Graphene bridged carbon-polyethylene glycol-coated Si nanoparticle as anode material for lithium ion battery

Si is a promising anode material for use in lithium-ion batteries. To solve the problems of rapid capacity decay and short cycle life caused by its huge volume expansion, a simple agitation and thermal reduction method to modify Si nanoparticles with polyethylene glycol-derived thin carbon (C-PEG@Si NPs) was used, and hierarchical graphene@C-PEG@Si NPs composites by bridge of graphene were prepared. A series of characterization test methods including SEM, TEM, X-ray diffraction and constant charge-discharge test were used to investigate the structure, morphology and electrochemical properties of graphene@C-PEG@Si NPs composites. The thin carbon from PEG and graphene wrapping was used to block electrolyte contact and buffer volume changes, respectively. The results show that compared to pure Si, the graphene@C-PEG@Si composites exhibit outstanding electrochemical performance with the reversible specific capacity of 1 032 mAh/g after 100 cycles at a current density of 210 mA/g, and a capacity higher than 430 mAh/g at a current density of 4 200 mA/g after 100 cycles.