CNT yarn based solid state linear supercapacitor with multi-featured capabilities for wearable and implantable devices

The revolutionary advancements of IoT technology, along with consistent technological developments in the fields like sports, healthcare, environment, etc., make human life technology-driven and smart. Emerging concepts like wearable electronic devices (WEDs), including e-textile and implantable electronic devices, are becoming the backbone of IoT technology, and this has created strong demand for the development of portable and miniaturized energy storage systems. For the practical realization of wearable and implantable electronic devices, these energy storage systems should be further flexible and weaveable into textile or bio-compatible and implantable. The practically applicable linear supercapacitors based on carbon nanotubes (CNTs) yarn, with their superior physical properties, have evolved as wearable and implantable energy storage devices. In this review article, the concept of the solid-state linear supercapacitor (SSLSc), the development history of CNTs yarn, methodologies used for its production and their properties, the progress in the design and developments of linear supercapacitor based on CNTs yarn for its application in wearable and implantable electronic devices is focused. The employed strategies such as core-sheath structure of metal-CNTs sheath and biscrolling of CNT sheet for forming robust hybrid SSLSc with very high loading of pseudocapacitor materials which are otherwise not spinnable for the ultimate enhancement of its electrochemical performance are reviewed. The adoption of the concepts like self-healable, stretchable, twistable, and biocompatible linear supercapacitors based on CNTs yarn for their applications in WED and implantable devices have also been discussed in the review.