Disodium Malate Electrolyte Additive Facilitates Dendrite-Free Zinc Anode: Deposition Kinetics and Interface...

Due to the presence of H₂O within the solvated sheath of [Zn(H₂O)₆]²⁺ as well as reactive free water in the electrolyte bulk phase, the extended cycling of aqueous zinc-ion batteries (AZIBs) is significantly affected by detrimental side reactions and the growth of Zn dendrites. This study significantly enhances the long-term cycling stability of AZIBs by introducing a small amount of disodium malate (DM) into a 2 m ZnSO₄ electrolyte solution. DM involvement in the solvation sheath of Zn²⁺ reduces the desolvation energy of Zn²⁺, thereby mitigating the corrosion and hydrogen evolution reaction (HER) of the negative electrode surface by [Zn(H₂O)₆]²⁺ ions. Additionally, DM adsorption on the zinc surface retards the reduction kinetics of Zn²⁺ at anode, promoting uniform distribution and predominant deposition on the flat (002) crystal plane, thus reducing dendrite formation. The assembled Zn||Zn symmetric cell exhibits stable cycling for over 500 h at 10 mA cm^-2 and 5 mAh cm^-2. The Zn||VO₂ full cells with DM additive exhibits an ultralong cycling lifespan without capacity loss.