Nanoflower porous carbon derived from bio-oils with enhanced supercapacitors by thermoplastic temperature control

The utilization of biomass resources in the development of carbon-based supercapacitor electrode materials shows considerable promise as an effective energy storage system. In this regard, the elevated carbon content and favorable thermoplasticity of bio-oils facilitate its utilization as a precursor for the manufacture of carbon electrode materials for supercapacitors. Herein, a flower-like hierarchical porous carbon was prepared via the chemical carbonization activation of heavy bio-oils derived from rice husk along with alkali magnesium carbonate (Mg(OH)₂•4MgCO₃•xH₂O), and potassium oxalate (K₂C₂O₄) as a hard template and chemical activator, respectively. The temperature-controlled synthesis of flower-like carbon materials (RK₁M₃C-800) with a maximum specific surface area of 1806.87 m² g⁻¹ was achieved with suitable additive ratios. When employed as a supercapacitor electrode, the RK₁M₃C-800 sample exhibited a specific capacitance of 248 F g⁻¹ in a three-electrode system (measured at 0.5 A g⁻¹). Further application to symmetric capacitors demonstrated a high energy density of 8.75 Wh kg⁻¹ in 6 M KOH electrolyte, corresponding to a power density of 142.33 W kg⁻¹. Additionally, excellent cycling stability was observed in 0.5 M Na₂SO₄ electrolyte. This research contributes to the development of a theoretical framework for the high-value utilization of heavy bio-oils, and represents a crucial step in the advancement of green energy storage technologies.