Unraveling the Role and Impact of Alumina on the Nucleation and Reversibility of β-LiAl in Aluminum Anode Based Lithium-Ion Batteries

Aluminum, due to its high abundance, very attractive theoretical capacity, low cost, low (de−) lithiation potential, light weight, and effective suppression of dendrite growth, is considered as a promising anode candidate for lithium-ion batteries (LIBs). However, its practical application is hindered due to multiple detrimental challenges, including the formation of an amorphous surface oxide layer, pulverization, and insufficient lithium diffusion kinetics in the α-phase. These outstanding intrinsic challenges need to be addressed to facilitate the commercial production of Al-based batteries. The native passivation layer, Al₂O₃, plays a critical role in the nucleation and reversibility of lithiating aluminum and is thoroughly investigated in this study using high precision electrochemical micro calorimetry. The enthalpy of crystallization of β-LiAl is found to be 40.5 kJ mol⁻¹, which is in a strong agreement with the value obtained by calculation using Nernst equation (40.04 kJ mol⁻¹). Surface treatment of the active material by the addition of 25 nm of alumina increases the nucleation energy barrier by 83 % over the native oxide layer. After the initial nucleation, the added alumina does not negatively impact the reversibility at 0.1 C rate, suggesting the removal of alumina is not necessary for improving the cyclability of aluminum anode based lithium-ion batteries. Moreover, the coulombic efficiencies are also found to be slightly higher in the alumina treated samples compared to the untreated ones.