Synthesis of lignite-derived carbon materials for fast sodium-ion storage in a wide temperature range by ultrafast Joule heating

The advancement of sodium-ion batteries is hindered by the imperative to reconcile extreme environmental conditions and high-rate demands, posing challenges in the synthesis of cost-effective and high-performance anode materials. Among the potential candidates, lignite-based soft carbon materials stand out due to their abundant resources and low cost. An ultrafast approach using high-temperature thermal shock pulses is reported for the synthesis of soft carbon anode from lignite, and the mechanism of “adsorption-intercalation-pore filling” is proposed. Based on structure analysis, in/ex-situ electrochemically characterization, and calculation/simulation, high concentration of defects and C=O contents, along with abundant closed pore structures, contribute to enhancing the sodium storage capabilities of the material. The optimized sample demonstrates a substantial reversible capacity of 300.6 mAh g⁻¹ at 0.1C and outstanding high-rate capability at 10.0C, which also maintains proper functionality in a wide temperature range (−40∼80 ​°C). This performance surpasses that of previously reported lignite-based soft carbon materials. Additionally, the assembled full-cell maintains a high-energy density of 235.8 ​Wh kg⁻¹. This work provides valuable insights into developing anode materials for coal-based SIBs at high-rate current densities in a wide range of temperatures.