Wu Hu, Lu Shiyao, Xu Siyuan, Zhao Jing, Wang Yuankun, Huang Chang, Abdelkader Amr, Wang Wei Alex, Xi Kai, Guo Yuzheng, Ding Shujiang, Gao Guoxin, Kumar Ramachandran Vasant
Xi'an Key Laboratory of Sustainable Energy Materials Chemistry, School of Chemistry, Xi'an Jiaotong University & Shaanxi Quantong Joint Research Institute of New Energy Vehicles Power, Xi'an Jiaotong University, Xi'an 710049, China.
Department of Chemistry, City University of Hong Kong, Hong Kong 999077, China.
ACS Nano. 2021 Feb 23;15(2):2506-2519. doi: 10.1021/acsnano.0c06667. Epub 2021 Jan 19.
Chalcogenide-based anodes are receiving increasing attention for rechargeable potassium-ion batteries (PIBs) due to their high theoretical capacities. However, they usually exhibit poor electrochemical performance due to poor structural stability, low conductivity, and severe electrolyte decomposition on the reactive surface. Herein, a method analogous to "blowing bubbles with gum" is used to confine FeS and FeSe in N-doped carbon for PIB anodes with ultrahigh cyclic stability and enhanced rate capability (over 5000 cycles at 2 A g). Several theoretical and experimental methods are employed to understand the electrodes' performance. The density functional theory calculations showed high affinity for potassium adsorption on the FeS and FeSe. The XRD and TEM analysis confirmed the formation of several intermediate phases of the general formula KFeS. These phases have high conductivity and large interlayer distance, which promote reversible potassium insertion and facilitate the charge transfer. Also, the calculated potassium diffusion coefficient during charge/discharge further proves the enhanced kinetics. Furthermore, The FeS@NC anode in a full cell also exhibits high cyclic stability (88% capacity retention after 120 cycles with 99.9% Coulombic efficiency). Therefore, this work provides not only an approach to overcome several challenges in PIB anodes but also a comprehensive understanding of the mechanism and kinetics of the potassium interaction with chalcogenides.
基于硫族化物的负极由于其高理论容量而在可充电钾离子电池（PIB）中受到越来越多的关注。然而，由于结构稳定性差、导电性低以及活性表面上严重的电解质分解，它们通常表现出较差的电化学性能。在此，一种类似于“用口香糖吹泡泡”的方法被用于将FeS和FeSe限制在氮掺杂碳中，用于具有超高循环稳定性和增强倍率性能的PIB负极（在2 A g下超过5000次循环）。采用了几种理论和实验方法来理解电极的性能。密度泛函理论计算表明钾在FeS和FeSe上具有高吸附亲和力。XRD和TEM分析证实了通式为KFeS的几种中间相的形成。这些相具有高导电性和大的层间距，这促进了钾的可逆嵌入并有利于电荷转移。此外，计算得到的充放电过程中的钾扩散系数进一步证明了动力学的增强。此外，全电池中的FeS@NC负极也表现出高循环稳定性（120次循环后容量保持率为88%，库仑效率为99.9%）。因此，这项工作不仅提供了一种克服PIB负极中几个挑战的方法，而且还提供了对钾与硫族化物相互作用的机理和动力学的全面理解。
