▎ 摘　　要

NOVELTY - A selenium/graphene/sodium-vanadium composite (I) sodium ion full cell system comprises active material anode electrode selenium/graphene, cathode active material sodium derivative (I), and electrolyte carbonate. The active material anode electrode is prepared by dispersing commercial selenium powder in 2-6 mg/mL graphene oxide solution at mass ratio of 1-10:1, freeze-drying for 10-60 hours to obtain selenium and graphene oxide mixed material, heating to 400-600 degrees C, and calcining for 2-10 hours. USE - Selenium/graphene/sodium-vanadium composite sodium ion full cell system. ADVANTAGE - The product has specific capacity retention rate of more than 75% after 1000 times circulation and capacity retention rate of 92.6% at high current density of 1 A g1 after 10000 times circulation, and exhibits excellent low temperature property. DETAILED DESCRIPTION - A selenium/graphene/sodium-vanadium composite of formula Na3V2(PO4)2O2F (I) sodium ion full cell system comprises active material anode electrode selenium/graphene (Se/G), active material cathode electrode sodium-vanadium composite (I), and electrolyte carbonate. The active material anode electrode is prepared by dispersing commercial selenium powder in 2-6 mg/mL graphene oxide solution at mass ratio of 1-10:1, freeze-drying for 10-60 hours to obtain selenium and graphene oxide mixed material, heating to 400-600 degrees C, and calcining for 2-10 hours. The active material cathode electrode sodium-vanadium composite (I) is prepared by dissolving vanadium pentoxide and oxalic acid in distilled water at molar ratio of 1:3, stirring at 0-100 degrees C for 0.1-24 hours, adding ammonium dihydrogen phosphate and sodium fluoride, stirring for 30 minutes, cooling to room temperature, adjusting pH using ammonia to 7 plus minus 0.5, changing color to green, pouring into reaction kettle at 100-200 degrees C for 12 hours, cooling to room temperature, washing twice by distilled water, and vacuum drying into drying box at 80 degrees C. An INDEPENDENT CLAIM is included for preparation of the selenium/graphene/sodium-vanadium composite (I) sodium ion full cell comprising mixing and grinding active material anode electrode, active material cathode electrode, conductive agent and binder to solvent to prepare electrode slurry, uniformly coating on current collector, drying into vacuum drying box at 60-120 degrees C for 6-24 hours, assembling anode shell, pre-sodiumized cathode plates, diaphragm plus electrolyte, anode plate and cathode shell, adding supporting body to keep anode and cathode plates close contact, putting into sealing machine, and sealing and standing for 0.5-72 hours. The mass ratio of active material anode electrode and active material cathode electrode, conductive agent and binder is 70-90:15-5:15-5. The conductive agent is acetylene black, conductive carbon black, carbon fiber, carbon nanotube and/or Ketjen black (RTM: carbon black). The binder is polyvinylidene fluoride, carboxymethyl cellulose, sodium alginate, polyacrylic acid and/or polyethylene pyrrolidone K30. The solvent is N-methyl pyrrolidone or water. The pre-sodiumized cathode plate is prepared by dropping plate with 0.05-1 mL electrolyte, putting cathode electrode sheet, and standing for 0.5-24 hours. The electrolyte solute is sodium perchlorate and/or sodium hexafluorophosphate. The electrolyte solution is ethylene carbonate, dimethyl carbonate, polycarbonate and/or fluoroethylene carbonate.