Catalyst-Free, High-Loading Silicon Nanowires Anodes for Lithium Ion Batteries

Abstract

We report on the scalable synthesis and characterization of novel architecture three-dimensional high-capacity amorphous Silicon Nanowires (SiNWs)-based anodes, with less than a third of the thickness of common graphite anodes. The SiNWs were grown by a novel, catalyst-free chemical vapor deposition (CVD) process, on a commercial stainless steel (SS) mesh. By using our novel, low-cost CVD procedure we synthesized binder-free anodes with loadings of up to 5mgSi/cm2, that have shown stable cycle life for over 600 cycles and provided capacities of up to 6mAh/cm2, very low (<10%) irreversible capacity and good compatibility with commercial cathodes. With the use of two- and three-electrodes coin cells we focus on studying their electrochemical performance and degradation mechanisms. It was found that the observed capacity loss of the SiNWs-based anodes is mainly caused by the increase in the resistivity of the SEI layer, along with the steady rise of the charge/discharge overpotential detected on both the anode and the cathode. Our anodes have been coupled with commercial cathodes (LFP and NCA), and have the potential to increase the energy density of LIBs by over 40%. In order to prove the scalability of our anodes, they have been successfully incorporated in industrial-size cylindrical cells, proving their potential as a viable candidate for anodes of the next generation lithium ion batteries for portable electronics and electric vehicles. Most recently, these anodes have been successfully coated with solid polymer electrolytes and cycled in all-solid state cells as a proof of concept, paving the way for safer, more durable LIBs.