Gel polymer electrolytes: Highly conductive MGPEs are developed by soaking ZrO₂-NHIF blended, SMA chain grafted P(VDF-HFP) based microporous polymer membranes in LiTFSI salt-dissolved IL electrolyte. Li/LFP and Li/NMC811 batteries assembled with MGPE deliver stable discharge capacity of 154 and 172 mAh g⁻¹ at 0.5 C with 96 % and 85 % capacity retention after 100 cycles.

Abstract

In this study, an organic-inorganic hybrid polymer membrane is successfully designed and developed by grafting stearyl methacrylate (SMA) side chains onto the backbone of the P(VDF-HFP) copolymer followed by blending with varying amounts of imidazolium ionic liquids functionalized ZrO₂ nanoparticles. Different microporous gel polymer electrolytes (MGPEs) are prepared by immersing the membranes into a LiTFSI salt-dissolved ionic liquid electrolyte. The membranes′ crystallinity, surface morphology, porosity, and thermal stability are investigated using various characterization techniques. The copolymer membrane blended with 60 wt % functionalized nanoparticles exhibits the highest porosity of 64.5 %, which allows it to achieve a maximum electrolyte uptake of 387 wt %. That enables the corresponding MGPE to achieve the highest room temperature lithium ion conductivity of ~5.34×10⁻³ S cm⁻¹ with a wide electrochemical stability window and good electrochemical stability against Li metal. Leveraging these advantageous characteristics, the lab-scale truly solid-state Li|MGPE|LiFePO₄ and Li|MGPE|LiNi_0.8Mn_0.1Co_0.1O₂ cells demonstrate excellent rate capability and reversible cycling stability while maintaining high specific capacities (up to 154 and 172 mAh g⁻¹, respectively, at 0.5 C) with >99.0 % coulombic efficiency over 100 cycles. Such exceptional interfacial compatibility with both low- and high-voltage cathodes establishes the applicability of these newly developed MGPEs in next-generation all-solid-state lithium-metal batteries.