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

Al is considered as a promising lithium-ion battery (LIBs) anode materials owing to its high theoretical capacity and appropriate lithation/de-lithation potential. Unfortunately, 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, this work 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 liberate the fresh Al core from re-oxidization and alleviate the volume swellings. 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), respectively. 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.