Electrochemical Synthesis of Multidimensional Nanostructured Silicon as a Negative Electrode Material for Lithium-Ion Battery

Silicon (Si) is a promising negative electrode material for lithium-ion batteries (LIBs), but the poor cycling stability hinders their practical application. Developing favorable Si nanomaterials is expected to improve their cyclability. Herein, a controllable and facile electrolysis route to prepare Si nanotubes (SNTs), Si nanowires (SNWs), and Si nanoparticles (SNPs) from halloysite clay (Al₂(OH)₄Si₂O₅·nH₂O) is developed. It is found that HCl-etching temperature and electrolysis potential play key roles in controlling the morphologies of Si. After being HCl-etched at 80 or 90 °C, halloysite clay can be reduced into Si nanotubes at a suitable potential of -1.45 V or Si nanowires at a wide potential from -1.40 to -1.60 V, respectively, while Si nanoparticles can be only obtained at a more negative potential of -1.60 V without HCl-etching. The different morphologies of Si are associated with the change of reduction kinetics after HCl-etching. Besides, when serving as negative electrode materials for LIBs, Si nanotubes exhibit better Li storage performance than Si nanoparticles and Si nanowires, showing a capacity of 3044 mAh g^-1 at 0.20 A g^-1 and 1033 mAh g^-1 after 1000 cycles at 1 A g^-1. This work provides a controllable approach for the synthesis of Si nanomaterials for LIBs.