Realizing High-Performance Li-Polysulfide Full Cells by using a Lithium Bis(trifluoromethanesulfonyl)imide Salt Electrolyte for Stable Cyclability.

Since concentrated electrolytes have attracted great attention for the stabilization of lithium-metal anodes for lithium-ion batteries, the demonstration of a full cell with an electrolyte concentration study has become a research topic of interest. Herein, we have demonstrated a proof of concept, a lithium-polysulfide full cell battery using various lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) electrolyte concentrations with glass-fiber-based composite and hard carbon as the cathode and anode, respectively. The initial capacity of the lithium-polysulfide full cell is found to be 970 mA h g-1 at 0.1 C. The capacity is stabilized at 870 mA h g-1 after 100 cycles with a capacity retention of 88.6 %. An excellent capacity retention of ≈80 % is achieved after long 800 cycles at 0.5 C by using full cell technology. Further, our post-mortem analysis sheds light on the difference in SEI layer formation on hard carbon anodes with changing electrolyte concentration, thereby indicating reasons for the obtainment of a high cyclic performance with 1 m LiTFSI salt electrolyte. The successful demonstration of the long cyclic performance of Li-polysulfide full cells is indeed a step towards producing high performance Li-polysulfide full cell batteries with long cycling using conventional LiTFSI salt electrolyte and commercial anode materials.