Zhao Jiajin, Chen Yan, Zhang Mengyan, An Ziqi, Nian Binbin, Wang Wenfeng, Wu Hao, Han Shumin, Li Yuan, Zhang Lu
College of Environment and Chemical Engineering, Hebei Key Laboratory of Applied Chemistry, State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, 066004, P. R. China.
State Key Laboratory of Materials-Oriented Chemical Engineering, School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, Jiangsu, 210009, P. R. China.
Adv Sci (Weinh). 2025 Jan;12(1):e2410988. doi: 10.1002/advs.202410988. Epub 2024 Nov 5.
Aqueous zinc-iodine (Zn-I) batteries are promising energy storage devices; however, the conventional single-electron reaction potential and energy density of iodine cathode are inadequate for practical applications. Activation of high-valence iodine cathode reactions has evoked a compelling direction to developing high-voltage zinc-iodine batteries. Herein, ethylene glycol (EG) is proposed as a co-solvent in a water-in-deep eutectic solvent (WiDES) electrolyte, enabling significant utilization of two-electron-transfer I/I/I reactions and facilitating an additional reversibility of Cl/Cl redox reaction. Spectroscopic characterizations and calculations analyses reveal that EG integrates into the Zn solvation structure as a hydrogen-bond donor, competitively binding O atoms in HO, which triggers a transition from water-rich to water-poor clusters of Zn, effectively disrupting the HO hydrogen-bond network. Consequently, the aqueous Zn-I cell achieves an exceptional capacity of 987 mAh g with an energy density of 1278 Wh kg , marking an enhancement of ≈300 mAh g compared to electrolyte devoid of EG, and enhancing the Coulombic efficiency (CE) from 68.2% to 98.7%. Moreover, the pouch cell exhibits 3.72 mAh cm capacity with an energy density of 4.52 mWh cm, exhibiting robust cycling stability. Overall, this work contributes to the further development of high-valence and high-capacity aqueous Zn-I batteries.
水系锌碘（Zn-I）电池是很有前景的储能装置；然而，碘阴极的传统单电子反应电位和能量密度不足以满足实际应用。高价碘阴极反应的活化引发了开发高压锌碘电池的一个引人注目的方向。在此，乙二醇（EG）被提议作为深共晶溶剂包水型溶剂（WiDES）电解质中的共溶剂，可实现双电子转移I/I/I反应的显著利用，并促进Cl/Cl氧化还原反应的额外可逆性。光谱表征和计算分析表明，EG作为氢键供体融入锌溶剂化结构，竞争性地结合HO中的O原子，这引发了从富水锌簇到贫水锌簇的转变，有效地破坏了HO氢键网络。因此，水系Zn-I电池实现了987 mAh g的优异容量，能量密度为1278 Wh kg，与不含EG的电解质相比，容量提高了约300 mAh g，并将库仑效率（CE）从68.2%提高到98.7%。此外，软包电池表现出3.72 mAh cm的容量，能量密度为4.52 mWh cm，展现出强大的循环稳定性。总体而言，这项工作有助于高价高容量水系Zn-I电池的进一步发展。
