Si@C/TiO2@C/Hollow-C Nanocomposite as a Lithium-Ion Battery Anode Produced by Refining Silicon and Ti-6Al-4V Residuals

TC4 (Ti-6Al-4V) nanoparticles (TC4NPs) and silicon nanoparticles (SiNPs) with a median size of 146 and 51 nm were prepared by sand milling from scrap produced by refining silicon and TC4. The SiNPs and TC4NPs are mixed, carbonized, and leached in different proportions to obtain Si@C/TiO2@C/Hollow-C anode materials. The special structure of the anode materials provided more space for the volume expansion of silicon. The anatase TiO2 in TC4NPs relieves the volume expansion and reduces the transfer impedance, and the lithiated TiO2 can promote the electrical conductivity of the Si@C/TiO2@C/Hollow-C anode during the charge/discharge process. Furthermore, the Si@C/TiO2@C/Hollow-C (SiNPs/TC4NPs = 2:1) electrode delivers excellent rate performance; after cycling at a series of higher current densities, 92% of the original level of the reversible capacity can be maintained. The Si@C/TiO2@C/Hollow-C (SiNPs/TC4NPs = 2:1) anode retains 558 mA h.g(-1) after 400 cycles with a large current density of 1000 mA.g(-1). The synthesis method of the Si@C/TiO2@C/Hollow-C anode is a low-cost, facile, and nontoxic process, endowing it with the potential for application as energy materials for mass production.

Automated summary

The Si@C/TiO2@C/Hollow-C anode materials prepared by mixing and carbonizing SiNPs and TC4NPs in different proportions provide ample space for the volume expansion of silicon while reducing transfer impedance. The anatase TiO2 in TC4NPs helps relieve volume expansion and enhance electrical conductivity during charge/discharge, leading to excellent rate performance and 92% reversible capacity retention after cycling at higher current densities.