Effects of microstructure on electrode properties of nanosheet-derived hx(Ni1/3co1/3mn1/3)o2 for electrochemical capacitors

Abstract

Nanosheet-derived Hx(Ni1/3 Co1/3 Mn1/3)O2 was prepared by restacking (Ni1/3 Co1/3 Mn1/3)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 Hx(Ni1/3 Co1/3 Mn1/3)O2 (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 (Ni1/3 Co1/3 Mn1/3)O2 nanosheets improved the electrochemical properties of Hx(Ni, Co, Mn)O2.