CoS₂@SC modified separator for high-performance lithium-sulfur batteries: suppression of polysulfide shuttling

Due to their high energy density and cost-effective electrode materials, lithium sulfur batteries (LSBs) have been considered as one promising candidate of energy devices. However, the practical application is impeded by the shuttle effect of lithium polysulfides and slow redox kinetics of electrode. Here, we report a successful synthesis of CoS₂@SC composite material via in-situ growth and sulfuration pyrolysis method and prepared CoS₂@SC modified separator. The carbon matrix derived from sucrose carbonization with a porous structure promotes the uniform distribution of active adsorption sites. According to Lewis acid–base interaction, CoS₂@SC separator exhibits strong chemisorption of lithium polysulfides, reducing the loss of active material during cycling. Furthermore, the enhanced wettability of the CoS₂@SC separator with the electrolyte accelerates the ion transfer, improving the reaction kinetics. Compared with the blank separator, the cell with CoS₂@SC separator has an initial specific capacity of 1135.5 mAh g⁻¹ and notably, the capacity decay rate of the modified battery is only 0.052% per cycle after 800 long cycles at 0.5 C. This unique attribute ensures enhanced stability and durability of the battery system. Consequently, LSBs with the CoS₂@SC separator exhibit an improved electrochemical performance.