Silicon has the advantages of high theoretical capacity and low redox potential, and is the most competitive negative electrode material in high specific energy lithium-ion batteries. Limited by the large volume expansion of the silicon negative electrode, the cycle performance of the silicon negative electrode is not good. The current method to improve the cycle performance of silicon is to design silicon nanomaterials with suitable structures.
However, the design of silicon nanostructured materials reported so far is mainly based on methods such as CVD, which not only requires the use of expensive silicon sources, but also requires additional templates or catalyst assistance. Therefore, it is imminent to explore short-process, low-cost, and controllable preparation methods of silicon nanomaterials.
The study found that the pre-treatment acid leaching temperature and electrolysis potential play a key role in the formation of nano-silicon. After the precursor is acid-treated at 80°C, it can be converted into SNTs by electrolysis at a precisely controlled constant potential of -1.45V (vs Ag+/Ag); Electrolysis at a constant potential between V (vs Ag+/Ag) can be converted into SNWs; when the precursor is directly electrolyzed, it can only be electrolyzed into SNPs at a constant potential of -1.6V (vs Ag+/Ag).
The formation process of these silicon nanomaterials with different morphologies is related to the reduction kinetics after acid treatment. The author also explored the electrochemical performance of SNTs, SNWs and SNPs as lithium battery anode materials. The study found that the SNTs electrode still maintained a high specific capacity of 1033.1 mAh g-1 after 1000 cycles at 1.0 A g-1, and each cycle Only 0.047% capacity fade.
Compared with Si nanoparticles and Si nanowires, Si nanotubes show higher reversible capacity and better cycle stability, due to the favorable hollow structure that can provide more Li storage sites and effectively buffer Si Volume change.