Activated Zn2+ and NH4+ Storage in MoS2 via Homologous Substitution with Highly Electronegative Elements

Aqueous energy storage devices hold great promise in the renewable energy field, owing to their low cost and environmental friendliness. MoS₂ is a potential electrode material due to its open layered structure, but its performance is constrained by inherently inert basal planes and scarcity of active sites. Herein, Mo_0.99W_0.01O_0.17S_1.83-x with localized 1T phases, lattice defects, and sulfur vacancies is prepared by a highly electronegative W/O co-substitution strategy. Theoretical calculations and experiments systematically reveal the multilevel advantages of the W/O co-substitution strategy, including optimization of the electronic structure, inducing defects and vacancies, which synergistically build charge and ion channels and lower energy barriers to accelerate the reaction kinetics. Therefore, Mo_0.99W_0.01O_0.17S_1.83-x exhibits excellent Zn²⁺ (284.7 mAh g^-1 at 0.10 A g^-1 and 80.4% capacity retention after 3200 cycles) and NH₄⁺ (153.4 mAh g^-1 at 0.50 A g^-1 and 82.6% capacity retention after 12,000 cycles) storage performance. Furthermore, ex situ characterizations suggest that the energy storage mechanism is reversible insertion/extraction of Zn²⁺ in layers and reversible adsorption/desorption of NH₄⁺, as well as dynamic reconfiguration of hydrogen bonds, accompanied by 2H/1T phase transitions. This work provides an effective approach for the universal design of aqueous energy storage systems.