Facile synthesis of-Li2S-polypyrrole composite structures for high-performance Li2S cathodes

Li2S is an attractive prelithiated cathode material with a high theoretical capacity of 1166 mA h g(-1), which is far above that of its transition metal oxide/phosphate counterparts. Here, we demonstrate facile, in situ synthesis of Li2S-polypyrrole composites for use as high-performance Li2S cathodes. The N atoms in polypyrrole were found to possess favorable Li-N interaction with Li2S, which enables polypyrrole to bind strongly onto and cover the surface of Li2S to constrain intermediate polysulfides during cycling. Polypyrrole, being a conducting polymer, also helps to facilitate electronic conduction. Using the Li2S-polypyrrole composites as a cathode material, we demonstrate a high discharge capacity of 785 mA h g(-1) of Li2S (similar to 1126 mA h g(-1) of S) with stable cycling over prolonged 400 charge/discharge cycles.