Theoretical and Experimental Study of the Crystal Orientation Effect of the Anode on the Aluminum-Air Battery Performance

The electrochemical characteristics of aluminum (Al) anodes in Al-air battery according to crystal orientation were theoretically and experimentally evaluated to analyze this phenomenon in detail. Density functional theory (DFT) calculations were performed on the open-circuit potential of the aluminum (111) plane and (100) plane in an alkaline solution. The theoretical values were obtained by DFT calculations when considering the surrounding environment and single-electron transfer. The open-circuit potentials calculated by DFT were similar to the measured potentials. These results indicate that the difference between the potential predicted by bulk thermodynamics and the potential obtained from the stepwise mechanism is related to the free energy asymmetry of the intermediate in the multi-electron transfer reaction and the chemical stabilization of the surrounding environment during the product formation. The crystal orientation affects the performance of Al-air battery by the above effects. Al (100) showed the highest output power depending on the orientation effect in the discharge test result and the I-P curve.