Optimization of the Cathode Composition for Aluminum Graphite Dual Ion Batteries

Li‐free aluminum graphite dual ion batteries (AGDIB) have attracted attention due to abundant raw materials and low costs. AGDIB uses Al foils as anode material, natural graphite flakes as cathode, and AlCl 3 /[EMIm]Cl as electrolyte. To allow future upscaling, a significant increase of the cathode loading and optimization of cathode composition are inevitable. This is systematically investigated by varying graphite loading, water‐soluble binders, such as sodium alginate and sodium carboxymethyl cellulose (CMC), as well as conductive additive content (Super C65, SC). The cathode loading was successfully increased to 10 mg cm −2 achieving a specific capacity of 62.2 mAh g −1 and a Coulombic efficiency of 97.5% at 1 C employing 700 kDa CMC and 5 wt% SC. At high currents, capacities fade more drastically when employing high‐loading electrodes—mainly caused by increasing anodic overpotentials and only minimally by the cathode. GITT measurements revealed increasing apparent diffusion coefficients ( D app ) for high C‐rates indicating pseudocapacitive kinetics and highlighting high‐power capabilities of AGDIB. Binder and electrode stability in the corrosive IL electrolyte is emphasized by a long‐term cycle stability >700 cycles (1 C). The optimized cathode recipe yields ~61% gain in absolute cell capacity providing a foundation for future scale‐up of AGDIBs.