Origin of Doping-Induced Structural Amorphization and Improved Cycling Performance in Aluminum Anodes for Lithium-Ion Batteries

Aluminum (Al) has been considered a promising anode material for advanced lithium-ion batteries (LIBs); however, it is prone to degradation after multiple electrochemical cycles. Using first-principles-based simulations, we emphasize the critical role of structural amorphization and demonstrate how doping influences structural disorder and, in turn, the cyclic stability of Al anodes. The amorphous phase of Al is found to be readily lithiated, whereas its crystalline counterpart exhibits resistance during the initial stage of lithiation. Our work reveals that silicon (Si) doping effectively stabilizes the Al amorphous structure, while iron (Fe) and copper (Cu) are ineffective in suppressing its recrystallization. This behavior is largely attributed to the strong Al–Si bonding interaction. In addition, our neural network potential-based molecular dynamics simulations illustrate that Li atoms preferentially incorporate around Si dopants, leading to facilitated and more spatially uniform lithiation in Si-doped Al compared to undoped Al. This, in turn, enhances structural integrity and promotes reversible volume changes during electrochemical cycling. Our findings highlight that the distinct lithiation behavior of Si-doped Al anodes may offer advantages over conventional alloy-type anodes that suffer from structural disintegration arising from large volume changes.