Ultra-fast and high-energy density polysulfide-eight ion batteries

Abstract

To meet the increasing demand for more efficient energy storage technologies, the battery systems with high energy density and fast charge/discharge processes are necessary to be developed immediately. Here we introduce an advanced semi-liquid battery of lithium-polysulfide-eight (PS8) catholyte system in which ions act as active material with a high theoretical capacity due to 14 electron exchange between anode and cathode. A 1.6–2.35 V charge-discharge potential window is selected purposely to avoid the solid sulfur formation, ensuring ultra-long cycling stability and a high inner conductivity. This lithium PS8 (0.5 M) catholyte system delivers a high capacity of 1302 mAh g−1 (2600 ± 18 Wh kg−1 or 333 ± 2 Wh L−1) at 0.2 C, and excellent rate capacity and cycling stability of 1020 ± 21 mA h g−1 (2040 ± 42 Wh kg−1 or 261 ± 5 Wh L−1) at 5 C. The performance of the PS8 batteries is superior to the Li–S batteries and other reported catholyte systems. The obtained outstanding electrochemical performance consents the system to be considered as a promising candidate for large-scale electrical energy storage in the future.