Heteroatom-doped core/shell carbonaceous framework materials: synthesis, characterization and electrochemical properties

Abstract

Organic–inorganic hybrid core@shell nanospherical particles with a diameter of 200 nm to 600 nm were formed between cyclomatrix poly(organophosphazenes) (POPs) and zeolitic imidazolate framework-8 (ZIF-8) in a methanol solution at room temperature. This facile synthesis route produced core@shell spheres with controlled structure and properties, such as mono-dispersed particles with 50 nm to 100 nm shell thickness and a surface area of 1557 m² g⁻¹ and homogenously doped Zn and heteroatoms (N, S, P, O, Cl). The POP/ZIF-8 core@shell structures were subsequently converted into porous carbonaceous materials and investigated as anode materials in a lithium-ion coin cell battery. They showed a stable discharge capacity of 538 mA h g⁻¹ over 250 cycles, high rate capability (0.1C to 1C) and excellent capacity retention, which are promising for rapid charge–discharge applications. A higher ZIF-8 mass loading ratio in the core@shell structure increased the capacity of the electrode materials and stabilised the lithiated active materials. The facile synthesis method and the carbonaceous framework materials are applicable for high performance energy storage materials in electrochemical power devices.