Electrolyte Fuel Cells Research Articles

Triptycene Branched Poly(aryl‐co‐aryl piperidinium) Electrolytes for Alkaline Anion Exchange Membrane Fuel Cells and Water Electrolyzers

AbstractAlkaline polymer electrolytes (APEs) are essential materials for alkaline energy conversion devices such as anion exchange membrane fuel cells (AEMFCs) and water electrolyzers (AEMWEs). Here, we report a series of branched poly(aryl‐co‐aryl piperidinium) with different branching agents (triptycene: highly‐rigid, three‐dimensional structure; triphenylbenzene: planar, two‐dimensional structure) for high‐performance APEs. Among them, triptycene branched APEs showed excellent hydroxide conductivity (193.5 mS cm−1@80 °C), alkaline stability, mechanical properties, and dimensional stability due to the formation of branched network structures, and increased free volume. AEMFCs based on triptycene‐branched APEs reached promising peak power densities of 2.503 and 1.705 W cm−2 at 75/100 % and 30/30 % (anode/cathode) relative humidity, respectively. In addition, the fuel cells can run stably at a current density of 0.6 A cm−2 for 500 h with a low voltage decay rate of 46 μV h−1. Importantly, the related AEMWE achieved unprecedented current densities of 16 A cm−2 and 14.17 A cm−2 (@2 V, 80 °C, 1 M NaOH) using precious and non‐precious metal catalysts, respectively. Moreover, the AEMWE can be stably operated under 1.5 A cm−2 at 60 °C for 2000 h. The excellent results suggest that the triptycene‐branched APEs are promising candidates for future AEMFC and AEMWE applications.

Development of a Composite Heterostructure Electrolyte for Low-Temperature Ceramic Fuel Cells: CaSnO3–ZnO Semiconductor Design and Optimization

Development of a Composite Heterostructure Electrolyte for Low-Temperature Ceramic Fuel Cells: CaSnO₃–ZnO Semiconductor Design and Optimization

High-performance BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) protonic ceramic fuel cell electrolytes by the Ba evaporation inhibition strategy

BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) as a potential candidate for protonic ceramic fuel cells (PCFCs) electrolytes, often suffers from its high sintering temperature, making it deviate from the stoichiometric ratio and present a poor electrochemical performance than expected. Here, we reported a Ba evaporation inhibition strategy to fabricate stoichiometric BZCYYb electrolyte. By using this strategy, Ba evaporation and Y2O3/Yb2O3 segregation can be effectively suppressed. The electrolyte's average grain size is ∼5.29 μm, significantly promoting grain growth. An improvement of 60 % in total conductivity is accomplished at 700 °C in humid air, approaching 2.7 × 10−2 S cm−1. By constructing the proton transport model, the reasons for the enhanced electrochemical performance are explained from both bulk and grain boundary. Finally, at 700 °C, an anode-supported single cell with stoichiometric BZCYYb electrolyte demonstrates a maximum power density of 0.65 W cm−2, showing that the barium evaporation inhibition strategy is a powerful tool to fabricate PCFCs with high performance.

Proton Conduction and Electrochemical Performance of La/Pr co-Doped Ceria Electrolyte in Ceramic Fuel Cell

Proton Conduction and Electrochemical Performance of La/Pr co-Doped Ceria Electrolyte in Ceramic Fuel Cell

Experimental and Theoretical Study of Gallium–Doped Cerium Electrolyte for Fuel Cells

Experimental and Theoretical Study of Gallium–Doped Cerium Electrolyte for Fuel Cells

Influence of K+ substitution on germanium doped strontium silicate (Sr3-3xK3xSi3-3yGe3yO9-δ; 0 ≤ x ≤ 0.20, y=0.1) for application as solid electrolyte

The different alkali metal substitution strategies of the strontium meta-silicate based ion conductors have been enormously cross-examined to synthesize cost-effective novel electrolyte for Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFCs). In the present investigation, crystal structure, phase formation, microstructure, total conductivity and stability of the Potassium and Germanium incorporated Sr3Si3O9 based system, Sr3-3xK3xSi3-3yGe3yO9-δ (0 ≤ x ≤ 0.20, y = 0.1), is examined for their application as solid electrolyte for electrochemical devices such as ITSOFCs. These samples have been made via solid state reaction route. X-ray Rietveld refinement method was used for the structural investigation. Raman and FT-IR spectroscopy were performed to examine the phase formation and absorption of light by the bonds of vibrating molecules to provide molecular characteristics and vibrational modes of the molecules. The X-ray Photoelectron Spectroscopy study was used to validate the characteristic valence states of the constituting elements. Thermo-gravimetric analysis was performed to inspect the thermal stability and weight changes in the compounds during heating process. In the SEM and EDS mapping, an amorphous phase of K2Si2O5 can be visualized which seems to segregate along grain boundaries and this amorphous complexion augmented with K+ dopant concentration. AC Electrical impedance spectroscopy studies suggest that the ionic conduction in Sr3-3xK3xSi3-3yGe3yO9-δ could be from the oxide ions along with mobility of K+ ions of the glassy phase. In this study, we also tried to get the optimal doping condition with compositions to minimize numerous concern of the system.

Enhancing the Performance of the p-n Heterostructure Electrolyte for Solid Oxide Fuel Cells via A-Site-Deficiency Engineering.

Semiconductor ionic electrolytes are attracting growing interest for developing low-temperature solid oxide fuel cells (LT-SOFCs). Our recent study has proposed a p-n heterostructure electrolyte based on perovskite oxide BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY) and ZnO, achieving promising fuel cell performance. Herein, to further improve the performance of the heterostructure electrolyte, an A-site-deficiency strategy is used to solely modify BCFZY for regulating the ionic conduction and catalytic activity of the heterostructure. Two new electrolytes, B0.9CFZY-ZnO and B0.8CFZY-ZnO, were developed and systematically studied. The results show that the two samples gain improved ionic conductivity and auxiliary catalytic activity after A-site deficiency as a result of the increment of the surface and interface oxygen vacancies. The single cells with B0.9CFZY-ZnO and B0.8CFZY-ZnO exhibit enhanced peak power outputs at 450-550 °C compared to the cell based on B1.0CFZY-ZnO (typically, 745 and 795 vs 542 mW cm-2 at 550 °C). Particular attention is paid to the impact of A-site deficiency on the interface energy band alignment between BxCFZY and ZnO, which suggests that the p-n heterojunction effect of BxCFZY-ZnO for charge carrier regulation can be tuned by A-site deficiency to enable high proton transport while avoiding fuel cell current leakage. This study thus confirms the feasibility of A-site-deficiency engineering to optimize the performance of the heterostructure electrolyte for developing LT-SOFCs.

Nanocrystal Engineering of Thin-Film Yttria-Stabilized Zirconia Electrolytes for Low-Temperature Solid-Oxide Fuel Cells.

To overcome significantly sluggish oxygen-ion conduction in the electrolytes of low-temperature solid-oxide fuel cells (SOFCs), numerous researchers have devoted considerable effort to fabricating the electrolytes as thin as possible. However, thickness is not the only factor that affects the electrolyte performance; roughness, grain size, and internal film stress also play a role. In this study, yttria-stabilized zirconia (YSZ) was deposited via a reactive sputtering process to fabricate high-performance thin-film electrolytes. Various sputtering chamber pressures (5, 10, and 15 mTorr) were investigated to improve the electrolytes. As a result, high surface area, large grain size, and residual tensile stress were successfully obtained by increasing the sputtering pressure. To clarify the correlation between the microstructure and electrolyte performance, a YSZ thin-film electrolyte was applied to anodized aluminum oxide-supported SOFCs composed of conventional electrode materials which are Ni and Pt as the anode and the cathode, respectively. The thin-film SOFC with YSZ deposited at 15 mTorr exhibited the lowest ohmic resistance and, consequently, the highest maximum power density (493 mW/cm2) at 500 °C whose performance is more than five times higher than that of the cell with YSZ deposited at 5 mTorr (94.1 mW/cm2). Despite the basic electrode materials, exceptionally high performance at low operating temperature was achieved via controlling the single fabrication condition for the electrolyte.

Advanced Manufacturing of Unique Solid Oxide Fuel Cell Electrode and Electrolyte Microstructures through Aerosol Deposition

Development of various additive manufacturing technologies over the years has given an opportunity for highly customizable and unique structures to be fabricated with applications towards several different industries. For ceramic manufacturing, techniques such as direct ink writing (DIW), stereolithography (SLA), and fused deposition modeling (FDM) have been utilized to construct very complex structures. These technologies have also been developed for use towards solid oxide fuel cells (SOFCs) where they have been utilized to manufacture components greater than 200 µm in thickness. Some components of the SOFC such as the electrodes, electrolyte, and barrier layer are much smaller and consist of thicknesses from 1 µm to 50 µm. Along with the reduced thickness, the electrodes of a SOFC are often comprised of a composite material where the previously mentioned technologies struggle with achieving both the required high resolution and compositional change needed to manufacture these specific components. This project’s goal is to develop an additive manufacturing technique that suits both requirements for manufacturing the electrodes, electrolyte, and barrier layer of a SOFC.The technology that has been developed to complete the manufacturing of highly customizable electrodes along with the electrolyte and barrier layer is Aerosol Deposition. The Aerosol Deposition system contains several different elements that lead to consistently tailored microstructures for the various 3-D printed parts including the use of syringe pumps, an ultrasonic atomizing nozzle from Sonaer Ultrasonics, an infrared heater, and a flexible automation system. The ultrasonic atomizing nozzle is used to convert a stream of liquid into a fine mist via mechanical vibrations. The liquid that is supplied to our ultrasonic atomizing nozzle is low solids loading solvent-based suspension containing approximately 1 - 5 vol% of solids and polymer pore formers. Suspensions are supplied to the nozzle by mechanical pressure provided from a programmable syringe pump. This technology accompanied with a flexible automation system gives the potential for highly customizable and repeatable microstructures that can aid in evaluating variables associated with the different components of the SOFC.Development of the additive manufacturing system to fabricate the anode functional layer, electrolyte, barrier layer, and cathode active and current collector layers through an automated process have been studied. For the electrodes, a microstructure that contains approximately 30% - 40% porosity is suitable to enhance the electrochemical performance of the electrode. Sintering temperatures for the electrodes typically range from 1000 °C to 1300 °C which can typically densify the microstructure and restrict the amount of porosity present. To implement porosity within the microstructure poly(methyl methacrylate) was incorporated into electrode suspensions due to their ability to diffuse out of the electrode microstructure at temperatures of ~450 °C. The electrical and mechanical properties of the separate components have been characterized accordingly utilizing electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Acknowledgements: This work was performed in support of the US Department of Energy’s Solid Oxide Fuel Cell Program. The authors would like to acknowledge the WVU Shared Research Facilities (SRF) and thank Dr. Thomas Kalapos from Leidos Research Support Team for his assistance.

Electrochemical Study of Zinc Adsorption on Yttria-Stabilized Zirconia-Water Interfaces

Research has shown that zinc ions can mitigate the corrosion of the alloy materials in nuclear power plants in addition to reducing radiation contaminations. Understanding how zinc ions alter the interfacial structure of the alloy surface is therefore important in improving the life cycle of the materials and achieving higher burnups of the nuclear fuels. While the corrosion mitigation of zinc on nickel and stainless-steel alloys has been widely studied and reported, its effect on zirconium oxide surfaces, i.e. the oxide layer of zirconium alloys exposed to the aqueous solution, has rarely been reported. Meanwhile, zirconium oxide also serves as the solid oxide fuel cell electrolyte in energy storage. The study of the corrosion mitigation mechanism on zirconia could also contribute to the successful commercialization of SOFC technologies as cleaner and more efficient energy conversion electrochemical systems. In this work, we utilize the electrochemical techniques to study the interfacial structure changes under the influence of zinc ions on the yttria-stabilized zirconia (YSZ) surfaces on the (100), (110), and (111) orientations in contact with aqueous solution with and without externally applied electric potentials. The experimental measurements indicated the modification of the interfacial structures by zinc on (100) and (111) surfaces is strongly influenced by the applied external electric fields, while the modification of surface structure by zinc ions is not as evident on the (110) surface. Our study also showed that the Zn2+ adsorption layers on the oxide surfaces could be better preserved by tuning the electric potential on the oxide substrates towards the negative potentials.

Bioinspired supramolecular macrocycle hybrid membranes with enhanced proton conductivity

AbstractEnhancing the proton conductivity of proton exchange membranes (PEMs) is essential to expand the applications of proton exchange membrane fuel cells (PEMFCs). Inspired by the proton conduction mechanism of bacteriorhodopsin, cucurbit[n]urils (CB[n], where n is the number of glycoluril units, n = 6, 7, or 8) are introduced into sulfonated poly(ether ether ketone) (SPEEK) matrix to fabricate hybrid PEMs, employing a nature-inspired chemical engineering (NICE) methodology. The carbonyl groups of CB[n] act as proton-conducting sites, while the host–guest interaction between CB[n] and water molecules offers extra proton-conducting pathways. Additionally, the molecular size of CB[n] aids in their dispersion within the SPEEK matrix, effectively bridging the unconnected proton-conducting sulfonic group domains within the SPEEK membrane. Consequently, all hybrid membranes exhibit significantly enhanced proton conductivity. Notably, the SPEEK membrane incorporating 1 wt.% CB[8] (CB[8]/SPEEK-1%) demonstrates the highest proton conductivity of 198.0 mS·cm−1 at 60 °C and 100% relative humidity (RH), which is 228% greater than that of the pure SPEEK membrane under the same conditions. Moreover, hybrid membranes exhibit superior fuel cell performance. The CB[8]/SPEEK-1% membrane achieves a maximum power density of 214 mW·cm−2, representing a 140% improvement over the pure SPEEK membrane (89 mW·cm−2) at 50 °C and 100% RH. These findings serve as a foundation for constructing continuous proton-conducting pathways within membranes by utilizing supramolecular macrocycles as fuel cell electrolytes and in other applications.

Effects of pH and calcination temperature on gel-combustion synthesizability of BaZr0.8Y0.2O3 perovskite

Solid oxide fuel cells with their advantages such as high efficiency are now considered as efficient power generation equipment. Because of its proton conductivity, perovskite is used in ceramic fuel cell electrolyte, and the addition of dopant can improve its proton conductivity. In this research, BaZr0.8-xSrxY0.2O3 (x=0, 0.05, 0.1, and 0.15) perovskites were synthesized by gel-combustion method. Barium nitrate, zirconium nitrate, yttrium nitrate and strontium nitrate were used as raw materials. Based on DTA and TGA analyses, the required temperature for calcination was determined to be around 1000 °C. XRD and FTIR analyses were used to identify the phases. The synthesis was carried out under different conditions and the effects of pH and dopant percentage on the morphology and size of the particles were investigated by FESEM. The sintering process was completed at different temperatures and a relative density of 94% was obtained at 1470 °C.

Chemical Compatibility and Electrochemical Performance of Ba7Ta3.7Mo1.3O20.15 Electrolytes for Solid Oxide Fuel Cells.

Hexagonal perovskite-related oxides Ba7Ta3.7Mo1.3O20.15 (BTM) have recently been reported as promising electrolyte materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). In this work, sintering properties, thermal expansion coefficient, and chemical stability of BTM were studied. In particular, the chemical compatibilities of (La0.75Sr0.25)0.95MnO3±δ (LSM), La0.6Sr0.4CoO3 (LSC), La0.6Sr0.4Co0.2Fe0.8O3+δ (LSCF), PrBaMn2O5+δ (PBM), Sr2Fe1.5Mo0.5O6-δ (SFM), BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY), and NiO electrode materials with the BTM electrolyte were evaluated. The results show that BTM is highly reactive with these electrodes, in particular, BTM tends to react with Ni, Co, Fe, Mn, Pr, Sr, and La elements in the electrodes to form resistive phases, thus deteriorating the electrochemical properties, which has not been reported before.

Differences in Water Dynamics between the Hydrated Chitin and Hydrated Chitosan Determined by Quasi-Elastic Neutron Scattering.

Recently, it was reported that chitin and chitosan exhibited high-proton conductivity and function as an electrolyte in fuel cells. In particular, it is noteworthy that proton conductivity in the hydrated chitin becomes 30 times higher than that in the hydrated chitosan. Since higher proton conductivity is necessary for the fuel cell electrolyte, it is significantly important to clarify the key factor for the realization of higher proton conduction from a microscopic viewpoint for the future development of fuel cells. Therefore, we have measured proton dynamics in the hydrated chitin using quasi-elastic neutron scattering (QENS) from the microscopic viewpoint and compared the proton conduction mechanism between hydrated chitin and chitosan. QENS results exhibited that a part of hydrogen atoms and hydration water in chitin are mobile even at 238 K, and the mobile hydrogen atoms and their diffusion increase with increasing temperature. It was found that the diffusion constant of mobile protons is two times larger and that the residence time is two times faster in chitin than that in chitosan. In addition, it is revealed from the experimental results that the transition process of dissociable hydrogen atoms between chitin and chitosan is different. To realize proton conduction in the hydrated chitosan, the hydrogen atoms of the hydronium ions (H3O+) should be transferred to another hydration water. By contrast, in hydrated chitin, the hydrogen atoms can transfer directly to the proton acceptors of neighboring chitin. It is deduced that higher proton conductivity in the hydrated chitin compared with that in the hydrated chitosan is yielded by the difference of diffusion constant and the residence time by hydrogen-atom dynamics and the location and number of proton acceptors.

Effect of Synthetic Approaches and Sintering Additives upon Physicochemical and Electrophysical Properties of Solid Solutions in the System (CeO2)1−x(Nd2O3)x for Fuel Cell Electrolytes

Finely dispersed (CeO2)1−x(Nd2O3)x (x = 0.05, 0.10, 0.15, 0.20, 0.25) powders are synthesized via liquid-phase techniques based on the co-precipitation of hydroxides and co-crystallization of nitrates. The prepared powders are used to obtain ceramic materials comprising fluorite-like solid solutions with the coherent scattering region (CSR) of about 88 nm (upon annealing at 1300 °C) and open porosity in the range of 1–15%. The effect of the synthesis procedure and sintering additives (SiO2, ZnO) on physicochemical and electrophysical properties of the resulting ceramics is studied. The prepared materials are found to possess a predominantly ionic type of electric conductivity with ion transfer numbers ti = 0.96–0.71 in the temperature range of 300–700 °C. The conductivity in solid solutions follows a vacancy mechanism with σ700 °C = 0.48 × 10−2 S/cm. Physicochemical properties (density, open porosity, type and mechanism of electrical conductivity) of the obtained ceramic materials make them promising as solid oxide electrolytes for medium temperature fuel cells.

A Novel Lanthanum-based Solid Oxide Fuel Cell Electrolyte Composite with Enhanced Thermochemical Stability toward Perovskite Cathode

Lanthanum-based electrolytes for Solid Oxide Fuel Cells (SOFCs) gain extensive attention due to their lower activation energy and low-cost preparation to convert the energy stored in gaseous chemicals into electricity. In this context, a La9.33Si6O26-La0.8Sr0.2Ga0.8Mg0.2O2.55 (LSO-LSGM) SOFC electrolyte composite with various mass ratio LSO:LSGM (w/w) (5:0, 4:1, 3:2, 2:2, 2:3, 1:4) are successfully prepared for the first time using different LSO precursors with various mass target of 3g (LSO-LSGMA) and 5g (LSO-LSGMB), respectively. The result shows that the lower mass target in the synthesis of LSO induced formation of protoenstatite and coesite secondary phases on the composite of LSO-LSGM based on XRD, FTIR, and XPS analysis. The SEM micrograph suggests that agglomeration occurred more in LSO-LSGMA than in LSO-LSGMB. Generally, the composites signified high chemical stability on La0.8Sr0.2Co0.6Fe0.4O2.55 (LSCF) cathode based on the XRD analysis. The LSO-LSGMA composites which contained a high percentage of protoenstatite and coesite resulted in an additional peak of MgSi2Sr, especially for the sample with the mass ratio of 41 (LSO-LSGM41) suggesting that the chemical stability of LSO-LSGMA on LSCF cathode is much lower than LSO-LSGMB.

Green Nanocomposite Electrodes/Electrolytes for Microbial Fuel Cells—Cutting-Edge Technology

Fuel cell efficiency can be improved by using progressive electrodes and electrolytes. Green nanomaterials and green technologies have been explored for the manufacturing of high-performance electrode and electrolyte materials for fuel cells. Platinum-based electrodes have been replaced with green materials and nanocomposites using green fabrication approaches to attain environmentally friendly fuel cells. In this regard, ecological and sustainable electrode- and electrolyte-based membrane electrode assemblies have also been designed. Moreover, green nanocomposites have been applied to form the fuel cell electrolyte membranes. Among fuel cells, microbial fuel cells have gained research attention for the incorporation of green and sustainable materials. Hence, this review essentially focuses on the potential of green nanocomposites as fuel cell electrode and electrolyte materials and application of green synthesis techniques to attain these materials. The design of and interactions with nanocomposites have led to synergistic effects on the morphology, impedance, resistance, power density, current density, electrochemical features, proton conductivity, and overall efficiency. Moreover, we deliberate the future significance and challenges of the application of green nanocomposites in electrodes and electrolytes to attain efficient fuel cells.

Effect of aid-sintering additives in processing of solid oxide fuel cells electrolytes by tape casting

This research aims to investigate the processing of the LSGM (Lanthanum Gallate doped with Strontium and Magnesium) as electrolyte material and the effect of additives on reducing its sintering temperature of ceramic processed by tape casting method. For this purpose, we tested three different additives: Zn, V and Fe salts and oxides. The slurry composition and thermal treatment were the same, being the green tapes sintered at 1350 °C by 6 h. Both, Fe and Zn additives allow obtaining dense electrolytes, with microstructure similar to those obtained for LSGM without additives at 1500 °C. On the contrary, the LSGM treated with V and without additives at 1350 °C shows incomplete sintering. Despite Fe and Zn act as sintering aids, we found by XRD the formation of secondary phases between LSGM and Zn. Once Fe was selected as the best additive, we treated the tapes at 1350 °C during different times to determine the optimum microstructure. In order to assess if the addition of additives affects the transport properties of the electrolytes, we measured its electrical properties as a function of temperature by conductivity measurements and electrochemical impedance spectroscopy (EIS). These results were analyzed in relation to the grain size and grain boundary density studied by Scanning Electron Microscopy and cation distribution through the electrolyte by TOF-SIMS characterization.

Preparation and electrical properties of pyrochlore R2(ZrTi)O7 for solid oxide fuel cell electrolyte

The electrolyte conduction is a factor that influences the power density of Solid oxide fuel cells (SOFCs). Pyrochlore phase is a superstructure of the fluorite, and it has an empty 8b site completely under ordered pyrochlore structure. Therefore, the pyrochlore structure oxides of R2(ZrTi)O7 series were considered that they might have potential to become an excellent SOFC electrolyte material in this report. R2(ZrTi)O7 (R = La, Nd, Sm, Eu, Gd, Dy, Y, Ho, Er and Yb) were made by mixed with Li2O flux and heat treatment by 1000 and 1400 °C. The crystal structures identified by XRD are all pyrochlore structures. The lattice parameters were obtained through Rietveld refinement. Scanning electron microscopy was used to observe microstructure directly and verify the relative density result which was obtained by Archimedes method. The Electrical properties of electrochemical impedance spectroscopy (EIS) were measured to compare with lattice parameters. Dy2(ZrTi)O7 has the highest conductivity of 5.37(1) × 10−4 S·cm−1 at 700 °C and Nd2(ZrTi)O7 has the lowest activation energy of 0.59(2) eV in R2(ZrTi)O7 series. Dy2(ZrTi)O7 was combined with carbonate to become composite material for electrical property observation and comparing with Dy2(ZrTi)O7.

New Synthetic Route for Reaching Higher Phase Stabilization in LAMOX‐Based Electrolyte for Solid Oxide Fuel Cells

AbstractS‐substituted La2Mo2O9 were synthesized by a solid‐state procedure employing ammonium sulfate (NH4)2SO4 as a sulfur source. The synthesized powders were examined using X‐ray diffraction (XRD), thermogravimetric analysis (TGA), infrared, and Raman spectroscopies. The results divulged that the stabilization of the β‐La2Mo2O9 polymorph occurred in the interval of sulfur composition 0.1≤y≤0.6. This substitution generates a linear dwindling of the unit cell volume. The decomposition of all substituted samples started above 900 °C with a total weight loss linearly dependent on the sulfur content. Electrical studies confirmed that substituting S6+ for Mo6+ suppresses the phase transition of La2Mo2O9 and stabilizes the cubic polymorph down to ambient temperature. It was also remarkable that this substitution caused a decrease in the conductivity, and unfortunately, none of the tested compositions allowed exceeding the conductivity of La2Mo2O9. Infrared and Raman spectra confirmed the presence of the characteristic peaks of sulfates and molybdates groups.