Silicon nanoparticles (Si NPs) were simply mixed with carbon nanofibers (CNFs) without any chemical process at various weight ratios, and the electrochemical properties of these nanoparticles as anode materials were investigated in lithium-ion batteries (LIBs). To study the effects of the physical incorporation of CNFs on the volumetric variations in Si NPs, the dilations of full cells were measured. The measured volumetric change of the anode using a mixture of Si NPs and CNFs was smaller than that calculated from the theoretical volumetric changes of Si and graphite. Although the reversible capacity of Si NPs faded sharply, the fading was mitigated by increasing the mixing ratio of CNFs. In particular, the Si NP/CNF mixture prepared at weight ratio retained a reversible capacity of >800 mAh/g with a capacity retention of 53.2% even after 100 cycles. CNFs alleviated stress and strain during the charge–discharge process even though there was no tight chemical bonding with Si NPs.

Phosphorous (P) incorporated silicon nanoparticles (Si NPs) were synthesized by using inductive coupled plasma (ICP) and a specially designed double tube reactor.Their microstructures were investigated by injecting various amounts of PH3 gas during the synthesis. Injection of PH3 gas during the synthesis resulted in a change from crystalline to amorphous phase, a reduction of particle size as well as process yield. These results were attributed to a lower plasma density when higher amount of PH3 was injected.From EDS, SIMS and XPS analysis, it was revealed that P was successively incorporated in Si NPs.However, secondary phases such as P4 (red P) and P2O5were formed as amorphous ones in nanoscale when a relatively large amount of PH3 was injected.