Tuning Electrolyte Performance via GOfMOs Nanofillers in Composite Polymer Electrolyte for Lithium-ion Batteries

Abstract

Solid electrolytes exhibiting high ion conductivity, outstanding Li-ion transference number, and electrochemical stability are required in solid-state lithium-ion batteries. Here, we report nanocomposite solid polymer electrolytes (NSPEs) with enhanced lithium-ion conductivity. The developed NSPEs are based on PVDF-HFP as polymer matrix, lithium perchlorate (LiCI04) as salt, succinonitrile (SN) as plasticizer and various metal oxides (Mn304, BaO, and CuO) nanoparticles grafted on graphene oxide (GO) nanosheets as nanofillers. Nanofi11 ers, content ranging from 0.2 to 0.6% was added in the prepared NSPEs. The structural changes and crystallinity of polymer matrix is analyzed by X-ray diffraction and differential scanning calorimetry. The sharp decrease in crystallinity of polymer matrix from 19% to 3% and 6% is observed by the addition of plasticizer and nanofiller respectively, showing their interaction to enhance the amorphous phase of the polymer matrix. FTIR analysis ascertains polymer phase modification from nonpolar a-phase to electroactive y-phase upon salt addition polymer-salt complexation. Nanofillers interact with salt, specifically its anionic component, leading to an augmentation of salt dissociation and an elevation in the free ion content. The polar groups on the nanofillers enhance the salt dissociation and thus increase the charge carrier concentration as clear from fraction offree ions i.e., addition of GO-BaO enhances the fraction of free ions upto 98%. A pronounced increase in ion conductivity is observed with the addition of plasticizer and fillers. The maximum room temperature ion conductivity on.55 x 10-4 Scm-1 is achieved for 0.2% GO-CuO-based NSPE. The dielectric and modulus analysis reveal faster relaxation phenomenon and hence high ion conductivity of the fabricated composite films.