Edge defect protection of graphitic carbon nanocages for stable potassium storage at low voltage

Graphitic nanocarbon possesses fast potassium storage capability at low voltage. However, a significant abundance of exposed edge surfaces and defects of graphitic nanocarbon would lead to a substantial number of irreversible reactions, thereby reducing the cyclic stability. Here, the edge defects of graphitic carbon nanocages (GCC) were protected by pitch-based disordered carbon shell to enhance the long-term cyclic stability. The mixture of GCC and pitch was compressed to ensure the full contact of the two components followed by carbonization at 1100 °C. The composite structure can protect the edge and defect of GCC to reduce the irreversible reactions. Moreover, the developed three-dimensional network can form interconnected paths to enhance the electron transfer. Benefiting from this structure, the composite anode achieves high reversible capacity below 1 V (214.1 mAh g−1 at 0.1 C) and high-rate (138.9 mAh g−1 at 1 C). Additionally, the composite anode exhibits higher cyclic stability (96.2% capacity retention from the first to the 80th cycle) than that of GCC (29.8%). This work presents a rational strategy to achieve the edge defect protection of graphitic nanocarbon, thereby facilitate the application of graphitic nanocarbon materials in potassium-ion batteries.