Three-dimensional Co3O4/C nanocomposites are synthesized via a hydrogel assisted synthesis route. The carbon has a three-dimensional interconnected network structure, and ultrathin Co3O4 nanosheets (≈5.0 nm) are parallelly and uniformly embedded in the two-dimensional carbon network walls. This unique structure restricts the aggregation and pulverization of active materials, and ensures the continuity and efficiency of electron and ion transmission during the lithiation/delithiation process. As a result, the Co3O4/C nanocomposites exhibit excellent cycling performance at different current densities. The discharge capacities remain at 905 mA h g-1 after 190 cycles at the current density of 100 mA g-1 and 561 mA h g-1 after 500 cycles at the current density of 2000 mA g-1. Since this approach is facile and large-scale, it is a rational way to engineer high capacity anodes to achieve improved electrochemical performances.