Spent battery graphite in biochar waste composites for supercapacitive electrodes
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-surfacearea 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.
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BibTeX
@article{singh2026spent,
title = {{Spent battery graphite in biochar waste composites for supercapacitive electrodes}},
author = {Akshita Singh and Vimal Chandra Srivastava and Izabela Janowska},
journal = {Materials Today Sustainability},
year = {2026},
month = jul,
doi = {10.1016/j.mtsust.2026.101425},
url = {https://hal.science/hal-05773536v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Spent battery graphite in biochar waste composites for supercapacitive electrodes
AU - Akshita Singh
AU - Vimal Chandra Srivastava
AU - Izabela Janowska
PY - 2026
DA - 2026/07/27
JO - Materials Today Sustainability
DO - 10.1016/j.mtsust.2026.101425
UR - https://hal.science/hal-05773536v1
AB - 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-surfacearea 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.
SN - 2589-2347
ER -