▎ 摘　　要

NOVELTY - A graphene/lithium iron phosphate compound material of sandwich structure comprises graphene layer sheets which are generated as block-shaped particles by completely packing with a lithium iron phosphate shell. The particles inside is a sandwich structure stacked by layers of one layer of lithium iron phosphate/one layer of graphene. USE - Graphene/lithium iron phosphate compound material of sandwich structure used as lithium ion battery positive electrode material. ADVANTAGE - The material has high capacity and good charging and discharging cycling performance. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of graphene/lithium iron phosphate compound material of sandwich structure, comprising: (A) dissolving potassium peroxydisulfate (0.2 g/mL) and phosphorus pentoxide (0.2 g/mL) in concentrated sulfuric acid, keeping temperature at 80 degrees C for several hours, adding adequate natural graphite powder into the solution, then cooling to room temperature, diluting using deionized water, standing overnight, filtering to remove residual acid, and vacuum drying; (B) dissolving obtained products in concentrated sulfuric acid, adding potassium permanganate in ice bath condition, stirring for several hours at constant temperature of 35 degrees C, then using deionized water to dilute, standing, adding adequate 30 wt.% hydrogen peroxide (H2O2) into the solution, then filtering, using hydrochloric acid solution to wash, then using deionized water to wash, where mass ratio of potassium permanganate and the products is 2:1-4:1 (C) adding deionized water into the solution to dilute, adding 10-30 mol/L solution containing water-soluble ferrite (0.01-0.1 mol/L) and water-soluble phosphate (0.01-0.1 mol/L), then adding adequate 30 wt.% of H2O2 after dissolving, stirring for several hours at room temperature, centrifuging and washing for several times, then putting obtained cream in a blast oven, and drying for several hours at 80 degrees C; (D) grinding dried material into powder, putting in a tube shape furnace, cooling naturally after annealing for 4-6 hours at 200-800 degrees C under protection of inert gas to obtain precursor of sandwich structure, where the precursor inserts lithium to obtain graphene/lithium iron phosphate of sandwich structure; (E) dissolving lithium iodide (0.2-1 mol/L) in adequate acetonitrile, then adding the annealed graphene/lithium iron phosphate precursor, where mass ratio of lithium iodide and graphene/lithium iron phosphate compound material is 2:1-4:1, stirring for 10-24 hours at room temperature, centrifuging and using acetonitrile to wash for several times, putting obtained sediment in a vacuum drying box, and drying for several times at 60-200 degrees C; and (F) putting the dried materials in the tube shape furnace, and cooling naturally after calcining for 2-10 hours at 500-800 degrees C under inert gas or reduced atmosphere to obtain uniformly dispersed graphene/lithium iron phosphate compound material.