Tuning the structure of in-situ synthesized few layer graphene/carbon composites into nanoporous vertically aligned graphene electrodes with high volumetric capacitance

TL;DR

This paper reports on the synthesis and optimization of few layer graphene/carbon composites with nanoporous structures, achieving high volumetric capacitance for energy storage applications through parameter tuning and structural control.

Contribution

It introduces a rapid, simple method to produce optimized FLG/C composites with high capacitance and stability, emphasizing the role of morphology and porosity in performance enhancement.

Findings

Highest volumetric capacitance of 467 F/cm3 achieved

Composites exhibit high capacity retention at high current densities

Structural features like nanoporosity and FLG alignment enhance performance

Abstract

Few layer graphene/carbon (FLG/C) composites are prepared directly via the rapid and simple exfoliation of expanded graphite in the presence of carbon based natural precursors (i.e. protein, polysaccharide) in water, followed by carbonization process. Several parameters such as nature of C-precursor, FLG/C ratio and carbonization conditions (gas, temperature) are modified in order to optimize the morphology, composition and porosity of FLG/C and thereby investigate their impact on gravimetric and volumetric capacitance, their stability and contribution of pseudocapacitance (Ps) vs. double-layer capacitance (DL). Few composites exhibit extremely high capacitance considering their low BET-surface area ranging in 130-260 m2/g. The highest gravimetric and volumetric capacitance of 322 F/g and 467 F/cm3 respectively (0.5 A/g); and energy/power performance is reached for FLG/C:1/2, synthesized from graphite-bovine serum albumin(BSA). Despite relatively high theoretical pseudocapacitance contribution of 69% (1.1V), this sample shows also high capacity retention at high current density and elevated energy-to-power densities. The overall great capacity performance is attributed to the high electrochemical surface area from combined structural features: nanoporosity, FLG alignment with high accessibility of FLG edges and elevated packing density.