Regulating the helmholtz plane by trace polarity additive for long-life Zn ion batteries

Zinc (Zn) metal possesses broad prospects because of its strong water-stability, intrinsic safety and high theoretical specific capacity, however, the instability of the interface between Zn electrode and electrolyte prevents its practical application. Herein, a trace maltose (Malt) additive with strong zincophilicity, firm inter-molecular hydrogen bond and abundant exposure of high-electronegativity hydroxyl is introduced to dynamically adjust the components in the Helmholtz plane (HP) to achieve highly stable and reversible Zn anode for aqueous zincion batteries (AZIBs). Especially, Malt molecules are preferentially adsorbed on (100) and (101) crystal planes to promote uniform and dense Zn2+ deposition along with (002) crystal plane. Benefiting from the unique dynamic HP, the Zn||Zn symmetric cell demonstrates the outstanding performance over 5300 h at 2 mA cm -2, and achieves the cumulative discharge capacity of 3.6 Ah cm -2 at 30 mA cm -2 and a high depth of discharge (DOD) of 51.3%. Meanwhile, the Zn//KVO full cell can operate stably for 800 cycles in a low negative -to -positive capacity ratio (N/P). This study provides a new perspective for the design of advanced aqueous electrolyte additives towards long-life AZIBs by dynamically regulating the Helmholtz plane near the surface of Zn metal.