Mn-Ni-based coating on flexible graphite fiber with high length capacitance for flexible supercapacitor applications

Abstract

Significant growth has been observed in the development of technologies that employ flexible displays and sensors; however, the progress made in the realm of flexible energy storage devices has been relatively limited. Because flexibility and stretchability are critical for wearable, biomedical, and portable electronic devices, flexible energy storage electrodes must be researched. In this work, electrochemical behaviors of alloy-coated graphite fibers having flexibility have been investigated. Mn-Ni-based modified graphite was obtained electrochemically from a deep eutectic solvent ionic liquid at a different static voltage. The electrochemical deposition performance of films in Ethaline deep eutectic solvent and cycling of the resulting electrodes in a KOH electrolyte were analyzed using a potential window of 0.7 V. Fabricated flexible electrodes were characterized via the SEM, EDX, FTIR, and XRD techniques to reveal their morphological, compositional, and structural properties. Length capacitance, charge-discharge and self-discharge behaviors of fabricated flexible electrodes were calculated. The performance of the electrode can be controlled by modifying the material structure through changes in the deposition conditions. The graphite fiber coated with MnNi by application of −1.75 V had a length capacitance of 40.3 mF cm−1. The film had high surface coverage and could potentially be suitable for energy storage purposes. It is possible to create stretchable electrodes for wearable electronics by knitting graphite fibers covered with metals or alloys.