Understanding sodium-ion diffusion in layered P2 and P3 oxides via experiments and first-principles calculations: A bridge between crystal structure and electrochemical performance

Shaohua Guo, Yang Sun, Jin Yi, Kai Zhu, Pan Liu, Yanbei Zhu, Guo Zhen Zhu, Mingwei Chen, Masayoshi Ishida, Haoshen Zhou

    Research output: Contribution to journalArticle

    39 Citations (Scopus)

    Abstract

    Layered NaxMeO2 (Me=transition metal) oxides, the most common electrode materials for sodium-ion batteries, fall into different phases according to their stacking sequences. Although the crystalline phase is well known to largely influence the electrochemical performance of these materials, the structure-property relationship is still not fully experimentally and theoretically understood. Herein, a couple consisting of P2-Na0.62Ti0.37Cr0.63O2 and P3-Na0.63Ti0.37Cr0.63O2 materials having nearly the same compositions is reported. The atomic crystal structures and charge compensation mechanism are confirmed by atomic-scale characterizations in the layered P2 and P3 structures, respectively, and notably, the relationship of the crystal structure-electrochemical performance is well defined in the layered P-type structures for the first time in this paper. The electrochemical results suggest that the P2 phase exhibits a better rate capability and cycling stability than the P3 phase. Density functional theory calculations combined with a galvanostatic intermittent titration technique indicates that the P2 phase shows a lower Na diffusion barrier in the presence of multi-Na vacancies, accounting for the better rate capability of the P2 phase. Our results reveal the relationship between the crystal structure and the electrochemical properties in P-type layered sodium oxides, demonstrating the potential for future electrode advancements for applications in sodium-ion batteries.

    Original languageEnglish
    Article numbere266
    JournalNPG Asia Materials
    Volume8
    Issue number4
    DOIs
    Publication statusPublished - 2016 Apr 22

    ASJC Scopus subject areas

    • Modelling and Simulation
    • Materials Science(all)
    • Condensed Matter Physics

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