Controlling Diffusion Dynamics Through Additive Electrolyte Chemistry in Flexible Free-Standing Electrode With...

High electronic conductivity and specific capacitance are critical challenges for free-standing electrodes in neutral electrolyte-based supercapacitors (SCs). This study introduces a 1D/2D heterostructure electrode composed of reduced graphene oxide/polyaniline/cerium-metal-organic framework (rGO/PANI/Ce-MOF), demonstrating enhanced mechanical strength, flexibility, and electrical conductivity. The integration of rGO into the in situ polymerized PANI and Ce-MOF facilitates improved charge transport under neutral electrolytic conditions. Additionally, hydrogen bond interactions were engineered using electrolyte additives, propanol, 1,2-propanediol, and glycerol (Gly) with water molecules to boost ion mobility. The rGO/PANI/Ce-MOF electrode achieved a specific capacitance of 1180 ± 5% F g^{- 1} at 2 A g^{- 1}in 1 M Na₂SO₄, which further increased to 1346 ± 5% F g^{- 1} in a Gly-modified electrolyte under the same conditions. Density functional theory (DFT) calculations using Na⁺(H₂O)₄ clusters provided molecular insights into ion interactions, while distribution of relaxation time (DRT) analysis of electrochemical impedance data revealed improved electrode kinetics. An assembled asymmetric SC delivered 205 F g^{- 1}, an energy density of 113 ± 5% W h kg^{- 1} at a power density of 1.1 ± 5% kW kg^{- 1}, and excellent cycling stability 98% retention. These results underscore the promise of 1D/2D rGO/PANI/Ce-MOF heterostructures and tailored electrolytes for high-performance, flexible energy storage in neutral conditions.