Development of a New Crosslinked Highly Conductive Hybrid Electrolyte based on Polyetherdiamine, Diphenylmethane Diisocyanate and Organosilanes for Efficient Lithium-Metal Battery

In this study, a new crosslinked organic-inorganic hybrid polymer electrolyte membrane is developed by first reacting polyetherdiamine with diphenylmethane diisocyanate, followed by addition of organosilane precursors 3-(glycidyloxypropyl) trimethoxysilane and 2-[methoxy(polyethyleneoxy) propyl] trimethoxysilane and LiClO₄ salt. Various characterization methods are employed to probe the crystallinity behavior, morphology, ionic interactions, thermal stability, architectural durability and dynamic performance of the hybrid solid polymer electrolyte (HSPE) membranes. Among the electrolytes, the HSPE membrane with [EO]/[Li] ratio of 32 delivers the excellent ionic conductivity value of 1.2×10⁻⁴ S cm⁻¹ at 30 °C. When the hybrid membrane without salt is plasticized with various electrolyte solvents, the ionic conductivity enhances significantly to values in the range of 1.2 to 1.8×10⁻³ S cm⁻¹ at 30 °C. The lithium metal battery (LMB) assembled with the gel polymer electrolyte (GPE), lithium anode and LiFePO₄ cathode provides excellent rate and cycle performances. The LMB delivers very stable discharge capacity of 121.1 mAh g⁻¹ after 150 cycles at the rate of 0.1 C with 97.6 % capacity holding compared to first cycle and exhibits above 99 % Coulombic efficiency values. The present crosslinked hybrid polymer electrolytes are potentially promising for the future development of high performance lithium-metal batteries.