High ion-conducting solid polymer electrolytes based on blending hybrids derived from monoamine and diamine polyethers for lithium solid-state batteries

Abstract

In this study, polyetheramine and polyetherdiamine were cross-linked separately with (3-glycidyloxypropyl)trimethoxysilane (GLYMO) and poly(ethylene glycol) diglycidyl ether (PEGDGE) and then blended in different ratios to obtain blended hybrid solid polymer electrolytes (SPEs). The blend network architecture improved the LiClO₄ salt dissociation, which led to a higher ionic conductivity of the SPEs (4.5 × 10⁻⁴ S cm⁻¹ at 60 °C and 1.2 × 10⁻⁴ S cm⁻¹ at 30 °C for the [O]/[Li] ratio of 16). When the salt concentration was increased, the phase of the SPEs changed from semi-crystalline to an amorphous state, as revealed by differential scanning calorimetry. Complexation with different constituents of the SPEs was evidenced from the Fourier transform infrared measurements, while ¹³C and ²⁹Si solid-state NMR spectroscopy provided information about the successful formation of the blend organic–inorganic hybrid with a silicate architecture, and ⁷Li NMR static linewidth measurements gave an insight into the dynamic behaviour of the lithium ions inside the SPEs. The blend hybrid SPEs demonstrated an electrochemical stability window of over 5 V. The electrochemical performance of the blend hybrid SPE assembled in a battery with lithium as the anode and LiFePO₄ as the cathode exhibited a good cycle life of over 100 cycles, with an initial discharge capacity of 110 mA h g⁻¹ and a coulombic efficiency of over 99%. With these good characteristic properties, the present blend hybrid SPE has the potential to be used in lithium solid-state batteries and other electrochemical devices.