Fraction-Dictated Conversion of Petroleum Asphalt into Tailored Activated Carbons for High-Performance Supercapacitors

Abstract

Direct conversion of raw petroleum asphalt into activated carbons (ACs) ignores its compositional heterogeneity and results in poor carbonization efficiency. Here we separate asphalt into saturates (SAT), asphaltenes (ASP), and an aromatics-resins blend (AR-R). SAT fully volatilizes below 400 °C and contributes no solid carbon. ASP, although accounting for only 8.9 wt % of the raw material, gives a precarbonization yield of 51.7 wt % – more than three times that of whole asphalt (16.4 wt %). The ASP-derived char is fragmented and accessible, enabling deep, uniform KOH etching. The resulting AC has a specific surface area of 2593 m2 g–1 with a hierarchical pore network. In contrast, AR-R char is dense and monolithic, restricting activator penetration and giving poorly developed porosity. The optimal ASP-based carbon delivers a competitive gravimetric capacitance of 357 F g–1, a volumetric capacitance of 180 F cm–3 in aqueous electrolyte, and an energy density of 40.18 Wh kg–1 in organic electrolyte for supercapacitors (SCs). This work demonstrates that precursor chemistry, specifically the H/C ratio and thermal stability, dictates char morphology and final carbon architecture. The component-targeted strategy identifies ASP as the active ingredient, turning a low-value byproduct into a high-performance SC electrode with clear scalability advantages over conventional one-step processing.