A method for modifying a positive electrode material for a lithium-ion battery. The method includes: a) stirring a liquid polyacrylonitrile (LPAN) solution at the temperature of between 80 and 300° C. for between 8 and 72 h to yield a cyclized LPAN solution; b) adding positive electrode material for a lithium-ion battery, in a powder form, to the cyclized LPAN solution, and evenly mixing a resulting mixture; c) grinding the mixture, and drying the mixture at room temperature; and d) calcining the mixture at the temperature of between 500 and 1800° C. for between 6 and 24 h in the presence of an inert gas to form a graphene-like structure by the cyclized LPAN. The graphene-like structure is evenly distributed in the positive electrode material of the lithium-ion battery to yield a graphene-like structure modified positive electrode material of the lithium-ion battery.