Mesoporous graphenoid nanosheets for high-rate and lean-electrolyte lithium-sulfur batteries

Lithium-sulfur batteries hold great promise for surpassing the energy density of commercial lithium-ion batteries while potentially being more cost-effective. However, practically their commercial viability is hindered by challenges such as polysulfide shuttling from the sulfur cathodes, poor cyclic stability and inadequate rate performance especially under lean-electrolyte conditions. In this study, we address these limitations by developing a novel host material of mesoporous graphenoid nanosheets (MGNSs) for cathodes. The new cathode demonstrates remarkable cyclic stability and rate performance under a low electrolyte-to-sulfur ratio of 6.5 μL mg⁻¹. The S@MGNS cathodes exhibit 737 mAh g⁻¹ after 270 cycles at 0.2 C, achieving only 0.0014 %/cycle average capacity decay; meanwhile at 0.5 C, the capacity retained 80 % after 400 cycles with only 0.05 %/cycle of decay. Furthermore, post-mortem structural analysis of both cycled cathodes and anodes revealed a more uniform precipitates of active materials on the S@MGNS cathodes, reduced structural damage of the anodes with a thinner layer of cycled-Li containing solid electrolyte interphase debris. Overall, the incorporation of MGNSs in sulfur cathodes presents a promising strategy to overcome existing limitations and paves the way for the development of efficient and commercially viable lean-electrolyte Li-S batteries with improved cyclic stability and rate performance.