Effects of Microstructure on Electrode Properties of Nanosheet-Derived H(x)(Ni(1/3)Co(1/3)Mn(1/3))O(2) for Electrochemical Capacitors

Nanosheet-derived H(x)(Ni(1/3)Co(1/3)Mn(1/3))O(2) was prepared by restacking (Ni(1/3)Co(1/3)Mn(1/3))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)(Ni(1/3)Co(1/3)Mn(1/3))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 mA·g(−1), and 430 F·g(−1) (100 mAh·g(−1)) at a large current density of 1000 mA·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 (Ni(1/3)Co(1/3)Mn(1/3))O(2) nanosheets improved the electrochemical properties of H(x)(Ni, Co, Mn)O(2).