Facile preparation of graphene/polyaniline composite hydrogel film by electrodeposition for binder-free all-solid-state supercapacitor

The combination of graphene and polyaniline (PANI) as electrodes for supercapacitors has attracted dramatic interests due to their synergistic effects. However, the preparation of the electrode materials usually involves complicated process and other additives. In this work, we report the facile fabrication of the graphene/PANI composite hydrogel film as the symmetric all-solid-state supercapacitor electrode. The free-standing reduced graphene oxide (rGO) hydrogel film is hydrothermally synthesized from a GO solution layer, which is used for subsequent electropolymerization of PANI. The electrochemical measurements of the resulting rGO/PANI hydrogel film present the capacitance of 853.7 F g−1 at 1 A g−1 with good rate capability and cycling stability. In addition, the hydrogel composite film is assembled into the symmetric all-solid-state capacitor without any additives and attains the capacitance of 741.8 F g−1 with a high capacitance retention of 92.6% after 8000 cycles. These excellent electrochemical properties of the composite film are ascribed to the joint effort of superior conductivity and porous structure of rGO matrix with the outstanding pseudocapacitive property of PANI. The convenient method could be considered for the preparation of graphene-based functional composite materials.