Synthesis of pitch-derived carbon anodes for high-performance potassium-ion batteries

Potassium-ion batteries (PIBs) hold promise for large-scale energy storage, necessitating the development of high-performance anode materials. Carbons with the advantage of structural versatility, are recognized as the most promising anode materials for their commercialization, however the relationship between the carbon anode structure and its electrochemical performance remains unclear. A series of pitch-based soft carbons with different structures were fabricated using carbonization temperatures in the range 600–1400 °C, and their changes in carbon configuration and K-storage performance as a function of carbonization temperature were investigated. Correlations between the carbon crystal size and the low-potential plateau region capacity and between the degree of structural disorder of the carbons with their sloping region capacity were revealed. Among all samples, that obtained by carbonization at 700 °C had a relatively high degree of disorder and a large interlayer spacing, and had a high reversible capacity of 329.4 mAh g⁻¹ with a high initial coulombic efficiency of 72.81%, and maintained a high capacity of 144.2 mAh g⁻¹ at the current rate of 5 C. These findings improve our fundamental understanding of the K-storage process in carbon anodes, and thus facilitate the advance of PIBs.