Dissolve your composite in low BP solvent and spread it on the electrode, evaporate the solvent and go for measurements

If your polymer nanocomposite is not enough conducting, then you have to add some conducting matrix like acetylene black and a binder too to find the capacities or energy densities. 

Briefly,the electrodes are prepared using following procedure: 85 wt% (vary with the materials) electroactive materials  were mixed with 10 wt% acetylene black (AB) and 5 wt% polytetrafluoroethylene (PTFE) to form a thick paste. The paste was then pressed into a thin sheet  using mortar and pastel. Finally, the  prepared electrodes were dried under vacuum. 

dear sir, sujoy sir.,,thanks for your answer it will be helpful for me