Three-dimensional carbon foam surrounded by carbon nanotubes and Co-Co3O4 nanoparticles for stable lithium-ion batteries

Three-dimensional (3D) carbon foams (CF) surrounded by carbon nanotubes (CNTs) and Co-Co 3 O 4 nanoparticles (NPs) (CF@Co-Co 3 O 4 /CNT) nanocomposites were prepared by a two-step method for stable lithium-ion batteries (LIBs). The low-cost melamine foams pre-soaked in cobalt nitrate solution were firstly carbonized under nitrogen atmosphere to form 3D CF surrounded by a large number of CNTs and Co NPs (CF@Co/CNT). Subsequently, the CF@Co/CNT was transformed into CF@Co-Co 3 O 4 /CNT nanocomposites by calcination in air. Here, Co NPs, CNT and 3D CF all improved the electrical conductivity of CF@Co-Co 3 O 4 /CNT nanocomposites. In addition, a large number of uniformly-dispersed small Co 3 O 4 NPs effectively increased Li + storage capacity of nanocomposites. At the same time, the 3D macroporous carbon frameworks surrounded by CNT could also relieve the volume deformation of Co 3 O 4 NPs to some extent. When it was employed as anode materials for LIBs, CF@Co-Co 3 O 4 /CNT nanocomposites exhibited the stable reversible capacities of about 500 mAh g −1 at 0.5 A g −1 , larger than that of commercial graphite and some other Co-based materials. The two-step preparation method was simple and convenient for large-scale production.