Journal of Energy Chemistry

Journal of Energy Chemistry ›› 2023, Vol. 79 ›› Issue (4): 45-53.DOI: 10.1016/j.jechem.2022.11.060

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Deciphering the potassium storage phase conversion mechanism of phosphorus by combined solid-state NMR spectroscopy and density functional theory calculations

Huixin Chena,b,d, Lingyi Mengb,d, Hongjun Yueb,d, Chengxin Pengf, Qiaobao Zhange,*, Guiming Zhongb,c,d,*, Ding Chena,*   

  1. aState Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, College of Mechanical and Vehicle Engineering, Hunan University, Changsha 410082, Hunan, China;
    bCAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, Fujian, China;
    cLaboratory of Advanced Spectro-electrochemistry and Li-ion Batteries, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China;
    dXiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, Fujian, China;
    eDepartment of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005, Fujian, China;
    fSchool of Materials Science and Chemistry, University of Shanghai for Science and Technology, Shanghai 200093, China
  • Received:2022-11-08 Revised:2022-11-30 Accepted:2022-11-30 Online:2023-04-15 Published:2023-05-30
  • Contact: * E-mail addresses: zhangqiaobao@xmu.edu.cn (Q. Zhang), gmzhong@dicp.ac.cn (G. Zhong), chending@hnu.edu.cn (D. Chen).

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Abstract: Phosphorus is the potential anode material for emerging potassium-ion batteries (PIBs) owing to the highest specific capacity and relatively low operation plateau. However, the reversible delivered capac-ities of phosphorus-based anodes, in reality, are far from the theoretical capacity corresponding to the formation of K3P alloy. And, their underlying potassium storage mechanisms remain poorly understood. To address this issue, for the first time, we perform high-resolution solid-state 31P NMR combined with XRD measurements, and density functional theory calculations to yield a systemic quantitative under-standing of (de)potassiation reaction mechanism of phosphorus anode. We explicitly reveal a previously unknown asymmetrical nanocrystalline-to-amorphous transition process via rP↔(K3P11, K3P7, beta-K4P6)↔(alpha-K4P6)↔(K1—xP, KP, K4—xP3, K1+xP)↔(amorphous K4P3, amorphous K3P) that are proceed along with the electrochemical potassiation/depotassiation processes. Additionally, the corresponding K-P alloys intermediates, such as the amorphous phases of K4P3, K3P, and the nonstoichiometric phases of ‘‘K1—xP”, ‘‘K1+xP”, ‘‘K4—xP3” are experimentally detected, which indicating various complicated K-P alloy species are coexisted and evolved with the sluggish electrochemical reaction kinetics, resulting in lower capacity of phosphorus-based anodes. Our findings offer some insights into the specific multi-phase evo-lution mechanism of alloying anodes that may be generally involved in conversion-type electrode mate-rials for PIBs.

Key words: Red phosphorus, Phase conversion, Solid-state NMR, Potassium ion batteries