FeSb@N-doped carbon quantum dots anchored in 3D porous N-doped carbon with pseudocapacitance effect enabling fast and ultrastable potassium storage

Potassium-ion batteries (PIBs) are promising next-generation energy storage candidates due to abundant resources and low cost. Sb-based materials with high theoretical capacity (660 mAh center dot g(-1)) and low working potential are considered as promising anode for PIBs. The remaining challenge is poor stability and slow kinetics. In this work, FeSb@N-doped carbon quantum dots anchored in three-dimensional (3D) porous N-doped carbon (FeSb@C/N subset of 3DC/N), a Sb-based material with a particular structure, is designed and constructed by a green salt-template method. As an anode for PIBs, it exhibits extraordinarily high-rate and long-cycle stability (a capacity of 245 mAh center dot g(-1) at 3,080 mA center dot g(-1) after 1,000 cycles). The pseudocapacitance contribution (83%) is demonstrated as the origin of high-rate performance of the FeSb@C/N subset of 3DC/N electrode. Furthermore, the potassium storage mechanism in the electrode is systematically investigated through ex-situ characterization techniques including ex-situ transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Overall, this study could provide a useful guidance for future design of high-performance electrode materials for PIBs.

Automated summary

The study designed and constructed a Sb-based material FeSb@C/N subset of 3DC/N, which showed high-rate and long-cycle stability as an anode for potassium-ion batteries. The research revealed that the high-rate performance of the FeSb@C/N subset of 3DC/N electrode originated from pseudocapacitance contribution.