Constructing Al@C-Sn pellet anode without passivation layer for Li-ion battery

Aluminum (Al) is considered as a promising lithium-ion battery (LIB) anode material owing to its high theoretical capacity and appropriate lithation-delithation potential. Unluckily, its inevitable volume expansion causes the electrode structure instability, leading to poor cyclic stability. What’s worse, the natural Al₂O₃ layer on commercial Al pellets is always existed as a robust insulating barrier for electrons, which brings the voltage dip and results in low reversible capacity. Herein, we synthesized core-shell Al@C-Sn pellets for LIBs by a plus-minus strategy. In this proposal, the natural Al₂O₃ passivation layer is eliminated when annealing the pre-introduced SnCl₂, meanwhile, polydopamine-derived carbon is introduced as dual functional shell to alleviate the volume swellings and liberate the fresh Al core from re-oxidization. Benefiting from the addition of C-Sn shell and the elimination of the Al₂O₃ passivation layer, the as-prepared Al@C-Sn pellet electrode exhibits little voltage dip and delivers a reversible capacity of 1018.7 mAh g⁻¹ at 0.1 A g^-1 and 295.0 mAh g^-1 at 2.0 A g^-1 (after 1000 cycles). Moreover, its diffusion-controlled capacity is muchly improved compared to those of its counterparts, confirming the well-designed nanostructure contributes to the rapid Li-ion diffusion and further enhances the lithium storage activity.