Structure and electrochemical properties of D-glucose-derived hard carbon as a negative electrode in potassium-ion batteries

Abstract

Hard carbons (HC) have been synthesized from D-glucose and pectin via a hydrothermal technique and pyrolized at 1200°C, 1400°C and 1600°C. Their structural evolution depending on the pyrolysis temperature was investigated with X-ray powder diffraction, Raman spectroscopy with additional characterization with scanning and transmission electron microscopy and gas adsorption/desorption measurements. More ordered and uniform structures were obtained at higher pyrolysis temperature. Correlations of the HC structure with the electrochemical properties as a negative electrode (anode) in potassium half-cells and interaction mechanism of K+ ions with HC were analyzed and discussed. The prevalence of pseudocapacitive contribution for K-ion interaction with HC was deduced from cyclic voltammograms. The hydrothermally pre-treated HC anodes annealed at higher temperature demonstrate less pseudocapacitive and more pronounced diffusion-controlled behavior causing a capacity decrease with increasing pyrolysis temperature from 277 mAh/g (1200°C) to 243 mAh/g (1400°C) and to 153 mAh/g (1600°C).

Keywords

• Hard carbon
• Electrode materials
• Negative electrode
• Potassium-ion batteries
• Hydrothermal synthesis
• High-temperature pyrolysis