Structural control of highly oxidized carbon nanotube networks for high electrochemical performance.

Highly conductive and porous CNT network films exhibiting a high electrochemical performance in aqueous media were fabricated through the filtration of a dispersant-free dispersion of oxidized carbon nanotubes by less defective chlorate-based oxidation and thermal deoxygenation in air. [Display omitted] Carbon nanotubes (CNTs) are one of the most suitable candidates for electrochemical applications because of their high electrical conductivity and large specific surface area. However, the bundling behavior of single-walled CNTs (SWCNTs) due to π–π interaction limits their solution processability and structural control. Herein, we report a fabrication method for highly conductive and porous CNT network films exhibiting a high electrochemical performance in aqueous media. This was achieved through the filtration of a dispersant-free dispersion of oxidized carbon nanotubes by less defective chlorate-based oxidation and thermal deoxygenation in air. To increase the proportion of mesopores in the film, oxidized long multi-walled CNTs (Ox-LMWCNTs) were incorporated into Ox-SWCNT networks. The Ox-SWCNT/Ox-LMWCNT (1/1 wt.%) hybrid film exhibited a large surface area of 492 m²/g, which decreased to 225 m²/g after thermal treatment at 200 °C in air with increasing electrical conductivity up to 29,500 S/m. In particular, the proportion of mesopores increased from 65 to 89%. The enhanced electrochemical capacity of the hybrid films (147 F/g and 99% retention at 10 A/g) could be attributed to the increased mesopores and enhanced electrical conductivity of LMWCNTs after thermal deoxygenation even in air. [ABSTRACT FROM AUTHOR]