Effects of inorganic nanofillers and fiber reinforcement on properties of Poly(ethylene oxide) as solid electrolyte for Lithium-Ion batteries

Abstract

This rescarch was aimed to study the effects of different inorganic nanofiller such as halloysite nanotube (HNT), montmorillonite (MMT) and silica (SiO2) at various weight percentage as 1, 5 and 10 on composite properties. The composites of PEO- LiCF3SOs and inorganic nanofiller were fabricated by solution casting and followed by hot compression technique to form solid polymer electrolyte membrane. The ionic conductivity increased upon the addition of 5wt% of inorganic filler into the PEO- 20%LiCF3SOs mixture using the magnetic stirrer. The ultrasonic at difference ultrasonication exposure time (15 and 30 min) was applied to disperse nanofillers in the PEO-20%LiCF3SO3-5%HNT. It was found that 15 min of ultrasonication exposure time gave the highest ionic conductivity as 1.09x104 S/cm. The ionic conductivity significantly increased for one to two orders of magnitude. The dispersion of HNT in the composite membrane by ultrasonication was observed by FE-SEM and EDS- mapping and TEM images. The interactions between PEO, LiCF3SO; and HNT were confirmed by ATR-FTIR spectra. XRD revealed that applying ultrasonication to the PEO-20%LiCF3SOs-5%HNT composite during the preparation resulted the crystallinity reduction of PEO. DSC curves showed the decrease of glass transition and melting temperatures of the composite membrane due to the addition of HNT and the applying of ultrasonication. In addition, ultrasonication strengthen tensile property of the composite membrane. More importantly, the electrochemical stability of the composite membrane was improved upon an addition of HNT into PEO-LiCF3SO3. The PEO-30%LiCF3SO3-5%HNT composite was reinforced by glass fiber (5, 10, and 15 wt%). The reinforced composites were fabricated by a 2-roll mill mixing and compression molding. The ionic conductivity was improved with the addition of glass fiber (GF). The ionic conductivity at room temperature was found maximum in PEO- 30%LiCF3SOs-5%HNT-10%GF as 1.45 x 10s S/cm. The addition of glass fiber increased the crystallinity of the composites. The storage modulus and Tg of composites tended to increase as well. Furthermore, the clectrochemical stability and tensile strength of the 10wt%GF reinforced composite were improved.