Enhanced Discharge Capacity of Boron-Doped Hard Carbon Anodes for Sodium-Ion Batteries

In this study, boron-doped hard carbon was synthesized and utilized as an anode material to improve the performance of sodium-ion batteries. The synthesized boron-doped hard carbon showed an optimized structure for sodium ion storage because boron atoms were successfully substituted into the carbon lattice. Specifically, the interlayer spacing was expanded to 0.40 nm, which facilitated the movement of sodium ions. Additionally, structural defects formed during the synthesis provided more active sites, making it suitable for high-capacity sodium storage. Through half-cell tests, the boron-doped hard carbon achieved a high discharge capacity of 364.80 mAh/g (an 11 % increase compared to pristine hard carbon) and maintained stable cycling performance over 100 cycles at 0.1 C. Additionally, rate capability tests (0.1 C to 5.0 C) revealed that the boron-doped hard carbon exhibited higher discharge capacities than the pristine hard carbon across all tested C-rates. These results confirm that the boron-doped hard carbon was successfully synthesized and is expected to contribute to enhancing the performance of sodium-ion batteries.