Immobilizing Polysulfide via Multiple Active Sites in W18O49 for Li-S batteries by Oxygen Vacancy Engineering

Abstract

Commercial lithium sulfur batteries are hindered by unstable and unreliable cycling performances due to the dissolution and shuttle of lithium polysulfides. Defect engineering with plentiful active sites and high surface binding energies to restrain polysulfides dissolution and promote the redox conversion polysulfides. Here, we present a nano carbon intercalated by W18O49 nanorods composite materials as functional sulfur host. With high W/O ratio of 0.367 in tungsten oxide famliy (WOx), W18O49 achieves abundant oxygen vacancy in intrinsic atomic structure. These oxygen vacancies not only provide stable active sites to stabilize the Li2S but also immobilize polysulfides by strong coulombic interactions of W-S and Li-O bondings. Accordingly, this cathode achieves stable long cycling performance with decay rate of 0.038 % per cycle at 2 C for 1200 cycles. With high sulfur loading of 6.4 mg·cm−2, the cathode also shows stable cycling at 0.2 C for 150 cycles. This immobilizations of polysulfides by oxygen vacancy engineering in W18O49 is referential for developing commercial useable Li-S batteries.