Correlation between Microstructure and Electrochemical Behavior of the Mesoporous Co3O4 Sheet and Its Ionothermal Synthesized Hydrotalcite-like α-Co(OH)2 Precursor

An ionothermal strategy is developed to synthesize hydrotalcite-like alpha-Co(OH)(2) sheets. The structure and interlayer chemistry of alpha-Co(OH)(2) are facilely manipulated, thus determining its pseudocapacitive performance. Significantly, a very large space of 11.2 angstrom in (003) plane induced by various intercalated species is found in the ionothermal synthesized alpha-Co(OH)(2) obtained at 210 degrees C (210-alpha-Co(OH)(2)), which delivers a better pseudocapacitive performance. Annealing the synthesized alpha-Co(OH)(2) generates mesoporous Co3O4 sheets or nanoparticles, which depends on the structure of the precursors. More defects in the alpha-Co(OH)(2) precursor provide larger driving force during the nucleation of Co3O4 nanocrystals, thus reducing the grain size. The architecture of the 210-Co3O4 derived from 210-alpha-Co(OH)(2) is featured as self-supporting mesoporous nanosheets composed of similar to 5 nm sized grains. The fine grains and ultralarge specific surface area of similar to 113.5 m(2) g(-1) in the 210-Co3O4 can trigger the formation of CoO intermediate during lithium ion insertion into the Co3O4. The 210-Co3O4 exhibits superior cycling performance as electrode for lithium ion battery and supercapacitor over the other Co3O4 samples due to its nanocrystallite constructed mesoporous sheet structure, which has a higher strain accommodation capability. The underlying mechanism discussed in this work provides guidance on structural design of advanced energy storage materials.