Multifunctional Structural Electrolyte with Glass FiberReinforced Polyvinyl Alcohol/Epoxy Matrix with Optimized Lithium Salt and Nanofiller

• Autor(es): Niazi, M ; Paiva, D ; Danzi, F ; Lopes, T ; Mendes, A ; Camanho, PP
• Data: 2025
• Identificador Persistente: https://hdl.handle.net/10216/169852
• Origem: Repositório Aberto da Universidade do Porto
• Tipo de Documento: Artigo científico
• Idioma: Inglês

Descrição

A novel multifunctional structural electrolyte is developed using plainweave glass fiber reinforced with a composite polymer matrix for loadbearing energystorage applications such as structural batteries. The composite matrix comprises polyvinyl alcohol (PVA) blended with epoxy, LiTFSI salt, and Al2O3 at optimized ratios. A set of techniques is used to evaluate and optimize the thermoelectromechanical properties of the matrix, including dynamic mechanical analysis (DMA), potentiostatic electrochemical impedance spectroscopy (PEIS), thermogravimetric analysis, differential scanning calorimetry, and Xray diffraction. The optimization reveals a clear tradeoff: increasing salt content enhances ionic conductivity but compromises mechanical properties, while the addition of nanofiller improves stiffness but reduces ionic conductivity. Based on multifunctionally balancing, a formulation of PVA0.34/epoxy0.14/LiTFSI0.32/(Al2O3)0.2 is obtained. The structural electrolyte, composed of glass fiber impregnated with the optimized matrix, is characterized using PEIS, DMA, tensile testing, and chargedischarge tests within lithium iron phosphate (LFP)/lithium metal and LFP/graphite cells. The electrolyte exhibits a storage modulus of 3GPa, an ionic conductivity of 1.74×104Scm1, a bulk stiffness of 1.82GPa, and a tensile strength of 56.9MPa. Fullcell testing demonstrates long cycle life and stable cyclability for 240 cycles, maintaining a high Coulombic efficiency of around 95% throughout cycling.