TiO2@Chlorella-Based Biomass Carbon Modified Separator for High-Rate Lithium–Sulfur Batteries

The lithium–sulfur battery (Li–S battery) has attracted extensive attention because of its high energy density, but a series of disadvantages caused by sulfur insulation and the shuttle effect hinder the large-scale application of the Li–S battery. The conductive skeleton with strong adsorption on lithium polysulfide can effectively build the electron transmission path and inhibit the shuttle effect. In this study, a new type of chlorella-based biomass carbon skeleton carrying TiO2 metal sites (TiO2@CBBC) is designed and synthesized, and it was used as a functional separator modification material for the lithium sulfur battery. The biomass carbon skeleton has a unique three-dimensional skeleton and a unique specific surface, which can carry uniform titanium active sites and rich oxygen negative ions, so as to build a functional network of electron conduction, adsorbing polysulfide intermediates and promoting the dynamics of the sulfur conversion reaction. The Li–S battery equipped with a functional TiO2@CBBC separator shows excellent rate performance and cycle performance. The initial capacity of the lithium sulfur battery is up to 1011 mAh g–1 at 2C and can maintain 92% of the specific capacity after 100 cycles. At a stricter rate of 3C, the battery can still operate stably, and the coulomb efficiency remains above 95% throughout the entire process. This work represents a promising approach for developing the stability of lithium–sulfur batteries at a high rate.