Micro-selection and Macro-orientation Strategy Enables High-Areal-Capacity Magnesium Metal Anode
Huanglin Dou, Wanyu Zhao, Xiaoli Zhao, Xiaomin Wang, Xiaowei Yang
Abstract
Developing magnesium (Mg) metal electrodes for extended cycling at practical areal capacities is crucial for the commercialization of Mg battery commercialization. However, a higher areal-capacity operation requires greater Mg nucleation ability, which is further complicated by the fact that Mg faces a higher desolvation barrier than Li. This study investigates the correlation between the operated areal capacity and a short circuit. Accelerated lifespan degradation (670 to 15 h) occurs with increased areal capacity due to a short circuit from uneven Mg plating. Using insights, a micro-selection and macro-orientation strategy inspired by glass fiber-MXene (GF-MXene) substrate is developed for controlling Mg plating/stripping at high areal capacity. Synchronous morphological analysis reveals selective Mg plating on microscale MXene sheets and oriented plating/stripping in the macroscopic substrate greatly mitigates short circuiting, delivering high Coulombic efficiency (∼99.4%) for 700 h under 2.5 mAh cm –2 and extended cycle life (340 h) at 5 mAh cm –2, providing practical possibilities for Mg metal anodes applications.