Aqueous Zinc-Ion Storage in MoS₂ by Tuning the Intercalation Energy

Aqueous Zn-ion batteries present low-cost, safe, and high-energy battery technology but suffer from the lack of suitable cathode materials because of the sluggish intercalation kinetics associated with the large size of hydrated zinc ions. Herein we report an effective and general strategy to transform inactive intercalation hosts into efficient Zn²⁺ storage materials through intercalation energy tuning. Using MoS₂ as a model system, we show both experimentally and theoretically that even hosts with an originally poor Zn²⁺ diffusivity can allow fast Zn²⁺ diffusion. Through simple interlayer spacing and hydrophilicity engineering that can be experimentally achieved by oxygen incorporation, the Zn²⁺ diffusivity is boosted by 3 orders of magnitude, effectively enabling the otherwise barely active MoS₂ to achieve a high capacity of 232 mAh g^-1, which is 10 times that of its pristine form. The strategy developed in our work can be generally applied for enhancing the ion storage capacity of metal chalcogenides and other layered materials, making them promising cathodes for challenging multivalent ion batteries.