Electrochemical insights into performance enhancement of protonic ceramic fuel cells with Ba(Zr,Ce,Y)O_3-δ electrolyte

Abstract

The burgeoning field of protonic ceramic fuel cells (PCFCs) is characterized by significant scientific and technological advancements, particularly with the incorporation of BaZr_0.1Ce_0.7Y_0.2O_3-δ (BZCY) as a proton-conducting electrolyte. In the modern energy materials field, the challenge is not only developing new materials but also understanding new mechanisms and gaining an in-depth understanding of their interaction with energy devices. To drive significant advances, it is crucial to address both material-specific challenges and device-level innovations that unlock the full potential of these materials. In this work, we introduced an electrochemical proton injection approach to successfully improve BZCY proton conductivity by an order of magnitude. We also delve into the electrode and interface kinetic processes and their interplay in proton transport within the bulk and grain boundary of the BZCY-electrolyte of PCFCs. These approaches have led to state-of-the-art advances, achieving a proton conductivity of 0.19 S cm^-1 and a device peak power density of 943 mW cm^-2 at 530 °C. Our results demonstrate that the bulk and grain boundary conduction significantly mitigate polarization losses by four to five orders of magnitude, thereby accelerating the kinetic process and further contributing to improved PCFC performance. The appearance of peaks and alterations in relaxation times further illustrate the electrode reactions and proton transport mechanisms. Beyond providing a comprehensive assessment of current technological progress, this article underscores the transformative potential of electrochemical processes in PCFCs, positioning them as a cornerstone in the quest for sustainable and clean energy technologies.

Keywords

Protonic ceramic fuel cell / electrochemical proton injection / ionic conduction / electrolyte / hydrogen oxidation reaction / oxygen reduction reaction

References

[1] Nasani N,Antunes I,Fagg DP.Electrochemical behaviour of Ni-BZO and Ni-BZY cermet anodes for protonic ceramic fuel cells (PCFCs) - A comparative study.Electrochim Acta2015;154:387-96

[2] Duan C,Zhu H.Highly durable, coking and sulfur tolerant, fuel-flexible protonic ceramic fuel cells.Nature2018;557:217-22

[3] Choi S,Liang Y.Exceptional power density and stability at intermediate temperatures in protonic ceramic fuel cells.Nat Energy2018;3:202-10

[4] Iwahara H,Uchida H.Proton conduction in sintered oxides and its application to steam electrolysis for hydrogen production.Solid State Ion1981;3-4:359-63

[5] Iwahara H,Ono K.Proton conduction in sintered oxides based on BaCeO₃.J Electrochem Soc1988;135:529-33

[6] Murakami T,Yashima M.High proton conductivity in Ba₅Er₂Al₂ZrO₁₃, a hexagonal perovskite-related oxide with intrinsically oxygen-deficient layers.J Am Chem Soc2020;142:11653-7

[7] Wei T,Chen Y,Liu M.Promising proton conductor for intermediate-temperature fuel cells: Li_13.9Sr_0.1Zn(GeO₄)₄.Chem Mater2017;29:1490-5

[8] Garcia-Barriocanal J,Varela M.Colossal ionic conductivity at interfaces of epitaxial ZrO₂: Y₂O₃/SrTiO₃ heterostructures.Science2008;321:676-80

[9] Xing Y,Li L.Proton shuttles in CeO₂/CeO_2-δ core-shell structure.ACS Energy Lett2019;4:2601-7

[10] Chen G,Luo Y.Advanced fuel cell based on new nanocrystalline structure Gd_0.1Ce_0.9O₂ electrolyte.ACS Appl Mater Interfaces2019;11:10642-50

[11] Liu X,Tong Y.Li effects on layer-structured oxide Li_xNi_0.8Co_0.15Al_0.05O_2-δ: improving cell performance via on-line reaction.Electrochim Acta2019;295:325-32

[12] Duan C,Zhu H.Highly efficient reversible protonic ceramic electrochemical cells for power generation and fuel production.Nat Energy2019;4:230-40

[13] Pei K,Xu K.Surface restructuring of a perovskite-type air electrode for reversible protonic ceramic electrochemical cells.Nat Commun2022;13:2207 PMCID:PMC9033792

[14] Ni M.Fuel cells that operate at 300° to 500 °C.Science2020;369:138-9

[15] Zhou X,Wang R,Yun S.Advances in lithium-ion battery materials for ceramic fuel cells.Energy Mater2022;2:200041

[16] Chen G,Luo Y.Investigation of layered Ni_0.8Co_0.15Al_0.05LiO₂ in electrode for low-temperature solid oxide fuel cells.Int J Hydrogen Energy2018;43:417-25

[17] Yuan K,Lu X,Zhu B.A new technology for spraying advanced low-temperature (300 ~ 600 °C) solid oxide fuel cells. 2017, pp. 132-7.

[18] He Y,Zhang X.Mechanism for major improvement in SOFC electrolyte conductivity when using lithium compounds as anode.ACS Appl Energy Mater2020;3:4134-8

[19] Xia C,Wang B.Mixed-conductive membrane composed of natural hematite and Ni_0.8Co_0.15Al_0.05LiO_2-δ for electrolyte layer-free fuel cell.Adv Mater Lett2017;8:114-21

[20] Park HC.Bimetallic (Ni-Fe) anode-supported solid oxide fuel cells with gadolinia-doped ceria electrolyte.J Power Sources2009;186:133-7

[21] Yu Y,Wang H.Synergistic proton and oxygen ion transport in fluorite oxide-ion conductor.Energy Mater Adv2024;5:0081

[22] Zhang Y,Yan M.Reconstruction of relaxation time distribution from linear electrochemical impedance spectroscopy.J Power Sources2015;283:464-77

[23] Wang J,Li W.Insight into the origin of pseudo peaks decoded by the distribution of relaxation times/differential capacity method for electrochemical impedance spectroscopy.J Electroanal Chem2022;910:116176

[24] Wang J,Wang J.Shape factor optimisation for the distribution of relaxation times to better deconvolute electrochemical impedance spectra.J Electroanal Chem2024;962:118272

[25] Norbya T.Proton conduction in oxides.Solid State Ion1990;40-1:857-62

[26] Uchida H,Iwahara H.Polarization at Pt electrodes of a fuel cell with a high temperature-type proton conductive solid electrolyte.J Appl Electrochem1985;15:93-7

[27] He F,Peng R.Cathode reaction models and performance analysis of Sm_0.5Sr_0.5CoO_3-δ-BaCe_0.8Sm_0.2O_3-δ composite cathode for solid oxide fuel cells with proton conducting electrolyte.J Power Sources2009;194:263-8

[28] Duan C,Sullivan N.Proton-conducting oxides for energy conversion and storage.Appl Phys Rev2020;7:011314

[29] Hayd J.Detailed electrochemical study on nanoscaled La_0.6Sr_0.4CoO_3-δ SOFC thin-film cathodes in dry, humid and CO₂-containing atmospheres.J Electrochem Soc2013;160:F1197-206

[30] Zhang Y,Li M,Ni M.A high-precision approach to reconstruct distribution of relaxation times from electrochemical impedance spectroscopy.J Power Sources2016;308:1-6

[31] Wang X,Zhang T.Charge-transfer modeling and polarization DRT analysis of proton ceramics fuel cells based on mixed conductive electrolyte with the modified anode-electrolyte interface.ACS Appl Mater Interfaces2018;10:35047-59

[32] Li M,Yang W.Mechanism for the enhanced oxygen reduction reaction of La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ by strontium carbonate.Phys Chem Chem Phys2016;19:503-9

[33] Wang J,Zang H.BaZr_0.1Fe_0.9-xNi_xO_3-δ cubic perovskite oxides for protonic ceramic fuel cell cathodes.Int J Hydrogen Energy2022;47:9395-407

[34] Yu S,Yang L.Enhancing the sinterability and electrical properties of BaZr_0.1Ce_0.7Y_0.2O_3-δ proton-conducting ceramic electrolyte.J Am Ceram Soc2021;104:329-42

[35] Guo R,Guan R.Sn-Dy-Cu triply doped BaZr_0.1Ce_0.7Y_0.2O_3-δ: a chemically stable and highly proton-conductive electrolyte for low-temperature solid oxide fuel cells.ACS Sustain Chem Eng2022;10:5352-62

[36] Zhu B,Xia C.A nanoscale perspective on solid oxide and semiconductor membrane fuel cells: materials and technology.Energy Mater2022;1:100002

[37] Wan S,Wang H,Zhu B.Exceptionally high proton conductivity in Eu₂O₃ by proton-coupled electron transfer mechanism.iScience2024;27:108612 PMCID:PMC10765062

[38] Wang S,Li Y,Yang J.Separating electronic and ionic conductivity in mix-conducting layered lithium transition-metal oxides.J Power Sources2018;393:75-82

[39] Moździerz M,Stępień A.Mixed ionic-electronic transport in the high-entropy (Co,Cu,Mg,Ni,Zn)_1-xLi_xO oxides.Acta Mater2021;208:116735

[40] Qiao Z,Cai Y.Electrochemical and electrical properties of doped CeO₂-ZnO composite for low-temperature solid oxide fuel cell applications.J Power Sources2018;392:33-40