Positive Electrode Active Material For A Lithium-Ion Battery, Positive Electrode For A Lithium-Ion Battery, Lithium-Ion Battery Using Same, And Precursor To A Positive Electrode Active Material For A Lithium-Ion Battery

Abstract

The present invention provides a positive electrode active material for lithium ion batteries, which realizes a lithium ion battery that is, while satisfying fundamental characteristics of a battery (capacity, efficiency, load characteristics), low in the resistance and excellent in the lifetime characteristics. In the positive electrode active material for lithium ion batteries, the variation in the composition of transition metal that is a main component inside of particles of or between particles of the positive electrode active material, which is defined as a ratio of the absolute value of the difference between a composition ratio inside of the particles of or in a small area between the particles of the transition metal and a composition ratio in a bulk state to the composition ratio in a bulk state of the transition metal, is 5% or less.

1 . A positive electrode active material for lithium ion batteries, which is composed of at least lithium and transition metal, wherein the variation in the composition of transition metal that is a main component inside of particles of or between particles of the positive electrode active material, which is defined as a ratio of the absolute value of the difference between a composition ratio inside of the particles of or in a small area between the particles of the transition metal and a composition ratio in a bulk state to the composition ratio in a bulk state of the transition metal, is 5% or less. 
     
     
         2 . The positive electrode active material for lithium ion batteries of  claim 1 , wherein the positive electrode active material is a lithium-containing transition metal oxide. 
     
     
         3 . The positive electrode active material for lithium ion batteries of  claim 2 , wherein the transition metal in the lithium-containing transition metal oxide is at least one or two or more kinds selected from the group consisting of Ni, Mn, Co and Fe. 
     
     
         4 . The positive electrode active material for lithium. ion batteries of any one of  claims 1  to  3 , wherein an average particle size of particles of the positive electrode active material is 2 to 8 μm, a specific surface area of the positive electrode active material is 0.3 to 1.8 m 2 /g, and the tap density of the positive electrode active material is 1.5 to 2.1 g/ml. 
     
     
         5 . A positive electrode for lithium ion batteries, comprising a positive electrode active material for lithium ion batteries of any one of  claims 1  to  3 . 
     
     
         6 . A lithium ion battery comprising a positive electrode for lithium ion batteries of  claim 5 . 
     
     
         7 . A precursor for positive electrode active material for lithium ion batteries, which is composed of secondary particles made of at least lithium and transition metal and formed by flocculating primary particles, wherein the variation in composition of transition metal that is a main component inside of secondary particles or between the secondary particles of the precursor for positive electrode active material, which is defined as a ratio of the absolute value of the difference between a composition ratio inside of the particles of or in a small area between the particles of the transition metal and a composition ratio in a bulk state to the composition ratio in the bulk state of the transition metal, is 5% or less. 
     
     
         8 . The precursor for positive electrode active material for lithium ion batteries of  claim 7 , including lithium and transition metal as main component.