Enhancing aluminium ion batteries with prussian blue analogues

Abstract

This study aims to modify the chemical composition of Prussian Blue Analogues (PBAs) to improve coulombic efficiency, specific capacity, and operating voltage in aqueous aluminium-ion batteries (AAIBs). It also explores the potential of bimetallic PBAs for enhanced electrochemical performance. CoHCF, NiCoHCF, and NiHCF were selected as cathode materials and synthesized via a co-precipitation method. Their structural and electrochemical characteristics were evaluated using SEM, XRD, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and battery cycling tests. Among them, CoHCF delivered the highest initial specific capacity(59.34 mAh/g) but lacked structural stability during cycling. NiHCF achieved a good balance between capacity(50.36 mAh/g) and stability, while NiCoHCF exhibited excellent cycling stability but lower capacity, possibly due to uneven distribution of nickel and cobalt. SEM analysis revealed surface cracking and irregular corrosion patterns, supporting the presence of compositional inhomogeneity in NiCoHCF. EIS results showed that NiCoHCF had lower charge-transfer resistance compared to the others. These results highlight that improving the distribution of metals in NiCoHCF and enhancing the environmental stability of NiHCF could further boost their performance in future AAIB applications.