Effects of Microstructure on Electrode Properties of Nanosheet-Derived H(NiCoMn)O₂ for Electrochemical Capacitors.

Nanosheet-derived H(NiCoMn)O₂ was prepared by restacking (NiCoMn)O₂ nanosheets with large or small lateral sizes and their electrochemical properties in a 1 M KOH aqueous solution; microstructural factors were compared with those of bulk H(NiCoMn)O₂ (HNCM). The electrodes composed of small nanosheets exhibited very large capacitances of 1241 F·g (395 mAh·g) at a current density of 50 mA·g, and 430 F·g (100 mAh·g) at a large current density of 1000 mA·g. These large capacitances resulted from a heterogeneous layer structure with a large surface area and pore volume. The electrodes of large nanosheets, with a strongly interconnected microstructure and a surface area slightly larger than that of HNCM, exhibited good cycle stability and capacitances larger than that of HNCM. Microstructural control through the restacking of (NiCoMn)O₂ nanosheets improved the electrochemical properties of H(Ni, Co, Mn)O₂.