Rational design of microstructure and interphase enables high-capacity and long-life carbon anodes for potassium ion batteries

Disordered carbon is considered as a potential anode material for potassium ion batteries (PIBs) due to its advantages in rate capability compared to graphite. Nevertheless, its capacity is usually limited below 300 mAh g⁻¹. Herein, we demonstrate the performance of low-cost pitch derived carbon could be significantly boosted through synergistic microstructure design and electrode/electrolyte interphase regulation. A considerable amount of mesopore is produced to provide the extra active sites for K ion storage and meanwhile, facilitate the charge transfer. The optimized carbon anode delivers a remarkable capacity of 460 mAh g⁻¹ with outstanding rate capability up to 4.0 A g⁻¹. In-situ Raman spectra reveal the superb performance originates from K ion storage in both the mesopore and disordered graphene layers. The construction of a robust solid electrolyte interphase in ethylene glycol diethyl ether derived electrolyte further improves the long-term stability, leading to an exceptional capacity retention of 80% after 2000 cycles under a current density of 1.0 A g⁻¹. This strategy provides a facile approach to enhance the performance of carbon materials for PIBs via structure and interphase design.