Polymeric carbon encapsulated Si nanoparticles from waste Si as a battery anode with enhanced electrochemical properties

A facile method is proposed to prepare Si nanoparticles encapsulated in polymeric carbon (SiNPs-PC) as anode materials for lithium ion batteries . Si nanoparticles (SiNPs) with average diameter of 125 nm are prepared. Under the aid of silane coupling agent, SiNPs are coated with phenolic resin , and SiNPs-PC composite is prepared after carbonization engineering. The SiNPs-PC anode with 63.7 wt% of Si exhibits greatly strengthened electronic conductivity and relatively stable electrode interface. The SiNPs-PC anode delivers a reversible capacity of 984 mA h g −1 with 84% capacity retention after 100 cycles at a current density of 0.1 A g −1 and 710 mA h g −1 after 800 cycles at a current density of 1 A g −1 . When cycled at a very larger current density of 10 A g −1 , a decent reversible capacity of 404 mA h g −1 can be harvested, which is still higher than the theoretical capacity of commercial graphite anode. The electrochemical performances are systematically discussed on microstructure and morphology of electrode materials . The feedstock of SiNPs is recycled from waste Si, and the preparation of SiNPs-PC composite is facile, cost-effective and environmentally benign, which shows great potential of industrial production.