Study on Preparation of All Lignin Derived Hard Carbon Electrode and Its Sodium Storage Performance
Sodium-ion capacitors have become a new generation of energy storage devices by combining the high energy density of battery-type anode and the high power density of capacitive cathode.Hard carbon materials as battery-type anodes are currently a research hotspot.In this study,lignin-derived hard carbon materials were prepared by lignin purification,pre-carbonization and high-temperature pyrolysis car-bonization using black liquor from pulping process as raw material.The variation of graphite layer spacing and crystallite structure with car-bonization temperature was analyzed.The electrochemical properties and sodium storage mechanism of lignin-derived hard carbon electrodes were studied.The results showed that with the increase of pyrolysis temperature from 800℃to 1600℃,the graphite layer spacing of hard carbon materials decreased from 0.406 nm to 0.378 nm,and the proportion of pseudo-graphite area increased from 52.69%to 77.60%.There-fore,more Na+is intercalated and deintercalated between the graphite layers during the charge and discharge process of the hard carbon elec-trode.The plateau capacity of the electrode increased from 56.8 mAh/g to 236.0 mAh/g and reversible capacity up to 333.7 mAh/g because of the significant increase in platform capacity.According to the Galvanostatic Intermittent Titration Technique(GITT)analysis,the storage mechanism of sodium ions in the lignin-derived hard carbon electrode conformed to the"Adsorption-Intercalation/Filling"hybrid model.
ligninhard carbondegree of graphitizationplateau capacitysodium-ion capacitor
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