Crystalline/amorphous heterostructure CoNi/MoO3-x as an bidirectional catalyst for polysulfide reaction to enable high‑sulfur-loading lithium‑sulfur battery

Abstract

Lithium‑sulfur batteries (LSBs) are a very promising next-generation battery due to their high theoretical specific capacity and specific energy. However, the commercialization process is impeded by high‑sulfur-loading cathodes due to the low conductivity of sulfur, the slow redox kinetics and the shuttle effect of soluble polysulfides. Herein, an amorphous MoO_3-x floral nanosheet structure embedded with CoNi alloy particles on carbon cloth (CoNi/MoO_3-x@CC) was developed as a interlayer to achieve fast redox reaction kinetics in LSBs. The 3D-supported conductive network structure architecture of the carbon cloth provides channels for the rapid electron and ion transfer. It was confirmed that the strong chemisorption and catalytic conversion for LiPSs were produced by the the synergistic effect of CoNi alloy and amorphous MoO_3-x. The LSBs assembled with CoNi/MoO_3-x@CC interlayer exhibit improved rate performance (reversible specific capacity of 525 mAh g⁻¹ at 2C) and outstanding cycling stability (capacity decay rate of 0.071 % after 500 cycles at 1C). Furthermore, the CoNi/MoO_3-x@CC interlayer was created for LSBs with high sulfur loading. After 50 cycles at 0.2C, the LSBs with higher sulfur loadings of 8.07 and 8.92 mg cm⁻² provide high reversible capacity of 1060 and 980 mAh g⁻¹, respectively.