Multi-heteroatom-doped hollow carbon nanocages from ZIF-8@CTP nanocomposites as high-performance anodes for sodium-ion batteries

Carbon-based material is one of the most promising candidates of anode materials for sodium-ion batteries (SIBs). However, the poor rate performance and low capacity due to intrinsic nature greatly impact their practical application. Heteroatom-doped carbon material is an efficient method to optimize the electrochemical performance of anode electrodes for SIBs. Herein, we report a template-initiated strategy to fabricate nitrogen, phosphorus, fluorine co-doped hollow carbon nanocages (NPF–HCN) derived from a rationally designed zeolitic imidazolate framework-8@covalent triazine polymer core-shell structured nanocomposites (ZIF-8@CTP). High proportions of tailored multi-heteroatom species within the CTP network contribute to the in-situ generation of N, P, F-doping in the resultant hollow carbon nanocages. Additionally, the hierarchical porous and hollow nanostructures of the NPF-HCN can promote the penetration of electrolytes, thus reduce diffusion barrier of Na⁺. As anode materials of SIBs, the as-prepared NPF-HCN delivers a higher initial capacity of 569.6 mA h/g at 1 A/g and a superior cycling behavior with a high capacity of 220.3 mA h/g at 5 A/g after 5000 cycles.