▎ 摘　　要

NOVELTY - Synthesis of sodium-iron-nickel-titanium oxide positive electrode material involves mixing sodium acetate, iron acetate, nickel acetate and titanium oxide to obtain a mixed powder, transferring to a planetary ball mill, adding 50 ml analytical pure ethanol, performing ball milling cycle process by performing forward rotation for 10 minutes, performing reverse rotation for 10 minutes, maintaining for 5 minutes and repeating the cycle process to obtain a mixture slurry, drying, compacting the dried powder material into a disc shape with a tablet press, placing the obtained tablet inside a corundum boat, performing continuous microwave irradiation heating, sintering, cooling, transferring obtained pure phase hexagonal sodium-iron-nickel-titanium oxide into an argon atmosphere glove box for storage, performing tablet crushing by adding sodium-iron-nickel-titanium oxide to a shearing force mechanical grinding mill, adding a graphene powder conductive agent, and grinding. USE - Synthesis of sodium-iron-nickel-titanium oxide used as positive electrode material for forming positive electrode for sodium-ion battery. ADVANTAGE - The method enables rapid and homogeneous synthesis of sodium-iron-nickel-titanium oxide. The positive electrode formed using the sodium-iron-nickel-titanium oxide provides sodium-ion battery having desired specific capacity, excellent rate performance and cycle stability, and long battery life. DETAILED DESCRIPTION - Synthesis of sodium-iron-nickel-titanium oxide (NaFe1/3Ni1/3Ti1/3O2) positive electrode material involves mixing (i) sodium acetate, iron acetate, nickel acetate and titanium oxide at a room temperature to obtain a mixed powder, in which stoichiometric ratio of sodium, iron, nickel and titanium is 1:1/3:1/3:1/3, accurately weighing 12 g mixed powder and transferring to a planetary ball mill comprising 304 stainless steel ball and having a volume of 200 ml and setting a ball-to-material ratio to 10:1, adding 50 ml analytical pure ethanol, adjusting the ball mill speed to 100-1500 rpm, performing ball milling cycle process by performing forward rotation for 10 minutes, performing reverse rotation for 10 minutes, maintaining for 5 minutes, and repeating the ball milling cycle process to obtain a mixture slurry, in which the total time for ball milling is 30-500 minutes, transferring (ii) the mixture slurry into a beaker, transferring into an electric vacuum-drying oven, setting a drying temperature of 60-70 degrees C and a constant temperature of 1-24 hours, and drying to obtain a dried powder material, compacting (iii) the dried powder material into a disc shape with a tablet press under the conditions of a tablet thickness of 10 mm, a tablet pressure of 10-20 MPa and a diameter of a tablet die of 10-80 mm, placing the obtained tablet inside a corundum boat having a diameter of 30 mm and a length of 150 mm, passing into a microwave sintering furnace, performing continuous microwave irradiation heating under the conditions of a flow of argon gas of 100 ml/minute, continuously purging the furnace component pipeline for 40 minutes, heating at 500-1200 degrees C at a heating rate of 5-10 degrees C/minute, continuously sintering for 1-20 hours, cooling to room temperature after sintering, and finally transferring the obtained pure phase hexagonal sodium-iron-nickel-titanium oxide with comprising a layered structure with smooth surface and uniform thickness, and having high crystallinity and no other impurities into an argon atmosphere glove box for storage, and performing (iv) tablet crushing process by adding 5 g sodium-iron-nickel-titanium oxide to a grinding tank of a shearing force mechanical grinding mill, adding 0.1000-1 g graphene powder conductive agent material having a specific surface area of 1800 m2/g and a sheet thickness of 6-11 nm, and grinding under the conditions of a speed of 10000-29000 rpm, a working power of 800-1200 W, a grinding temperature of 25 degrees C and a grinding time of 5-30 minutes to obtain a spherical-shaped sodium-iron-nickel-titanium oxide coated with 20 nm graphene material with a diameter of 15-25 mu m. The spherical-shaped sodium-iron-nickel-titanium oxide coated with graphene material is assembled in a sodium ion half-cell by adding the spherical-shaped sodium-iron-nickel-titanium oxide coated with graphene material, polyvinylidene fluoride as a binder and acetylene black conductive agent in a mass ratio of 8:1:1, mixing evenly to obtain a mixture, accurately weighing 2 g mixture, adding N-methylpyrrolidone solvent in an amount of 8 times the total mass of the mixture, placing in a planetary ball mill comprising a stainless steel ball with a diameter of 5 mm and setting a ball-to-material ratio to 20:1, setting the ball mill speed to 600 rpm, performing ball milling cycle process by performing forward rotation for 10 minutes, performing reverse rotation for 10 minutes, maintaining for 5 minutes, and repeating the ball milling cycle process to obtain a black viscous slurry, in which the total time for ball milling is 1-3 hours, and evenly coating the black viscous slurry on a conductive aluminum foil with a thickness of 25 mu m, placing in a vacuum-drying oven, setting a constant temperature heating temperature to 120 degrees C and heating for 24 hours to obtain a sodium-iron-nickel-titanium oxide positive electrode material, using a metal sodium sheet with a thickness of 0.5-1 mm as a negative electrode material, using a porous organic diaphragm as a battery diaphragm, preparing an organic electrolyte comprising 0.5-1 mol/L sodium hexafluorophosphate, and a solvent comprising ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, assembling the sodium-iron-nickel-titanium oxide positive electrode material, negative electrode material, battery diaphragm and organic electrolyte in a double-station glove box which is protected with an inert argon gas to obtain a sodium-ion battery, testing an internal resistance and an alternate current impedance of the battery, maintaining the battery in a constant temperature environment of 25 degrees C for 1 day, measuring the battery on a potentiostatic instrument, and measuring discharging performance at different rates of 0.5C, 1C, 2C, 5C and 10C to monitor specific capacity and cycle stability changes of battery.