N‐methyl Formamide Electrolyte Additive Enabling Highly Reversible Zn Anodes

Parasitic side reactions and dendrites formation hinder the application of aqueous zinc ion batteries due to inferior cycling life and low reversibility. Against this background, N-methyl formamide (NMF), a multi-function electrolyte additive is applied to enhance the electrochemical performance. Studied via advanced synchrotron radiation spectroscopy and DFT calculations, the NMF additive simultaneously modifies the Zn²⁺ solvation structure and ensures uniform zinc deposition, thus suppressing both parasitic side reactions and dendrite formation. More importantly, an ultralong cycling life of 3115 h in the Zn||Zn symmetric cell at a current density of 0.5 mA cm^-2 is achieved with the NMF additive. Practically, the Zn||PANI full cell utilizing NMF electrolyte shows better rate and cycling performance compared to the pristine ZnSO₄ aqueous electrolyte. This work provides useful insights for the development of high-performance aqueous metal batteries.