A robust in-situ catalytic graphitization combined with salt-template strategy towards fast lithium-ions storage

Lithium-ion hybrid supercapacitors (LIHSs) have received significant attention in electrochemical energy-related areas. However, the sluggish anode kinetics hinders the improvement of power density and cycling stability. Herein, an in-situ catalytic graphitization with a salt-template strategy was applied to prepare the porous graphitic carbon nanosheets. The results demonstrated that the addition of KCl led to a higher specific surface area and higher porous structure. The as-prepared potassium-induced porous graphitic carbon flakes (PPGCs) exhibited an electrochemical plateau capacity of 240.1 mAh g−1 and an electrochemical slope capacity of 129.0 mAh g−1. PPGCs also delivered superior rate performance of 60.8 mAh g−1 even at 5.0 A g−1, which was much better than graphitic carbon flakes (GCFs) and potassium-induced graphitic carbon flakes (PGCFs). When assembled into LIHSs devices with commercial activated carbon, the energy density reached 75.6 Wh kg−1, and the power density was as high as 5.05 kW kg−1. After 10,000 cycles at 5.0 A g−1, the energy density was maintained at 39.2 Wh kg−1, revealing excellent long-term cycling performance. This work may provide a promising solution to obtain graphitic carbon with a high graphitization degree and highly porous structure.