Effects of ammonolysis and of sol-gel titanium oxide nitride coating on carbon fibres for use in flexible supercapacitors

Smooth titanium oxide nitride coatings have been deposited on carbon fibres using a non-oxide sol-gel method based on self-condensation of titanium alkylamide species. Both the coating and a nitridation of the fibres resulting from the coating process increase the capacitance of the fibres measured in aqueous acid conditions, with significant redox capacitance contributions. When flexible symmetric capacitors were made from the coated fibres and an acid gel electrolyte they provided competitive energy and power densities. Their capacitance was retained very effectively on bending up to 180 degrees.