Synergistically Stabilizing Zinc Anodes by Molybdenum Dioxide Coating and Tween 80 Electrolyte Additive for High-Performance Aqueous Zinc-Ion Batteries

Abstract

Recently, aqueous zinc-ion batteries (ZIBs) have become increasingly attractive as grid-scale energy storage solutions due to their safety, low cost, and environmental friendliness. However, severe dendrite growth, self-corrosion, hydrogen evolution, and irreversible side reactions occurring at Zn anodes often cause poor cyclability of ZIBs. This work develops a synergistic strategy to stabilize the Zn anode by introducing a molybdenum dioxide coating layer on Zn (MoO 2 @Zn) and Tween 80 as an electrolyte additive. Due to the redox capability and high electrical conductivity of MoO 2 , the coating layer can not only homogenize the surface electric field but also accommodate the Zn 2+ concentration field in the vicinity of the Zn anode, thereby regulating Zn 2+ ion distribution and inhibiting side reactions. MoO 2 coating can also significantly enhance surface hydrophilicity to improve the wetting of electrolyte on the Zn electrode. Meanwhile, Tween 80, a surfactant additive, acts as a corrosion inhibitor, preventing Zn corrosion and regulating Zn 2+ ion migration. Their combination can synergistically work to reduce the desolvation energy of hydrated Zn ions and stabilize the Zn anodes. Therefore, the symmetric cells of MoO 2 @Zn∥MoO 2 @Zn with optimal 1 mM Tween 80 additive in 1 M ZnSO 4 achieve exceptional cyclability over 6000 h at 1 mA cm –2 and stability (>700 h) even at a high current density (5 mA cm –2 ). When coupling with the VO 2 cathode, the full cell of MoO 2 @Zn∥VO 2 shows a higher capacity retention (82.4%) compared to Zn∥VO 2 (57.3%) after 1000 cycles at 5 A g –1 . This study suggests a synergistic strategy of combining surface modification and electrolyte engineering to design high-performance ZIBs.

Ti4O7 coating creates a highly stable Zn anode for aqueous zinc-ion batteries

“…An excellent coating should be hydrophilic, conductive, and zincophilic to inhibit the formation of zinc dendrites effectively. To date, many coating materials, such as metals 13,16,17 or metal oxides, [18][19][20][21] inorganic acid salts, [22][23][24] carbon-based materials, [25][26][27] and polymers, [28][29][30][31] have been adopted. Metal oxides and porous inorganic acid salts are usually hydrophilic, but their electro-conductibility is poor.…”

Rational Design of Ni-Doped V2O5@3D Ni Core/Shell Composites for High-Voltage and High-Rate Aqueous Zinc-Ion Batteries

“…To overcome these issues, researchers are exploring the feasibility of other active metals in energy storage devices to replace LIBs in the future [8,9]. Among all candidates, aqueous zinc-ion batteries (ZIBs) have received increasing attention as promising candidates for large-scale energy storage devices [10] due to the apparent advantages of using metallic Zn as the anode, including its high theoretical capacity (5855 mAh cm −3 ) [11], low redox potential (−0.76 V vs. a standard hydrogen electrode (SHE)) and low-cost benefit from its vast reserve (the cost of Zn (0.5-1.5 USD/lb) is much smaller than that of Li (8-11 USD/lb)) [12][13][14]. However, finding suitable cathode materials for high-performance ZIBs has become a top priority [15][16][17][18][19].…”