多硫化物
化学
氧化还原
碱金属
无机化学
电解质
硫黄
溶剂化
半反应
溶剂
金属
物理化学
电极
有机化学
作者
Qingli Zou,Zhuojian Liang,Guan Ying Du,Chi You Liu,Elise Y. Li,Yi‐Chun Lu
摘要
Alkali metal sulfur redox chemistry offers promising potential for high-energy-density energy storage. Fundamental understanding of alkali metal sulfur redox reactions is the prerequisite for rational designs of electrode and electrolyte. Here, we revealed a strong impact of alkali metal cation (Li+, Na+, K+, and Rb+) on polysulfide (PS) stability, redox reversibility, and solid product passivation. We employed operando UV-vis spectroscopy to show that strongly negatively charged short-chain PS (e.g., S42-/S32-) is more stabilized in the electrolyte with larger cation (e.g., Rb+) than that with the smaller cation (e.g., Li+), which is attributed to a stronger cation-anion electrostatic interaction between Rb+ and S42-/S32- owing to its weaker solvation energy. In contrast, Li+ is much more strongly solvated by solvent and thus exhibits a weaker electrostatic interaction with S42-/S32-. The stabilization of short-chain PS in K+-, Rb+-sulfur cells promotes the reduction of long-chain PS to short-chain PS, leading to high discharge potential. However, it discourages the oxidation of short-chain PS to long-chain PS, leading to poor charge reversibility. Our work directly probes alkali metal-sulfur redox chemistry in operando and provides critical insights into alkali metal sulfur reaction mechanism.
科研通智能强力驱动
Strongly Powered by AbleSci AI