Towards Sustainable Solid‐State Aluminum‐ion Batteries: Multi‐Functional Conductive Graphite Cathode from CO ₂ Reduction

Abstract The dual pressures of escalating energy demands and environmental degradation necessitate transformative sustainable technologies. Herein, a molten salt electrochemical strategy is reported that directly converts CaCO 3 , generated through CO 2 fixation, into two functionally distinct conductive carbon materials: highly conductive graphite (KCG) and hierarchically porous graphite (NCG), achieves through precise modulation of KCl‐CaCl 2 and NaCl‐CaCl 2 electrolytic environments. Structural analyses reveal KCG's enhances defect density (I D /I G ratio 0.89) and strong π–π interactions, whereas NCG exhibits low disorder (I D /I G ratio 0.84). Electrochemical profiling in solid‐state aluminum‐ion batteries (SEAIBs) demonstrates KCG's surface‐capacitance‐dominated charge storage (85.6% contribution at 5 mV s −1 ), enabling exceptional rate capability. NCG delivers high specific capacity (74 mAh g −1 ) and cycling stability, attributed to optimized ion diffusion pathways. The methodology establishes a dual‐function material platform, addressing both conductive matrix and ion‐host requirements for next‐generation energy storage systems, with direct implications for sustainable battery manufacturing.