Origami of Solid-State Supercapacitive Microjunctions Operable at 3 V with High Specific Energy Density for Wearable Electronics

Flexible, solid-state energy storage devices with higher operational voltage and large energy density are in increasing demand for powering microelectronic devices on wearable platforms. Addressing this, we demonstrate an all solid-state, mechanically robust electrochemical supercapacitor operating at 3 V with <5% loss in performance over 10 000 charge–discharge cycles. Single-walled carbon nanotube-coated cellulose yarns (CNT-wires) are interwoven through a cellulosic polymer–ionic liquid (ion-gel) electrolyte sheet to create supercapacitive microjunctions that deliver high energy density (∼50 Wh kg–1) and power density (∼4400 W kg–1). Three-dimensional ion-transport microchannels that form within the polymeric scaffold are observed by micro-Raman spectro-microscopy and are engineered to achieve low iRdrop (2.5%), high energy density, and Coulombic efficiency (95% at 3 V). The interwoven microjunctions are further integrated through origami to realize their parallel and series combinations for a wide-ranging performance (50–189 Wh kg–1). This combination of operability at 3 V and excellent performance with electrochemical and mechanical durability is used to power a light-emitting diode (LED) and suggests potential applications in portable electronics.