N-Doped Carbon-Wrapped Cobalt–Manganese Oxide Nanosheets Loaded into a Three-Dimensional Graphene Nanonetwork as a Free-Standing Anode for Lithium-Ion Storage

A high-quality and centimeter-level three-dimensional (3D) nitrogen-doped graphene (NG) nanonetwork is synthesized via a chemical vapor deposition method to serve as a substrate and a current collector, which directly germinates active metal oxides to act as a free-standing electrode in lithium-ion batteries. By means of facile electrodeposition and annealing processes, the tetragonal spinel cobalt–manganese oxide nanosheets wrapped with polypyrrole pyrolytic carbon are in situ hybridized with a 3D NG nanonetwork. In particular, the introduced carbon protective layer can enhance the Li-ion storage capacity and cycle stability of the composite electrode. The metallic synergistic effect and rational carbonaceous hybridization jointly provide high-performance charge storage and cycle stability. Notably, the surface-controlled capacitive effect stands out contributing to the total charge storage more than ever in nanostructure electrodes.