负载ZnS的介孔炭复合硫正极材料的制备及性能研究

为了获得高性能的锂硫电池正极材料, 采用先超声分散再进行热处理的方法制备了负载ZnS的介孔炭复合材料(ZnS/MC), 进而用热复合法获得负载有ZnS的介孔炭复合硫正极材料(ZnS/MC/S)。XRD、SEM、EDS和N2吸附脱附等温线表明, 当ZnS含量低于17wt%时, 通过超声波分散, ZnS可以均匀负载到介孔炭中; 但热处理或提高ZnS含量时ZnS会发生聚集, 形成闪锌矿型ZnS晶相。循环伏安测试表明, ZnS对多硫离子的氧化起促进作用; 充放电测试表明, ZnS/MC/S电极的初始放电比容量为1354.6 mAh/g, 首次充放电库仑效率为98.7%; 50次循环后容量仍有650 mAh/g。

Preparation of Mesoporous Carbon/Sulfur Composite Loaded with ZnS and Its Property for Lithium-sulfur Batteries

With the aim to obtain high performance cathode materials for lithium-sulfur batteries, composite of mesoporous carbon (MC) loaded with ZnS (ZnS/MC) was prepared through ultrasonic dispersion and heat treatment. The as-prepared composite was blended with elemental sulfur by heating, then cathode materials (ZnS/MC/S) was obtained. The ZnS/MC composite was characterized by XRD, SEM, EDS and N₂ adsorption-desorption isotherms. The results showed that ZnS particle was uniformly loaded to the surface of MC through ultrasonic dispersion when content of ZnS was less than 17wt%. ZnS nanoparticles aggregated to form sphalerite ZnS by heat treatment or increasing content of ZnS. Cyclic voltammetry test showed that ZnS accelerated the oxidation process of polysulfides. Charge/ discharge tests indicated that the initial discharge specific capacity was 1354.6 mAh/g, while the coulombic efficiency of the first charge and discharge was 98.7%. The capacity still remained 650 mAh/g after 50 cycles.