<i>In Situ</i> Synthesis of Trifluoroacetic Acid-Doped Polyaniline/Reduced Graphene Oxide Composites for High-Performance All-Solid-State Supercapacitors
Zhiyong Zhao, Zhihua Liu, Qishi Zhong, Yujun Qin, Aizhen Xu, Wen Li, Jiahua Shi
Abstract
Trifluoroacetic acid (TFA) is used for the first time as dopant in the synthesis of the graphene oxide/polyaniline (GO/PANI) composite. The composite was prepared through fast in situ polymerization of aniline (ANI) on GO sheets. After filtration and freeze-drying, the GO/PANI was reacted with hydrazine hydrate to produce reduced graphene/polyaniline (rGO/PANI). In the rGO/PANI, the morphology of PANI can be easily controlled by adjusting the mass ratio of GO to ANI. Oriented PANI was evenly and tightly attached on the rGO backbone to form a hierarchical composite for use as an electrode material in a flexible all-solid-state supercapacitor (ASSSC) with symmetric structure. At the optimal ratio of GO to ANI, the rGO/PANI on carbon cloth attained a high specific capacitance of 810 F g–1 at a current density of 1 A g–1 in a three-electrode system. The energy storage mechanism of the rGO/PANI was found to be mainly controlled by the surface redox reaction process. The rGO/PANI-based symmetric ASSSC displayed considerable capacitance retention of 91.3% after 2000 cycles. Furthermore, the device exhibited a maximum energy density of 62.2 Wh kg–1 at a power density of 0.8 kW kg–1. These favorable properties are primarily attributed to the enhanced interaction between rGO and PANI after the introducing of TFA, which accelerates the electron/ion transfer during charging and discharging by the synergistic effects of double-layer capacitance and pseudocapacitance.