High-strength carbon nanotube buckypaper composites as applied to free-standing electrodes for supercapacitors

Buckypaper is an attractive candidate material for free-standing electrodes in supercapacitors due to its high electrochemical performance, light weight, and thin dimensions. At present, however, free-standing buckypapers exhibit severe limitations in terms of product quality, especially mechanical properties, which hinder their commercial applications. We here report a new method of co-packaging buckypaper with conducting polymer and thermosetting resin to fabricate cellular SWNT buckypaper materials with excellent mechanical properties, high electrical conductivity, and enhanced electrochemical properties. This new fabrication method involves wrapping of the as-prepared buckypaper with a uniform coaxial coating of polypyrrole (PPy) on the individual SWNT or SWNT bundle surfaces via a pulsed electrochemical deposition method, followed by further packaging with cyanate ester resin via a full dip infiltration. The resulting material exhibits a significant improvement in mechanical properties (improvement over unmodified buckypaper of about 400% in tensile modulus and strength) and enhanced electrochemical performance (320 F g^-1 at a current density of 1 A g^-1) without sacrificing electrical and thermal properties. This material is a promising candidate for use as a free-standing electrode material in small-size, light-weight, and high-temperature supercapacitors.