Electrochemical Preparation of Nano-Sized Silicon as a Lithium-Ion Battery Anode Material

Abstract

Highly pure silicon is an important component in photovoltaic applications and has potential in battery technology. In this study, the electrochemical behavior of Si (IV) was discussed in a NaF−LiF−Na2SiO3−SiO2 electrolyte at 750 °C, and lithium-ion battery performance with electrodeposited silicon powder as anode material were investigated. The cyclic voltammograms illustrated that the reduction of Si(IV) on an Ag electrode followed an irreversible two-step, two-electron process: Si(IV) → Si(II) and Si(II) → Si(0). Both reduction steps involved diffusion control, and the diffusion coefficients were 1.18 and 1.22 × 10−6 cm2 s−1, respectively. Nanoscale spherical silicon was deposited between potentials of −1.0 to −1.6 V (vs Pt) with support of X-ray diffraction patterns, Raman spectra, and scanning electron microscopy analysis. Combining the fabricated silicon with carbon, a Si@C composite anode material for lithium-ion batteries was prepared, and its specific capacity reached 1260 mA·h g−1. Notably, a capacity of 200 mA·h g−1 was maintained over 100 cycles.

Study of the Silicon Electrochemical Nucleation in LiCl-KCl-CsCl-K2SiF6 Melt

“…4, 29 which is used for calculation in the case of an irreversible cathodic process: At a temperature of 540°C, the diffusion coefficient of silicon ions to GC substrate was 8.44 • 10 −11 m 2 s −1 (8.45 • 10 −7 cm 2 s −1 ). In other works reported about diffusion coefficients in 10 −8 -10 −4 cm 2 s −1 ranges, 13,[30][31][32][33] but there are several factors that need to discuss. First, most research provided in higher temperatures than present investigation.…”