Carbon encapsulation has been proved effective for improvement of the performance of Si nanoparticle as a Li-ion battery anode. This presentation reports a scalable simple CVD process using a reaction mixture of CH4, H2 and Ar for Si nanoparticle encapsulation. Due to easier diffusion of the reaction gases, every Si nanoparticle was coated uniformly to form discrete nanographene encapsulated Si nanoparticles. The nanographene coating is comprised of two parts, one is a conformed nanographene shell surrounding the Si nanoparticles with 4-10 layers of the graphenes and the other is vertically grown nanographene spikes on the top of the conformed coating. Before electrochemical evaluation, controlled void space was created between Si and nanographene shell by removing SiO2 layer generated by thermal oxidation on the surface of Si nanoparticles to accommodate volume expansion upon LixSi alloy formation. A specific Li anode capacity close to theoretical capacity was realized for nanoparticles with void space sufficient to accommodate volume expansion. The excellent rate performance was also measured. Both can be attributed to high conductivity and structural stability of the nanographene shell.

Discrete nanographene encapsulated Si nanoparticles and their properties as Li-ion battery anode

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.