Activating sulfur oxidation reaction<i>via</i>six-electron redox mesocrystal NiS2 for sulfur-based aqueous batteries
Zhoudong Yang, Boya Wang, Yongjin Chen, Wanhai Zhou, Hongpeng Li, Ruizheng Zhao, Xinran Li, Tengsheng Zhang, Fanxing Bu, Zaiwang Zhao, Wei Li, Dongliang Chao, Dongyuan Zhao
Abstract
ABSTRACT Sulfur-based aqueous batteries (SABs) are deemed promising candidates for safe, low-cost, and high-capacity energy storage. However, despite their high theoretical capacity, achieving high reversible value remains a great challenge due to the thermodynamic and kinetics problems of elemental sulfur. Here, the reversible six-electron redox electrochemistry is constructed by activating the sulfur oxidation reaction (SOR) process of the elaborate mesocrystal NiS2 (M-NiS2). Through the unique 6e− solid-to-solid conversion mechanism, SOR efficiency can reach an unprecedented degree of ca. 96.0%. The SOR efficiency is further revealed to be closely associated with the kinetics feasibility and thermodynamic stability of the M-NiS2 intermedium in the formation of elemental sulfur. Benefiting from the boosted SOR, compared with the bulk electrode, the M-NiS2 electrode exhibits a high reversible capacity (1258 mAh g−1), ultrafast reaction kinetics (932 mAh g−1 at 12 A g−1), and long-term cyclability (2000 cycles at 20 A g−1). As a proof of concept, a new M-NiS2‖Zn hybrid aqueous battery exhibits an output voltage of 1.60 V and an energy density of 722.4 Wh kgcath−1, which opens a new opportunity for the development of high-energy aqueous batteries.