Analytical Observation of Cathodic Zinc Deposition in High-Capacity Zinc Oxide Electrodes for Rechargeable Zinc-based Batteries: Influence of the Current Rate in the First Charging (Supporting Information)

The effects of the current rate used during the first charging (pre-charging: so-called “formation”) on the cathodic deposition of metallic zinc (Zn) were analyzed for the high capacity (thick) zinc oxide (ZnO) electrode in rechargeable Zn-based batteries. Pre-charging at a lower current rate (1.875 mA cm−2) enabled greater electrode performances for the subsequent charge-discharge cycles. The Zn deposition profiles were investigated by conventional postmortem X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy using a scanning electron microscope, as well as in situ synchrotron XRD and ex situ synchrotron X-ray computed tomography. The results revealed significant differences in the deposition profiles of the metallic Zn depending on the current rates used during pre-charging. The higher rate (18.75 mA cm−2) resulted in an inhomogeneous deposition of Zn, whereas the lower rate yielded finer Zn particles dispersed homogeneously throughout the thick ZnO electrode. These morphological and spatial variations in the Zn deposition during pre-charging affected the subsequent cycling behavior of the thick ZnO electrode.

本研究对首次充电（预充电，所谓‘成膜’阶段）所使用的电流密度对可充电锌基电池中高容量（厚型）氧化锌（ZnO）电极阴极沉积金属锌（Zn）的影响进行了分析。在较低的电流密度（1.875 mA cm−2）下进行预充电，能够显著提升后续充放电循环的电极性能。通过传统X射线衍射（XRD）和能谱X射线光谱学，结合扫描电子显微镜，以及原位同步辐射XRD和离位同步辐射X射线断层扫描技术，对Zn沉积剖面进行了研究。结果显示，预充电过程中使用的电流密度对金属Zn的沉积剖面存在显著差异。较高的电流密度（18.75 mA cm−2）导致Zn沉积不均匀，而较低的电流密度则使Zn颗粒在整个厚型ZnO电极中均匀分散。预充电阶段Zn沉积的形态和空间变化影响了厚型ZnO电极的后续循环行为。