Anion-immobilized solid composite electrolytes based on metal-organic frameworks and superacid ZrO2 fillers for high-performance all solid-state lithium metal batteries

• Published in: International journal of minerals, metallurgy and materials metallurgy and materials, 2021-10, Vol.28 (10), p.1636-1646
• Main Authors: Wei, Tao, Zhang, Zao-hong, Zhang, Qi, Lu, Jia-hao, Xiong, Qi-ming, Wang, Feng-yue, Zhou, Xin-ping, Zhao, Wen-jia, Qiu, Xiang-yun
• Format: Article
• Language: English
• Subjects: Anions; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composite materials; Composites; Corrosion and Coatings; Electrochemistry; Electrolytes; Electrolytic cells; Electron microscopes; Fillers; Glass; Hydrogen bonds; Ion currents; Lewis acid; Lithium; Lithium batteries; Lithium ions; Materials Science; Metal-organic frameworks; Metallic Materials; Metals; Molten salt electrolytes; Natural Materials; Polymers; Short circuits; Solid electrolytes; Solid state; Specific capacity; Surfaces and Interfaces; Thin Films; Tribology; Vinylidene; Vinylidene fluoride; X-ray diffraction; X-ray spectroscopy; Zirconium dioxide
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-021-2289-z

Anion-immobilized solid composite electrolytes (SCEs) are important to restrain the propagation of lithium dendrites for all solid-state lithium metal batteries (ASSLMBs). Herein, a novel SCEs based on metal-organic frameworks (MOFs, UiO-66-NH 2 ) and superacid ZrO 2 (S-ZrO 2 ) fillers are proposed, and the samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), thermo-gravimetric analyzer (TGA) and some other electrochemical measurements. The -NH 2 groups of UiO-66-NH 2 combines with F atoms of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) chains by hydrogen bonds, leading to a high electrochemical stability window of 5 V. Owing to the incorporation of UiO-66-NH 2 and S-ZrO 2 in PVDF-HFP polymer, the open metal sites of MOFs and acid surfaces of S-ZrO 2 can immobilize anions by strong Lewis acid-base interaction, which enhances the effect of immobilization anions, achieving a high Li-ion transference number ( t + ) of 0.72, and acquiring a high ionic conductivity of 1.05×10 −4 S·cm −1 at 60°C. The symmetrical Li/Li cells with the anion-immobilized SCEs may steadily operate for over 600 h at 0.05 mA·cm −2 without the short-circuit occurring. Besides, the solid composite Li/LiFePO 4 (LFP) cell with the anion-immobilized SCEs shows a superior discharge specific capacity of 158 mAh·g −1 at 0.2 C. The results illustrate that the anion-immobilized SCEs are one of the most promising choices to optimize the performances of ASSLMBs.