Well-developed capacitive-capacity of metal-organic framework derived Co₃O₄ films in Li ion battery anodes

Porous Co₃O₄ films derived from Co-based metal-organic framework (MOF) are anchored by Ti nanowire arrays to form self-supported electrodes, which realize remarkable rate capability as Li ion battery (LIB) anodes owing to the homogeneous distribution of active grains, conductive scaffold and mass transport channels in them. The MOF films comprising Co₃(HCOO)₆ blocks are anchored on Ti nanowire arrays through a hydrothermal process, then the films are pyrolyzed to porous Co₃O₄/C films. Scanning electron microscope images reveal the blocks are clenched firmly on Ti substrates by Ti nanowires inserting into them. The LIB battery tests indicate that, thanks to the good adherence, Co₃O₄ films present outstanding durability (maintaining 2000 cycles at 20 A g⁻¹ without obvious decay). Furthermore, the carbon scaffold generated from the pyrolysis in inert gas is crucial to the rate capability of Co₃O₄ self-supported anodes. The homogeneous distribution of carbon in Co₃O₄ films leads to facilitated electron transport, which can help the films releasing their capacitive potential adequately. This enables the films possessing a capacity of 400 mAh g⁻¹ at 20 A g⁻¹, much better than the films from pyrolysis in air (100 mAh g⁻¹ at 20 A g⁻¹).