Petroleum pitch derived hard carbon via NaCl-template as anode materials with high rate performance for sodium ion battery

Sodium-ion batteries (SIBs) have garnered significant interest in energy storage due to their similar working mechanism to lithium ion batteries and abundant reserves of sodium resource. Exploring facile synthesis of a carbon-based anode materials with capable electrochemical performance is key to promoting the practical application of SIBs. In this work, a combination of petroleum pitch and recyclable sodium chloride is selected as the carbon source and template to obtain hard carbon (HC) anode for SIBs. Carbonization times and temperatures are optimized by assessing the sodium ion storage behavior of different HC materials. The optimized HC exhibits a remarkable capacity of over 430 mA·hg⁻¹ after undergoing full activation through 500 cycles at a density of current of 0.1 A·g⁻¹. Furthermore, it demonstrates an initial discharge capacity of 276 mAh·g⁻¹ at a density of current of 0.5 A·g⁻¹. Meanwhile, the optimized HC shows a good capacity retention (170 mAh·g⁻¹ after 750 cycles) and a remarkable rate ability (166 mAh·g⁻¹ at 2 A·g⁻¹). The enhanced capacity is attributed to the suitable degree of graphitization and surface area, which improve the sodium ion transport and storage.