In Situ Intercalation Polymerization Fabrication of Polyaniline/Graphene Composites via Supercritical CO2 Assistance: Toward High-Performance Supercapacitor Electrodes

Polyaniline coupled with graphene (PANI/GR) serves as a competitive electrode material for supercapacitors, benefiting from its high theoretical capacity and superior electrical conductivity. Nevertheless, conventional PANI/GR composites generally suffer severe structural collapse, resulting in limited energy density and inferior cycling durability. Herein, a supercritical CO2 (scCO2)-assisted synthesis strategy is developed to prepare layered PANI/GR nanocomposites (denoted as SC). Benefiting from supercritical fluid treatment and anilinium cation intercalation, in situ polymerization of interlayered anilinium produces well-coupled layered architectures. Such a layered structure effectively suppresses PANI volume variation, accelerates ion transport and strengthens interfacial contact, thus boosting electronic conduction. The SC composite marked SC-11 delivers a specific capacity of 669 F g−1 (1 A g−1) and outstanding cycling stability with a capacity retention of 92.5% (5000 cycles). The fabricated SC-11//AC device (SC-11 cathode, activated carbon anode) reaches a peak energy density of 29.2 Wh kg−1 at 650 W kg−1. This facile strategy enables fabrication of high-performance layered graphene-based electrode materials for energy storage.