Study on the Application of Aluminum Chloride Electrode in All‐Solid‐State Aluminum‐Graphite Battery: Microstructure Characteristics of Electrode and Charge–Discharge Mechanism

Aluminum‐ion batteries (AIBs) have attracted significant attention as a cost‐effective and resource‐abundant alternative to lithium‐ion systems, owing to their high theoretical capacity and environmental compatibility. In this study, an all‐solid‐state AIB (ASS‐AIB) is fabricated using an aluminum chloride (AlCl 3 )‐treated aluminum anode, a sodium phosphate‐modified graphite foil cathode (GFN), and a magnesium silicate‐based solid electrolyte. Structural characterization via scanning electron microscopy, X‐ray diffraction, and electron probe microanalyzer reveals a 48 μm‐thick interfacial reaction layer on the anode surface, with transmission electron microscopy analysis confirming the formation of a 33 μm AlCl 3 ·6H 2 O and AlC 3 composite sublayer that enhances ion transport. The ASS‐AIB exhibits stable charge–discharge cycling at room temperature, consistently delivering specific capacities above 600 mAh g −1 over 100 cycles under ambient conditions. While elevated temperatures (55 C) initially produce higher capacities exceeding 6000 mAh g −1 , this performance is transient and unsustainable due to electrolyte dehydration. Temperature‐dependent testing shows recoverable performance loss at low temperatures and irreversible degradation at elevated temperatures due to interlayer water evaporation. Additionally, a flexible large‐area module demonstrates promising potential for practical energy storage applications, operating a fan continuously for over 3 h and 40 min. These findings underscore the promise of AlCl 3 ‐assisted interface engineering in enabling high‐performance solid‐state AIBs.