Positive electrode active substance for lithium secondary battery, positive electrode for lithium secondary battery and lithium secondary battery, and methods for producing these

Patent metadata

Field	Value
Publication number	US-10833369-B2
Application number	US-201615778905-A
Country	US
Kind code	B2
Filing date	Oct 31, 2016
Priority date	Dec 2, 2015
Publication date	Nov 10, 2020
Grant date	Nov 10, 2020

Abstract

An object of the present invention is to provide a positive electrode active substance capable of suppressing gas generation associated with charge and discharge in a lithium secondary battery, and capable of suppressing gas generation associated with charge and discharge particularly even in cases where the use voltage of the lithium secondary battery is high, a positive electrode and a lithium secondary battery using the positive electrode active substance, and methods for producing these. The present invention is a positive electrode active substance for a lithium secondary battery, comprising a coated positive electrode active substance wherein a surface of a positive electrode active substance is directly coated with lithium metaphosphate.

First claim

The invention claimed is:

1. A positive electrode active substance for a lithium secondary battery, comprising:
a coated positive electrode active substance obtained by directly coating a surface of a positive electrode active substance with lithium metaphosphate,
wherein the lithium metaphosphate is chemically bound to the surface of the positive electrode active substance, and
a mass ratio (A/B) of the lithium metaphosphate (A) with respect to the positive electrode active substance (B) is 0.001 to 0.10.

2. The positive electrode active substance for a lithium secondary battery according to claim 1 , wherein the positive electrode active substance comprises a lithium transition metal composite oxide.

3. The positive electrode active substance for a lithium secondary battery according to claim 1 , wherein the positive electrode active substance comprises at least one selected from:
a lithium transition metal composite oxide comprising at least one transition metal element selected from nickel, cobalt and manganese;
a lithium transition metal composite oxide obtained by replacing a part of a transition metal of the above lithium transition metal composite oxide by at least one element selected from Sn, Mg, Fe, Ti, Al, Zr, Cr, V, Ga, Ge, Sm, Zn, Cu, Bi, Mo and La, or/and replacing a part of oxygen atoms by S or F;
a phosphoric acid compound having an olivine structure; and
an active substance obtained by coating a surface of the positive electrode active substance with an oxide containing any of the above elements.

4. The positive electrode active substance for a lithium secondary battery according to claim 1 , wherein the positive electrode active substance comprises at least one selected from:
a lithium transition metal composite oxide represented by one of the following composition formulas:
Li 1+a Ni x Mn y O 2 (0<a≤0.5, 0<x<1, 0<y<1),
Li 1+a Ni x Mn y M z O 2 (0<a≤0.5, 0<x<1, 0<y<1, 0<z<1, and M is Co or/and Fe),
LiCo 1-x Ni x O 2 (0.01<x<1),
LiNi x Co y Mn z O 2 (x+y+z=1, 0.01<x, 0.01<y, 0.01<z), and
LiNi β Co γ Al δ O 2 (β+γ+δ=1, 0.7≤β<1, 0<γ≤0.2, 0≤0.1);
a lithium transition metal composite oxide obtained by replacing a part of at least one element of Ni, Co and Mn of the above lithium transition metal composite oxide by at least one element selected from Sn, Mg, Fe, Ti, Al, Zr, Cr, V, Ga, Ge, Sm, Zn, Cu, Bi, Mo and La, or/and replacing a part of oxygen atoms by S or F; and
an active substance obtained by coating a surface of the positive electrode active substance with an oxide containing any of the above elements.

5. A positive electrode for a lithium secondary battery, comprising: a positive electrode current collector; and a positive electrode active substance layer comprising the positive electrode active substance for a lithium secondary battery according to claim 1 on the positive electrode current collector.

6. A lithium secondary battery, comprising: the positive electrode for a lithium secondary battery according to claim 5 ; a negative electrode comprising a negative electrode active substance; a nonaqueous electrolyte solution; and an outer package accommodating these.

7. The lithium secondary battery according to claim 6 , wherein the negative electrode comprises at least one of simple silicon, silicon oxide and carbon.

8. The lithium secondary battery according to claim 6 , wherein the nonaqueous electrolyte comprises at least one of a chain carbonate-based solvent and a cyclic carbonate-based solvent.

9. A method for producing the positive electrode active substance for a lithium secondary battery according to claim 1 , the method comprising:
soaking the positive electrode active substance in a coating-forming liquid comprising lithium metaphosphate;
separating and removing the coating-forming liquid; and
thereafter washing the positive electrode active substance with a solvent capable of dissolving lithium metaphosphate not bound to the surface of the positive electrode active substance.

10. A method for producing a lithium secondary battery, comprising:
forming a coated positive electrode active substance by the method according to claim 9 ;
forming a positive electrode by using the coated positive electrode active substance;
forming a negative electrode; and
accommodating the positive electrode, the negative electrode and an electrolyte solution in an outer package.

11. The positive electrode active substance for a lithium secondary battery according to claim 1 , wherein a phosphorus atom (P) of the residue part of metaphosphoric acid of the lithium metaphosphate and a metal atom of the positive electrode active substance are bound through an oxygen atom (O).

12. The method for producing the positive electrode active substance for a lithium secondary battery according to claim 9 , wherein in the soaking, the positive electrode active substance is soaked at 40 to 100° C. to react and bind the lithium metaphosphate with the positive electrode active substance.

13. A positive electrode active substance for a lithium secondary battery, comprising a coated positive electrode active substance wherein a surface of a positive electrode active substance is directly coated with lithium metaphosphate,
wherein the positive electrode active substance comprises at least one selected from:
a lithium transition metal composite oxide comprising at least one transition metal element selected from nickel, cobalt and manganese;
a lithium transition metal composite oxide obtained by replacing a part of a transition metal of the above lithium transition metal composite oxide by at least one element selected from Sn, Mg, Fe, Ti, Al, Zr, Cr, V, Ga, Ge, Sm, Zn, Cu, Bi, Mo and La, or/and replacing a part of oxygen atoms by S;
a phosphoric acid compound having an olivine structure;
an active substance obtained by coating a surface of the positive electrode active substance with an oxide containing any of the above elements;
the lithium metaphosphate is chemically bound to the surface of the positive electrode active substance; and
a mass ratio (A/B) of the lithium metaphosphate (A) with respect to the positive electrode active substance (B) is 0.001 to 0.10.

14. The positive electrode active substance for a lithium secondary battery according to claim 13 , wherein a phosphorus atom (P) of the residue part of metaphosphoric acid of the lithium metaphosphate and a metal atom of the positive electrode active substance are bound through an oxygen atom (O).

15. A positive electrode for a lithium secondary battery, comprising:
a positive electrode current collector; and
a positive electrode active substance layer comprising the positive electrode active substance for a lithium secondary battery according to claim 13 on the positive electrode current collector.

16. A lithium secondary battery, comprising:
the positive electrode for a lithium secondary battery according to claim 15 ;
a negative electrode comprising a negative electrode active substance;
a nonaqueous electrolyte solution; and
an outer package accommodating these.

17. A positive electrode active substance for a lithium secondary battery, comprising a coated positive electrode active substance wherein a surface of a positive electrode active substance is directly coated with lithium metaphosphate,
wherein the positive electrode active substance comprises at least one selected from:
a lithium transition metal composite oxide represented by one of the following composition formulas:
Li 1+a Ni x Mn y O 2 (0<a≤0.5, 0<x<1, 0<y<1),
Li 1+a Ni x Mn y M z O 2 (0<a≤0.5,

Assignees

• Nec Corp

Inventors

• Maeda Katsumi
• Hattori Sadanori

Classifications

• H01M4/661

  Metal or alloys, e.g. alloy coatings (H01M4/669 take precedence) · CPC title

• H01M4/505

  of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy · CPC title

• H01M4/366 Primary

  as layered products · CPC title

• H01M4/525

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title

• H01M10/0569

  characterised by the solvents · CPC title