Cathode active material, cathode, and nonaqueous electrolyte secondary battery
View Patent ↗The present application provides a nonaqueous electrolyte secondary battery which includes a cathode having a cathode active material layer, an anode, and a nonaqueous electrolyte, wherein the cathode active material layer includes secondary particles of a lithium phosphate compound having olivine structure, an average particle diameter A of primary particles constituting the secondary particles is 50 nm or more and 500 nm or less, and a ratio B/A of a pore diameter B of the secondary particles to the average particle diameter A of the primary particles is 0.10 or more and 0.90 or less.
1. A nonaqueous electrolyte secondary battery comprising:
a cathode having a cathode active material layer;
an anode; and
a nonaqueous electrolyte, wherein:
the cathode active material layer includes secondary particles constituted by primary particles;
the primary particles are carbon material-coated lithium phosphate compound particles;
an average particle diameter A of primary particles is 50 nm or more and 500 nm or less;
a ratio B/A of a pore diameter B of the secondary particles to the average particle diameter A of the primary particles is 0.10 or more and 0.75 or less;
the average diameter A is an average particle diameter of a total diameter of the carbon-coated lithium phosphate compound particles including carbon, and
the pore diameter B is a diameter of a void present between the carbon-coated lithium phosphate compound particles.
2. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the cathode active material layer contains a fibrous carbon.
3. A cathode active material comprising:
secondary particles constituted by primary particles; wherein:
the primary particles are carbon material-coated lithium phosphate compound particles,
an average particle diameter A of the primary particles is 50 nm or more and 500 nm or less and a ratio B/A of a pore diameter B of the secondary particles to the average particle diameter A of the primary particles is 0.10 or more and 0.75 or less,
the average diameter A is an average particle diameter of a total diameter of the carbon-coated lithium phosphate compound particles including carbon, and the pore diameter B is a diameter of a void present between the carbon-coated lithium phosphate compound particles.
4. A cathode comprising:
a cathode active material which contains secondary particles constituted by primary particles, wherein:
the primary particles are carbon material-coated lithium phosphate compound particles,
an average particle diameter A of the primary particles is 50 nm or more and 500 nm or less and a ratio B/A of a pore diameter B of the secondary particles to the average particle diameter A of the primary particles is 0.10 or more and 0.75 or less,
the average diameter A is an average particle diameter of a total diameter of the carbon-coated lithium phosphate compound particles including carbon, and
the pore diameter B is a diameter of a void present between the carbon-coated lithium phosphate compound particles.
5. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the pore diameter B is 11 nm or more and 295 nm or less.
6. The cathode active material according to claim 3 , wherein the pore diameter B is 11 nm or more and 295 nm or less.
7. The cathode according to claim 4 , wherein the pore diameter B is 11 nm or more and 295 nm or less.
8. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the cathode active material layer comprises a conductive agent selected from the group consisting of: fibrous carbon, spherical carbon and carbon black.
9. The cathode according to claim 4 , comprising a conductive agent selected from the group consisting of: fibrous carbon, spherical carbon and carbon black.
10. The nonaqueous electrolyte secondary battery according to claim 8 , wherein the conductive agent is fibrous carbon.
11. The cathode according to claim 9 , wherein the conductive agent is fibrous carbon.
12. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the lithium phosphate compound is a compound represented by LiFe 1−y M y PO 4 , wherein M is at least one selected from the group consisting of cobalt, manganese, nickel, magnesium, aluminum, boron, titanium, vanadium, niobium, copper, zinc, molybdenum, calcium, strontium, tungsten, and zirconium, and 0<y<1.0.
13. The cathode active material according to claim 3 , wherein the lithium phosphate compound is a compound represented by LiFe 1−y M y PO 4 , wherein M is at least one selected from the group consisting of cobalt, manganese, nickel, magnesium, aluminum, boron, titanium, vanadium, niobium, copper, zinc, molybdenum, calcium, strontium, tungsten, and zirconium, and 0<y<1.0.
14. The cathode according to claim 4 , wherein the lithium phosphate compound is a compound represented by LiFe 1−y M y PO 4 , wherein M is at least one selected from the group consisting of cobalt, manganese, nickel, magnesium, aluminum, boron, titanium, vanadium, niobium, copper, zinc, molybdenum, calcium, strontium, tungsten, and zirconium, and 0<y<1.0.
15. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the lithium phosphate compound has an olivine structure.