3D Flexible Electrospun Nanocomposite Polymer Electrolyte Based on Li1.45Al0.45Ge0.2Ti1.35(PO4)3 for Lithium Metal Batteries

Solid-state lithium batteries recently gained significant attention because of their enhanced safety compared to that of liquid-based battery systems. However, ceramic solid-state electrolytes suffer from various challenges such as electrode–electrolyte interface issues and poor flexibility. In this scenario, combining the solid electrolytes with polymer electrolytes would be a wise choice. Polymer electrolytes such as poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) show good thermal stability and mechanical strength. On the other hand, NASICON (sodium superionic conductor)-structured lithium aluminum titanium phosphate (LATP) ceramic solid electrolytes exhibit high lithium-ion conductivity, and thus, NASICON-type nanocomposite polymer electrolytes have both advantages. This composition has enhanced interfacial stability, ionic conductivity, and mechanical strength, making it ideal for developing high-performance nanocomposite polymer electrolytes. In this work, a germanium-doped LATP (Li1.45Al0.45Ge0.2Ti1.35(PO4)3)-PVdF-HFP nanocomposite polymer electrolyte has been prepared by the electrospinning technique. Electrochemical analysis shows that 8 wt % Li1.45Al0.45Ge0.2Ti1.35(PO4)3 in the PVdF-HFP nanocomposite polymer electrolyte (NPE-8) exhibits high lithium-ion conductivity, good wettability, and enhanced interface stability and inhibits dendrite propagation. NPE-8 exhibits a wide electrochemical potential window of up to 5 V. A full cell with lithium metal as an anode and lithium iron phosphate as a cathode fabricated by incorporating NPE-8 as an electrolyte delivers an initial discharge capacity of 154 mA h g–1 at 0.1C with a Coulombic efficiency of 98% at room temperature. The fabricated cell demonstrates a superior capacity retention and stable cycling than the pristine PVdF-HFP electrolyte.