Low-Cost Pitch Derived Lamellar N-Doped Carbon as a High-Performance Potassium-Ion Battery Anode

Carbon anode materials play a significant role in high-performance potassium ion batteries owing to their low price, rich resources, and high conductivity. However, they suffer from small interlayer spacing obstructing electrochemical performance due to a larger K-ion radius. In this work, lamellar N-doped carbon (LNC) with porous structure was fabricated by facile heat treatment from mid temperature pitch. The pitch was carbonized under 800 °C (LNC-800), which possesses an expanded interlayer distance of 0.400 nm and more mesoporous structure (compared with LNC-1000 and LNC-1200). Benefiting from its appropriate structure, LNC exhibits a high initial discharge capacity of 557.3 mA h g–1 at 50 mA g–1 in potassium-ion half cells. Furthermore, it delivered 218 mA h g–1 after 150 cycles at 100 mA g–1 and 71.2% of capacity retention rate, indicating its excellent electrochemical stability. LNC-800 exhibits a discharge capacity of 180 mA h g–1 higher than LNC-1000 and LNC-1200 at 1A g–1. DFT calculations proved that potassium ions were more easily diffused in graphite with large interlayer spacing. The carbon prepared in this study could be used in potassium ion batteries to promote the development of the energy industry.