Insight into the performance of the mesoporous structure SiOx nanoparticles anchored on carbon fibers as anode material of lithium-ion batteries

Vanadium-Tailored Silicon Composite with Furthered Ion Diffusion Behaviors for Longevity Lithium-Ion Storage

As one of the promising anode materials, silicon has attracted much attention due to its high theoretical specific capacity (∼3579 mAh g^-1) and suitable lithium alloying voltage (0.1-0.4 V). Nevertheless, the enormous volume expansion (∼300%) in the process of lithium alloying has a great negative effect on its cyclic stability, which seriously restricts the large-scale industrial preparation of silicon anodes. Herein, we design a facile synthesis strategy combining vanadium doping and carbon coating to prepare a silicon-based composite (V-Si@C). The prepared V-Si@C composite does not merely show improved conductivity but also improved electrochemical kinetics, attributed to the enlarged lattice spacing by V doping. Additionally, the superiority of this doping strategy accompanied by microstructure change is embodied in the relieved volume changes during the repeated charging/discharging process. Notably, the initial capacity of the advanced V-Si@C electrode is 904 mAh g^-1 (1 A g^-1) and still holds at 1216 mAh g^-1 even after 600 cycles, showing superior electrochemical performance. This study offers an alternative direction for the large-scale preparation of high-performance silicon-based anodes.

Constructing the Single-Phase Nanotubes with Uniform Dispersion of SiOx and Carbon as Stable Anodes for Lithium-Ion Batteries

SiOx is an attractive anode material for lithium-ion batteries due to its considerable capacity. However, its obvious volume expansion and low conductivity result in poor electrochemical performance. Herein, a novel single-phase nanotube structure with uniform distribution of nanoscale SiOx units and amorphous carbon matrix was fabricated. The hollow nanotube and homogeneously distributed ultrafine SiOx units greatly alleviate volume changes. The amorphous carbon facilitates electron transport throughout the network and offers a buffer to further reduce the volume expansion of SiOx. Benefiting from this unique structure, as-prepared single-phase SiOx/C NTs demonstrate excellent durability and rate capability. Specifically, it delivers a high reversible specific capacity (713 mAh g^-1 at 0.1 A g^-1 after 200 cycles); negligible capacity decay is confirmed after 500 cycles at high density current (544 mAh g^-1 at 1 A g^-1 after 500 cycles).