Synergistic effect of NiCo alloy and NiCoS integrated with N doped carbon for superior rate and ultralong-lifespan lithium sulfur batteries

The transition-metal-based alloy and chalcogenides have been widely investigated as efficient sulfur host for lithium sulfur batteries (LSB), yet the synergistic effect of both has been rarely reported. Herein, nickel cobalt alloy (NiCo) and nickel cobalt sulfides (NiCoS) have been simultaneously constructed on the nitrogen-doped carbon substrate (NiCo-NiCoS/NC) via facile calcination-sulfurization of NiCo Prussian blue analogue (NiCo-PBA). The abundantly exposed NiCo alloy and NiCoS domains act as adsorption and catalytic sites that enable effective capture and catalytic conversion of polysulfides, and the highly conductive NiCo-NiCoS integrated with N-doped carbon provides a facile Li⁺ transfer channel. As a result, S@NiCo-NiCoS/NC electrode delivers a high initial discharge capacity of 1345.1 mA h g⁻¹ at the current density of 0.1 C, superior rate capability of 692.1 mA h g⁻¹ up to 5 C, and ultralong lifespan over 1500 cycles with a small capacity decay of 0.055% per cycle at the current density of 1.0 C.