Knitted and screen printed carbon-fiber supercapacitors for applications in wearable electronics

The field of energy textiles is growing but continues to face two main challenges: (1) flexible energy storage does not yet exist in a form that is directly comparable with everyday fabrics including their feel, drape and thickness, and (2) in order to produce an "energy textile" as part of a garment, it must be fabricated in a systematic manner allowing for multiple components of e-textiles to be integrated simultaneously. To help address these issues, we have developed textile supercapacitors based on knitted carbon fibers and activated carbon ink. We show capacitances as high as 0.51 F cm −2 per device at 10 mV s −1 , which is directly comparable with those of standard activated carbon film electrodes tested under the same conditions. We also demonstrate the performance of the device when bent at 90°, 135°, 180° and when stretched. This is the first report on knitting as a fabrication technique for integrated energy storage devices. Energy storage is a key challenge to the full implementation of wearable electronics. In this work, custom knitted and screen printed supercapacitors are fabricated. Assembled devices have capacitances per area as high as 0.51 F cm −2 per device.