Method to prepare a composition for forming an electrode of a lithium secondary battery

Abstract

A method to prepare an electrode active material of formula (1) for a secondary battery, comprising: preparing carbon coated particles of a lithium metal phosphate composite of formula (1): LiFe1−xMxPO4   (1) wherein x is a number from 0 to 1, inclusive, M is at least one metallic element selected from the group consisting of Mn, Co, Ni and V; preparing a first active material of the carbon coated particles of formula (1) comprising secondary particles of a coated. primary particle of the composite material of formula (1), where a surface of the primary particle is coated with conductive carbon and an average particle diameter of the coated primary particle is from 50 to 300 nm, and an average particle diameter of the secondary particle is from 300 nm to 3 μm; and granulating secondary particles of a carbon-coated primary particle of the composite material of formula (1), or uncoated primary particles of the composite material of formula (1) and a precursor of conductive carbon, to prepare a second active material of spherical granulated particles, wherein an average particle diameter of the primary particle is from 50 to 300 nm and an average particle diameter of the granulated particle is from 8 to 30 μm; wherein the secondary particle of the first active material is prepared without undergoing a grinding operation of a force that would result in a D50 particle size of the secondary particle being reduced by at least one half.

Dependencies are inferred from the claim text.