Post-mortem study and long cycling stability of silica/carbon composite as anode in Li-ion cells

The present work emphases on the post-mortem study of silica/carbon composite as functional anode in Li-ion batteries (LIBs). Herein, the silica/carbon composite is synthesized by facile in-situ hydrothermal technique. The x-ray diffraction (XRD) pattern indicates the amorphous nature of silica/carbon composite. The stacked sheet-like morphology of silica/carbon composite is seen in the high-resolution transmission electron microscopy (HR-TEM) & scanning electron microscopy (SEM) images. In addition, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, energy dispersive x-ray analysis (EDAX), and x-ray photoelectron spectra (XPS) characterizations of silica/carbon composite has been studied in detail. The rate capability of silica/carbon composite anode in LIB indicates 99% capacity retention after applying current density ranging from 50 mA g-1 to 1000 mA g-1, successively. The composite anode delivers a stable specific capacity similar to 300 mAh g-1 at a current density of 100 mA g-1 for 500 cycles. Electrochemical impedance spectroscopy (EIS) study analyzed the faster Li-ion diffusion and increment in the diffusion coefficient by a factor of 1000 after 500 cycles. To the best of our knowledge, this is the first work on the post-mortem study of silica/carbon composite as anode in LIB. Post-cycling characterizations including XRD, FTIR, and SEM reveal the absence of any impurity phases and negligible volumetric expansion after prolonged cycling. It further confirms that the carbon present in the silica/carbon composite helps to accommodate the volumetric expansion of silica and prevents cracking of the anode over 500 cycles.