中空多壳层结构TiN修饰隔膜对锂硫电池性能增强研究
摘要
<p indent="0mm">Lithium-sulfur (Li-S) batteries have garnered extensive attention due to their high theoretical capacity and cheap sulfur cathodes. However, sulfur has quite poor conductivity and exhibits large volume change during lithiation-delithiation processes, inducing poor structure stability. Moreover, intermediate products released during discharge, i.e., lithium polysulfides, tend to dissolve in the electrolyte and pass through the separator to the anodic side, resulting in a severe “shuttle effect”. Hence, the cyclic stability and rate capability of Li-S batteries are poor, hindering their commercialization. Several approaches have been developed to address the above challenges, mainly including an S host construction, electrolyte modification, separator modification, and so on. Among them, separator modification has been widely explored because it is simple to process and economical while effectively improving the Li-S battery performance. However, due to the nonideal composition and structure design, the Li-S battery performance remains undesirable. Herein, to simultaneously address the above issues, a titanium nitride hollow multishelled structure (TiN HoMS) was designed and employed for preparing different separator modification materials. TiN exhibits remarkable electrical conductivity and can catalyze the redox conversion of sulfur and polysulfides. HoMS can not only offer multiple physical barriers and abundant adsorption sites to inhibit the “shuttle effect” but also reduce the charge diffusion path. TiN HoMS was synthesized using a modified sequential templating approach followed by a nitridation of TiO<sub>2</sub> HoMS. Using the hydrothermal method and sucrose as the carbon source, uniform carbon sphere templates were obtained by controlling the temperature and duration of the hydrothermal method. Subsequently, TiCl<sub>4</sub> solution was adsorbed by these templates to yield titanium-rich composite spheres. Further, TiO<sub>2</sub> HoMS with