Supercapacitors fabricated from fiber materials are becoming important electrochemical energy storage devices owing to their high flexibility, light weight and high energy density. They are used in electronic systems such as information sensing, computation, communication and electronic textiles due to their higher power density than standard parallel plate capacitors and batteries. Here, the effects of the composition, spinning and fabrication conditions on the electrochemical performance of supercapacitors fibers made from carbon nanotubes, graphene and poly(3,4- ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) are reviewed in the context of wearable energy storage devices.

One of the most important research areas related to Li-ion batteries is the replacement of the graphite anode with other carbon materials such as hard carbons, activated carbons, carbon nanotubes, graphene, porous carbons, and carbon fibers. Although such materials have shown better electrochemical performance for lithium storage compared to graphite, there is plenty of room for improvement. One of the most effective approaches is to dope heteroatoms (e. g. nitrogen) in the structure of the carbon materials to improve their electrochemical performance when they are used as anode materials. We first describe how N-doping has a positive effect on lithium storage and then provide numerous selected examples of this approach being applied to various carbon materials. The characterization of N doped in the structure of different carbon materials by X-ray photoelectron spectroscopy and scanning tunneling microscopy is then presented since they are able to characterize the N in these structures with a high (atomic) resolution. Finally, a statistical analysis is performed to show how the amount of doped N affects the specific capacity of the N-doped carbon materials.