A composite cathode with undoped LaFeO₃ for protonic ceramic fuel cells

Choi, J.,Kim, B.,Song, S.H.,Park, J.S. Pergamon Press ; Elsevier Science Ltd 2016 International journal of hydrogen energy Vol.41 No.22

<P>A composite cathode for protonic ceramic fuel cells was developed using undoped, electronically conductive LaFeO3 (LF) and proton conductive Ba(Ce0.51Zr0.3Y0.15Zn0.04)O-3-8 (BCZY). A comparison of the cathodic performance of Sr-doped LaFeO3 (LSF), a material with both electronic and oxygen-ion conductivity, with that of the undoped LF revealed the effect of oxygen-ion conductivity on the cathodic performance in protonic ceramic fuel cells (PCFCs). The cathodic performances of the LF/BCZY and LSF/BCZY composites were similar; this implied that the oxygen-ion conductivity had a minimal contribution toward the cathodic performance in PCFCs, unlike the case with oxygen-ion conducting fuel cells. Based on these results, an alternative electrochemical reaction mechanism was proposed for producing water at the cathode using protons and oxygen. (C) 2016 Hydrogen Energy Publications. LLC. Published by Elsevier Ltd. All rights reserved.</P>

Operation Protocols To Improve Durability of Protonic Ceramic Fuel Cells

Park, Ka-Young,Kim, You-Dong,Lee, John-In,Saqib, Muhammad,Shin, Ji-Seop,Seo, Yongho,Kim, Jung Hyun,Lim, Hyung-Tae,Park, Jun-Young American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.1

<P>To develop reliable and durable protonic ceramic fuel cells (PCFCs), the impacts of the operation protocols of PCFCs on the cell durability are investigated through analyses of the main degradation mechanisms. We herein propose three appropriately designed control protocols, including cathode air depletion, shunt current, and fuel cell/electrolysis cycling, to fully circumvent the operating-induced degradation of PCFCs. For this purpose, anode-supported cells, comprised of a NiO-BaCe<SUB>0.7</SUB>Zr<SUB>0.1</SUB>Y<SUB>0.1</SUB>Yb<SUB>0.1</SUB>O<SUB>3−δ</SUB> anode, BaCe<SUB>0.7</SUB>Zr<SUB>0.1</SUB>Y<SUB>0.1</SUB>Yb<SUB>0.1</SUB>O<SUB>3−δ</SUB> electrolyte, and NdBa<SUB>0.5</SUB>Sr<SUB>0.5</SUB>Co<SUB>1.5</SUB>Fe<SUB>0.5</SUB>O<SUB>5+δ</SUB>-Nd<SUB>0.1</SUB>Ce<SUB>0.9</SUB>O<SUB>2−δ</SUB> composite cathode, are prepared, and their long-term performances are evaluated under a galvanostatic condition of 0.5 A·cm<SUP>-2</SUP> at 650 °C. The cell voltages of the protected cells using the operation protocols to prevent performance degradation are stably maintained under the applied current density for more than 1200 h without any noticeable degradation, whereas the performance of the unprotected cell gradually decreased with time, and the decay ratio was 14.9% over 850 h. The significant performance decay of the unprotected cell is strongly associated with the cathode degradation phenomenon, which was caused by the water vapor continuously produced during the electrochemical reactions. Hence, the performance recovery of the PCFCs with the operation protocols is achieved by incrementally decreasing the cathode potential (close to a value of zero) to minimize the effect of high <I>P</I><SUB>H</SUB><SUB><SUB>2</SUB></SUB><SUB>O</SUB> and <I>P</I><SUB>O</SUB><SUB><SUB>2</SUB></SUB> during the PCFC operations.</P> [FIG OMISSION]</BR>

High-Performance Protonic Ceramic Fuel Cells with Thin-Film Yttrium-Doped Barium Cerate–Zirconate Electrolytes on Compositionally Gradient Anodes

Bae, Kiho,Lee, Sewook,Jang, Dong Young,Kim, Hyun Joong,Lee, Hunhyeong,Shin, Dongwook,Son, Ji-Won,Shim, Joon Hyung American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.14

<P>In this study, we used a compositionally gradient anode functional layer (AFL) consisting of Ni-BaCe0.5Zr0.35Y0.15O3-delta (BCZY) with increasing BCZY contents toward the electrolyte -anode interface for high-performance protonic ceramic fuel cells. It is identified that conventional homogeneous AFLs fail to stably accommodate a thin film of BCZY electrolyte. In contrast, a dense 2 mu m thick BCZY electrolyte was successfully deposited onto the proposed gradient AFL with improved adhesion. A fuel cell containing this thin electrolyte showed a promising maximum peak power density of 635 mW cm(-2) at 600 degrees C, with an open-circuit voltage of over 1 V. Impedance analysis confirmed that minimizing the electrolyte thickness is essential for achieving a high power output, suggesting that the anode structure is important in stably accommodating thin electrolytes.</P>

반응가스 분압에 따른 박막 프로톤 전도성 고체산화물 연료전지의 구동 특성 분석 연구

배기호(Kiho Bae),장동영(Dong Young Jang),네오 케 체안(Ke Chean Neoh),구준모(Junmo Koo),박석원(Suk Won Park),손지원(Ji-Won Son),심준형(Joon Hyung Shim) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

According to partial pressure of reactant gases, electrochemical performance variation of thin film-protonic ceramic fuel cells (PCFCs) is investigated during fuel cell operation. Concentrations of hydrogen and air are changed from 100% to 50% at the anode and cathode sides, respectively, by controlling flow rates with nitrogen valance. Fuel cell performances were collected each partial pressure conditions at an operating temperature of 600 ℃. Ohmic and polarization resistances were estimated through electrochemical impedance spectroscopy analysis. From the performance comparison, a noticeable result is identified that PCFCs strongly depend on hydrogen partial pressure rather than oxygen partial pressure on it, which is opposite trend of the conventional solid oxide fuel cells.

고체산화물 연료전지와 양성자 전도성 세라믹 물질의 응용

정동휘(Donghwi Jeong),김건태(Guntae Kim) 한국세라믹학회 2018 세라미스트 Vol.21 No.4

Solid oxide fuel cells (SOFCs) are promising eco-friendly energy conversion system due to their high efficiency, low pollutant emission and fuel flexibility. High operating temperatures, however, leads to the crucial drawbacks such as incompatibility between the components and high thermal stress. Proton-conducting ceramic fuel cells (PCFCs) with proton-conducting oxide (PCO) materials are new types of fuel cells that can solve the problems of conventional SOFCs. Many studies have been proceeded to improve the performance of electrolytes and electrodes, and triple conductive oxides (TCOs) have attracted significant attention as high performance PCFC electrodes.

Cerium Pyrophosphate-based Proton-conducting Ceramic Electrolytes for Low Temperature Fuel Cells

Singh, Bhupendra,Kim, Ji-Hye,Im, Ha-Ni,Song, Sun-Ju The Korean Ceramic Society 2014 한국세라믹학회지 Vol.51 No.4

Acceptor-doped cerium pyrophosphates have shown significant proton conductivity of > $10^{-2}Scm^{-1}$ in the range of $100-300^{\circ}C$ and are considered promising candidates for use as electrolytes in proton-conducting, ceramic electrolyte fuel cells (PCFCs). But, cerium pyrophosphates themselves do not have structural protons, and protons incorporate into their material bulk only as impurities on exposure to a hydrogen-containing atmosphere. However, proton incorporation and proton conduction in these materials are expected to be affected by factors such as the nature (ionic size and charge) and concentration of the aliovalent dopant, processing history (synthesis route and microstructure), and the presence of residual phosphorous phosphate ($P_mO_n$) phases. An exact understanding of these aspects has not yet been achieved, leading to large differences in the magnitude of proton conductivity of cerium pyrophosphates reported in various studies. Herein, we systematically address some of these aspects, and present an overview of factors affecting proton conductivity inacceptor-doped $CeP_2O_7$.

Cerium Pyrophosphate-based Proton-conducting Ceramic Electrolytes for Low Temperature Fuel Cells

Bhupendra Singh,김지혜,임하니,송선주 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.4

Acceptor-doped cerium pyrophosphates have shown significant proton conductivity of >10-2 S cm-1 in the range of 100 - 300oCand are considered promising candidates for use as electrolytes in proton-conducting, ceramic electrolyte fuel cells (PCFCs). But,cerium pyrophosphates themselves do not have structural protons, and protons incorporate into their material bulk only as impuritieson exposure to a hydrogen-containing atmosphere. However, proton incorporation and proton conduction in these materialsare expected to be affected by factors such as the nature (ionic size and charge) and concentration of the aliovalent dopant, processinghistory (synthesis route and microstructure), and the presence of residual phosphorous phosphate (PmOn) phases. An exactunderstanding of these aspects has not yet been achieved, leading to large differences in the magnitude of proton conductivity ofcerium pyrophosphates reported in various studies. Herein, we systematically address some of these aspects, and present anoverview of factors affecting proton conductivity inacceptor-doped CeP2O7.

SiO₂ ceramic nanoporous substrate-reinforced sulfonated poly(arylene ether sulfone) composite membranes for proton exchange membrane fuel cells

Seol, J.H.,Won, J.H.,Yoon, K.S.,Hong, Y.T.,Lee, S.Y. Pergamon Press ; Elsevier Science Ltd 2012 International journal of hydrogen energy Vol.37 No.7

Porous substrate-reinforced composite membranes have been extensively investigated due to their promising application to proton exchange membrane fuel cells (PEMFC). In this study, we develop a new ceramic-based reinforcing porous substrate, which consists of hygroscopic silica (SiO<SUB>2</SUB>) nanoparticles interconnected by 3-glycidoxypropyltrimethoxysilane (GPTMS)-based silicate binders and a poly(paraphenylene terephthalamide) (PPTA) nonwoven support. This unusual ceramic substrate is featured with the strong mechanical strength, well-developed nanoporous structure (i.e., nanosized interstitial voids formed between the close-packed SiO<SUB>2</SUB> nanoparticles), high hydrophilicity, and more notably, good water retention capability. The nanostructured pores of the ceramic substrate are subsequently impregnated with sulfonated poly(arylene ether sulfone) (SPAES, degree of sulfonation = 49.3%). In comparison to a pristine SPAES membrane, the ceramic substrate-reinforced SPAES composite membrane offers the significantly improved dimensional change and also effectively mitigates the steep decline of proton conductivity at low humidity conditions, which is further discussed by considering the state of water in the reinforced composite membrane.

Performance of Proton-conducting Ceramic-electrolyte Fuel Cell with BZCY40 electrolyte and BSCF5582 cathode

Lim, Dae-Kwang,Kim, Ji-Hye,Chavan, Archana U.,Lee, Tae-Ryong,Yoo, Young-Sung,Song, Sun-Ju Elsevier 2016 CERAMICS INTERNATIONAL Vol.42 No.3

<P><B>Abstract</B></P> <P>In the present research, Proton conducting Ceramic electrolyte Fuel Cell (PCFC) has been fabricated with BaZr<SUB>0.4</SUB>Ce<SUB>0.45</SUB>Y<SUB>0.15</SUB>O<SUB>3−<I>δ</I> </SUB> electrolyte, NiO–BaZr<SUB>0.4</SUB>Ce<SUB>0.45</SUB>Y<SUB>0.15</SUB>O<SUB>3</SUB> <SUB>−<I>δ</I> </SUB> as anode and Ba<SUB>0.5</SUB>Sr<SUB>0.5</SUB>Co<SUB>0.8</SUB>Fe<SUB>0.2</SUB>O<SUB>3</SUB> <SUB>−<I>δ</I> </SUB> as a cathode material. The effects of anodic and cathodic gas flow rates and partial pressures on PCFC performance are studied by varying the gas flow rates between 50 and 200sccm while partial pressures between 0.25 and 1atm at one electrode by keeping constant gas flow rate and partial pressure at another electrode. The different electrode processes occurring at the electrodes and electrode/electrolyte interfaces are analyzed by electrochemical impedance spectroscopy. It is observed that gas flow rate doesn’t affect more on the fuel cell performance while increase in gas partial pressure changes the performance of PCFC. The variation in cathodic <I>p</I>O<SUB>2</SUB> shows that the oxygen dissociation and charge transfer at cathode electrode are the major contributors toward overall electrode polarization resistance. A peak power density of ~0.80W/cm<SUP>−2</SUP> is achieved at 700°C with 200sccm of wet H<SUB>2</SUB> and air. The stability of the PCFC is also studied under CO<SUB>2</SUB> condition and it has shown stable performance without any degradation.</P>

PrBa0.5Sr0.5Co1.5Fe0.5O5+δ composite cathode in protonic ceramic fuel cells

Im Seunghyeok,Lee Jong-Ho,지호일 한국세라믹학회 2021 한국세라믹학회지 Vol.58 No.3

The need for high performance of protonic ceramic fuel cells (PCFCs) has created significant interest in highly active cathode materials. Since a major charge carrier in PCFCs is proton, the use of triple conducting oxide (TCO) materials, in which oxygen ion, hole, and proton can be transported, is expected to improve the electrochemical performance of PCFCs. In this study, the applicability of PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ (PBSCF) cathode, known as TCO material, in PCFCs is investigated. The chemical compatibility of PBSCF with BaCe 0.55 Zr 0.3 Y 0.15 O 3–δ (BCZY3) proton-conducting electrolyte at high temperature is examined by XRD. To improve the interfacial structure between BCZY3 electrolyte and single-phase PBSCF cathode, PBSCF-BCZY3 composite layer is inserted between both layers. The optimization of sintering temperature and thickness of cathode results in the successful fabrication of PCFCs, exhibiting low ohmic resistance and high electrochemical performance.