Coated lithium-nickel composite oxide particles, and method for producing coated lithium-nickel composite oxide particles

Abstract

Provided are excellent coated lithium-nickel composite oxide particles with which it is possible, due to the high environmental stability thereof, to minimize the incidence of impurities owing to absorption of moisture and carbon dioxide gas, said particles having high adhesiveness such that the coating layer does not easily delaminate, and having lithium-ion conductivity. The coated lithium-nickel composite oxide particles, in which an electroconductive polymer is cross-linked to the lithium-nickel composite oxide particles by a three-dimensional structure, are electrically and ionically conductive, and the compound is capable of suppressing the transmission of moisture and carbon dioxide. It is therefore possible to provide coated lithium-nickel composite oxide particles for a lithium-ion cell positive-electrode active substance that is excellent for use in a lithium-ion cell.

1 . Coated lithium-nickel composite oxide particles for a lithium-ion battery positive-electrode active substance, comprising: nickel-based lithium-nickel composite oxide particles, surfaces of which are coated with a conductive polymer. 
     
     
         2 . The coated lithium-nickel composite oxide particles according to  claim 1 , wherein a coating amount of the conductive polymer is from 0.1 to 5.0% by mass based on 100% by mass of the lithium-nickel composite oxide particles. 
     
     
         3 . The coated lithium-nickel composite oxide particles according to  claim 1 , wherein the conductive polymer is a polymer or copolymer including at least one selected from the group consisting of polypyrrole, polyaniline, polythiophene, poly(p-phenylene), polyfluorene, and a derivative thereof. 
     
     
         4 . The coated lithium-nickel composite oxide particles according to  claim 1 , wherein the lithium-nickel composite oxide is represented by the following Formula (1),
   Li x Ni (l-y-z) M y N z O 2    (1)
   wherein x is a value of from 0.80 to 1.10, y is a value of from 0.01 to 0.20, z is a value of from 0.01 to 0.15, and l-y-z is a value exceeding 0.65, and M represents at least one element selected from Co or Mn, and N represents at least one element selected from Al, In or Sn.   
     
     
         5 . The coated lithium-nickel composite oxide particles according to  claim 1 , wherein the coated lithium-nickel composite oxide particles are spherical particles having an average particle diameter of from 5 to 20 μm. 
     
     
         6 . A method for producing the coated lithium-nickel composite oxide particles according to  claim 1 , comprising:
 preparing a resin solution for coating by dissolving a conductive polymer into a good solvent that dissolves the conductive polymer;   adding a poor solvent that does not dissolve a resin for coating and has a boiling point higher than that of the good solvent into the resin solution for coating;   adding the lithium-nickel composite oxide particles into the resin solution for coating to prepare a slurry; and   removing the good solvent and the poor solvent sequentially from the slurry.