High energy Li-ion capacitor and battery using graphitic carbon spheres as an insertion host from cooking oil

Abstract

We report a facile low-temperature synthesis of graphitic carbons with a spherically shaped morphology (CO-CS) and high purity by the modified catalytic chemical vapour deposition using vegetable cooking oil as a carbon source. The excellent Li-insertion properties are noted with high reversibility (∼369 mA h g⁻¹) in the half-cell assembly, which is very close to the theoretical capacity of graphite. Further explored the suitability to be used as an anode in the practical configurations, the intercalation type LiFePO₄ and double layer forming activated carbon (AC) have been used as the cathodes toward the fabrication of Li-ion battery (LIB) and Li-ion capacitor (LIC), respectively. Prior to the LIC assembly, CO-CS has been pre-lithiated electrochemically. Both LiFePO₄/CO-CS and AC/CO-CS assemblies display a maximum energy density of ∼337 and ∼108 W h kg⁻¹ (based on an active material loading), respectively. The obtained values are better than those of the state-of-the-art LIB and LIC based on a graphitic anode. A decent cycle-ability is also registered for both cases.