific surface area and containing a sulfate and/or a phosphate of a specific metal with a powder P1 containing a lithium metal composite oxide.

Inventors

  • Masashi Inoue
  • Yukako AOYAMA

Assignees

  • SUMITOMO METAL MINING CO., LTD.

Dates

Publication Date
20260505
Application Date
20220727
Priority Date
20210803

Claims (19)

  1. 1 . A method for producing a positive electrode active material for a lithium secondary battery, the method comprising a mixing step of mixing a powder P1 containing a lithium metal composite oxide and a powder P2 containing an additive compound to obtain a mixture, wherein the lithium metal composite oxide has a layered structure and contains Ni, the additive compound is a salt of a cation of at least one element A selected from the group consisting of Al, Mg, Ca, Sr, Zr, Ti, Co, La, and Ce and any one anion selected from the group consisting of SO 4 2− , PO 4 3− , HPO 4 2− , and H 2 PO 4 − , and the powder P2 has a molar specific surface area S2, calculated by a formula (2) below, of 0.05 m 2 /mmol or more, S ⁢ 2 = BET ⁢ 2 × F ⁢ 2 / ( 1000 × N ⁢ 2 ) ( 2 ) (in the formula (2), BET2 represents a BET specific surface area [m 2 /g] of the powder P2, F2 represents a formula weight [g/mol] of a compositional formula of the additive compound, and N2 represents the number of element A in the compositional formula of the additive compound).
  2. 2 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 1 , wherein a compositional formula of the lithium metal composite oxide is represented by a formula (I) below, Li[Li m (Ni (1-n) X n ) 1-m ]O 2 (I) (in the formula (I), X represents one or more elements selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Ca, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, B, Si, S, and P, and −0.1≤m≤0.2 and 0≤n≤0.3 are satisfied).
  3. 3 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 2 , comprising a step of obtaining the lithium metal composite oxide by mixing and calcining a lithium compound and a metal composite compound containing Ni before the mixing step.
  4. 4 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 2 , wherein a ratio S2/S1 of a molar specific surface area S1 [m 2 /mmol] of the lithium metal composite oxide calculated by a formula (1) below to the molar specific surface area S2 [m 2 /mmol] of the powder P2 is 1.5 or more and 50 or less, S ⁢ 1 = BET ⁢ 1 × F ⁢ 1 / 1000 ( 1 ) (in the formula (1), BET1 represents a BET specific surface area [m 2 /g] of the lithium metal composite oxide, and F1 represents a formula weight [g/mol] of the compositional formula of the lithium metal composite oxide).
  5. 5 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 2 , comprising a classification step of classifying the mixture with a sieve after the mixing step.
  6. 6 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 5 , wherein D90 (P1)/OP, which is a ratio of a 90% cumulative volume particle diameter D90 (P1) [μm] of the lithium metal composite oxide to a mesh opening OP [μm] of the sieve, is 0.1 or more and 0.8 or less.
  7. 7 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 2 , wherein a ratio of an amount of element A contained in the additive compound to a total amount of metal elements other than Li contained in the lithium metal composite oxide in the mixture is 0.2 mol % or more and 3.0 mol % or less.
  8. 8 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 2 , wherein a liquid mixture to be obtained by mixing the powder P2 and water at a ratio of the additive compound:water=0.1 mol:1 L in the powder P2 has a pH of less than 8.3 at 25° C.
  9. 9 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 2 , wherein the positive electrode active material for the lithium secondary battery has a 50% cumulative volume particle diameter D50 of 5 μm or more and 30 μm or less.
  10. 10 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 2 , wherein the positive electrode active material for the lithium secondary battery has a BET specific surface area of 0.1 m 2 /g or more and 3 m 2 /g or less.
  11. 11 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 1 , comprising a step of obtaining the lithium metal composite oxide by mixing and calcining a lithium compound and a metal composite compound containing Ni before the mixing step.
  12. 12 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 1 , wherein a ratio S2/S1 of a molar specific surface area S1 [m 2 /mmol] of the lithium metal composite oxide calculated by a formula (1) below to the molar specific surface area S2 [m 2 /mmol] of the powder P2 is 1.5 or more and 50 or less, S ⁢ 1 = BET ⁢ 1 × F ⁢ 1 / 1000 ( 1 ) (in the formula (1), BET1 represents a BET specific surface area [m 2 /g] of the lithium metal composite oxide, and F1 represents a formula weight [g/mol] of the compositional formula of the lithium metal composite oxide).
  13. 13 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 1 , comprising a classification step of classifying the mixture with a sieve after the mixing step.
  14. 14 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 5 , wherein D90 (P1)/OP, which is a ratio of a 90% cumulative volume particle diameter D90 (P1) [μm] of the lithium metal composite oxide to a mesh opening OP [μm] of the sieve, is 0.1 or more and 0.8 or less.
  15. 15 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 1 , wherein a ratio of an amount of element A contained in the additive compound to a total amount of metal elements other than Li contained in the lithium metal composite oxide in the mixture is 0.2 mol % or more and 3.0 mol % or less.
  16. 16 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 1 , wherein a liquid mixture to be obtained by mixing the powder P2 and water at a ratio of the additive compound:water=0.1 mol:1 L in the powder P2 has a pH of less than 8.3 at 25° C.
  17. 17 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 1 , wherein the positive electrode active material for the lithium secondary battery has a 50% cumulative volume particle diameter D50 of 5 μm or more and 30 μm or less.
  18. 18 . The method for producing the positive electrode active material for the lithium secondary battery according to claim 1 , wherein the positive electrode active material for the lithium secondary battery has a BET specific surface area of 0.1 m 2 /g or more and 3 m 2 /g or less.
  19. 19 . A method for producing a positive electrode for a lithium secondary battery, comprising: a step of obtaining the positive electrode active material for the lithium secondary battery by the method for producing the positive electrode active material for the lithium secondary battery according to claim 1 ; and a step of supporting a positive electrode mixture containing the positive electrode active material for the lithium secondary battery on a positive electrode current collector.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims priority under 35 U.S.C. § 371 to International Patent Application No. PCT/JP2022/028917, filed Jul. 27, 2022, which claims priority to and the benefit of Japanese Patent Application No. 2021-127585, filed Aug. 3, 2021. The contents of these applications are hereby incorporated by reference in their entireties. TECHNICAL FIELD The present invention relates to a method for producing a positive electrode active material for a lithium secondary battery and a method for producing a positive electrode for a lithium secondary battery. BACKGROUND ART Lithium metal composite oxides are used as a matrix for positive electrode active materials for lithium secondary batteries. Known techniques related to lithium metal composite oxides or positive electrode active materials for lithium secondary batteries include, for example, the following techniques. Patent Literature 1 discloses a positive electrode material for a lithium secondary battery consisting of a lithium transition metal composite oxide containing Group 1 and/or Group 2 element components (excluding lithium) of 100 to 1500 ppm and sulfate ion components of 150 to 10000 ppm. Patent Literature 2 discloses a method for producing a positive electrode active material, including a step of adhering at least one of a sulfate and a boric acid compound to composite oxide particles containing lithium and at least one of nickel and cobalt, and a step of heating the composite oxide particles to which at least one of the sulfate and the boric acid compound is adhered in an oxidizing atmosphere. Patent Literature 3 discloses a positive electrode composition for non-aqueous electrolyte secondary batteries, comprising a lithium transition metal composite oxide represented by a specific general formula and an acidic oxide. CITATION LIST Patent Literatures [Patent Literature 1] JP2002-15739A[Patent Literature 2] JP2009-146739A[Patent Literature 3] JP2013-131437A SUMMARY OF INVENTION Technical Problems However, there has been room for improvement in the aforementioned conventional art, for achieving a method for producing a positive electrode active material for a lithium secondary battery capable of reducing the amount of the alkaline lithium compound to be eluted and improving a cycle characteristic and a discharge rate characteristic of a lithium secondary battery. It is an object of an aspect of the present invention to achieve a method for producing a positive electrode active material for a lithium secondary battery, capable of reducing the amount of the alkaline lithium compound to be eluted and improving the cycle characteristic and the discharge rate characteristic of the lithium secondary battery. Solution to Problem The present invention includes the following aspects. <1> A method for producing a positive electrode active material for a lithium secondary battery, including a mixing step of mixing a powder P1 containing a lithium metal composite oxide and a powder P2 containing an additive compound to obtain a mixture, in which the lithium metal composite oxide has a layered structure and contains Ni, the additive compound is a salt of a cation of at least one element A selected from the group consisting of Al, Mg, Ca, Sr, Zr, Ti, Co, La, and Ce and any one anion selected from the group consisting of SO42-, PO43-, HPO42-, and H2⁢PO4-, and the powder P2 has a molar specific surface area S2, calculated by a formula (2) below, of 0.05 m2/mmol or more. S⁢2=BET⁢2×F⁢2/(1000×N⁢2)(2) (In the formula (2), BET2 represents a BET specific surface area [m2/g] of the powder P2, F2 represents a formula weight [g/mol] of a compositional formula of the additive compound, and N2 represents the number of element A in the compositional formula of the additive compound.) <2> The method for producing the positive electrode active material for the lithium secondary battery according to <1>, in which a compositional formula of the lithium metal composite oxide is represented by a formula (I) below. Li[Lim(Ni(1-n)Xn)1-m]O2  (I) (In the formula (I), X represents one or more elements selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Ca, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, B, Si, S, and P, and −0.1≤m≤0.2 and 0≤n≤0.3 are satisfied.) <3> The method for producing the positive electrode active material for the lithium secondary battery according to <1> or <2>, including a step of obtaining the lithium metal composite oxide by mixing and calcining a lithium compound and a metal composite compound containing Ni before the mixing step. <4> The method for producing the positive electrode active material for the lithium secondary battery according to any one of <1> to <3>, in which a ratio S2/S1 of a molar specific surface area S1 [m2/mmol] of the lithium metal composite oxide calculated by a formula (1) below to the molar specific surface area S2 [m2/mmol] of the powder P2 is 1.5 or more and 50 or less. S⁢1=BET⁢1×F⁢1/1000(