Toward Stable Al Negative Electrodes of Aluminum‐Ion Batteries: Kinetic Parameters and Electrode Structure

Rechargeable aluminum-ion batteries have attracted significant attention as candidates for next-generation energy storage devices owing to their high theoretical capacity, safe performance, and abundance of raw materials. Al metal is the best option as the negative electrode, while its issues such as dendrite growth and corrosion accompanying hydrogen evolution in ionic liquid electrolyte have been seriously overlooked. Understanding the electrochemical mechanism of the surface evolution behavior of Al metal is a vital pathway for solving these issues. Kinetic parameters and electrode structure are the two key parameters that affect the surface evolution behavior of Al negative electrodes. Herein, the qualitative relationship between the kinetic parameters and surface evolution behavior of the Al negative electrode was established through a combination of in-situ optical technology and multi-physical field numerical simulation method. The key kinetic parameters, including ion concentration and transfer coefficient, exhibited different laws of influence on the surface evolution behavior, such as dendrite growth and corrosion. The electrochemical mechanism on the surface evolution was explored to guide the optimization design of Al-ion batteries. Based on the coupling design of the electrode structure and kinetic parameters, a highly stable porous aluminum structure composed of Al powder with a particle size of 100 μm was constructed to obtain highly stable and high-performance aluminum-ion batteries. This method provides new sight into the design of high-performance aluminum-ion batteries.