Sandwich-like strontium fluoride graphene-modified separator inhibits polysulfide shuttling and lithium dendrite growth in lithium–sulfur batteries

Abstract

Due to their high energy density, lithium sulfur (Li–S) batteries have attracted extensive attention as promising candidates for next-generation energy storage. However, the defects in battery electrodes seriously hinder commercial applications, such as the shuttle effect of polysulfides and the uncontrolled growth of lithium dendrites. In this work, a modified separator with a sandwich-like structure was prepared using nanoscale flower-like strontium fluoride and graphene, which were filtered onto a PP separator. The strontium fluoride graphene (SrF₂-G) sandwich separator can effectively inhibit the shuttling of polysulfides, promote the rapid transfer of ions and electrons, and also effectively inhibit the irregular growth of lithium dendrites. This mainly benefits the efficient physical barrier effect and strong chemical catalysis, and the unique structure leads to high conductivity. The SrF₂-G-based battery exhibits excellent electrochemical performance, including a high initial discharge capacity of 1140 mA h g⁻¹ that is maintained at 873 mA h g⁻¹ over 300 cycles at 0.5C, a high-rate performance of 878 mA h g⁻¹ at 3C, and an extremely low capacity decay rate of 0.05% at 1C after 350 cycles. This work solves the inherent problems of lithium sulfur batteries to some extent and provides insight for practical applications in the future.