Unconventional Current-Morphology Dependence in Electrodeposition of Zn Anode Revealed by In Situ XRD

Aqueous Zn-ion batteries (ZIBs) show great promise for large-scale energy storage due to their use of safe, low-cost aqueous electrolytes and earth-abundant elements such as Zn and Mn. Similar to Li-ion and Na-ion batteries, ZIBs face challenges with harmful zinc dendrites forming on the anode, significantly reducing cycling life. Previous studies have demonstrated that the morphology and texture of deposited Zn are crucial for the cycling life of ZIBs. A (002)-textured Zn surface, where the (002) planes are uniformly oriented parallel to the substrate/current collector, is reported to be beneficial as it is dense, flat, and free of dendrites.<br/>The deposition current significantly influences the formation of the (002) texture, but the current-texture dependence and its underlying mechanism remain unclear, primarily due to the lack of in situ characterization capabilities. Here, we report new findings on the current-texture dependence in Zn deposition and its underlying mechanism, revealed by our recently developed synchrotron-based high-throughput in situ X-ray diffraction tool (HT in situ XRD). Using this tool, we systematically investigated zinc deposition under various conditions, including different current densities, electrolyte concentrations, and types of substrates, in an expedited high-throughput manner. We also developed a unique quantitative texture characterization protocol.<br/>Our results reveal an unprecedented growth mechanism of deposited Zn, summarized as an "evolutionary orientation selection" mechanism. These new findings advance our understanding of metal deposition and provide valuable guidelines for developing new cycling protocols for ZIBs, significantly extending their durability.