@article{Xu2025, 
author = {Xinyue Xu and Guodong Li and Hao Zhang and Nan Wang and Tinghang Xu and Hui Yang and Jie Xu and Baofeng Wang and Junxi Zhang and Zhaolu Liu and Yongjie Cao},
title = {A new iron-based sulfate cathode material for high-performance potassium-ion battery},
year = {2025},
journal = {Nano Research},
volume = {18},
number = {11},
pages = {94908121},
keywords = {energy storage, potassium-ion batteries, polyanion-type cathode materials, iron-based sulfate, high working potential},
url = {https://www.sciopen.com/article/10.26599/NR.2025.94908121},
doi = {10.26599/NR.2025.94908121},
abstract = {Iron-based sulfates have emerged as promising cathode materials for potassium-ion batteries due to their low cost, high working potential, and environmentally friendly. However, the relatively large ionic radius and sluggish diffusion coefficient of K-ion pose significant challenges to the electrochemical performance and structural stability of cathode materials in potassium-ion batteries (PIBs). In this work, we successfully synthesis a new iron-based sulfate cathode material, potassium sodium iron sulfate (K1.66Na1.02Fe1.66(SO4)3, KNFS), through an electrochemical ion exchange method. As a cathode material, it exhibits a reversible specific capacity of 83 mAh·g−1 and an average working potential of 3.84 V (vs. K/K+) at 0.1 C in PIBs. Even at 2 C, it still demonstrates a reversible specific capacity of 52 mAh·g−1 with a capacity retention ratio of 88.2% after 300 cycles. The in-situ X-ray diffraction (XRD) and ex-situ X-ray absorption spectroscopy reveal that the K-ion storage mechanism in KNFS is predominantly governed by the reversible Fe3+/Fe2+ redox couple, which provides a theoretical specific capacity of 94 mAh·g−1 and involves minimal volume change (2.57%). The first-principles calculations combined with XRD results indicate that the KNFS cathode exhibits a typical alluaudite-type crystal structure with multiple fast K-ion migration channels along the three-dimensional orientation.}
}