▎ 摘　　要

NOVELTY - Preparing lithium manganate/three-dimensional graphene composite material, comprises e.g. placing manganese source and strong oxidant in a beaker, then adding deionized water, stirring and mixing strong oxidant and manganese source thoroughly at room temperature with DF-101S collector type thermostatic magnetic stirrer, then transferring mixture to polytetrafluoroethylene lining and sealing the polytetrafluoroethylene lining into a stainless steel reactor, then setting at a temperature of 80-200 degrees C, insulating, cooling, filtering, and drying to obtain black powder manganese(IV) oxide precursor, then placing manganese(IV) oxide precursor and lithium source in a beaker and adding absolute ethanol, then shaking, drying, grinding, calcining and cooling to obtain lithium manganate, then preparing three-dimensional graphene, and mixing lithium manganate and three-dimensional graphene, and adding absolute ethanol during grinding and heating. USE - The method is useful for preparing lithium manganate/three-dimensional graphene composite material. ADVANTAGE - The graphene composite material: has excellent electrochemical performance includes magnification performance and cycle performance, and the method has simple process and low production cost. DETAILED DESCRIPTION - Preparing lithium manganate/three-dimensional graphene composite material comprises (i) placing 0.01-0.2 mol manganese source and 0.01-0.2 mol strong oxidant in a beaker, then adding 40-200 ml deionized water; then stirring and mixing strong oxidant and manganese source thoroughly at room temperature with DF-101S collector type thermostatic magnetic stirrer, then transferring mixture to 50-300 ml polytetrafluoroethylene lining and sealing the polytetrafluoroethylene lining into a stainless steel reactor, then setting at a temperature of 80-200 degrees C, insulating for 8-24 hours, cooling to room temperature, filtering, and drying at 60-120 degrees C for 18-48 hours to obtain black powder manganese(IV) oxide precursor, (ii) placing 0.001-0.2 mol manganese(IV) oxide precursor obtained in step (i) and 0.001-0.2 mol lithium source in a beaker and adding 40-100 ml absolute ethanol, then shaking for 20-60 minutes, drying in the oven at 60-120 degrees C, grinding in the mortar for 10-120 minutes, then placing the sample in the muffle furnace for pre-sintering at 250-650 degrees C for 2-10 hours, calcining at 650-850 degrees C for 10-30 hours, and cooling to room temperature with the furnace to obtain lithium manganate, (iii) placing a beaker containing 1-100 ml 98% concentrated sulfuric acid in an ice water bath at a temperature of 1-20 degrees C, adding 1-10 g of graphite powder and 1-10 g sodium nitrate and 1-10 g potassium permanganate for 1 to 3 hours under stirring, and then transferring to a 20-100 degrees C water bath, reacting for 1-10 hours, then adding 50-200 ml deionized water to the reaction for 1-50 minutes, then moving to 20-100 degrees C water bath for 1-50 minutes, adding 1-100 ml 30% hydrogen peroxide to the bright yellow solution to produce no bubbles, hot filtering, and washing 7 times with diluted hydrochloric acid and deionized water having a concentration of 5% to prepare an aqueous solution of graphite oxide having a concentration of 1-10 mg/ml and adding 0.01-0.1 g nickel(II) chloride hexahydrate into 10-100 ml of solution, then stirring, and sonicating for 1-5 hours at room temperature, adding into 50-200 ml reactor lining with polytetrafluoroethylene, reacting at 80-200 degrees C for 6-20 hours, cooling to room temperature, taking out the three-dimensional graphene gel and washing with deionized water, freezing for 12-96 hours, and then drying in a freeze dryer for 12-96 hours to obtain three-dimensional graphene, and (iv) mixing 0.1-2 g lithium manganate obtained in step (ii) and 0.1-2 g three-dimensional graphene obtained in step (ii) in a mortar for 1-3 hours, and adding 1-3 drops of absolute ethanol during the grinding process, placing resulting mixture in a muffle furnace and heating at a heating rate of 2-10 degrees C/minute to 80-400 degrees C for 3-6 hours, and cooling to room temperature with the furnace to obtain final product, where the strong oxidant is ammonium persulfate, potassium perchlorate, potassium permanganate, hydrogen peroxide and/or sodium persulfate; the lithium source is lithium acetate, lithium carbonate and/or lithium hydroxide; the manganese source is manganese acetate, manganese carbonate, manganese sulfate and/or manganese nitrate.