Anthracite coal from Vang Danh – Quang Ninh as anode material for rechargeable Li-ion batteries

Abstract

This study investigated the structure of anthracite material (ATC) exploited from the Vang Danh mine (Quang Ninh) and its application as an anode for rechargeable Li-ion batteries. After the chemical treatment, the material was heated at 800 oC, 1000 oC, or 1200 oC for 2 hours, 3 hours, or 4 hours, respectively. Scanning electron microscopy (SEM) confirms that the raw material was polyhedral and sharp particles. The impurities in raw material, especially the metal compounds, was significantly reduced after the chemical-treated process. As a result, the carbon content increased from 78.91% in raw material to 86.94% in the chemical-treated sample. Regarding the structure, the Raman spectra showed that the AD/AG ratio decreased with increasing temperature and heating time. This confirmed that the more disordered structures were obtained at low temperatures and heating times. In addition, the interlayer spacing (d002) between the aromatic layers in the crystalline regions varied from 0.35 to 0.36 nm, while the lateral sizes (La) were 3.0-4.1 nm, and the stacking heights (Lc) were 1.4-2.0 nm. The ATC materials can serve as anode for rechargeable Li-ion batteries with high Coulombic efficiency (nearly 100%) and impressing capacity retention (nearly 100% after 40 cycles). Among the investigated samples, ATC 8002 delivers the highest capacity of 286.3 mAh/g with a high capacity retention of 88.5% after 40 cycles.