A new strategic approach to modify electrode and electrolyte for high performance Li–S battery

Abstract

Lithium-sulfur batteries have been strongly advocated as prominent candidate for the next-generation energy storage device. The shuttling of lithium polysulfide (LiPS) during cycling is inherent problem in these batteries which results in huge capacity fading and impede their practical applications. A simple but effective method is adopted to synthesize polypyrrole coated sulfur nanoparticle which retard the LiPS dissolution in electrolyte. The polypyrrole coated continuous conducting network cathode with nano size (~70 nm) sulfur particle and a stable solid electrolyte interface (SEI) layer protected anode for high performance Li–S battery is demonstrated in this study. Such engineered structure can minimize the fast capacity fading considerably and nano size sulfur makes themselves more accessible to ions and electrons. Strategically, for Li anode protection, LiPS based ternary salt electrolyte (Li2S6, LiNO3 and LiTFSI) is used which form a stable SEI-layer on Li anode during initial cycles. The composite cathode exhibit an initial discharge capacity of 1085 mAh g−1 at 0.2 Ag-1 current density with a low capacity decay of 0.31% per cycles and cycled up to 165 cycles. The post-mortem analysis validates efficient trapping of LiPS in the cathode side and formation of a stable protective SEI layer on Li anode.