▎ 摘　　要

NOVELTY - Preparing nano-germanium/three-dimensional porous graphene composite material comprises (i) ultrasonically dispersing graphite oxide in deionized water, (ii) preparing cationic polyelectrolyte-modified polystyrene microsphere dispersion by (iia) dissolving tris(hydroxymethyl)aminomethane hydrochloride and cationic polyelectrolyte in sodium chloride solution respectively, adding polystyrene microspheres, ultrasonically treating, and obtaining cationic polyelectrolyte-modified polystyrene microspheres, and (iib) preparing cationic polyelectrolyte-modified polystyrene microsphere deionized water dispersion, and (iii) preparing nano-germanium/three-dimensional porous graphene composites by (iiia) preparing sodium hydroxide solution, slowly adding polyvinylpyrrolidone and germanium dioxide, adding graphene oxide dispersion liquid, dripping hydrochloric acid solution, and dripping to sodium borohydride solution, and (iiib) heating product in inert/reducing mixed gas. USE - The composite material is useful in cathode of lithium-ion battery (claimed). ADVANTAGE - The method: utilizes template-assisted thermal reduction combined with freeze-drying method to prepare nano-germanium/three-dimensional porous graphene composite material; has simple and feasible operation process, and short reaction time; is environmentally friendly and economical; and has easy industrialized implementation. The material: has excellent lithium storage properties. DETAILED DESCRIPTION - Preparing nano-germanium/three-dimensional porous graphene composite material comprises (i) ultrasonically dispersing graphite oxide in deionized water to obtain a graphene oxide dispersion having a concentration of 1-2 mg/ml, (ii) preparing cationic polyelectrolyte-modified polystyrene microsphere dispersion by (iia) dissolving tris(hydroxymethyl)aminomethane hydrochloride and cationic polyelectrolyte in sodium chloride solution respectively, then adding polystyrene microspheres, ultrasonically treating for 1-3 hours, stirring for 2-8 hours, centrifuging, washing the product with deionized water, and freeze-drying to obtain cationic polyelectrolyte-modified polystyrene microspheres, where the mass ratio of the cationic polyelectrolyte, tris(hydroxymethyl)aminomethane hydrochloride, sodium chloride and polystyrene microspheres is 12:2:1:1-3 and (iib) preparing cationic polyelectrolyte-modified polystyrene microsphere deionized water dispersion with a concentration of 1-2 mg/ml, preferably 1 mg/ml, and (iii) preparing nano-germanium/three-dimensional porous graphene composites by (iiia) preparing 0.4-0.6 mol/l sodium hydroxide solution, preferably 0.5 mol/l, slowly adding polyvinylpyrrolidone and germanium dioxide respectively, stirring and dissolving, adding to the dispersion of polystyrene microspheres modified by cationic polyelectrolyte, and stirring for 4-8 hours, preferably 6 hours, then adding graphene oxide dispersion liquid, stirring for 10-14 hours, preferably 7 hours, dripping hydrochloric acid solution to adjust pH to 7-13, preferably 7, dripping to the sodium borohydride solution at 0-4℃, preferably 0℃, heating at 60-80℃ for 1-4 hours, preferably at 60℃ for 3 hours, naturally cooling, centrifugally separating, washing the product with deionized water, and freeze-drying, where the molar ratio of sodium hydroxide and germanium dioxide is 2:1-0.5, preferably 2:1, and the mass ratio of germanium dioxide and polyvinylpyrrolidone is 10:1-3, preferably 10:1, the volume ratio of sodium hydroxide solution, cationic polyelectrolyte-modified polystyrene microsphere dispersion, graphene oxide dispersion and sodium borohydride solution is 1:4:2-4:1, preferably 1:4:3:1 and (iiib) heating product in an inert/reducing mixed gas at 600-800℃ for 4-8 hours, preferably at 650℃ for 6 hours to obtain the finished product. An INDEPENDENT CLAIM is also included for a nano-germanium/three-dimensional porous graphene composite material prepared by the above-mentioned method.