Binder-Free FeS₂@CNT Self-Supported Film as Cathode for Chloride Molten Salt Aluminium Batteries

Rechargeable molten salt aluminium batteries have emerged as a highly promising candidate technology for large-scale energy storage systems, owing to their high energy density, low cost, and excellent cycling stability. This study aims to improve the electrochemical performance of chloride molten salt aluminium batteries by addressing the limitations of FeS 2 cathode material, including particle agglomeration, volume expansion, and poor conductivity. FeS 2 and FeS 2 @CNT were prepared using hydrothermal and in situ growth methods, respectively, with comprehensive characterisation and electrochemical techniques. By forming a unique “point-line” contact structure with functionalized CNT, it enhances ion diffusion and structural stability, providing a pathway for electron transport. In terms of electrochemical performance, FeS 2 @CNT significantly outperforms pristine FeS 2 : excellent initial discharge specific capacity (191.2 mAh g −1 at 0.5 A g −1 ), reduced polarization (ΔEp = 0.10 V at 0.1 mV s −1 ), outstanding rate performance (151.5 mAh g −1 at 1 A g −1 ), and exceptional cycling stability (89.6% capacity retention after 800 cycles at 0.5 A g −1 ). Ex-situ tests confirmed the reversible insertion/extraction process of AlCl 4 − , revealing the energy storage mechanism. The in situ growth strategy constructs a F-CNT conductive network, significantly enhancing the conductivity of FeS 2 (Rct = 0.88 Ω), offering a novel pathway to optimize sulphide cathodes for high-performance RABs.