rGO-S-CPEs复合正极的制备及其全固态锂硫电池的电化学性能

Preparation of rGO-S-CPEs composite cathode and electrochemical performance of all-solid-state lithium-sulfur battery

聚合物基复合电解质(CPE)应用于全基固态锂硫电池在保证高能量密度的同时,改善了电解质与电极之间的界面接触,具有更为广阔的应用前景。但硫正极固有的绝缘性会导致较低的电子/离子传输速率,通常选用高导电性的碳材料和高离子电导率的电解质材料来改善复合硫正极的电子/离子传输速率。制备了高离子电导率的聚合物基聚氧化乙烯(PEO)-双三氟甲磺酰亚胺锂(LiTFSI)-锆酸镧锂(LLZO)复合电解质,在20和60℃下离子电导率分别为1.16×10-4和7.26×10^(-4)S/cm,同时将其与硫-还原氧化石墨烯制备rGO-S-CPEs复合硫正极,在改善了正极中离子传输速率的同时,取代了粘结剂的作用。探究了正极材料中不同含量的复合电解质对电池性能的影响。测试结果表明,当硫正极中复合电解质含量为40%(质量分数)时,全固态锂硫电池的电化学性能最佳,在0.2 C、45℃下,首次充放电比容量为923 mAh/g,50次循环后比容量为653 mAh/g。

The application of polymer based composite electrolyte in all-solid-state lithium-sulfur battery can guarantee high energy density and improve the interface contact between electrolyte and electrode,which has a broader application prospect.However,the inherent insulation of the sulfur cathode leads to a low electron/ion transfer rate.Carbon materials with high electronic conductivity and electrolyte materials with high ionic conductivity are usually selected to improve the electron/ion transfer rate of the composite sulfur cathode.PEO-LiTFSI-LLZO composite electrolyte with high ionic conductivity was prepared.The ionic conductivity is 1.16×10^(-4)and 7.26×10^(-4)S/cm at 20 and 60℃,respectively.Meanwhile,the composite sulfur cathode was prepared with S-rGO.In addition to improving the ion transfer rate in the cathode,it replaces the role of binder.The influence of different contents of composite electrolyte in the cathode material on the performance of the battery was investigated.The results show that the electrochemical performance of the all-solid-state lithium-sulfur battery is the best when the content of the composite electrolyte in the cathode is 40%.Under the condition of 0.2 C and 45℃,the initial charging and discharging special capacity is 923 mAh/g,and the special capacity is 653 mAh/g after 50 cycles.