An extremely high rate Li–S battery with hybrid electrolyte

Abstract

Polysulfide shuttling and lithium dendrites are two major issues which hinder the development of high-performance Li–S batteries. An ideal solution is to employ hybrid electrolyte consisting of sulfide solid electrolyte (SSE) and liquid electrolyte (LE), where SSE functions as a barrier for suppressing polysulfide shuttling and lithium dendrite growth while LE works as fast Li+ transport media. In this work, Li10SnP2S12 membranes, with a ceramic-like dense structure, provide a rigid barrier for preventing polysulfide shuttling and lithium dendrite growth. Meanwhile, its high ionic conductivity of 3.33 × 10−3 S/cm (25 °C), accompanied with good wetting and Li+ transport abilities of LE, renders the hybrid electrolyte system an excellent Li+ dynamic property. Consequently, the Li–S batteries fabricated with this SSE-based hybrid electrolyte system can operate at an extremely high charge/discharge rate. At a rate of 5C (7.10 mA/cm2), the batteries show an initial discharge capacity of 659.4 mAh/g, maintain at 471.4 mAh/g and 413.3 mAh/g after 50 and 100 cycles，showing a capacity retention of 71.53% and 62.67%, respectively. It is also proposed that a competitive mechanism exists between the electrochemical reaction and side reaction during cycling, where the electrochemical reaction dominates at high rates.