Silica-templated hierarchically porous carbon modified separators for lithium-sulfur batteries with superior cycling stabilities

Abstract

Lithium-sulfur batteries (LSBs) have attracted considerable attention for use in next-generation rechargeable storage devices owing to their high theoretical capacities (1675 mA h g(-1)) and natural abundance of sulfur. However, the commercialization of LSBs is hindered by the polysulfide shuttle effect and unstable cycling performances of the conventional cell configurations. As the separator is a crucial component of the cell assembly, separator modification is considered an effective approach to the fabrication of a high-performance LSB without the use of a sophisticated cathode. In this study, hierarchically porous carbons are used for the fabrication of multi-functional glass fiber (GF) separators as upper current collectors and polysulfide trapping materials. An optimized porous carbon (denoted as MC-SM) is fabricated by tuning the porosity properties such as the Brunauer-Emmett-Teller surface area and pore distribution. The MC-SM-coated GF separator provides excellent discharge capacity of 1019 mA h g(-1) and Columbic efficiency (similar to 100%) at a current density of 0.2C after 150 cycles. Even at high current rates, the cell with the fabricated porous carbon can deliver considerable reversible capacities of 700 mA h g(-1) at 1C and 591 mA h g(-1) at 2C after 500 cycles.