Effects of Microstructure on Electrode Properties of Nanosheet-Derived Hx(Ni1/3Co1/3Mn1/3)O2 for Electrochemical Capacitors

Nanosheet-derived H-x(Ni1/3Co1/3Mn1/3)O-2 was prepared by restacking (Ni1/3Co1/3Mn1/3)O-2 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-x(Ni1/3Co1/3Mn1/3)O-2 (HNCM). The electrodes composed of small nanosheets exhibited very large capacitances of 1241 F.g(-1) (395 mAh.g(-1)) at a current density of 50 mAh.g(-1), and 430 F.g(-1) (100 mAh.g(-1)) at a large current density of 1000 mAh.g(-1). 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 (Ni1/3Co1/3Mn1/3)O-2 nanosheets improved the electrochemical properties of H-x(Ni, Co, Mn)O-2.