Stretchable Electrode based on Laterally-Combed Vertical Carbon Nanotubes for Energy Devices

Abstract

Electrical power supply to the mobile electronics in general requires a physical connection to the external power sources through a long wire, which causes inconvenience to the users. As the mobile electronics have been miniaturized, their lightweight, thinness, flexibility, and stretchability became the key issues in developing the wearable and epidermal electronic devices. Consequently, their autonomous power generation and storage devices are also necessary to be light, thin, and deformable. In this study, vertically-aligned carbon nanotubes were used to fabricate the stretchable electrodes for triboelectric generator which harvest electrical energy from the human body motion, energy storage devices including supercapacitor and lithium ion battery, and wireless power transmission coil. Vertically-aligned carbon nanotubes synthesized on the silicon wafer were partially interfused by polydimethylsiloxane ink-jet-printed on it and peeled off to be the stretchable electrode in the desired shape. Then, its electrical conductivity and percolation effect were improved by combing the air-exposed carbon nanotubes to be laterally-aligned and electroplating its surface with nickel metal. As the interconnection between other devices, the electrode could be printed in the serpentine pattern to reduce the uniaxial strain stress while stretched. The pattern in microscale could be realized by using photolithography on the catalyst layer for carbon nanotubes. As the electrode for triboelectric generator, supercapacitor and lithium ion battery, the large area was patterned to accomplish their high output power. The fabricated energy devices maintained their performance within 30% strain stretching, which realized the autonomous power generation and storage system for the wearable and epidermal electronics.