EFFECT OF PRE-TREATMENT CONDITIONS ON THE ELECTROCHEMICAL PERFORMANCE OF BIO-WASTE DERIVED CARBON

Abstract

Energy companies like CATL, SVOLT, Tiamat, and Natron are actively working on commercializing Sodium-ion Batteries. These batteries offer advantages over Lithium-ion batteries, due to even sodium distribution, relatively inexpensive electrode materials, and safer transportation. The synthesis of Hard-Carbons as anode material is a promising avenue for developing high-capacity Sodium-ion Batteries, given their low insertion voltage and wide interlayer spacing, which enhances sodium-ion insertion. While traditionally these Hard-Carbons are derived from costly carbonaceous materials, the use of abundantly available carbonaceous bio-waste like coffee-waste as Hard-Carbon precursors would not only lower production costs but also contribute to global waste management and disposal. However, the electrochemical performance of bio-waste-derived Hard-Carbon is significantly affected by pre-treatment conditions, both before and after thermal treatment. This research employed characterization techniques like XRD, TEM, and SEM to investigate the impact of pre-treatment conditions, such as washing with various solvents (organic solvent, acid, or distilled water), pre-oxidation and pre-pyrolysis on the coffee-waste-derived hard carbon structure and purity, which consequently influence the electrochemical capacity of the synthesized negative electrode for Sodium-ion Batteries. A 23% yield mesoporous hard-carbon synthesized from washing coffee grounds with de-ionized water and pre-oxidation at 150℃ before thermal treatment at 1300℃ using 5℃/min ramping rate in an argon environment demonstrated an excellent deliverable capacity of 304mAhg-1 and an Initial Coulombic Efficiency of 78%. This study highlights how the washing solvent and pre-oxidation improved the electrochemical performance due to the presence of inorganic impurities and expansion of the graphite inter-layer distance which improves the carbon-oxygen composition, electronic conductivity and sodium insertion of the electrode.