A promising silicon/carbon xerogel composite for high-rate and high-capacity lithium-ion batteries

Abstract

Silicon-based anodes are widely studied as an alternative to graphite anodes for lithium-ion batteries. Nevertheless, their practical application is mainly limited by the huge volume change that silicon particles undergo due to alloying and de-alloying with lithium ions during discharge/charge processes, which result in cracks and electrode degradation. In the present study, porous silicon-carbon composites are investigated as anode materials for next-generation lithium-ion batteries. These composites are prepared by a cost-effective, easily-scalable method based on a microwave assisted approach for the carbon matrix, followed by dispersion of the silicon in 2-propanol. The electrochemical behavior of the Si/C composites with different proportions of silicon is evaluated in terms of alloying and de-alloying mechanisms of lithium ions, battery reversible capacity, irreversible capacity in the first cycle, retention of capacity along cycling, and cycle efficiency. The composite with 30 wt.% of silicon presents specific discharge capacity as high as 917 mAh g−1 after 200 cycles and excellent stability in the long-term at high current density, which makes it a promising candidate for the lithium-ion battery market.