Fabrication of graphene-encapsulated CoO/CoFe2O4 composites derived from layered double hydroxides and their application as anode materials for lithium-ion batteries

Bicomponent CoO/CoFe2O4 composites with tunable particle sizes are prepared using Co-Fe layered double hydroxides (LDHs) or Co-Fe hydroxides as precursors. Moreover, graphene-encapsulated CoO/CoFe2O4 composites (labeled as G-CoO/CoFe2O4) are fabricated by co-assembly of graphene oxide nanosheets and Co-Fe LDHs/hydroxides, and then thermal decomposition of Co-Fe LDHs/hydroxides. Compared to uncoated CoO/CoFe2O4, G-CoO/CoFe2O4 composites exhibit enhanced cycle performances and rate capabilities. The superior performance may be attributed to the graphene encapsulation that prevents the aggregation of CoO/CoFe2O4 particles, buffers the strain from the volume variation of CoO/CoFe2O4, and improves the electronic conductivity of the composite electrode. The electrochemical properties of G-CoO/CoFe2O4 can be further improved by reducing the particle size of CoO/CoFe2O4 due to the enlarged interface between graphene nanosheets and CoO/CoFe2O4 particles.