Different approaches to obtain functionalized alumina as additive in polymer electrolyte membranes

Abstract

A series of sulfated aluminum oxides (S-Al2O3), investigated as an electrolyte additive in Nafion membranes, was synthesized via three different methods: (i) sol–gel sulfation starting from an aluminum alkoxide precursor, (ii) room temperature sulfation of fumed aluminum oxide, and (iii) hydrothermal sulfation of fumed aluminum oxide. Through the characterization of the synthesized S-Al2O3 by means of X-ray diffraction (XRD), thermogravimetric analysis (TGA), and infrared (IR) spectroscopy, a higher sulfation rate was found to be achieved via a hydrothermal sulfation, and the coordination state of sulfate groups was identified as monodentate. By using this hydrothermally synthesized S-Al2O3 as additive, a composite Nafion-based membrane was realized and compared to plain Nafion, by means of thermal analyses and fuel cell tests. Although higher hydration degree was found for the undoped membrane by differential scanning calorimetry (DSC), improved retention of fuel cell performance upon the increase of operation temperature was observed by using the composite electrolyte, confirming the stabilizing effect of the acidic inorganic additive.

Super Hygroscopic Non‐Stoichiometric Cerium Oxide Particles as Electrode Component for PEM Fuel Cells

“…To highlight this interesting aspect, the membrane internal resistance was estimated by using the current interrupt method (Figure S6). Based on the R Ω values obtained, the ionic conductivity (σ) was estimated for each sample and reported in the same Figure S6 [54] . If one considers that the electrolyte used is always a commercial Nafion membrane, the lower ohmic resistance obtained when both composite catalysts are used, with respect to bare Pt‐based fuel cell, is clearly due to the presence of the hygroscopic cerium oxide at the cathode side.…”

“…A Nafion membrane was prepared from the Nafion 5 wt.% dispersion (E.W. 1100, Ion Power Inc, München Germany), according to the following procedure reported elsewhere [54,56] . The Nafion dispersion was heated at 80 °C to gradually replace the solvents, water and alcohols, with N,N‐dimethylacetamide (>99.5 %, Sigma Aldrich, St. Louis, MO, USA) at 80 °C.…”

“…1100, Ion Power Inc, München Germany), according to the following procedure reported elsewhere. [54,56] The Nafion dispersion was heated at 80 °C to gradually replace the solvents, water and alcohols, with N,N-dimethylacetamide (> 99.5 %, Sigma Aldrich, St. Louis, MO, USA) at 80 °C. Afterwards, the solution obtained was casted on a Petri dish and dried at 80 °C overnight.…”

Controlling the Potential of Affordable Quasi‐Solid Composite Gel Polymer Electrolytes for High‐Voltage Lithium‐Ion Batteries

“…In response to these challenges, research endeavors are shifting towards developing safer alternatives to liquid electrolytes, with a focus on solid-state batteries (SSBs). [7][8][9] To mitigate the limitations linked with liquid electrolytes and enhance the security of Li metal anodes, pure solid electrolytes (SEs) have emerged as a promising solution.…”

Toward Sustainable Solid Polymer Electrolytes for Lithium-Ion Batteries

“…The filler incorporated into the polymer matrix can have either active or passive roles with respect to battery electrochemical performance. The most used passive fillers are ceramic [barium titanate (BaTiO 3 ), 17 aluminum oxide (Al 2 O 3 ), 18 silicon dioxide (SiO 2 ), 19 and titanium dioxide (TiO 2 ) 20 ] or carbonaceous (graphite 100 ), with the function of improving properties such as mechanical or thermal stability. The most common active fillers are ionic liquids [1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, (EMIM)(TFSI); 22 1-butyl-3-methylimidazolium chloride, (BMIM)(Cl) 101 ] and various lithium salts [lithium tetrafluoroborate (LiBF 4 ), 24 lithium hexafluorophosphate (LiPF 6 ), 25 lithium hexafluoroarsenate (LiAsF 6 ), 26 lithium perchlorate (LiClO 4 ), 27 and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) 28 ], among others, with the function of increasing SPE ionic conductivity, both in terms of intrinsic value and thermal characteristics.…”