Regulating solvation structure and enhancing anion-derived solid electrolyte interphase with N, N'-Dimethylpropyleneurea Co-solvent for long-term and dendrite-free Zn metal anodes

Aqueous zinc-ion batteries (ZIBs) are troubled by conventional weak acidic electrolyte, triggering undesirable side reactions and detestable dendrites, thus leading to low Coulombic efficiency (CE) and poor cycle stability. Herein, an organic solvent, N, N′- Dimethylpropyleneurea (DMPU), is introduced as an additive and co-solvent to achieve high-performance ZIBs. As a co-solvent, DMPU can coordinate with Zn²⁺to replace partial water (H₂O) in solvation sheath and limit free H₂O activity by H-bond interaction. As an additive, meanwhile, it possesses high Zn absorbability to form a stable inorganic/organic shielding layer for remodeling Zn surface, thus enhancing Zn²⁺ de-solvation kinetics and restraining unwanted reactions. Distinctly, DMPU regulates non-dendritic Zn plating/stripping behaviors, thus achieving a high CE of 99.3 % and a long cycling life of 2760 h (h) at 2 mA cm⁻² and 2 mA h cm⁻². The Zn//NaV₃O₈·1·5H₂O (NVO) full cell with DMPU can operate stably for 5850 cycles with a retention of 80.6 % at 3 A g⁻¹. This strategy represents a good point to choose organic co-solvent for practical high-performance ZIBs.