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Preparation and characterization of PEO/PEG- POSS/LiBOB nanocomposite polymer electrolyte

Novel nanocomposite polymer electrolytes based on poly(ethylene oxide) (PEO)/polyethylene glycol functionalized polyhedral oligomeric silsesquioxane (PEG-POSS) complexed with lithium bis(oxalato)borate (LiBOB) were successfully prepared using hot-melt extrusion. The amount of LiBOB was fixed at the EO/Li = 8 based on the amount of ethylene oxide in the PEO while the relative amount of PEG-POSS to PEO was added up to 15 wt %. Structural, thermal, and electrochemical studies were performed to evaluate the potential of this system for application in rechargeable lithium-ion batteries. Fourier transform infrared spectroscopy (FTIR) confirmed the interaction between PEO, PEG-POSS and LiBOB. Differential scanning calorimetry (DSC) analysis showed that the addition of LiBOB and PEG-POSS causes the disappearance of the crystallinity of PEO. Its crystalline nature is known as the main drawback that causes low ionic conductivity of polymer electrolytes based on PEO at room temperature. Furthermore, the Li+ coordination with PEO reduces the chain segmental motion of PEO which is evident from the increase of the glass transition temperatures. Electrochemical impedance spectroscopy (EIS) revealed that the combined effect of the PEG-POSS and LiBOB increases the ionic conductivity of PEO at room temperature. The results also showed that the ionic conductivity of the analysed samples is governed by the amount of PEG-POSS as a nanofiller. Finally, these results confirm the potential of this system to be used as the solid electrolyte for lithium-ion batteries.

nanocomposites, poly(ethylene-oxide), crystallinity

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