Dual-confined SeS2 cathode based on polyaniline-assisted double-layered micro/mesoporous carbon spheres for advanced Li–SeS2 battery

Selenium-sulfur solid solutions (SexSy) attracts soaring attention owing to its improved electrical conductivity over sulfur and higher theoretical specific capacity than selenium. Herein, high-performance lithium-selenium/sulfur batteries with a dual-confined cathode configuration by encapsulating SeS2 in double-layered hollow micro/mesoporous carbon spheres (DSMCs) with a conductive polyaniline (PANI) protection sheath are proposed. Polysulfides/polyselenides are efficiently restricted in the cathode via physical and chemical entrapment from DSMCs and PANI as well as chemical binding between selenium and sulfur. Benefiting from the distinct advantages of SeS2 and the well-constructed host framework, the cathode achieves high capacity utilization of 1018 mAh g−1 at 0.2 A g−1, together with outstanding rate capability of 619 mAh g−1 at 2 A g−1 and excellent cycle life over 500 cycles with almost 100% Coulombic efficiency. The novel SexSy-based cathode demonstrates a promising route to surmount some bottlenecks of current lithium-sulfur systems for high-performance rechargeable batteries.