Work

Spent battery graphite in biochar waste composites for supercapacitive electrodes

Year: 2026

Type: article

Abstract: According to the waste management concept, the biomass and spent Li-ion batteries have been valorized to synthesize sustainable supercapacitor electrodes. The peanut shell-derived biochar, along with recovered spent graphite (RSG) from battery waste, upon chemical activation with KOH, yielded a microporous, high-surface-area composite (AC/RSG) with efficient charge transport. It reveals a specific capacitance of 376 F/g at 10 mV/s (and 197 F/g at 0.4 A/g) in a three-electrode cell set-up using 1 M KOH electrolyte. The reference samples are porous activated carbon (AC) and another composite containing few-layer graphene (FLG) from commercial expanded graphite. The addition of RSG and FLG to activated carbon increases capacitance by approximately 70% and 50%, with significant stability at extreme conditions (high current density and potential sweep rate), thus maintaining the energy density with power density increase. The capacitance retention increases from 48% (and 49%) for porous carbon to 89% (and 83%) and 81% (and 78%) for AC/RSG (and AC/FLG) composites, at 17.7 A/g (and 200 mV/s). The structural features of the three materials, particularly of the composites, impacting the storage behavior, are investigated with help of auxiliary samples (KOH-activated RSG and FLG). The cyclic stability test for the best-performing composite (AC/RSG) revealed 94% capacitance retention and 99.6% Coulombic efficiency over 5000 cycles at 4.4 A/g. Beside enhanced conductivity, the electrochemical analysis revealed a significant benefic impact of diffusion and charge transfer in the composites. Additionally, conductive carbon black (CB) additive is successfully replaced by RSG. This study paves the way for improving the electrochemical performance of traditional biomass-derived activated carbons by the incorporation of graphite waste.

Source: Materials Today Sustainability

DOI: 10.1016/j.mtsust.2026.101425

Authors: Akshita Singh, Vimal Chandra Srivastava, Izabela Janowska

Institutions: Centre National de la Recherche Scientifique, Indian Institute of Technology Roorkee, Institut de Chimie et Procédés pour l'Energie, l'Environnement et la Santé, Université de Strasbourg

Language: English

Topic: Supercapacitor Materials and Fabrication

Subfield: Electronic, Optical and Magnetic Materials

Field: Materials Science

Domain: Physical Sciences

SDGs: Affordable and clean energy, Responsible consumption and production

Open Access status: gold

Estimated APC paid: $2,530