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.