A Low-Processing Graphite–Paraffin Biocomposite with Torrefied Cagaita Biomass for Enhanced Charge Storage

Abstract A sustainable graphite–paraffin biocomposite was developed by directly incorporating torrefied cagaita (Eugenia dysenterica DC) pulp biomass (TBCP) into the composite matrix. The biomass was mildly treated at 250 °C for 1 h in air, without chemical activation or inert-atmosphere carbonization. Electrodes containing 0–15 wt.% TBCP were evaluated in 1.0 mol L⁻¹ NaOH, with the highest response obtained at 5 wt.% TBCP (≈13 mF cm⁻²), indicating an optimum balance between the biomass-derived contribution and preservation of the conductive graphite network. Trasatti analysis showed that TBCP increased the total accessible capacitance from 0.219 to 25.68 mF cm⁻² and the apparent electrochemical porosity from 18.6 to 91.4%. Chronoamperometric analysis further showed an increase in total apparent areal capacitance from 0.113 to 19.37 mF cm⁻², while the characteristic time of the dominant slow relaxation process decreased from 3.958 to 1.744 s. Galvanostatic measurements yielded 21.05 mF cm⁻² at 1.0 × 10⁻⁴ A. These results demonstrate that a small amount of minimally processed lignocellulosic biomass can effectively enhance charge storage in graphite-based composites, providing a simple and sustainable route to improved electrochemical performance.