An efficient molten‐salt electro‐deoxidation strategy enabling fast‐kinetics and long‐life aluminum–selenium batteries

Aluminum–selenium (Al–Se) batteries have been considered as one of the most promising energy storage systems owing to their high capacity, energy density, and cost effectiveness, but Se falls challenges in addressing the shuttle effect of soluble intermediate product and sluggish reaction kinetics in the solid–solid conversion process during cycling. Herein, we propose an unprecedented design concept for fabricating uniform Se/C hollow microspheres with controllable morphologies through low‐temperature electro‐deoxidation in neutral NaCl–AlCl3 molten salt system. Such Se/C hollow microspheres are demonstrated to hold a favorable hollow structure for hosting Se, which can not only suppress the dissolution of soluble intermediate products into the electrolyte, thereby maintaining the structural integrity and maximizing Se utilization of the active material, but also promote the electrical/ionic conductivity, thus facilitating the rapid reaction kinetics during cycling. Accordingly, the as‐prepared Se/C hollow microspheres exhibit a high reversible capacity of 720.1 mAh g−1 at 500 mA g−1. Even at the high current density of 1000 mA g−1, Se/C delivers a high discharge capacity of 564.0 mAh g−1, long‐term stability over 1100 cycles and high Coulombic efficiency of 98.6%. This present work provides valuable insights into short‐process recovery of advanced Se‐containing materials and value‐added utilization for energy storage.