Integrating molybdenum sulfide selenide-based cathode with C–O–Mo heterointerface design and atomic engineering for superior aqueous Zn-ion batteries

Transition metal dichalcogenides (TMDs) have been regarded as promising cathodes for aqueous zinc-ion batteries (AZIBs) but suffer from sluggish reaction kinetics due to their poor conductivity and the strong electrostatic interaction between Zn-ion and cathode materials. Herein, a well-defined structure with MoSSe nanosheets vertically anchored on graphene is used as the cathode for AZIBs. The dissolution of Se into MoS₂ lattice together with heterointerface design via developing C–O–Mo bonds improves the inherent conductivity, enlarges interlayer spacing, and generates abundant anionic vacancies. As a result, the Zn²⁺ intercalation/deintercalation process is greatly improved, which is confirmed by theoretical modeling and ex-situ experimental results. Remarkably, the assembled AZIBs exhibit high-rate capability (124.2 mAh·g⁻¹ at 5 A·g⁻¹) and long cycling life (83% capacity retention after 1,200 cycles at 2 A·g⁻¹). Moreover, the assembled quasi-solid-state Zn-ion batteries demonstrate a stable cycling performance over 100 cycles and high capacity retention over 94% after 2,500 bending cycles. This study provides a new strategy to unlock the electrochemical activity of TMDs via interface design and atomic engineering, which can also be applied to other TMDs for multivalent batteries.