Lin Cheng-Hung, Wang Lei, King Steven T, Bai Jianming, Housel Lisa M, McCarthy Alison H, Vila Mallory N, Zhu Hengwei, Zhao Chonghang, Zou Lijie, Ghose Sanjit, Xiao Xianghui, Lee Wah-Keat, Takeuchi Kenneth J, Marschilok Amy C, Takeuchi Esther S, Ge Mingyuan, Chen-Wiegart Yu-Chen Karen
Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, New York 11794, United States.
Energy and Photon Sciences Directorate, Brookhaven National Laboratory, Upton, New York 11973, United States.
ACS Cent Sci. 2021 Oct 27;7(10):1676-1687. doi: 10.1021/acscentsci.1c00878. Epub 2021 Sep 16.
Aqueous electrochemical systems suffer from a low energy density due to a small voltage window of water (1.23 V). Using thicker electrodes to increase the energy density and highly concentrated "water-in-salt" (WIS) electrolytes to extend the voltage range can be a promising solution. However, thicker electrodes produce longer diffusion pathways across the electrode. The highly concentrated salts in WIS electrolytes alter the physicochemical properties which determine the transport behaviors of electrolytes. Understanding how these factors interplay to drive complex transport phenomena in WIS batteries with thick electrodes via deterministic analysis on the rate-limiting factors and kinetics is critical to enhance the rate-performance in these batteries. In this work, a multimodal approach-Raman tomography, X-ray diffraction refinement, and synchrotron X-ray 3D spectroscopic imaging-was used to investigate the chemical heterogeneity in LiVO-LiMnO WIS batteries with thick porous electrodes cycled under different rates. The multimodal results indicate that the ionic diffusion in the electrolyte is the primary rate-limiting factor. This study highlights the importance of fundamentally understanding the electrochemically coupled transport phenomena in determining the rate-limiting factor of thick porous WIS batteries, thus leading to a design strategy for 3D morphology of thick electrodes for high-rate-performance aqueous batteries.
由于水的电压窗口较小（1.23 V），水系电化学系统存在能量密度低的问题。使用更厚的电极来提高能量密度以及使用高浓度的“盐包水”（WIS）电解质来扩展电压范围可能是一个有前景的解决方案。然而，更厚的电极会产生更长的跨电极扩散路径。WIS电解质中的高浓度盐会改变决定电解质传输行为的物理化学性质。通过对限速因素和动力学进行确定性分析，了解这些因素如何相互作用以驱动具有厚电极的WIS电池中的复杂传输现象，对于提高这些电池的倍率性能至关重要。在这项工作中，采用了一种多模态方法——拉曼断层扫描、X射线衍射精修和同步加速器X射线3D光谱成像——来研究在不同倍率下循环的具有厚多孔电极的LiVO-LiMnO WIS电池中的化学不均匀性。多模态结果表明，电解质中的离子扩散是主要的限速因素。这项研究突出了从根本上理解电化学耦合传输现象在确定厚多孔WIS电池限速因素方面的重要性，从而为高倍率性能水系电池的厚电极三维形态设计策略提供了指导。
