Boosting the sodium storage performance of coal-based carbon materials through structure modification by solvent extraction

High-performance carbon anodes for sodium-ion batteries (SIBs) were synthesized with bituminous coal as precursor through solvent extraction and carbonization. The solvent extraction endows the coal-based carbon a hierarchical pore structure and enlarged interlayer distance, which can shorten the charge diffusion distance, alleviate the volume variation, and improve the ion diffusion rate. As a result, the modified coal-based electrodes exhibit impressive cycling stability (92% capacity retention after 7000th cycle at 2 A g−1) and excellent rate capability (79 mA h g−1 at 10 A g−1).