Unveiling the role of oxidative treatments on the electrochemical performance of carbon nanotube-based cotton textile supercapacitors

Abstract

Herein, all-solid-state textile supercapacitors (TSCs) were produced using a cost-effective readily-available natural fabric as substrate (cotton) and different types of oxidized multiwalled carbon nanotubes (MWCNTs) as electrode nanomaterials. The MWCNT oxidative treatments were performed using three agents, HNO3, H2SO4 and HNO3/H2SO4, to unveil their role on the performance and energy storage mechanism of the resulting TSCs. The TSCs based on the oxidized MWCNTs exhibited up to 106% enhanced energy density than the device based on pristine MWCNTs (up to 3.48 W h kg−1 vs. 1.69 W h kg−1) and up to 98% capacitance retention over 5000 cycles. A balance between the extent of oxidation of the MWCNTs, their specific surface area and electrical conductivity was required to boost the performance. The MWCNT oxidation with HNO3 promoted the highest increase of the specific surface area, the creation of redox-active surface oxygen-based groups and optimum surface oxygen loading (4.0%). The synergy between these features endowed a pseudocapacitive contribution to the energy storage mechanism, leading to the TSC with the best performance. This work constitutes a breakthrough on the rational design of easily scalable TSCs directly produced on natural non-conductive substrates using tuned oxidized MWCNT electrode nanomaterials to meet the demands of the thriving Era of wearable electronics.