Interface Chemistry Guided Long-Cycle-Life Li-S Battery

To date, most of the research on electrodes for energy storage has been focused on the active material itself. It is clear that investigating isolated active materials is no longer sufficient to solve all kinds of technological challenges for the development of modern battery infrastructure. From the interface chemistry point of view, a system-level strategy of designing polydopamine coated reduced graphene oxide/sulfur composite cathodes aimed at enhancing cyclic performance was reported in this work. As a soft buffer layer, the polydopamine shell was used to accommodate the volume expansion of S and avoid the leakage of polysulfide during cycling. A cross-link reaction between polydopamine buffer and poly(acrylic acid) binder was further designed to improve the strength of the entire electrode. As a result, the electrode demonstrated excellent cyclic performance with a discharge capacity of 728 mAh/g after 500 cycles at the current density of 0.5 A/g (a very small capacity loss of 0.41 mAh/g per cycle). Most importantly, 530 mAh/g was obtained even at a higher current density of 1 A/g after 800 cycles. Our results indicate the importance of chemically designing interfaces in the whole electrode system on achieving improved performance of electrodes of rechargeable lithium ion batteries.