Lithiated cellulose nanofibers addressing the trade-off between ionic conductivity and interfacial stability in poly(vinylidene fluoride-co-hexafluoropropylene) gel polymer electrolytes for lithium metal batteries

초록

Gel polymer electrolytes (GPEs) have attracted considerable attention as electrolytes for lithium metal batteries because they combine solid-like mechanical integrity with liquid-assisted ion transport. However, their practical application remains limited by an intrinsic trade-off between ionic conductivity and interfacial stability, which critically affects lithium deposition behavior, cycling stability, and safety. Here, we investigate how processinginduced microstructural regulation governs this trade-off in poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based GPEs. By controlling the initial convection drying time, the membrane architecture transitions from porous to dense morphologies. Porous structures enhance electrolyte uptake and lithium-ion transport but increase susceptibility to lithium dendrite penetration, whereas rapid drying induces surface densification that stabilizes the lithium interface at the expense of ion transport. To overcome this limitation, lithiumfunctionalized cellulose nanofibers are incorporated into the dense PVDF-HFP matrix. Acting as a transportactive component, these nanofibers promote Li+ transport behavior while reinforcing the dense polymer framework. As a result, the optimized composite electrolyte simultaneously achieves improved ionic transport and robust interfacial stability, enabling stable long-term lithium cycling and enhanced rate performance in both symmetric and full-cell configurations. This work demonstrates an effective electrolyte design strategy for addressing a key limitation in high-energy-density lithium metal batteries.

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