Lithium battery cathode composite material

Abstract

A lithium battery cathode composite material includes a number of composite particles. Each of the composite particles includes one lithium vanadium phosphate particle and a lithium iron phosphate layer. The lithium iron phosphate layer is disposed on a surface of the lithium vanadium phosphate particle. The lithium iron phosphate layer includes a number of uniformly disposed lithium iron phosphate particles.

1 . A lithium battery cathode composite material comprising a plurality of composite particles, each of the composite particles comprising a lithium vanadium phosphate particle and a lithium iron phosphate layer disposed on a surface of the lithium vanadium phosphate particle, wherein the lithium iron phosphate layer comprises a plurality of lithium iron phosphate particles. 
     
     
         2 . The lithium battery cathode composite material of  claim 1 , wherein the composite particles have core-shell structures. 
     
     
         3 . The lithium battery cathode composite material of  claim 1 , wherein the lithium vanadium phosphate particle in each compound particle is substantially ball-shaped, and a diameter of the lithium vanadium phosphate particle is in a range from about 1 micrometer to about 50 micrometers. 
     
     
         4 . The lithium battery cathode composite material of  claim 1 , wherein the lithium iron phosphate layer comprises a plurality of pores defined by the lithium iron phosphate particles. 
     
     
         5 . The lithium battery cathode composite material of  claim 1 , wherein the lithium iron phosphate particles are substantially ball-shaped, and diameters of the lithium vanadium phosphate particle are in a range from about 50 nanometers to about 10 micrometers. 
     
     
         6 . The lithium battery cathode composite material of  claim 1 , wherein a weight ratio between the lithium iron phosphate layer and the lithium vanadium phosphate particle is larger than 1.5. 
     
     
         7 . The lithium battery cathode composite material of  claim 1 , wherein a thickness of the lithium iron phosphate layer is less than or equal to 10 micrometers. 
     
     
         8 . The lithium battery cathode composite material of  claim 1 , wherein the composite particle comprises carbon material disposed therein, and a weight ratio between the carbon material in each composite particle and the lithium vanadium phosphate particle is in a range from about 0.005 to about 0.1. 
     
     
         9 . The lithium battery cathode composite material of  claim 8 , wherein the carbon material exists as a carbon layer disposed between the lithium vanadium phosphate particle and the lithium iron phosphate layer. 
     
     
         10 . The lithium battery cathode composite material of  claim 8 , wherein the carbon material exists as a carbon layer disposed on a surface of each of the lithium iron phosphate particles. 
     
     
         11 . The lithium battery cathode composite material of  claim 8 , wherein the carbon material exists as carbon particles disposed in the lithium iron phosphate layer. 
     
     
         12 . The lithium battery cathode composite material of  claim 1 , wherein the lithium iron phosphate particles are doped by metal ions. 
     
     
         13 . The lithium battery cathode composite material of  claim 12 , wherein the lithium iron phosphate particles comprise a plurality of iron ions (Fe 2+ ), nickel ions (Ni 2+ ), cobaltco ions (Co 3+ ), magnesium irons (Mg 2+ ), or vanadium ions (V 3+ ). 
     
     
         14 . The lithium battery cathode composite material of  claim 13 , wherein a chemical formula of the lithium iron phosphate particles doped with the metal ions is LiFe (1-xy/2) M x PO 4 , wherein M is a metal doped in the lithium iron phosphate particles, X is a number of M ion in one lithium iron phosphate molecule, and Y is a charge number of one M ion. 
     
     
         15 . The lithium battery cathode composite material of  claim 14 , wherein X is in a range from about 0.01 to about 0.08. 
     
     
         16 . A lithium battery cathode composite material comprising a plurality of composite particles, each of the composite particles having a core and a shell, wherein the core comprises one lithium vanadium phosphate particle, and the shell comprises a lithium iron phosphate layer defining a plurality of pores. 
     
     
         17 . The lithium battery cathode composite material of  claim 16 , wherein the lithium iron phosphate layer comprises a plurality of lithium iron phosphate particles dispersed uniformly on a surface of the lithium vanadium phosphate particle. 
     
     
         18 . The lithium battery cathode composite material of  claim 17 , wherein the lithium iron phosphate particles are doped by metal ions. 
     
     
         19 . The lithium battery cathode composite material of  claim 18 , wherein the lithium iron phosphate particles are doped by vanadium ions (V 3+ ). 
     
     
         20 . A lithium battery cathode composite material comprising a plurality of composite particles, each of the composite particles having a core and a shell, wherein the core is a lithium vanadium phosphate particle, the shell is a lithium iron phosphate layer comprised of a plurality of lithium iron phosphate particles, and a plurality of pores are defined by the plurality of lithium iron phosphate particles.