Student Science

Intel ISEF 2013 Finalist Profile

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Design and Synthesis of Hydrogenated TiO2-Polyaniline Nanorods for Flexible High-Performance Supercapacitors

Eesha Khare

Lynbrook High School, San Jose, CA

With the rapid growth of portable electronics, it has become necessary to develop efficient energy-storage technology to match this development. While batteries are currently used for energy-storage, they are not ideal because of slow charging times and short cycle life. Supercapacitors have attracted attention as energy-storage devices due to their long cycle life and high power density. However, supercapacitor use is limited because they store less energy than batteries. Increasing supercapacitor energy density, while maintaining good power density and cycle life, remains a key challenge in energy-storage research. This work designed, synthesized, and characterized a novel core-shell nanorod electrode with hydrogenated TiO2 (H-TiO2) core and polyaniline shell. H-TiO2 acts as the double layer electrostatic core. Good conductivity of H-TiO2 combined with high pseudocapacitance of polyaniline results in significantly higher overall capacitance and energy density while retaining good power density and cycle life. Structural and electrochemical evaluation of the resulting supercapacitor demonstrated high capacitance of 238.5 F/g compared to the next best alternative supercapacitor in previous research of 80 F/g. This resulted in excellent energy density of 20.1 Wh/kg, comparable to batteries, while maintaining a high power density of 20.5 kW/kg. It also demonstrated a much higher cycle life compared to batteries, with a low 32.5% capacitance loss over 10,000 cycles at a high scan rate of 200 mV/s. This new electrode was fabricated into a flexible solid-state device to light an LED to test it in a practical application. This work is an important initial step in introducing this new electrode material in supercapacitors to replace conventional batteries.

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