Coiled and twisted nanofiber yarns for electrochemically harvesting electrical energy from mechanical deformation

Abstract

Yarn energy harvesters containing conducing nanomaterials (such as carbon nanotube (CNT) yarn harvesters) that electrochemically convert tensile or torsional mechanical energy into electrical energy. Stretched coiled yarns can generate 250 W/kg of peak electrical power when cycled up to 24 Hz, and can generate up to 41.2 J/kg of electrical energy per mechanical cycle. Unlike for other harvesters, torsional rotation produces both tensile and torsional energy harvesting and no bias voltage is required, even when electrochemically operating in salt water. Since homochiral and heterochiral coiled harvester yarns provide oppositely directed potential changes when stretched, both contribute to output power in a dual-electrode yarn. These energy harvesters were used in the ocean to harvest wave energy, combined with thermally-driven artificial muscles to convert temperature fluctuations to electrical energy, sewn into textiles for use as self-powered respiration sensors, and used to power a light emitting diode and to charge a storage capacitor.