Lin Cheng-Hung, Sun Ke, Ge Mingyuan, Housel Lisa M, McCarthy Alison H, Vila Mallory N, Zhao Chonghang, Xiao Xianghui, Lee Wah-Keat, Takeuchi Kenneth J, Takeuchi Esther S, Marschilok Amy C, Chen-Wiegart Yu-Chen Karen
Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, NY 11794, USA.
National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA.
Sci Adv. 2020 Mar 6;6(10):eaay7129. doi: 10.1126/sciadv.aay7129. eCollection 2020 Mar.
Water-in-salt (WIS) electrolytes provide a promising path toward aqueous battery systems with enlarged operating voltage windows for better safety and environmental sustainability. In this work, a new electrode couple, LiVO-LiMnO, for aqueous Li-ion batteries is investigated to understand the mechanism by which the WIS electrolyte improves the cycling stability at an extended voltage window. Operando synchrotron transmission x-ray microscopy on the LiMnO cathode reveals that the WIS electrolyte suppresses the mechanical damage to the electrode network and dissolution of the electrode particles, in addition to delaying the water decomposition process. Because the viscosity of WIS is notably higher, the reaction heterogeneity of the electrodes is quantified with x-ray absorption spectroscopic imaging, visualizing the kinetic limitations of the WIS electrolyte. This work furthers the mechanistic understanding of electrode-WIS electrolyte interactions and paves the way to explore the strategy to mitigate their possible kinetic limitations in three-dimensional architectures.
盐包水（WIS）电解质为水系电池系统提供了一条充满希望的途径，可扩大工作电压窗口，以实现更好的安全性和环境可持续性。在这项工作中，研究了一种用于水系锂离子电池的新型电极对LiVO-LiMnO，以了解WIS电解质在扩展电压窗口下提高循环稳定性的机制。对LiMnO阴极进行的原位同步加速器透射X射线显微镜观察表明，WIS电解质除了延缓水分解过程外，还抑制了对电极网络的机械损伤和电极颗粒的溶解。由于WIS的粘度明显更高，因此用X射线吸收光谱成像对电极的反应不均匀性进行了量化，直观显示了WIS电解质的动力学限制。这项工作进一步加深了对电极-WIS电解质相互作用的机理理解，并为探索减轻其在三维结构中可能存在的动力学限制的策略铺平了道路。
