Improving Discharge Voltage of Al-Air Batteries by Ga³⁺ Additives in NaCl-Based Electrolyte

The application of NaCl-based aluminum-air batteries is limited due to the passivation of the aluminum anode. In an effort to solve this problem, this work studied the influence of different concentrations of Ga³⁺ additives on the discharge behavior of Al in the NaCl electrolyte. The results of both experiments and theoretical calculations have shown that commercial purity aluminum could be significantly activated by Ga³⁺. Based on microstructure observations and electrochemical impedance spectroscopy, the influence activation mechanism of Ga³⁺ on the discharge behavior of commercial purity Al is clarified. The addition of Ga³⁺ biased the surface charge of aluminum along the activation direction, forming activation sites, and then destroyed the surface passivation film. Due to the formation of a gallium-aluminum amalgam, the Al-air battery had the best discharge characteristics in the electrolyte with 0.2 M Ga³⁺, and its discharge voltage reached 0.9734 V with a remarkable increase compared with that of NaCl solution (0.4228 V). Therefore, Ga³⁺ additive is a promising choice for NaCl-based Al-air batteries to improve their discharge voltage.