High-Valent Thiosulfate Redox Electrochemistry for Advanced Sulfur-Based Aqueous Batteries
Yutong Feng, Boya Wang, Wanhai Zhou, Hongrun Jin, Xiaoyu Yu, Tengsheng Zhang, Jian Zhao, Hongpeng Li, Jingwen Zhao, Wei Li, Chenyan Ma, Dongliang Chao, Dongyuan Zhao
Abstract
Sulfur-based aqueous batteries (SABs) are promising for safe, low-cost, and high-capacity energy storage. However, the low output voltage of sulfur cannot meet the demands of high-energy cathode applications due to its intrinsic negative potential (E 0 = −0.51 V vs SHE) of low-valent polysulfide redox (S 2– /S 0 ). Here, instead of relying on traditional aqueous polysulfide redox, for the first time, we demonstrate a high-valent thiosulfate redox (S 2 O 3 2– /S 4 O 6 2– ) electrochemistry, exhibiting positive redox potential (E 0 > 0 V vs SHE) and reversible cation storage in aqueous environment. Operando X-ray absorption fine structure spectroscopy, in situ Raman spectroscopy, and density functional theory calculations reveal the high reversibility and dynamic charge transfer process of high-valent thiosulfate redox. Significantly, the aqueous thiosulfate redox exhibits a high operating voltage of approximately 1.4 V, a reversible capacity of 193 Ah L –1, and a long cycling life of over 1000 cycles (99.6% capacity retention). This work provides new insights into the high-valent S-based electrochemistry and opens a new pathway to achieve energetic aqueous batteries.