Lifetime prediction and dynamics modeling of Al-air batteries optimized by Al-Zn energy transfer strategy for efficient energy storage

Abstract

Al-air batteries exhibit extraordinary potential for efficient energy storage, but the parasitic hydrogen evolution caused by the contact of Al with free H₂O sacrifices the energy efficiency significantly. The protective layer formed by Al-Zn energy transfer strategy has been demonstrated to be conspicuously efficacious in inhibiting anode self-discharge and extending battery's lifetime. However, the transfer dynamics of energy, mass and charge in proposed strategy remains unclear. In this work, the mechanism of Al-Zn energy transfer is analyzed experimentally and a numerical model of the battery is developed theoretically. The results show that the model attains high-accuracy in predicting battery lifetime. The anode mass associated with battery discharge, substitution reaction and hydrogen evolution follows the second-order functions of absolute surface coverage. Furthermore, variations in the concentrations of Al(OH)₄^-, Zn(OH)₄^2- and OH^-, along with changes in electrode overpotential, are identified. Finally, the formation of insoluble metal hydroxide/oxide proves to be a critical barrier, hindering the mass transport and charge transfer of Al anode, thereby limiting the high potential output of the battery.