▎ 摘　　要

NOVELTY - Cathode material comprises active material particles with yolk-shell structure comprising a multiple of nano particles have a core-shell structure. The inner core of the nano-particles comprises a composite metal oxide and the shell of the nano-particles comprises graphene quantum dots, where the composite metal oxide is MxOy , where x = 1-3 and y = 1-4 and M is chosen from at least two kinds of metal in transition metal comprising iron, cobalt, nickel, copper, zinc, molybdenum or manganese. USE - The cathode material is useful for lithium ion battery (claimed). ADVANTAGE - The cathode material has high volume expansion in the circulation process with increased circulation stability. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) Preparing cathode material; and (2) Lithium ion battery.