Copper hydroxide-embedded PVDF composite membranes with asymmetric ion-conducting pathways for high performance lithium metal batteries

• Published in: European polymer journal Vol. 225; p. 113725
• Main Authors: Liao, Ssu-Ping, Chang, Chih-Min, Ou, Shu-Ching, Kuan, Wei-Fan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 14.02.2025
• Subjects: Electrolyte; Energy; Lithium metal battery; Membrane; β-PVDF; Membrane; β-PVDF; Energy; Electrolyte; Lithium metal battery
• ISSN: 0014-3057
• DOI: 10.1016/j.eurpolymj.2025.113725

[Display omitted] •Asymmetric PVDF-Cu(OH)2 composite membranes are employed as gel polymer electrolyte.•Formation of β-phase PVDF is enhanced by a low doping level of 3 wt% Cu(OH)2.•Promoted ionic conductivity and t+ along with suppressed Li dendrite growth are achieved.•In-situ polymerized DOL into PVDF-Cu(OH)2 scaffold membrane forms high performance quasi-solid-state electrolytes.•PVDF-Cu-polyDOL enables Li metal batteries with extended voltage and high capacities. High safety and prolonged cycling stability are vital for the widespread commercialization of lithium (Li) metal batteries. In this study, we report a copper hydroxide (Cu(OH)2)-embedded polyvinylidene difluoride (PVDF) composite membrane with asymmetric porous structure for gel polymer electrolytes. Our experimental results combined with molecular dynamics simulations reveal that incorporating a low doping content of 3 wt% Cu(OH)2 into PVDF membrane (PVDF-CH-3) significantly enhance the ion transport properties of gel polymer electrolyte, delivering an ionic conductivity of 1.35 mS cm−1, elevated transference number of 0.69, low interfacial impedance with Li, and uniform Li deposition. These improvements are primarily attributed to the enriched β-phase PVDF crystallinity (61 %) within the membrane. Additionally, long cycle lifespan of PVDF-CH-3 gel polymer electrolytes in Li||Li (>500 cycles), Li||Cu (>100 cycles), and Li||LFP (>200 cycles) cells are achieved with high coulombic efficiency (>97 %). Moreover, the porous PVDF-CH-3 membranes are applied as a scaffold to host the in-situ polymerization of 1,3-dioxolane and obtain quasi-solid-state electrolytes, that exhibit outstanding battery performance at high rate of 10 C under room temperature. In sum, this work presents a novel route for the design of composite membranes for the development of gel-type and quasi-solid-state Li metal batteries with high capacity and stability.