Understanding the synergistic improving adsorbed and catalytic activity of polysulfide by design of oxygen vacancies and Li+ lithiation/delithiation behavior in Titanium Oxide separator

Abstract

The commercialization of lithium-sulfur (Li-S) battery is hindered by severe shuttle effect and sluggish electrochemical kinetics, which are induced by the high dissolution of intermediate lithium polysulfides (LiPSs) in cathode side. Here, we describe a strategy towards efficient adsorption and conversion of polysulfides by designing a functional TiO2-based separator. The enhanced overall electrochemical performance of cells is highly related to the synergistic effect of mutually transformational of TiO2 and LixTiO2 and the existence of oxygen vacancies (OVs). During the charging and discharging process of Li-S cell, the in-situ formation of LixTiO2 assigned to lithiation of anatase TiO2 plays a pivotal role in reversible adsorption and desorption of LiPSs. In addition, we also discussed the effect of OVs, which can act as active sites to accelerate electrochemical kinetics and exhibit stronger chemical interaction with LiPSs. The synergy of lithiation and delithiation process of TiO2 with OVs not only offers an effective pathway towards the improvement of LiPSs adsorption and catalytic performance but could also inspire new ideas on developing functional metal oxides modified separator for Li-S battery. We anticipate that this work will provide new avenues for Li-S battery commercialization.