Lithium-ion batteries are currently the alternative of choice to overcome the increasing demand of energy. However, besides the scarcity of lithium and limited geolocation, it is believed that such batteries have already reached their maximum maturity. Sodium batteries emerge as an alternative to produce the new, so called, postlithium batteries. In this study, we explore (i) the effect of sodium content and sintering temperature in solid electrolytes based in NASICON-type compounds and (ii) the use of two methodologies to obtain porous NASICON samples: application of natural substances and organic materials as pore-formers and freeze casting. The main purpose is the attainment of hybrid quasi-solid state electrolytes, with enhanced room temperature conductivity, based on porous ceramic electrolyte layers infiltrated with ionic liquids. Using this approach, porous samples with different microstructure and porous morphology and distribution were achieved, providing an enhancement in conductivity (ranging from 0.45 to 0.96 mS cm-1 at 30 degrees C) of one order of magnitude for infiltrated samples respect to pore-free samples. According to these results the porous NASICON might be considered as a functional macroporous inorganic separator that can act as a Na+ reservoir.

Macroporous separators play a crucial role regarding safety in current Li-ion batteries. Most separators used in battery applications are based on polyolefin and present shrinkage and a decrease in mechanical properties when used at high temperatures, both detrimental in the battery performance. In search of more suitable alternatives that render to more stable and safer batteries, in this work, non-woven separators based on polyacrylonitrile blended with cellulose and para-aramid fibers are systematically investigated. This study has been carried out in terms of microstructure, mechanical properties, ionic conductivity and thermal and electrochemical stability (using Li4Ti5O12/LiCoO2 full cells with a nominal potential of approximate to 2.5 V). Although conductivity values of separators are somewhat modest, the electrochemical performance developed when used in Li4Ti5O12/LiCoO2 cells are, at moderate C rates, comparable to commercial Celgard(C)2400 separator. At high C rates, in particular at 2C, DwG40 exhibits much higher capacities than the whole of the separators, including Celgard (R) 2400. This study responds to the continuous need reflected not only by the scientific community but also by the industrial one when new materials for electrolytes and electrodes should be tested, since there is a lack of reports characterizing such elements in the literature. (C) 2021 Elsevier Ltd. All rights reserved.

This work studies calcium-conducting, solvent-free polymer electrolytes in the framework of today's post-lithium battery strategies. The samples consist of three calcium salts: (i) Ca(CF3SO3)(2); (ii) Ca(TFSI)(2); and (iii) CaI2 hosted by commercial poly (oxyethylene) (POE). The data collected from X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) indicate that the polymer electrolytes consist of stable macromolecular solutions of these calcium salts. The polymer electrolytes yield conductivities exceeding 0.1 mS cm(-1); POECa(CF3SO3)(2) reaching, at the moderate concentration O/Ca = 30, a conductivity of 0.47 mS cm(-1). This preliminary and fundamental study, which demonstrates the stability of Ca-conducting polymer electrolytes, paves the way to the development of improved polymer electrolytes based on oxyethylene repeat units and new calcium salts. (c) 2020 Elsevier Ltd. All rights reserved.

Polysulfone acidic ionomers have been extensively used as Fuel Cell membranes, mainly because of their mechanical, thermal, chemical and electrochemical stability as well as their excellent film-forming capability. This contribution deals with the development of blends based on polysulfone-sodium sulfonate and macromolecular/molecular solvents, consisting of poly(oxyethylene), POE, and propylene carbonate, PC, respectively. The objectives were to take advantage of both the thermomechanical performances and the macromolecular polyanions provided by the polysulfone ionomer. Combining POE/PC solvents, didn’t allow obtaining sufficient blend’s conductivities. Nevertheless, the addition of very low amounts of sodium perchlorate led to appreciable conductivities.

Macroporous separators are critical components in liquid electrolyte batteries. Besides preventing physical contact between electrodes, they enable free ionic transport, electronic isolation and thermal shutdown. Nevertheless, separators also increase electrical resistance and takes up limited space inside the battery, affecting ionic conductivity. Widely used in lithium-ion batteries, commercial polyolefin-based separators operate in a limited temperature range, mainly ranging from −20°C to +60°C. The purpose of this contribution is to assess the possibility to use these separators in lithium-ion batteries operating at extended temperatures, i.e. between −20°C and 120°C. For this purpose, four commercially available macroporous separators based on polyethylene and polypropylene, were investigated. To determine the effect of temperature on their performance, they were aged for one week at 120°C. Evolution of their morphology and thermomechanical behavior was investigated using XRD, SEM, DSC, TGA and DMA. The thermal aging impact on the ionic conductivity was also investigated using LP30® as reference electrolyte. Thermal aging, i.e. partial clogging of the porosity, was found to have significant effects mainly on mechanical strength, morphology and conductivity.