Kihun Jang

Aligned nickel-cobalt hydroxide nanorod arrays for electrochemical pseudocapacitor applications

Nanorod arrays were grown directly on a stainless steel substrate by the chemical bath deposition method. Parallel arrays of nanorods show a specific capacitance of 456 F g−1 with an energy density of 12.8 W h kg−1. This approach provides a one-step, seedless and cost-effective route for fabricating pseudocapacitive materials in 3-D form.

Binary metal hydroxide nanorods and multi-walled carbon nanotube composites for electrochemical energy storage applications

Carbon nanotube and metal oxide/hydroxide hybrids have attracted much interest as electrode materials for electrochemical supercapacitors because of their dual storage mechanism. They can complement or replace batteries in electrical energy storage and harvesting applications, where high power delivery or uptake is needed. Multi-walled carbon nanotube (MWCNT) and nickel–cobalt binary metal hydroxide nanorod hybrids have been developed through the chemical synthesis of binary metal hydroxide on a MWCNT surface. These hybrids show enhanced supercapacitive performance and cycling ability. Growth of a thin film consisting of a coating of binary metal hydroxide, as well as further growth of nanorod structures, is demonstrated using FESEM and TEM, showing that this film is a promising structure for supercapacitor applications. These electrodes yield a significantly high capacitance of 502 F g−1 with a high energy density of 69 W h kg−1 at a scan rate of 5 mV s−1. The film is stable up to 5000 cycles with greater than 80% capacitance retention.

Novel supercapacitor materials including OLED emitters

This study constitutes the first attempt to use an OLED emitter material as a novel supercapacitor component. In supercapacitor tests, the specific capacitance (33.07 F g−1) of a poly(9-(3-vinyl-phenyl)-anthracene) (PVPA)/multi-walled carbon nanotube (MWCNT) mixture was found to be approximately three times that of the system composed of the MWCNTs alone.