Abstract <p>Graphene has emerged as a critical electronic material for next-generation supercapacitors, yet scalable synthesis routes that balance performance, reproducibility, and sustainability remain underexplored. In this study, six synthesis methods—electrochemical exfoliation, plasma-assisted treatment, arc discharge, thermal shock, liquid-phase exfoliation, and flame oxidation—were systematically benchmarked under unified fabrication and testing protocols. Electrochemically exfoliated graphene achieved the highest capacitance (~430&#xa0;F&#xa0;g⁻¹ at 1&#xa0;A&#xa0;g⁻¹) with &gt; 95% retention after 10,000 cycles, owing to a wrinkled nanosheet morphology and controlled defect density. Plasma-assisted functionalization further reduced charge-transfer resistance (~1.5&#xa0;Ω) and enhanced high-rate capability, enabling device-level energy and power densities of 40&#xa0;Wh&#xa0;kg⁻¹ and 8.2&#xa0;kW&#xa0;kg⁻¹, respectively. Raman spectroscopy, scanning electron microscopy (SEM), and impedance spectroscopy confirmed structure–performance correlations, while multiscale modeling including density functional theory (DFT), finite element analysis (FEA), and molecular dynamics (MD) provided mechanistic insights into ion transport and defect engineering. Comparative sustainability analysis identified electrochemical and plasma-assisted methods as the most viable for industrial adoption, offering low energy demand and minimal environmental impact. These findings establish graphene synthesized via eco-aligned, scalable routes as a competitive electronic material platform for supercapacitors, bridging laboratory performance with device-level integration.</p> Graphical Abstract <p></p>