**Conflict of interest**

*Science, Technology and Advanced Application of Supercapacitors*

In this chapter, we have discussed the increased attention being given to fiber supercapacitors and their relevance to wearable electronics. We also revealed the role of carbon nanostructured fiber as energy storage devices and the challenges they face. We have successfully synthesized CNT fibers by CVD and dry spinning, applied a post-processing technique to these fibers (oxygen plasma functionalization) and by means of oxidation polymerization doped these fibers with PANI. These fibers were characterized electrochemically, by Raman spectroscopy and with SEM. These fibers were then used as electrodes to create simple fiber devices. The obtained devices produced energy densities of up to 6.16 Wh/ kg and 630 W/kg when using EMIMBF4 as electrolytes corresponding to almost a 64% increment in energy density and 335% increment in power density from devices fabricated with PVA-H2SO4 (3.77 Wh/kg, 188 W/kg). These devices also maintained excellent capacitance retention (88%) over 1000 charge-discharge cycles. When a comparison was however made with other devices with respect to areal energy density and power density it was observed that the asymmetrical device comprising of an OPFCNT and PANI-CNT showed the best data. This was attributed to the combined redox reactions of both the OPFCNT and PANI-CNT

*Cyclic stability for PANI-CNT EMIMBF4 device Inset: galvanostatic charge/discharge curve after 500 cycles.*

This work was funded by NASA NNX13AF46A and the National Institute for Occupational Safety and Health through the Pilot Research Project Training Program of the University of Cincinnati Education and Research Center Grant # T42OH008432. One of the authors (P. K. A.) would like to thank the Department

of Chemical and Environmental Engineering at UC for a partial financial

**48**

support.

**4. Conclusion**

**Figure 10.**

electrodes with the electrolyte.

**Acknowledgements**

The authors declare there is no conflict of interest.
