Relay-Type Catalysis by a Dual-Metal Single-Atom System in a Waste Biomass Derivative Host for High-Rate and Durable Li–S Batteries

An environmental-friendly and sustainable carbon-based host is one of the most competitive strategies for achieving high loading and practicality of Li–S batteries. However, the polysulfide conversion reaction kinetics is still limited by the nonuniform or monofunctional catalyst configuration in the carbon host. In this work, we propose a catalysis mode based on "relay-type" co-operation by adjacent dual-metal single atoms for high-rate and durable Li–S batteries. A discarded sericin fabric-derived porous N-doped carbon with a stacked schistose structure is prepared as the high-loading sulfur (84 wt %) host by a facile ionothermal method, which further enables the uniform anchoring of Fe/Co dual-metal single atoms. This multifunctional host enables superior lithiophilic–sulfiphilic and electrocatalytic capabilities contributed by the "relay-type" single-atom modulation effects on different conversion stages of liquid polysulfides and solid Li2S2/Li2S, leading to the suppression of the "shuttle effect", alleviation of nucleation and decomposition barriers of Li2Sx, and acceleration of polysulfide conversion kinetics. The corresponding Li–S batteries exhibit a high specific capacity of 1399.0 mA h g–1, high-rate performance up to 10 C, and excellent cycling stability over 1000 cycles. They can also endure the high sulfur loading of 8.5 mg cm–2 and the lean electrolyte condition and yield an areal capacity as high as 8.6 mA h cm–2. This work evidentially demonstrates the potential of waste biomass reutilization coupled with the design of a single-atom system for practical Li–S batteries with high energy density.