An Improved Li–SeS₂ Battery with High Energy Density and Long Cycle Life

Selenium–sulfur solid solutions are a class of potential cathode materials for high energy batteries, since they have higher theoretical capacities than selenium and improved conductivity over sulfur. Here, a high-performance cathode material by confining 70 wt% of SeS₂ in a highly ordered mesoporous carbon (CMK-3) framework with a polydopamine (PDA) protection sheath for novel Li–Se/S batteries is reported. With a relatively high SeS₂ mass loading of 2.6–3 mg cm⁻², the CMK-3/SeS₂@PDA cathode exhibits a high capacity of >1200 mA h g⁻¹ at 0.2 A g⁻¹, excellent C-rate capability of 535 mA h g⁻¹ at 5 A g⁻¹, and prolonged life over 500 cycles. Benefitting from the unique advantages of SeS₂ and the rationally designed host framework, this new cathode material demonstrates a feasible strategy to overcome the bottlenecks of current Li–S systems for high energy density rechargeable batteries.