Characteristics of lithium-ion-loaded poly(m-aminophenol) as solid-state electrolyte

A simple method was adopted to prepare varying amounts of lithium-ion loaded poly(m-aminophenol) for optimizing its characteristics as a solid-state electrolyte. A highest 34% lithium-ion loading was achieved with having number of lithium atoms per repeating unit as ~ 8. The lowest band gap energy of 1.8 eV for the highest lithium-ion-loaded sample was calculated from UV–VIS spectra. This sample was found to have an AC-conductivity of 5.0 × 10⁻⁴ Scm⁻¹ due to the formation of –O-Li⁺ or = NLi⁺– or trapping of Li⁺ inside the coiled pocket of PmAP depending on the loading of Li⁺ inside poly(m-aminophenol). A crystalline microstructure with nano-flake morphology of the lithium-loaded samples was confirmed from XRD and FESEM analysis. The thermal stability of the poly(m-aminophenol) up to 250 °C considered as application temperature was decreased with increasing the lithium-ion loading. 24% thermal shrinkage of the optimized lithium-ion-loaded sample at 100 °C was increased to 38% at 200 °C. A lithium-ion transference number of 0.65 was calculated for the optimized lithium-ion loaded sample and it showed good electrochemical stability within the tested potential window from 0 to 10 V. The above lithium-loaded polymer was found to have good impedance properties with very small interfacial resistance and very fast relaxation even at varying temperatures. Therefore, the lithium-ion-loaded poly(m-aminophenol) should be considered as a promising solid-state electrolyte for potential use in electrical energy storage systems, especially in lithium-ion batteries.