Positive active material and lithium-ion battery

Abstract

The present application provides a positive active material, a positive electrode and a lithium-ion battery. The positive active material comprising a first particle and a second particle, wherein the first particle has a chemical formula of Li e Co g M 1-g O 2-i , and the second particle has a chemical formula of Li f Co h N 1-h O 2-j , the element M is at least two selected from a group consisting of Ni, Mn, Al, Mg, Ti, La, Y and Zr, the element N is at least one selected from a group consisting of Ni, Mn, Al, Mg, Ti, La, Y and Zr, and 0.8≤e≤1.2, 0<g<1, −0.1≤i≤0.2, 0.8≤f≤1.2, 0<h<1, −0.1≤j≤0.2, the number of types of the element M in the first particle is greater than the number of types of the element N in the second particles. The positive active material of the present application has a good stability and can improve the capacity retention rate of the lithium-ion battery.

What is claimed is: 
     
         1 . A positive active material, comprising a first particle and a second particle, wherein the first particle has a chemical formula of Li e Co g M 1-g O 2-i , and the second particle has a chemical formula of Li f Co h N 1-h O 2-j , the element M is at least two selected from a group consisting of Ni, Mn, Al, Mg, Ti, La, Y and Zr, the element N is at least one selected from a group consisting of Ni, Mn, Al, Mg, Ti, La, Y and Zr, and 0.8≤e≤1.2, 0<g<1, −0.1≤i≤0.2, 0.8≤f≤1.2, 0<h<1, −0.1≤j≤0.2, the number of types of the element M in the first particle is greater than the number of types of the element N in the second particles. 
     
     
         2 . The positive active material according to  claim 1 , wherein the first particle has a chemical formula of Li n Co x M 1-x O 2-y , and the second particle has a chemical formula of Li n Co x N 1-x O 2-y , and 0.8≤n≤1.2, 0<x<1, −0.1≤y≤0.2. 
     
     
         3 . The positive active material according to  claim 1 , wherein the particle diameter of the first particle is smaller than the particle diameter of the second particle. 
     
     
         4 . The positive active material according to  claim 3 , wherein the particle diameter of the first particle is smaller than Dv50 of the positive active material, and the particle diameter of the second particle is larger than Dv50 of the positive active material. 
     
     
         5 . The positive active material according to  claim 1 , wherein each of the elements M is contained in the first particle in an amount of more than 200 ppm, and each of the elements N is contained in the second particle in an amount of more than 200 ppm. 
     
     
         6 . The positive active material according to  claim 1 , wherein the positive active material meets the following formula (1):
   ( a/b )/( c/d )>1   formula (1)
   a represents the total mass of the element M in the first particle;   b represents the mass of the element Co in the first particle;   c represents the total mass of the element N in the second particle;   d represents the mass of the element Co in the second particle.   
     
     
         7 . The positive active material according to  claim 1 , wherein the positive active material meets the following formula (2):
   ( A/B )/( C/D )>1   formula (2)
   A represents the total molar amount of the element M in the first particle;   B represents the molar amount of the element Co in the first particle;   C represents the total molar amount of the element N in the second particle;   D represents the molar amount of the element Co in the second particle.   
     
     
         8 . The positive active material according to  claim 6 , wherein the positive active material has a value of (a/b)/(c/d) of 1.3 to 10. 
     
     
         9 . The positive active material according to  claim 1 , wherein the volume-based particle size distribution curve of the positive active material comprises a first peak and a second peak. 
     
     
         10 . The positive active material according to  claim 9 , wherein the peak height of the second peak is greater than the peak height of the first peak. 
     
     
         11 . The positive active material according to  claim 1 , wherein the particle diameter of the positive active material meets the following formula (3):
   ( Dv 90− Dv 50)−( Dv 50− Dv 10)≤2.5   formula (3).
   
     
     
         12 . A positive electrode, wherein comprising a positive active material, wherein the positive active material comprising a first particle and a second particle, wherein the first particle has a chemical formula of Li e Co g M 1-g O 2-i , and the second particle has a chemical formula of Li f Co h N 1-h O 2-j , the element M is at least two selected from a group consisting of Ni, Mn, Al, Mg, Ti, La, Y and Zr, the element N is at least one selected from a group consisting of Ni, Mn, Al, Mg, Ti, La, Y and Zr, and 0.8≤e≤1.2, 0<g<1, −0.1≤i≤0.2, 0.8≤f≤1.2, 0<h<1, −0.1≤j≤0.2, the number of types of the element M in the first particle is greater than the number of types of the element N in the second particles. 
     
     
         13 . The positive electrode according to  claim 12 , wherein the particle diameter of the first particle is smaller than the particle diameter of the second particle. 
     
     
         14 . The positive electrode according to  claim 13 , wherein the particle diameter of the first particle is smaller than Dv50 of the positive active material, and the particle diameter of the second particle is larger than Dv50 of the positive active material. 
     
     
         15 . The positive electrode according to  claim 12 , wherein each of the elements M is contained in the first particle in an amount of more than 200 ppm, and each of the elements N is contained in the second particle in an amount of more than 200 ppm. 
     
     
         16 . The positive electrode according to  claim 12 , wherein the positive active material meets the following formula (1):
   ( a/b )/( c/d )>1   formula (1)
   a represents the total mass of the element M in the first particle;   b represents the mass of the element Co in the first particle;   c represents the total mass of the element N in the second particle;   d represents the mass of the element Co in the second particle.   
     
     
         17 . The positive electrode according to  claim 12 , wherein the positive active material meets the following formula (2):
   ( A/B )/( C/D )>1   formula (2)
   A represents the total molar amount of the element M in the first particle;   B represents the molar amount of the element Co in the first particle;   C represents the total molar amount of the element N in the second particle;   D represents the molar amount of the element Co in the second particle.   
     
     
         18 . A lithium-ion battery, wherein comprising a positive electrode with a positive active material, wherein the positive active material comprising a first particle and a second particle, wherein the first particle has a chemical formula of Li e Co g M 1-g O 2-i , and the second particle has a chemical formula of Li f Co h N 1-h O 2-j , the element M is at least two selected from a group consisting of Ni, Mn, Al, Mg, Ti, La, Y and Zr, the element N is at least one selected from a group consisting of Ni, Mn, Al, Mg, Ti, La, Y and Zr, and 0.8≤e≤1.2, 0<g<1, −0.1≤i≤0.2, 0.8≤f≤1.2, 0<h<1, −0.1≤j≤0.2, the number of types of the element M in the first particle is greater than the number of types of the element N in the second particles. 
     
     
         19 . The lithium-ion battery according to  claim 18 , wherein the compact density of the positive electrode is g/cm 3 . 
     
     
         20 . The lithium-ion battery according to  claim 18 , wherein the particle diameter of the first particle is smaller than the particle diameter of the second particle.