High Energy Density based Flexible Electrochemical Supercapacitors from Layer-by-Layer Assembled Multiwall Carbon Nanotubes and Graphene

• Layer-by-layer (LBL) assembly of MWCNTs and graphene.
• Thin film electrodes for high energy density based flexible supercapacitors.
• MWCNTs prevent the stacking of graphene sheets and also act as a conductive additive, spacer, and binder.
• The supercapacitor devices exhibit excellent cycling stability, retaining over 97% of its initial charge after 25,000 cycles.

Thin film electrodes for high energy density based flexible supercapacitors are fabricate using layer-by-layer (LBL) assembly of MWCNTs and graphene. The addition of conductive spacer of MWCNTs between the layers of graphene prevents the agglomeration between each other and therefore facilitates the maximum number of active sites for electrolyte ion intercalation. The supercapacitor devices based on this flexible LBL assembly show very high electrochemical capacitance (390 Fg−1) and exhibit excellent cycling stability, retaining over 97% of its initial charge after 25,000 cycles. The addition of MWCNTs between the layers of graphene raised the energy density by 31% and power density by 39% more than the bare graphene electrodes. The LBL films of MWCNTs-graphene yield ultra-high energy density of 168 Whkg−1 which is very promising for future potential application in high performance flexible energy storage devices.