Singh Gurpreet, Tang Christopher R, Nicoll Andrew, Torres Jonah, Housel Lisa M, Wang Lei, Takeuchi Kenneth J, Takeuchi Esther S, Marschilok Amy C
Institute for Energy Sustainability and Equity, Stony Brook University, Stony Brook, New York 11794, United States.
Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States.
J Phys Chem C Nanomater Interfaces. 2023 Feb 8;127(8):3940-3951. doi: 10.1021/acs.jpcc.2c08255. eCollection 2023 Mar 2.
Herein, zinc vanadium oxide (ZVO) and zinc hydroxy-sulfate (ZHS) formation as discharge products in sodium vanadium oxide (NVO) cathode materials of two distinct morphologies, NVO(300) and NVO(500), is studied with and X-ray diffraction methods. ZHS formation upon discharge is shown to be favored at higher current densities and reversible upon charge, while ZVO formation is found to be favored at lower current densities but persists throughout cycling. synchrotron-based energy dispersive X-ray diffraction (EDXRD) reveals reversible expansion of the NVO lattice due to Zn during discharge, spontaneous ZVO formation following cell assembly, and ZHS formation concomitant with H insertion at potentials less than ∼0.8 V vs Zn/Zn. With spatially resolved EDXRD, ZVO formation is show to occur near the separator region first, eventually moving to the current collector region as discharge depth increases. ZHS formation, however, is found to originate from the current collector side of the positive electrode and then propagate through the porous electrode network. This study highlights the special benefits of the EDXRD method to gain mechanistic insight into structural evolution within the electrode and at its interface.
在此，采用X射线衍射方法研究了两种不同形貌的氧化钒钠（NVO）正极材料NVO(300)和NVO(500)中作为放电产物的氧化锌钒（ZVO）和羟基硫酸锌（ZHS）的形成情况。结果表明，放电时ZHS的形成在较高电流密度下更有利，且充电时可逆，而ZVO的形成在较低电流密度下更有利，但在整个循环过程中持续存在。基于同步加速器的能量色散X射线衍射（EDXRD）揭示了放电过程中由于锌导致的NVO晶格可逆膨胀、电池组装后自发形成ZVO以及在相对于Zn/Zn小于约0.8 V的电位下伴随氢插入形成ZHS。通过空间分辨EDXRD表明，ZVO的形成首先发生在隔膜区域附近，随着放电深度增加最终移动到集流体区域。然而，发现ZHS的形成起源于正极的集流体一侧，然后通过多孔电极网络传播。这项研究突出了EDXRD方法在深入了解电极内部及其界面结构演变机理方面的特殊优势。
