Engineering a well-connected ion-conduction network and interface chemistry for high-performance PVDF-based polymer-in-salt electrolytes

The challenges posed by the low ionic conductivity at room temperature and the poor compatibility of the Li metal/electrolyte interface restrict the practical application of solid-state polymer electrolytes. Herein, a bifunctional heptafluorobutyric anhydride (HFA) additive has been proposed to over...

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Veröffentlicht in:Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2024-03, Vol.12 (13), p.7645-7653
Hauptverfasser: Li, Xiaodan, Wang, Yucheng, Zhou, Qingfeng, Kuai, Hongxiang, Ji, Chuang, Xiong, Xunhui
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Sprache:eng
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Zusammenfassung:The challenges posed by the low ionic conductivity at room temperature and the poor compatibility of the Li metal/electrolyte interface restrict the practical application of solid-state polymer electrolytes. Herein, a bifunctional heptafluorobutyric anhydride (HFA) additive has been proposed to overcome the abovementioned problems of the polyvinylidene fluoride (PVDF)-based polymer-in-salt solid electrolyte. The experimental data, density functional theory (DFT) calculations and the molecular dynamics (MD) simulations demonstrate that the HFA additive can promote the formation of nanometric aggregates (n-AGGs), which can construct a continuous and fast Li + ion transport network in the solid electrolyte. Meanwhile, the HFA additive exhibits a lower LUMO energy level, and then it can contribute a LiF-rich SEI at the Li metal/electrolyte interface. As a result, the fabricated solid electrolytes with HFA additive can deliver an improved ion conductivity of 2.41 × 10 −4 S cm −1 at room temperature, which makes the symmetric Li|Li batteries show an ultra-long cycle life ( 1700 h at 0.1 mA h cm −2 ). Besides, the HFA-containing solid electrolytes show greatly enhanced cycle stability compared to the pristine electrolyte in the full cells when paired with a LiFePO 4 cathode or high-voltage LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) cathode. This work provides a critical insight into the mechanism of a new additive to enhance the electrochemical performances of PVDF-based polymer-in-salt solid-state electrolytes. We incorporate HFA into PVDF-based polymer-in-salt solid electrolyte to form n-AGGs with continuous Li-ion transport path and a LiF-rich SEI, enhancing both ionic conductivity and stability. NCM622|Li cells stably operate over 600 cycles at 0.2C.
ISSN:2050-7488
2050-7496
DOI:10.1039/d3ta08117f