Metal-Organic Framework Derived Porous Hollow CoO/N-C Polyhedron Composite with Excellent Energy Storage Capability.

Metal-organic frameworks (MOFs) derived transition metal oxides exhibit enhanced performance in energy conversion and storage. In this work, porous hollow CoO with N-doped carbon coating (CoO/N-C) polyhedrons have been prepared using cobalt-based MOFs as a sacrificial template. Assembled from tiny nanoparticles and N-doped carbon coating, CoO/N-C composite shortens the diffusion length of Li/Na ions and possesses an enhanced conductivity. And the porous and hollow structure is also beneficial for tolerating volume changes in the galvanostatic discharge/charge cycles as lithium/sodium battery anode materials. As a result, it can exhibit impressive cycling and rating performance. At 1000 mA g, the specific capacities maintaine stable values of ∼620 mAh g within 2000 cycles as anodes in lithium ion battery, while the specific capacity keeps at 229 mAh g within 150 cycles as sodium ion battery anode. Our work shows comparable cycling performance in lithium ion battery but even better high-rate cycling stability as sodium ion battery anode. Herein, we provide a facile method to construct high electrochemical performance oxide/N-C composite electrode using new MOFs as sacrificial template.