Activated porous carbons derived from the Indonesian snake fruit peel as anode materials for sodium ion batteries

In this present work, activated porous carbons (APCs) are derived from the Indonesian snake fruit peel using a pre-carbonization and followed by KOH-chemical activation at 800 degrees C. The as-obtained carbons are then characterized by scanning electron microscope (SEM), nitrogen adsorption-desorption, x-ray diffraction (XRD) and Raman spectroscopy. It is found that snake fruit derived APCs possessed disordered micro-structures, continuous distribution between micropore/mesopore structures and large interlayer spacing. The APCs are then tested as anode materials for sodium ion battery in half-cell configuration with sodium metal as counter/reference electrode. The electrochemical characteristics are investigated by cyclic voltammetry (CV), galvanostatic charge discharge and electrochemical impedance spectroscopy. Measured at the voltage range between 0.01 and 2.0 V, the best performance of APC samples can maintain a specific discharge capacity of 255 mAh g(-1) until the 100 cycles under current density 0.1 A g(-1). Furthermore, when the current density increases to 2 and 5 A g(-1), the carbon anodes exhibit a high specific discharge capacity of 116 and 90 mAh g(-1). Using the impedance spectroscopy, the sodium ion diffusion coefficient may be estimated to be 1.86 x 10(-11) cm(2) s(-1). Based on those results, it can be said that snake fruit peel is a promising and low cost precursor for carbon anodes in sodium ion batteries.