Composite gel polymer electrolytes based on a perfluorinated sulfonic acid cation-exchange MF-4SC membrane containing surface-sulfonated nanoparticles of aluminum oxide, cerium (IV) oxide, and titanium oxide (sAl(2)O(3), sCeO(2), and sTiO(2), respectively) were prepared by casting from a dispersion inN,N-dimethylformamide and plasticized with a 1,3-dioxolane/1,2-dimethoxyethane mixture. The influence of the filler nature on ionic conductivity, solvent uptake, activation energy, lithium transference numbers, and electrochemical stability was investigated. The membrane with sAl(2)O(3) exhibits the highest conductivity (1.0 & times; 10(-4) S cm(-1)at 25 degrees C). In symmetric Li||Li cells, all membranes provide stable cycling for over 600 h. The Li(+)transference numbers reach 0.83-0.87, which substantially exceed those of liquid electrolytes. LiFePO4||Li cells with all composite electrolytes revealed an initial discharge capacity of up to similar to 150 mAh g(-1)(at 0.1C rate). The effect of membrane composition on a Coulombic efficiency and cycling stability is discussed. The obtained results demonstrate the promise of modified MF-4SC membranes as gel polymer electrolytes for lithium metal batteries.
Recent advances in PEO-based polymer all-solid-state batteries (ASSBs), including optimized composite cathode formulations, are bringing this technology closer to practical deployment. However, temperature remains a limiting factor, as PEO-based SPEs typically require around 70 °C to ensure adequate ionic transport, while operation at higher temperatures may introduce mechanical, interfacial and long-term stability limitations. Since real applications involve dynamic temperature profiles differing from nominal conditions, quantifying the cell response beyond thermal activation becomes essential for the design of any application from an engineering perspective. With this aim, three lab-scale monolayer pouch cells incorporating a previously optimized 700 kg mol−1 PEO-based LiFePO4 composite cathode are characterized through galvanostatic discharge experiments at different temperatures and currents. The analysis provides engineering-relevant parameters, including storage capacity, limiting discharge current, open-circuit voltage (OCV), and area-specific effective full-cell conductance (Y). The thermal dependence of equilibrium and charge-transport properties is interpreted through Seebeck-type and Vogel–Tammann–Fulcher (VTF) relationships, enabling an experimental estimation of the OCV temperature coefficient (dOCV/dT) and temperature-dependent charge transport response. In addition, the cathode electronic conductivity is also measured as a function of temperature. These results provide electro–physical parameters for electrochemical modelling, thermal management design, and operating strategy assessment of PEO-based ASSBs under non-isothermal operating conditions.
