Three-dimensional spongy nanographene-functionalized silicon anodes for lithium ion batteries with superior cycling stability

An innovative spongy nanographene (SG) shell for a silicon substrate was prepared by low-temperature chemical vapor deposition on a hierarchical nickel nanotemplate. The SG-functionalized silicon (Si@SG) composite shows outstanding properties, which may be helpful to overcome issues affecting current silicon anodes used in lithium ion batteries such as poor conductivity, large volume expansion and high mass transfer resistance. The hierarchical nanographene shell exhibits elastic, sponge-like features that allow it to self-adaptively change its volume to accommodate the volume expansion of silicon. In addition, the porous, spongy framework containing randomly stacked graphene nanosheets presents low diffusion barriers and provides sufficiently free and short-haul channel segments to allow the fast migration of Li and electrolyte ions. The unique properties of the present silicon anode result in excellent electrochemical performances in terms of long-term cycling stability (95% capacity retention after 510 cycles), rate performance, and cycling behavior for high mass loadings at different current densities.