Polymer-MTiO3 (M = Ca, Sr, Ba) composites as facile and scalable supercapacitor separators

Abstract

The quantum of research in the area of supercapacitors is typically focused on the electrode materials. As such, there are many opportunities for the optimization of the other components, such as the separators, to further increase the power, efficiency, and longevity of supercapacitors. To contribute to this field of research, we present an innovative alternative for the fabrication of separators; using polymer/ceramic composites (PCC) based on polyvinylidene fluoride (PVDF) and polypropylene (PPG) mixed with different alkaline earth metal-based titanates (eg barium, calcium, and strontium). The PCC separators were prepared via phase inversion precipitation technique, a feasible and scalable method for the fabrication of these composites. Different additives were used to modulate the porosity and thus, improve the charge transfer rates. Then, a heating process ensured a uniform organization of the composites. Furthermore, we tested the effect of thermally annealing the ceramics on the separators’ performance. The precursor materials and the PCC's were extensively characterized by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical, mechanical, and dielectric properties of the PCC's were measured and compared to common commercial separators used today. Results suggest that thermal treatment improves tensile strength of the separators by at least ca. 60% without compromising the similar electrochemical profile to the commercial separators (44.52 ± 2.82 Ω vs 67.65 ± 29.01 Ω). Lastly, all of the fabricated PCC's showed higher dielectric constants (4.52 in average for the as prepared separators and 2.99 for the heated PCC's) than the polymer based commercial separators (2.2).