Progress and potential for symmetrical solid oxide electrolysis cells

Electrolysis is the core technology of power-to-X solutions, where X can be hydrogen, syngas, or synthetic fuels. Solid oxide electrolysis cells (SOECs) have received growing attention because unrivaled conversion efficiencies—a result favorable thermodynamics and kinetics at higher operating temperatures. SSOECs with same electrode materials as both anode cathode attracted lots their simple manufacturing process low cost. However, there has not been a comprehensive critical review to summarize recent progress so far. This timely, it gives overview development history, fundamental mechanisms, electrolyte materials, fabrication methods, potential applications. In end, we share our perspectives on remaining challenges solutions for driving this emerging field forward. will provide food thought researchers in jump-start beginners who want join exciting field. Recently, symmetrical solid (SSOECs) Moreover, narrow trouble chemical incompatibility thermal mismatching, also, these are more convenient practical applications without distinction anode. no paper, methods highlighted. Fuel-assisted that decrease overpotential other based introduced. Furthermore, prospects future research into included, some extent offering insights useful guidelines knowledge-based rational design better electrodes commercially viable SSOECs. With rapid social economy, demand energy from human beings further increased. Nowadays, consumption environmental pollution caused by traditional fossil-energy-based systems resulted series serious problems life.1Zaman K. Abd-el Moemen M. Energy consumption, carbon dioxide emissions economic development: evaluating alternative plausible hypothesis sustainable growth.Renew. Sust. Energy. Rev. 2017; 74: 1119-1130Crossref Scopus (164) Google Scholar Therefore, using clean renewable become common goal throughout world. 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It seen SOECs most type cost efficiency.Table 1Comparison cellsAlkaline (AEC)Polymer (PEMEC)Solid (SOEC)Temperature<100°C<150°C>500°CElectrolyteLiquid solutionPolymerCeramicCathodeMetalMetalPerovskiteAnodePtIr/PtCermet/perovskiteCharge carrierOH–H+O2?/H+Efficiency60%–75%70%–90%85%–100%Lifetime80,000 h60,000 hExpected value 40,000 hEnergy (KWh/Nm3)4.5–5.53.8–5.02.6–3.6Investment costs (€/kW)8001,0001,500AdvantageRich productsHigh Faradaic efficiencyRich current densityHigh efficiencyHigh efficiencyGood stabilityHigh efficiencyDisadvantageLow densityPoor efficiencyInsufficient stabilityPoor stabilitySimple productsChemical under temperatures Open table tab cleanly efficiently convert redundant (solar, wind, tidal energy) energy, which plays vital role peak fill grid, especially background vigorously developing energy. The schematic diagram shown Figure electrolyze H2O produce reduce emission, co-electrolyze H2O/CO2 syngas (H2/CO) production. Its product applied many fields steel plants, agriculture, aerospace, life support. For utilization, et al. reviewed four CO2-conversion-related processes SOEC technology. related mechanism each reaction elucidated concluded accordingly.20Li J.L. devices dense membranes utilization.Electrochem. Energ. 2021; 518-544Crossref (0) summarized detail low-carbon fuel. optimization performance, stability SOECs, material technological approaches, improvement all highlighted.21Zheng fuels.Electrochem. 508-517Crossref (5) existing technical directions proposed order maturity feasibility. also provided problem oxygen presented enhancing stability.22Chen S.P. Surface segregation electrodes: phenomena, properties.Electrochem. 3: 730-740Crossref (24) numerous advantages: range application, current, modular design, reliability. Overall, huge potential, lot high-quality work reviews emerged,23Zhang Song Co-electrolysis high-temperature advance cathodes.J. 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Deconvolution transmission-line-model impedances Ni-YSZ/YSZ/LSM mechanistic insights.Electrochim. Acta. 188: 240-253Crossref Scholar,30Tian Jia Pu Chi double perovskite-type NdBa0.5Ca0.5Co1.5Fe0.5O5+? reversible cell.J. 43: 108-115Crossref (18) preparation usually necessary prepare support tape-casting dry-pressing then screen-printing. addition, sintering complicated. first step sinter support, another sequentially required. complex process, least two steps required cells. More production mean consumption. asymmetric following disadvantages: cost, kinds electrode-electrolyte interfaces, mismatching electrolyte, 2A . If electrodes, (SSOECs),31Sreedhar Agarwal Goyal advances aspects cells.Electroanal. 848: 113315Crossref (35) A/B/A-type structures great advantages over conventional 2B. Compared SOEC, only one material. screen-printing simple, completed treatment. alleviate application Shao (SSOFCs) identical electrodes.32Su Tadé M.O. Progress electrodes.Adv. 2015; 5: 1500188Crossref date, lack suggest articulating differences various literature due would very helpful well providing development. Herein, SSOECs, discussing history mechanisms. We spotlight examples fuel-assisted As was O2 Mars NASA’s missions 1969.33Weissbart Smart Wydeven Oxygen reclamation electrolyte.Aerosp. Med. 1969; 40: 136-140PubMed 1980s, Isenberg means H2/CO O2.34Isenberg temperatures.Solid State Ionics. 1981; 431-437Crossref (252) After that, paid increasingly prominent crisis problems. Badding SSOFCs 2001,35Badding M.E. Brown Ketcham T.D. Julien D.J.S. Wusirika R.R. Performance Electrolyte Fuel Cells. Patents, 2003Google on, emerged.32Su Scholar,36Zhang H.M. Du ?wierczek High-performance SmBaMn2O5+? cell.Chem. 3784-3793Crossref (44) 37Fan Sun Bai Cheng Highly stable ferrite cells.ACS Appl. Interfaces. 23168-23179Crossref (23) 38Gu Ge PrBaMn2O5+? praseodymium nano-catalyst cells.Appl. 257: 117868Crossref (22) 39Bian Duan O'Hayre Chou K.-C. Ce-doped La0.7 Sr0.3Fe0.9Ni0.1O3?? direct hydrocarbon cells.J. 15253-15259Crossref 40Zhou Ni growth nanoparticles layered La0.8Sr1.2Fe0.9Co0.1O4?? active 28: 2981-2993Crossref 2010, investigated novel (Sr2Fe1.5Mo0.5O6-? [SFM]) electrical conductivity air environments, excellent redox promising SSOFCs. achieves density 835 mW·cm?2 230 900°C H2 wet CH4 fuel, respectively.41Liu Dong Xiao SOFCs.Adv. 2010; 22: 5478-5482Crossref (496) year, SSOEC H2O. report about SSOECs.42Liu Yang Sr2Fe1.5Mo0.5O6-? cells.Int. 35: 10039-10044Crossref (125) According electrolytes, divided categories: ion (O-SOECs) (H-SOECs). utilized transporting ions protons, should good migration ability. corresponding basic working principles illustrated Figures 3A 3B , respectively. Specifically, O-SOECs, molecules obtain electrons effect voltage, generating O2?. O2? anions driven electric Then, produced, released. H-SOECs, lose H+ O2. cations H2.43Bi Shafi Da'as E.H. Traversa Tailoring cathode–electrolyte interface boosting chemically proton-conducting electrolytes.Small. 14: 1801231Crossref (102) 44Huan Shi Tan Xia Peng Lu New, efficient, reliable 1761-1770Crossref (69) 45Jin Characteristics steam process.J. Electrochem. 2011; 158: B1217-B1223Crossref (30) SSOECs’ unique all-solid-state device characteristics make them ideal operation 700°C–1,000°C. On hand, conducive accelerate resistance, thus improving occupies large part total electrolysis, when nuclear reactor geothermal (?H) consists (?G) (T?S), Equation 1:?H=?G+T?S(Equation 1) relationship 4.46Kleiminger Kelsall Syngas (CO-H2) micro-tubular electrolysers.Electrochim. 179: 565-577Crossref (26) increases, heat demanded gradually decreases. Especially trend increasing noticeable reducing function transport isolate gas oxidizing gas. closely associated thickness difference types, categories electrolytes commonly used, namely O-SOECs H-SOECs. O-SOECsFor O-SOEC must meet conditions:47Singh Ghosh Aich Roy Low (LT-SOE): review.J. Power Sourc. 339: 103-135Crossref (118) Scholara.High negligible electronic conductivity;b.Good stability. maintain chemical, structural, dimensional atmosphere. They do react material;c.Need made avoid leakage;d.Low easy process. At present, O-SSOECs mainly include yttrium-stabilized zirconia (YSZ), 8 mol % yttria-doped (8YSZ), scandium-stabilized (SSZ), strontium- magnesium-doped lanthanum gallium (La0.9Sr0.1Ga0.8Mg0.2O3, LSGM). lowest 8YSZ suitable mechanical properties atmospheres. compatibility containing La Sr element weak, generate high-resistance phases La2Zr2O7 SrZrO3.48Kostogloudis G.C. Tsiniarakis Ftikos Chemical SOFC cathodes yttria stabilized zirconia.Solid 2000; 135: 529-535Crossref (91) Scholar,49Adijanto Küngas Bidrawn Gorte Vohs Stability infiltrated La0.8Sr0.2CoxFe1?xO3 Sm0.2Ce0.8O1.9 interlayers.J. Sources. 196: 5797-5802Crossref (52) YSZ medium (600°C–800°C) 0.003–0.03 S·cm?1, limits intermediate temperature.50Yamamoto Temperature Electrolytes Catalysts. Handbook John Wiley & Sons, Ltd., 2010Google minimum 700°C. SSZ achieved ionic than YSZ. doping amount 10 Sc composition highest, results superior densities operation. 1,000°C, times YSZ, temperature.51Laguna-Bercero Skinner Kilner scandia stabilised zirconia.J. 2009; 192: 126-131Crossref (104) strength lower YSZ; therefore, SSZ-based normally electrolyte-supported strengthened 1 Ce, enhances conductivity. SSZ-type drawn much past several years. Indeed, thoroughly studied stacks. abundance price prevents promotion. Although, CeO2-based temperatures, gadolinium-doped ceria (GDC) (Ce0.9Gd0.1O2-?). few studies try GDC conditions reported far.52Li Hua Zhong Charge transfer dynamics RuO2/perovskite nanohybrid enhanced electrocatalysis electrolyzers.Nano 57: 186-194Crossref (20) Ce4+ reduced Ce3+ atmosphere, resulting partial conductance eventually leads Faraday efficiency.53Sumi Suda Mori Blocking layer prevention leakage ceria-based electrolyte.Int. 4449-4455Crossref (29) almost (?1,500°C) remains challenging, restricts co-sintering possibilities. Taking account quality mixed conductor often added improve electrode. LSGM currently concerned conductivity, reach 0.17 S·cm?1 800°C.47Singh satisfactory perform