Understanding the Influence of Electrolyte Optimization and Graphene Paper Cathodes on the Electrochemical Performance of Aluminum Dual-Ion Batteries

This study examines the electrochemical performance of aluminum dual-ion batteries (ADIBs) using binder-free graphene paper as the cathode and different molar ratios of AlCl₃ to 1-ethyl-3-methylimidazolium chloride [EMIm]Cl as the electrolyte. The graphene paper, with a thickness of 35 µm, offers high electrical conductivity and mechanical strength, making it a strong candidate for scalable energy storage systems. Three electrolyte compositions with AlCl₃ molar ratios of 1.3:1, 1.5:1, and 1.7:1 were tested to assess their effects on battery cell performance. Among these, the 1.7:1 composition exhibited the best electrochemical performance, with faster ion movement, lower charge transfer resistance, and more efficient aluminum-ion intercalation, leading to higher capacity retention. In contrast, the 1.3:1 ratio had limited ion mobility and increased internal resistance, while the 1.5:1 ratio offered a compromise between charge transfer efficiency and capacity retention. Electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic cycling confirmed that the optimized 1.7:1 electrolyte composition, combined with graphene paper, significantly improved the battery’s rate capability and energy efficiency. These findings highlight the promise of binder-free graphene paper and optimized electrolyte compositions in advancing ADIB technology for high-performance and scalable energy storage applications.