Achieving High Cycling Rates via In Situ Generation of Active Nanocomposite Metal Anodes

The morphological control of electrochemically deposited metallic anodes, such as Li, Zn, and Mg, under high applied rates is essential for the development of high-energy-density batteries. For transportation applications, maximizing high rates and high energy density is key to attaining viable customer acceleration and range expectations, respectively. In this work, the in situ generation of Mg nanocrystals allowed cycling under high rates (10 mA cm–2) and reduced temperature (0 °C) for the very first time. Through operando STEM analysis, we discovered a highly functional SEI, a first of its kind, which enabled continuous deposition and dissolution of Mg without internal shorting. The unique morphology of the deposited Mg and the functional capability of the SEI are key to future development of practical metallic Mg anodes.