Development of Vang Danh anthracite as a cost-effective anode for sodium-ion batteries through a heat-treatment process

This study focuses on the effects of the chemical process and heating time at 900 °C on pristine anthracite coal (provided by Vang Danh coal, Quang Ninh province, Vietnam) and explores its structure and electrochemical performance when used as an anode in Na-ion batteries. After chemical treatment with NaOH and H2SO4, the impurity content in the raw material decreased significantly (e.g., ash content dropped from 4.4% to 0.9%, etc.). The interspacing between the graphene layers in the anthracite structure also increased after the heat treatment. Besides, on extending the heating time, the anthracite structure became more disordered than the samples heated for shorter times. Therefore, the intercalation ability of Na+ ions in the anthracite structure increased, and the sample heated at 900 °C for 6 hours exhibited the highest reversible capacity of up to 160 mA h g-1 with adequate capacity retention after 100 cycles at C/10 rate.