TiO<sub>2</sub>@Chlorella-Based Biomass Carbon Modified Separator for High-Rate Lithium–Sulfur Batteries
Xin Wang, Liwen Yang, Qian Li, Yang Wang, Yanjun Zhong, Yang Song, Yanxiao Chen, Zhenguo Wu, Benhe Zhong, Xiaodong Guo
Abstract
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.