Activating and Stabilizing a Reversible four Electron Redox Reaction of I<sup>−</sup>/I<sup>+</sup> for Aqueous Zn‐Iodine Battery
Chenggang Wang, Xiaoxing Ji, Jianing Liang, Shunshun Zhao, Xixi Zhang, Guangmeng Qu, Wenfeng Shao, Chuanlin Li, Gang Zhao, Xijin Xu, Huiqiao Li
Abstract
Abstract Low capacity and poor cycle stability greatly inhibit the development of zinc‐iodine batteries. Herein, a high‐performance Zn‐iodine battery has been reached by designing and optimizing both electrode and electrolyte. The Br − is introduced as the activator to trigger I + , and coupled with I + forming interhalogen to stabilize I + to achieve a four‐electron reaction, which greatly promotes the capacity. And the Ni−Fe−I LDH nanoflowers serve as the confinement host to enable the reactions of I − /I + occurring in the layer due to the spacious and stable interlayer spacing of Ni−Fe−I LDH, which effectively suppresses the iodine‐species shuttle ensuring high cycling stability. As a result, the electrochemical performance is greatly enhanced, especially in specific capacity (as high as 350 mAh g −1 at 1 A g −1 far higher than two‐electron transfer Zn‐iodine batteries) and cycling performance (94.6 % capacity retention after 10000 cycles). This strategy provides a new way to realize high capacity and long‐term stability of Zn‐iodine batteries.