High mass-loading polyaniline anode with high areal capacity and excellent cycling stability for AlCl2+ storage

Abstract

Rechargeable aqueous aluminum ion batteries (AIBs) are inspiring researchers’ enthusiasm due to the low cost and high theoretical capacity of aluminum. Polyaniline (PANI) materials have the potential for aluminum ion storage due to the properties of its excellent conductivity and inherent theoretical capacity. However, the poor cycling stability and low loadings of PANI limit its application in energy storage. In this study, PANI-x electrodes with high mass loadings are successfully prepared by the electrodeposition method for reversible AlCl₂⁺ storage. Among them, the PANI-2 electrode possesses the highest areal capacity (0.59 and 0.51 mAh cm⁻² at the current density of 0.5 and 10 mA cm⁻²) and excellent cycling stability in saturated AlCl₃. Ex situ N 1s fitting spectra of PANI-2 and molecular dynamics simulations of 1 M, 3 M, and saturated AlCl₃ electrolytes demonstrate that PANI can achieve reversible redox reactions in saturated AlCl₃, thereby achieving its excellent stability. Density functional theory calculations and ex situ spectra characterizations of PANI-2 demonstrate the insertion/de-insertion mechanism in the form of AlCl₂⁺ ions. In conclusion, PANI-2|Saturated AlCl₃|EG (exfoliated graphite foil) full cell is assembled successfully. This work provides promising guidance for the preparation of high-loading electrodes for AIBs.