High-Performance Aqueous Zinc-Ion Batteries with Synergistic Stabilized Zinc Anodes Through Molybdenum Dioxide Coating and Tween 80 Electrolyte Additive

Owing to their low cost, safety, environmental friendliness, and high energy density, aqueous zinc-ion batteries (AZIBs) have recently been considered a promising candidate for the new-generation energy storage systems. However, AZIBs usually suffer from poor cyclability due to various factors, including severe dendrite growth, self-corrosion, hydrogen evolution, and irreversible side reactions occurring at the Zn anodes. This work proposes a novel approach to develop a highly stable Zn anode by combining a surface coating layer with electrolyte additives. Molybdenum dioxide (MoO₂) is introduced as a coating layer, and Tween 80 acts as an electrolyte additive. As MoO₂ is structured in nanoplates, the coating layer facilitates the rapid diffusion of Zn²⁺ ions, which assists in inhibiting dendrite growth and by-products. Also, the MoO₂ coating layer shows a large redox capability due to the multivalent of Mo atoms in the nanostructure, which may be capable of homogenizing the concentration field of Zn²⁺ in the vicinity of the Zn anode. In addition, Tween 80, a surfactant additive, functions as an inhibitor of Zn metal corrosion as it is preferentially absorbed to the surface of the Zn anode to induce the deposition of Zn²⁺ ions. The MoO₂-coated Zn anode (MoO₂@Zn) then exhibits excellent electrochemical stability in a mildly acidic electrolyte due to the dual synergistic effects of the MoO₂ coating layer and Tw80 additive. With an optimal 1 mM Tw80, the symmetric cells of MoO₂@Zn achieve exceptional cyclability for 6000 h at 1 mA cm⁻². Even at a high current density of 5 mA cm⁻², the cells remained stable over 700 h. When assembled with the VO₂ cathode, the full cells exhibit a high capacity of 105.6 mAh g⁻¹ after 1000 cycles with outstanding rate performance (171.4 mAh g⁻¹ at 10 A g⁻¹). Hence, this study suggests an innovative strategy for stabilizing Zn anodes to develop long-life, cost-effective, and scalable AZIBs.