▎ 摘　　要

NOVELTY - Preparation of modified three-dimensional graphene/polyaniline-coated sulfur positive electrode involves dissolving three-dimensional graphene aerogel in deionized water, ultrasonically-processing, adding isoamyl nitrite and 4-aniline sulfonic acid, reacting, and washing and freeze-drying, dissolving the obtained sulfonated modified three-dimensional graphene in deionized water and stirring, slowly adding mixed solution formed by dissolving ammonium sulfate in hydrochloric acid solution, and adding aniline, and washing and freeze-drying, and compression-molding the obtained modified three-dimensional graphene/polyaniline composite material using a mold, adding elemental sulfur in the composite material, placing the composite material in a quartz tube under vacuum, heating the quartz tube at 150-160 degrees C for 9-11 hours, and cooling to room temperature. USE - Preparation of modified three-dimensional graphene/polyaniline-coated sulfur positive electrode used for lithium-sulfur battery. ADVANTAGE - The method enables preparation of modified three-dimensional graphene/polyaniline-coated sulfur positive electrode having improved mechanical strength and conductivity, and suppressed volume change in sulfur positive electrode during charging/discharging. The graphite powder is oxidized and peeled to form graphene oxide, and the three-dimensional graphene is formed by high-temperature heating and freeze-drying. The three-dimensional graphene is sulfonated, and combined with polyaniline through in-situ reaction to form modified three-dimensional graphene/polyaniline composite material. The elemental sulfur is coated in the modified three-dimensional graphene/polyaniline composite material by melt impregnation method, so as to realize the suppression of dissolution and shuttle of polysulfide in the electrochemical reaction. DETAILED DESCRIPTION - Preparation of modified three-dimensional graphene/polyaniline-coated sulfur positive electrode involves preparing (i) graphene oxide by uniformly dissolving graphite powder and sodium nitrate and dispersing in concentrated sulfuric acid under ice water bath conditions to form a reaction solution, slowly adding potassium permanganate to the reaction solution, controlling the temperature of the reaction solution to 15-25 degrees C for 1.3-1.7 hours, increasing the temperature to 30-40 degrees C for 0.8-1.2 hours, adding deionized water to the reaction solution, increasing the temperature to 90-100 degrees C and maintaining for 30-50 minutes, finally adding hydrogen peroxide to the reaction solution, reacting for 50-70 minutes, and washing and drying the reaction product, preparing (ii) three-dimensional graphene aerogel by dispersing the graphene oxide in deionized water, ultrasonically-processing to form a graphene oxide dispersion liquid, placing the graphene oxide dispersion liquid in a reaction kettle, heating at 90-110 degrees C and maintaining for 30-60 minutes, heating at 160-200 degrees C for 18-24 hours, naturally cooling to room temperature, and washing and freeze-drying the obtained graphene aerogel, preparing (iii) sulfonated modified three-dimensional graphene by dissolving the three-dimensional graphene aerogel in deionized water, ultrasonically-processing, adding isoamyl nitrite and 4-aniline sulfonic acid, reacting at 70-100 degrees C for 18-24 hours, and washing and freeze-drying the obtained graphene aerogel, preparing (iv) a modified three-dimensional graphene/polyaniline composite material by dissolving the sulfonated modified three-dimensional graphene in deionized water, stirring at 0 degrees C to form a modified three-dimensional graphene dispersion, controlling the temperature to 0 degrees C, dissolving ammonium sulfate in hydrochloric acid solution, adding aniline to the ammonium sulfate-hydrochloric acid solution to form a mixed solution, slowly adding the mixed solution to the modified three-dimensional graphene dispersion, stirring at 0 degrees C, and washing and freeze-drying the obtained reaction product, and preparing (v) modified three-dimensional graphene/polyaniline-coated sulfur positive electrode by compression-molding the modified three-dimensional graphene/polyaniline composite material using a mold, adding elemental sulfur in the composite material, placing the composite material in a quartz tube under vacuum, heating the quartz tube at 150-160 degrees C for 9-11 hours, and cooling to room temperature.