A chelation process by an amino alcohol electrolyte additive to capture Zn2+ and realize parallel Zn deposition for aqueous Zn batteries

Zn anode experiences dendrite issues in aqueous Zn batteries. They result from uneven Zn2+ flux and Sand behavior depending on the current density. Herein, the amino alcohol of 2,2′,2′'-nitrilotriethanol (NTE) additive with chelation ability is introduced to achieve stable and parallel Zn deposition. NTE preferentially adsorbs on Zn surface, which chelates with Zn2+ at interface upon geometry transformation. It not only homogenizes Zn2+ flux to inhibit dendrites at low current densities, but also supply sufficient Zn2+ to delay Sand behavior at high current densities. Parallel growth of Zn hexagonal plates is realized. Thus, Zn plating/stripping in symmetric cells at 10 mA cm−2 reaches >1600 h cycle life with the addition of 2.5% NTE in the ZnSO4 electrolyte, corresponding to a high cumulative plated capacity of 8.5 Ah cm−2. At the conditions of 5°C or 70% depth of discharge, the lifespans of symmetric cells also extend to 6977 hours and 230 hours, respectively. In anode free full cells, a Zn2+ pre-inserted V6O13·H2O cathode retains 250 mAh g−1 capacity after 300 cycles at 6 A g−1, superior to 83 mAh g−1 with NTE free electrolyte.