Reconstruction of coordination effect-induced solvation structures and electrode interface for dendrite-free zinc anodes

The aqueous zinc-ion batteries (AZIBs) with high theoretical capacity, superior safety, and low enthalpy have received the attention of many researchers. However, their practical applications suffer from the dendrite growth and side reactions of electrode interface, as well as poor cycling stability. Herein, the environmentally friendly zinc picolinate (ZPL), as a multifunctional electrolyte modifier is incorporated into traditional electrolyte to stabilize zinc electrodes and improve AZIBs performance. The inherently picolinate ions (PL − ) can regulate the solvent sheath structure of Zn 2+ through a weak solvation effect to promote the desolvation of Zn 2+ . Concurrently, the anion tends to preferentially adsorb on the electrode surface, facilitating the dense deposition and ordered transport of Zn 2+ . As a result, Zn-symmetric cell containing ZPL additive achieves an extended cycle life that more than 2100 h at current density of 0.5 mA cm −2 . And the Cu-asymmetric cell enables an ultralong-life reversible Zn plating/stripping process, achieving over 2700 cycles with an average coulombic efficiency (CE) as high as 99.72 %. Furthermore, the Zn||CNT-MnO 2 full battery exhibits enhanced capacity retention and cycling stability with ZPL molecules. This study develops a new additive with synergistic effects for achieving dendrite-free Zn anodes and designing high-performance AZIBs. • Trace ZPL additive can optimize the Zn 2+ solvation structure to reduce water activity. • The picolinate ions can facilitate the formation of an electrostatic protective layer to homogenization of Zn deposition. • ZPL additive is conducive to achieving a highly stable, reversible, and dendrite-free Zn anodes. • The symmetrical battery sustains a long cycle life for 2100 h with the assistance of ZPL additive.