Improve the Capacity of MoS₂ for Aqueous Zinc Ion Batteries by Regulating the Electron Spin States of Mo via Se Doping

Molybdenum disulfide (MoS 2 ) is now being considered a feasible cathode candidate for aqueous zinc ion batteries (AZIBs) because of its two-dimensional layered structure that facilitates ion intercalation/deintercalation at edge sites. However, the inherent poor electron conductivity and sluggish kinetics of zinc ions diffusion severely restricts its development and applicability. In this work, we develop a selenium (Se)-doped MoS 2 cathode material for AZIBs with a high capacity and long cycle stability. The doped Se alters the electron spin states of the Mo atoms, enhancing their reactivity during intercalation and reducing the diffusion barrier for Zn 2+ . As a result, synthesized Se-doped MoS 2 (MoS 2 –Se) has a high capacity of 151 mAh g –1 at 1 A g –1, which is superior to the capacity of the original MoS 2 (109 mAh g –1 at 1 A g –1 ). Encouragingly, MoS 2 –Se also achieved a satisfactory rate performance (45% capacity retention at 10 A g –1 ) and cycle life (93% of its initial capacity over approximately 500 cycles at 4 A g –1 ). Furthermore, the fabricated MoS 2 –Se//Zn battery exhibits a peak energy density of 77 Wh kg –1 and a power density of 0.41 kW kg –1 . This work introduces a new design of MoS 2 with a substantial capacity, deepening the comprehension of cathodes for AZIBs.