Single-walled carbon nanotube-mediated physical gelation of binary polymer blends: An efficient route to versatile porous carbon electrode materials

Abstract

A non-covalent approach to prepare nanotube-containing gels was developed based on the physical gelation of two polymers, polyvinyl alcohol (PVA) and polyacrylonitrile (PAN), with different microphase behaviors in water/dimethyl sulfoxide (DMSO) mixture. Single-walled carbon nanotubes (SWNTs) were incorporated into the binary-polymer/binary-solvent system to alter the physical gelation behavior and, in turn, to achieve unique physicochemical characteristics of the resulting gels. SWNTs were wrapped with PVA, which extended the binary polymer system to a ternary polymer system consisting of PVA bound to SWNTs, free PVA, and PAN. It was observed that the SWNT/PVA/PAN ensembles gelled with appropriate amounts of water in DMSO and the gelation behavior was reversible. The amounts of water and SWNT were determined to be key parameters affecting the formation of the gels. The SWNT/PVA/PAN gels were successfully converted to carbonaceous gels via heat treatment in an inert atmosphere, which can be extended to several applications such as electrode materials. The macroporous carbonaceous gels were further functionalized via manganese deposition followed by potassium hydroxide activation, which yielded excellent cell performance in a neutral electrolyte with the energy density of 9.6–24.8 Wh kg−1 and power density of 8.0–0.1 kW kg−1.