利用二硫苏糖醇夹层抑制锂硫电池的穿梭效应

为了抑制锂硫电池的穿梭效应,改善锂硫电池的电化学性能,尝试以二硫苏糖醇(DTT)为剪切剂,对高阶多硫化物进行剪切以阻止其溶解。将二硫苏糖醇(DTT)掺入多壁碳纳米管(MWCNTs)纸中,制得DTT夹层,将该DTT夹层置于锂硫扣式半电池正极片和隔膜之间,正极片的载硫面密度约为2 mg/cm2。SEM观察结果证实DTT均匀分散在MWCNTs纸的表面和空隙中。电化学测试结果表明引入DTT夹层结构的锂硫电池在0.05C倍率首次放电比容量达到1 288 mAh/g,首次库伦效率接近100%,在0.5C、2C、4C倍率下充放电时的比容量分别达到650mAh/g、600mAh/g、410mAh/g。DTT夹层结构的引入可有效剪切高阶多硫化物并阻止其迁移到锂负极,从而抑制穿梭效应,改善锂硫电池的循环稳定性和库伦效率。

Inhibiting the Shuttle Effect of Lithium-Sulfur Batteries byIntroducing a Dithiothreitol Interlayer

The present work aimed to restrain shuttle effect of lithium-sulfur (Li-S)batteries and improve the cycle perfor-mance,and made an attempt to utilize dithiothreitol (DTT)as scission reagent to prevent dissolution of lithium polysulfur (LiPS). The prefabricated MWCNTs paper was immersed in the DTT solution and dried to obtain a DTT interlayer,which was subsequently located between the cathode disk(with a sulfur areal loading of 2 mg/cm2)and the separator of a Li-S coin half-cell.The morphologi-cal and structural observation over the DTT interlayer by scanning electron microscopy (SEM)validated the uniform dispersion of DTT in the MWCNTs paper.The electrochemical test showed that the Li-S half-cell with the DTT interlayer possesses an initial dis-charge capacity of 1 288 mAh/g and a Coulombic efficiency approaching 100%,and moreover,maintains specific capacities of 650 mAh/g,600 mAh/g and 410 mAh/g under the current rates of 0.5C,2C and 4C respectively.Our experiment indicated DTT can ef-fectively slice high-order LiPS and hinder its migration to the anode,and in consequence,significantly improve the cycle stability and Coulombic efficiency of Li-S battery.