Electrochemically Surface‐modified Aluminum Electrode Enabling High Performance and Ultra‐long Cycling Life Al‐ion Batteries

Abstract Innovation in electronic devices has created a demand for energy storage systems. Recently, rechargeable Al‐ion batteries (AIBs) have received significant attention owing to their high gravimetric capacity and low cost. In this study, the electrochemical performances of pristine, etched, and electropolished Al negative electrodes via surface modification were investigated to determine their efficiency in AIBs. Herein, pristine, etched, and electropolished Al acted as the negative electrodes (anodes), and pure graphite and aluminum chloride (AlCl 3 )/1‐ethyl‐3‐methylimidazolium chloride ([EMIm]Cl) were used as the positive electrode (cathode) and ionic liquid electrolyte, respectively. This new type of electropolished Al‐based battery cell shows good cyclability and high performance compared to pristine and etched Al electrodes. The electropolished Al electrode stabilized at an average capacity of 50 mAh g −1 over 10,000 cycles at an ultrafast current rate of 5,000 mA g −1 .