Organic pH Buffer for Dendrite-Free and Shuttle-Free Zn-I 2 Batteries

• Published in: Angewandte Chemie International Edition 2023-05, Vol.62 (21), p.e202303011
• Main Authors: Lyu, Yanqiu, Yuwono, Jodie A, Wang, Pengtang, Wang, Yanyan, Yang, Fuhua, Liu, Sailin, Zhang, Shilin, Wang, Baofeng, Davey, Kenneth, Mao, Jianfeng, Guo, Zaiping
• Format: Article
• Language: English
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202303011

Aqueous Zn-Iodine (I ) batteries are attractive for large-scale energy storage. However, drawbacks include, Zn dendrites, hydrogen evolution reaction (HER), corrosion and, cathode "shuttle" of polyiodines. Here we report a class of N-containing heterocyclic compounds as organic pH buffers to obviate these. We evidence that addition of pyridine /imidazole regulates electrolyte pH, and inhibits HER and anode corrosion. In addition, pyridine and imidazole preferentially absorb on Zn metal, regulating non-dendritic Zn plating /stripping, and achieving a high Coulombic efficiency of 99.6 % and long-term cycling stability of 3200 h at 2 mA cm , 2 mAh cm . It is also confirmed that pyridine inhibits polyiodines shuttling and boosts conversion kinetics for I /I . As a result, the Zn-I full battery exhibits long cycle stability of >25 000 cycles and high specific capacity of 105.5 mAh g at 10 A g . We conclude organic pH buffer engineering is practical for dendrite-free and shuttle-free Zn-I batteries.