Nanocomposite Polymer Electrolytes for Zinc and Magnesium Batteries: From Synthetic to Biopolymers

The diversification of current forms of energy storage and the reduction of fossil fuel consumption are issues of high importance for reducing environmental pollution. Zinc and magnesium are multivalent ions suitable for the development of environmentally friendly rechargeable batteries. Nanocomposite polymer electrolytes (NCPEs) are currently being researched as part of electrochemical devices because of the advantages of dispersed fillers. This article aims to review and compile the trends of different types of the latest NCPEs. It briefly summarizes the desirable properties the electrolytes should possess to be considered for later uses. The first section is devoted to NCPEs composed of poly(vinylidene Fluoride-co-Hexafluoropropylene). The second section centers its attention on discussing the electrolytes composed of poly(ethylene oxide). The third section reviews the studies of NCPEs based on different synthetic polymers. The fourth section discusses the results of electrolytes based on biopolymers. The addition of nanofillers improves both the mechanical performance and the ionic conductivity; key points to be explored in the production of batteries. These results set an essential path for upcoming studies in the field. These attempts need to be further developed to get practical applications for industry in large-scale polymer-based electrolyte batteries.

Preparation and characterization of novel potassium ion conducting nanocomposite polymer electrolytes based on PEMA

Potassium ion conducting nanocomposite polymer electrolytes was prepared by employing the solvent casting technique. Poly ethyl methacrylate (PEMA), potassium thiocyanate (KSCN) and nano-strontium titanate (SrTiO3) (<100 nm) was used as a polymer host, an electrolyte and a filler, respectively. The complex formation between PEMA, KSCN and SrTiO3 was confirmed through Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis, respectively. This system exhibited two ionic conductivity maxima, but the sample, PEMA/KSCN/4 wt% SrTiO3 delivered a maximum ionic conductivity of 3.07 × 10−5 Scm−1 at room temperature, which was 102 times greater than that of PEMA/KSCN system. Truckhan model was employed to determine the diffusion coefficient, mobility and mobile ion concentration of the system. The remarkable change in surface morphology of the sample was observed through Scanning Electron Microscopy (SEM) micrograph.

Nanocomposite Polymer Electrolytes of Sodium Alginate and Montmorillonite Clay

Nanocomposite polymer electrolytes (NPEs) were synthesized using sodium alginate (Alg) and either sodium (SCa-3-Na+)- or lithium (SCa-3-Li+)-modified montmorillonite clays. The samples were characterized by structural, optical, and electrical properties. SCa-3-Na+ and SCa-3-Li+ clays’ X-ray structural analyses revealed peaks at 2θ = 7.2° and 6.7° that corresponded to the interlamellar distances of 12.3 and 12.8 Å, respectively. Alg-based NPEs X-ray diffractograms showed exfoliated structures for samples with low clay percentages. The increase of clay content promoted the formation of intercalated structures. Electrochemical Impedance Spectroscopy revealed that Alg-based NPEs with 5 wt% of SCa-3-Na+ clay presented the highest conductivity of 1.96 × 10−2 S/cm2, and Alg with 10 wt% of SCa-3-Li+ showed conductivity of 1.30 × 10−2 S/cm2, both measured at 70 °C. From UV-Vis spectroscopy, it was possible to infer that increasing concentration of clay promoted a decrease of the samples’ transmittance and, consequently, an increase of their reflectance.