Pure silicon thin-film anodes for lithium-ion batteries: A review

Renewable energy has become a mandatory pursuit towards solving the world's reliance on fossil fuels, an environmentally damaging and finite resource. Many renewable energy sources are intermittent in nature, so storage must be incorporated as part of any energy solution. Lithium-ion batteries (LIBs) now represent the fastest growing energy storage system compared to all other technologies. Thus increasing their energy storage capacity is the subject of ongoing research for inclusion in many modern applications and the near exclusive reliance on graphitic anodes represents a limiting factor for LIBs. While silicon-based anodes have an energy capacity that is up to 11 times greater than their graphite-based equivalents, they have yet to be fully commercialized. This is due to silicon-based anodes suffering from unacceptable electrochemical and mechanical degradation as silicon undergoes a large volume expansion (≈400%) during charge/discharge cycling. This review gives a comprehensive overview and understanding of pure thin-film silicon anodes using physical vapor and chemical vapor deposition (PVD & CVD) and the factors affecting their electrochemical performance and cyclability. A deeper understanding of these factors will enable researchers to take appropriate steps towards improving the performance of LIBs which will ultimately result in the commercialization of silicon-based anodes for LIBs.