Hardcarbon Synthesis From Nipah Palm (

Lithium-ion batteries are among the most widely used energy storage systems. The negative electrode (anode) material plays a crucial role in determining their electrochemical performance. However, graphite anodes face several drawbacks, including high cost. Hard carbon has emerged as a promising alternative due to its high storage capacity and cycling stability. This study aims to synthesize and characterize hard carbon derived from nipah palm shell waste as a sustainable anode material. Nipah biomass was selected as the precursor because of its high cellulose (36.5%) and lignin (27.3%) content, which are essential for forming a robust hard carbon structure. The conversion process was carried out through a one-stage pyrolysis method consisting of three steps: pre-treatment, pyrolysis, and activation. The nipah shells were washed, dried, and pyrolyzed at 800 °C under a nitrogen atmosphere. The resulting hard carbon was activated using acidic and basic solutions (HCl, KOH, and NaOH), rinsed with deionized water until neutral pH, and subsequently dried. SEM–EDX analysis revealed that HCl activation produced a morphology most like commercial hard carbon. XRD analysis showed a strong peak near 2θ = 23° and a weaker peak at 2θ = 41°. FTIR spectra confirmed the presence of oxygen-containing functional groups (C–O and C=O), with absorption peaks around 1050 cm⁻1 (C–O stretching) and 1600 cm⁻1 (C=C/C=O stretching), typical of biomass-derived hard carbon. The HCl-activated sample exhibited weaker oxygen-related bands compared to NaOH- and KOH-activated samples, indicating a cleaner carbon surface and supporting its closer similarity to commercial hard carbon. Electrochemical evaluation demonstrated that HCl-activated hard carbon delivered a specific capacity of ~28 mAh g⁻1 at 0.5C, maintained stable capacity up to 3C, and achieved 78.79% retention after 20 cycles. These findings confirm the successful conversion of nipah palm shell waste into hard carbon and highlight its potential as a sustainable anode material for lithium-ion batteries.