A short review on dissolved lithium polysulfide catholytes for advanced lithium-sulfur batteries

Abstract

Lithium-sulfur battery (LSB) technology has drawn enormous attention during the last decade. Benefitting from the high theoretical specific discharge capacity (1,675 mAh g−1) and energy density (2,600 Wh kg−1), LSBs have proved to be a suitable candidate for electric vehicles and large-scale power grid electrical energy storage systems. However, the commercialization of LSB is hindered by various barriers, which include the high insulating nature of sulfur and its discharge products, severe polysulfide shuttling phenomenon, extreme volume expansion during charging/discharging, and poor stability of Li metal anodes. Additionally, LSB technology faces considerable battery design challenges, which allows high sulfur content and/or sulfur-loading while simultaneously maintaining a low electrolyte/sulfur ratio. Therefore, in this review, we highlight recent effective strategies that lead to more practical and commercial LSBs. We restrict ourselves to various cathode architectures designed specifically to absorb dissolved polysulfide catholyte. The integration of dissolved lithium polysulfide catholyte with specially designed cathode substrates efficiently allows ultra-high sulfur loading and/or sulfur-content with low electrolyte/sulfur ratio while still exhibiting reasonable electrochemical performance and cycling stability. The effect of concentration variation of dissolved lithium polysulfide catholyte on the cell performance is also discussed in detail. Therefore, the present review encapsulates feasible strategies with practical parameters to address the problems associated with LSBs.