Regulating positions of TiO2 on TiO2/biomass carbon composite surface to enhance conversion abilities of polysulfides

Abstract

• The crystallinity of TiO 2 is controlled by the amount of added surfactant. • Enhanced crystallinity of composite enhances ability to capture polysulfides. • C:H(1:1)/S electrodes possess good cycling stabilities. Serious shuttle effects always happen on polysulfides during the electrochemical reaction of Li-S batteries, which limits further increase of capacity. Preparing titanium dioxide/biomass carbon composite electrodes can effectively solve problems of shuttle effects. However, relationships between titanium dioxide position and polysulfide capture and conversion abilities are not clear. In this paper, a sol–gel method is used to obtain titanium dioxide/biomass carbon composite electrode. Four composite structures with different titanium dioxide loading positions are obtained by controlling the amount of added surfactant. When the mass ratio of biomass carbon to surfactant is 1:1, titanium dioxide is mainly loaded on the surface of biomass carbon with strong crystallinity. The composite material has strong polysulfide capture and conversion capabilities, which lead to stable capacity storage. The C:HA(1:1)/S electrode remains at 254.5 mAh·g −1 after 500 cycles at 1C. Good cycling stability depends on titanium dioxide with strong crystallinity on the surface of biomass carbon.