Exploring new strategies for improved aluminium-ion batteries through dual-anion modeling

Abstract

Aluminium-ion batteries (AIBs) offer numerous advantages, including high capacity, safety, and environmental sustainability, positioning them as a promising technological solution for mobile power and energy storage applications. Nevertheless, the effect of excess electrolytes reduces energy density, and the thermal instability of large-capacity batteries represents a major obstacle to large-scale applications. The energy storage mechanism of AIBs involves the reversible deposition/dissolution of metallic aluminium (Al) at the anode within a chloroaluminate ionic liquid electrolyte, coupled with the intercalation/deintercalation of AlCl₄⁻ at the graphite cathode. These processes lead to dynamic changes in the concentrations of two anions (AlCl₄⁻ and Al₂Cl₇⁻), which in turn affect conductivity, diffusion coefficients, and battery polarization. This unique dual-anion property presents challenges for understanding the operating mechanisms and studying the internal states, both of which are critical factors for developing high-performance AIBs. Based on extensive geometric, kinetic and thermodynamic data, derive and calculate the behavior of the two anions. We have pioneered an AIBs electrochemical model with dual-anion characteristics which can accurately simulate the external and internal states such as battery potential with a simulation error of less than 0.38 %, temperature and optimize the mass ratio of the cathode material to electrolyte at 1.85:1. In addition, this constructed AIBs model explores a novel strategy to improve the battery management system, increase the operation efficiency and thermal management, and create a theoretical basis for further optimization of the battery design.