Pyrolyzed Hydrogenated Anthracite as Anode Materials for Sodium-ion Batteries

Anthracite has a great application potential in energy storage because of its low cost, but the reversible capacity of raw anthracite as an anode material for the sodium-ion battery is rather low. In this paper, anthracite was pyrolyzed at different temperatures. The results show that the reversible capacity of anthracite pyrolyzed at 1300 ℃ (A-1300) is 307 mA·h/g at 20 mA/g, which is the maximum value among the pyrolyzed anthracites. However, the reversible capacity of A-1300 at 500 mA/g is only 105 mA·h/g, exhibiting an inferior rate performance. The two-step strategy via hydrogenation and pyrolysis can decrease the pyrolyzed temperature and improve the rate performance. Hydrogenated anthracite turns into an easy-graphitized precursor. The reversible capacity of hydrogenated anthracite pyrolyzed at 900 ℃ (H300-3-900) can retain 113 mA·h/g at 500 mA/g after 500 cycles, exhibiting a superior rate performance and an easier commercial production at a lower temperature.