Tunable Syntheses of Advanced Silicon Anodes Using Cyclohexasilane

Abstract

The ability to develop fast charging lithium-ion batteries with high-energy density is being pursued intensively due to increasing demands of portable electronics and electric vehicles. Replacing the conventional graphite anode with a silicon-based one offers several advantages, namely the roughly 10 times higher gravimetric capacity and the safer lithium alloying potential. However, full scale realization of replacing graphite with silicon has been hampered due to the large volumetric expansion silicon typically suffers which causes mechanical degradation, low electrical conductivity, and multiple-step syntheses from a traditional silicon precursor which leads to higher cost. Here we present a silicon precursor, cyclohexasilane, that can offer solutions to all three of those limitations. Cyclohexasilane (CHS) exists as a liquid at room temperature and is relatively low boiling (~ 200 °C) relatively facile synthesis of nanostructured silicon materials, significantly reducing the volumetric expansion typically observed. Cyclohexasilane can be readily used to manufacture silicon/carbon composite materials and is readily chemically functionalized allowing the development of tailored materials with improved electrical conductivity. CHS may also be tailored to deliver structures with engineered artificial SEIs during the device fabrication step, offering an efficient and direct route to electrode structures. Moreover, cyclohexasilane is relatively inexpensive and its physical properties allow for roll-to-roll manufacturing with significantly reduced capital costs. Relevant comparisons of this technology compared to incumbent technologies will be given.