Editors⇔ choice⇔mechanistic elucidation of anion intercalation into graphite from binary-mixed highly concentrated electrolytes via complementary 19F MAS NMR and XRD studies

Lukas Haneke, Joop Enno Frerichs, Andreas Heckmann, Michael M. Lerner, Taner Akbay, Tatsumi Ishihara, Michael Ryan Hansen, Martin Winter, Tobias Placke

    研究成果: ジャーナルへの寄稿総説査読

    9 被引用数 (Scopus)

    抄録

    Dual-graphite batteries have emerged as promising candidate for sustainable energy storage due to their potentially low costs and absence of toxic materials. However, the mechanism of anion intercalation and the structures of the resulting graphite intercalation compounds (GICs) are still not well understood. Here, we systematically evaluate the anion intercalation characteristics into graphite for three highly concentrated electrolytes containing LiPF6, LiTFSI and their equimolar binary mixture. The binary mixture exhibits a significantly enhanced capacity retention and improved intercalation kinetics compared to the single-salt electrolytes in graphite ∣∣ Li metal cells. In situ X-ray diffraction studies prove the formation of stage 1-GICs and a homogeneous distribution of anions within graphite. From ex situ solid-state 19F magic-angle spinning (MAS) nuclear magnetic resonance (NMR) measurements, GICs can be identified at various states-of-charge (SOCs). The 19F chemical shifts of intercalated anions indicate no significant charge transfer between anion and graphite. The observed narrow 19F linewidths of the GIC-signals are most likely caused by a high translational and/or rotational mobility of the intercalates. Furthermore, the 19F MAS NMR studies allow the identification of the molar ratios for PF6 and TFSI anions intercalated into graphite, suggesting a preferred intercalation of PF6 anions, especially at lower SOCs.

    本文言語英語
    論文番号140526
    ジャーナルJournal of the Electrochemical Society
    167
    14
    DOI
    出版ステータス出版済み - 11月 2020

    !!!All Science Journal Classification (ASJC) codes

    • 電子材料、光学材料、および磁性材料
    • 再生可能エネルギー、持続可能性、環境
    • 表面、皮膜および薄膜
    • 電気化学
    • 材料化学

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