Exfoliation and Reassembly of Cobalt Oxide Nanosheets into a Reversible Lithium-Ion Battery Cathode

An exfoliationreassemblyactivation (ERA) approach to lithium-ion battery cathode fabrication is introduced, demonstrating that inactive HCoO2 powder can be converted into a reversible Li1-xHxCoO2 thin-film cathode. This strategy circumvents the inherent difficulties often associated with the powder processing of the layered solids typically employed as cathode materials. The delamination of HCoO2 via a combination of chemical and mechanical exfoliation generates a highly processable aqueous dispersion of [CoO2]- nanosheets that is critical to the ERA approach. Following vacuum-assisted self-assembly to yield a thin-film cathode and ion exchange to activate this material, the generated cathodes exhibit excellent cyclability and discharge capacities approaching that of low-temperature-prepared LiCoO2 (similar to 83 mAh g-1), with this good electrochemical performance attributable to the high degree of order in the reassembled cathode.