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A perspective on influences of cathode material degradation on oxygen transport resistance in low Pt PEMFC

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Nano Research 2023年第1期16卷 377-390页

作者： Huiyuan Li Xiaojing Cheng Xiaohui Yan shuiyun shen Junliang Zhang Institute of Fuel Cells School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China MOE Key Laboratory of Power&Machinery Engineering Shanghai Jiao Tong UniversityShanghai 200240China

A large-scale industrial application of proton exchange membrane fuel cells(PEMFCs)greatly depends on both substantial cost reduction and continuous durability ***,compared to effects of material degradation on apparent activity loss,little attention has been paid to influences on the phenomena of mass *** this review,influences of the degradation of key materials in membrane electrode assemblies(MEAs)on oxygen transport resistance in both cathode catalyst layers(CCLs)and gas diffusion layers(GDLs)are comprehensively explored,including carbon support,electrocatalyst,ionomer in CCLs as well as carbon material and hydrophobic polytetrafluoroethylene(PTFE)in *** is analyzed that carbon corrosion in CCLs will result in pore structure destruction and impact ionomer distribution,thus affecting both the bulk and local oxygen transport *** the catalyst degradation,an eventual decrease in electrochemical active surface area(ECSA)definitely increases the local oxygen transport resistance since a decrease in active sites will lead to a longer oxygen transport *** is also noted that problems concerning oxygen transport caused by the degradation of ionomer chemical structure in CCLs should not be *** cation contamination and chemical decomposition will change the structure of ionomer,thus worsening the local oxygen ***,it is found that the loss of carbon and PTFE in GDLs lead to a higher hydrophilicity,which is related to an occurrence of water flooding and increase in the oxygen transport resistance.

关键词： proton exchange membrane fuel cells(PEMFC) oxygen transport resistance degradation cathode catalyst layer gas diffusion layer

The use of phase-change cooling strategy in proton exchange membrane fuel cells:A numerical study

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Science China(Technological Sciences) 2021年第12期64卷 2762-2770页

作者： YAN XiaoHui PENG YiMeng shen YuanTing shen shuiyun WEI GuangHua YIN JieWei ZHANG JunLiang Institute of Fuel Cells School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China MOE Key Laboratory of Power Machinery and Engineering Shanghai Jiao Tong UniversityShanghai 200240China SJTU-Paris Tech Elite Institute of Technology Shanghai Jiao Tong UniversityShanghai 200240China

Thermal management is considered a critical issue in proton exchange membrane fuel cells(PEMFCs),since it not only influences the cell performance but also impacts PEMFC’s reliability and *** the ever-increasing power density of PEMFC,traditional cooling approaches including air cooling and water cooling become difficult to meet the demand for highpower heat ***,phase-change cooling is proposed for fuel cell application in this work,and the potential advantages are discussed and demonstrated via a mathematical model incorporating phase-change heat *** thermal management performance is evaluated by temperature uniformity,maximum temperature difference,and the cooling capacity to compare the difference between phase-change cooling and traditional methods,which demonstrates that phase-change cooling owns a greatly improved thermal management *** addition,a simple method to broaden the operating temperature of phase-change cooling based on one certain coolant is offered,which is pressurizing in the coolant channel to regulate the boiling temperature that could further improve the application feasibility of phase-change cooling strategy in fuel cells.

关键词： PEMFC thermal management cooling method temperature distribution phase-change cooling

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Facile controlled synthesis of hierarchically structured mesoporous Li_(4)Ti_(5)O_(12)/C/rGO composites as high-performance anode of lithium-ion batteries

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Frontiers in Energy 2022年第4期16卷 607-612页

作者： Cehuang FU shuiyun shen Ruofei WU Xiaohui YAN Guofeng XIA Junliang ZHANG Institute of Fuel Cells Key Laboratory of Power and Machinery EngineeringSchool of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

t In this paper,a facile strategy is proposed to controllably synthesize mesoporous Li_(4)Ti_(5)O_(12)/C nanocomposite embedded in graphene matrix as lithium-ion battery anode via the co-assembly of Li_(4)Ti_(5)O_(12)(LTO)precursor,GO,and phenolic *** obtained composites,which consists of a LTO core,a phenolic-resin-based carbon shell,and a porous frame constructed by rGO,can be denoted as LTO/C/rGO and presents a hierarchical *** to the advantages of the hierarchical structure,including a high surface area and a high electric conductivity,the mesoporous LTO/C/rGO composite exhibits a greatly improved rate capability as the anode material in contrast to the conventional LTO electrode.

关键词： Li_(4)Ti_(5)O_(12) phenolic-resin-based carbon mesoporous composite graphene

Influence of Fe on electrocatalytic activity of iron-nitrogendoped carbon materials toward oxygen reduction reaction

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Frontiers in Energy 2022年第5期16卷 812-821页

作者： Lin LI Cehuang FU shuiyun shen Fangling JIANG Guanghua WEI Junliang ZHANG Institute of Fuel Cells School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China SJTU-ParisTech Elite Institute of Technology Shanghai Jiao Tong UniversityShanghai 200240China

The development of highly active nitrogendoped carbon-based transition metal(M-N-C)compounds for the oxygen reduction reaction(ORR)in proton exchange membrane fuel cells(PEMFCs)greatly helps reduce fuel cell cost,thus rapidly promoting their commercial *** different M-N-C electrocatalysts,the series of Fe-N-C materials are highly favored because of their high ORR ***,there remains a debate on the effect of Fe,and rare investigations focus on the influence of Fe addition in the second heat treatment usually performed after acid leaching in the catalyst *** is thus very critical to explore the influences of Fe on the ORR electrocatalytic activity,which will,in turn,guide the design of Fe-N-C materials with enhanced ***,a series of Fe-N-C electrocatalysts are synthesize and the influence of Fe on the ORR activity are speculated both experimentally and *** is deduced that the active site lies in the structure of Fe-N4,accompanied with the addition of appropriate Fe,and the number of active sites increases without the occurrence of agglomeration ***,it is speculated that Fe plays an important role in stabilizing N as well as constituting active sites in the second pyrolyzing process.

关键词： oxygen reduction reaction Fe-N-C active sites Fe addition second heat treatment

Improved cyclic stability of LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2) cathode enabled by a novel CEI forming additive

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Frontiers in Energy 2024年第4期18卷 535-544页

作者： Zulipiya SHADIKE Yiming CHEN Lin LIU Xinyin CAI shuiyun shen Junliang ZHANG Institute of Fuel Cells School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The undesired side reactions at electrode/electrolyte interface as well as the irreversible phase evolution during electrochemical cycling significantly affect the cyclic performances of nickel-rich NMCs electrode *** optimization is an effective approach to suppress such an adverse side reaction,thereby enhancing the electrochemical ***,a novel boron-based film forming additive,tris(2,2,2-trifluoroethyl)borate(TTFEB),has been introduced to regulate the interphasial chemistry of LiNi0.8Mn0.1Co0.1O2(NMC811)cathode to improve its long-term cyclability and rate *** results of multi-model diagnostic study reveal that formation lithium fluoride(LiF)-rich and boron(B)containing cathode electrolyte interphase(CEI)not only stabilizes cathode surface,but also prevents electrolyte ***,homogenously distributed B containing species serves as a skeleton to form more uniform and denser CEI,reducing the interphasial ***,the Li/NMC811 cell with the TTFEB additive delivers an exceptional cycling stability with a high-capacity retention of 72.8%after 350 electrochemical cycles at a 1 C current rate,which is significantly higher than that of the cell cycled in the conventional electrolyte(59.7%).These findings provide a feasible pathway for improving the electrochemical performance of Ni-rich NMCs cathode by regulating the interphasial chemistry.

关键词： NMC811 cathode electrolyte interphase film forming additives cyclic stability

Thermal annealing synthesis of double-shell truncated octahedral Pt-Ni alloys for oxygen reduction reaction of polymer electrolyte membrane fuel cells

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Frontiers in Energy 2020年第4期14卷 767-777页

作者： Xiashuang LUO Yangge GUO Hongru ZHOU Huan REN shuiyun shen Guanghua WEI Junliang ZHANG Institute of Fuel Cells School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Shanghai Hydrogen Propulsion Technology Co. LtdShanghai 201804China SJTU-Paris Tech Elite Institute of Technology Shanghai Jiao Tong UniversityShanghai 200240China Institute of Fuel Cells School of Mechanical EngineeringMOE Key Laboratory for Power Machinery and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Shape-controlled Pt-Ni alloys usually offer an exceptional electrocatalytic activity toward the oxygen reduction reaction(ORR)of polymer electrolyte membrane fuel ceils(PEMFCs),whose tricks lie in welldesigned structures and surface *** this paper,a novel synthesis of truncated octahedral PtNi_(3.5) alloy catalysts that consist of homogeneous Pt-Ni alloy cores enclosed by NiO-Pt double shells through thermally annealing defective heterogeneous PtNi35 alloys is *** tracking the evolution of both compositions and morphologies,the outward segregation of both PtOv and NiO are first observed in Pt-Ni *** is speculated that the diffusion of low-coordination atoms results in the formation of an energetically favorable truncated octahedron while the outward segregation of oxides leads to the formation of NiO-Pt double *** is very attractive that after gently removing the NiO outer shell,the dealloyed truncated octahedral core-shell structure demonstrates a greatly enhanced ORR *** asobtained truncated octahedral Pt_(2.1)Ni core-shell alloy presents a 3.4-folds mass-specific activity of that for unannealed sample,and its activity preserves 45.4%after 30000 potential cycles of accelerated degradation test(ADT).The peak power density of the dealloyed truncated octahedral Pt2jNi core-shell alloy catalyst based membrane electrolyte assembly(MEA)reaches 679.8 mW/cm^(2),increased by 138.4 mW/cm^(2) relative to that based on commercial Pt/C.

关键词： dealloyed Pt-Ni alloys truncated octahedron double-shell thermal annealing oxygen reduction reaction(ORR)

Exploration of the oxygen transport behavior in non-precious metal catalyst-based cathode catalyst layer for proton exchange membrane fuel cells

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Frontiers in Energy 2023年第1期17卷 123-133页

作者： Shiqu CHEN Silei XIANG Zehao TAN Huiyuan LI Xiaohui YAN Jiewei YIN shuiyun shen Junliang ZHANG Institute of Fuel Cells School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China School of Vehicle and Mobility State Key Laboratory of Automotive Safety and EnergyTsinghua UniversityBeijing 100084China

High cost has undoubtedly become the biggest obstacle to the commercialization of proton exchange membrane fuel cells(PEMFCs),in which Pt-based catalysts employed in the cathodic catalyst layer(CCL)account for the major portion of the *** nonprecious metal catalysts(NPMCs)show appreciable activity and stability in the oxygen reduction reaction(ORR),the performance of fuel cells based on NPMCs remains unsatisfactory compared to those using Pt-based ***,most studies on NPMC-based fuel cells focus on developing highly active catalysts rather than facilitating oxygen *** this work,the oxygen transport behavior in CCLs based on highly active Fe-N-C catalysts is comprehensively explored through the elaborate design of two types of membrane electrode structures,one containing low-Pt-based CCL and NPMCbased dummy catalyst layer(DCL)and the other containing only the NPMC-based *** Zn-N-C based DCLs of different thickness,the bulk oxygen transport resistance at the unit thickness in NPMC-based CCL was quantified via the limiting current method combined with linear fitting ***,the local and bulk resistances in NPMC-based CCLs were quantified via the limiting current method and scanning electron microscopy,*** show that the ratios of local and bulk oxygen transport resistances in NPMCbased CCL are 80%and 20%,respectively,and that an enhancement of local oxygen transport is critical to greatly improve the performance of NPMC-based ***,the activity of active sites per unit in NPMCbased CCLs was determined to be lower than that in the Pt-based CCL,thus explaining worse cell performance of NPMC-based membrane electrode assemblys(MEAs).It is believed that the development of NPMC-based PEMFCs should proceed not only through the design of catalysts with higher activity but also through the improvement of oxygen transport in the CCL.

关键词： proton exchange membrane fuel cells(PEMFCs) non-precious metal catalyst(NPMC) cathode catalyst layer(CCL) local and bulk oxygen transport resistance

Potential-dependent insights into the origin of high ammonia yield rate on copper surface via nitrate reduction:A computational and experimental study

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Journal of Energy Chemistry 2024年第9期96卷 272-281页

作者： Yangge Guo Nannan Sun Liuxuan Luo Xiaojing Cheng Xueying Chen Xiaohui Yan shuiyun shen Junliang Zhang Institute of Fuel Cells School of Mechanical EngineeringMOE Key Laboratory of Power&Machinery EngineeringShanghai Jiao Tong UniversityShanghai 200240China Department of Chemical and Biological Engineering The Hong Kong University of Science and TechnologyClear Water BayKowloon 999077Hong KongChina Paris Elite Institute of Technology Shanghai Jiao Tong UniversityShanghai 200240China

Focusing on revealing the origin of high ammonia yield rate on Cu via nitrate reduction(NO3RR),we herein applied constant potential method via grand-canonical density functional theory(GC-DFT)with implicit continuum solvation model to predict the reaction energetics of NO3RR on pure copper surface in alkaline *** potential-dependent mechanism on the most prevailing Cu(111)and the minor(100)and(110)facets were established,in consideration of NO_(2)_(−),NO,NH_(3),NH_(2)OH,N_(2),and N_(2)O as the main *** computational results show that the major Cu(111)is the ideal surface to produce ammonia with the highest onset potential at 0.06 V(until−0.37 V)and the highest optimal potential at−0.31 V for ammonia production without kinetic obstacles in activation energies at critical *** other minor facets,the secondary Cu(100)shows activity to ammonia from−0.03 to−0.54 V with the ideal potential at−0.50 V,which requires larger overpotential to overcome kinetic activation energy *** least Cu(110)possesses the longest potential range for ammonia yield from−0.27 to−1.12 V due to the higher adsorption coverage of nitrate,but also with higher tendency to generate di-nitrogen *** evaluations on commercial Cu/C electrocatalyst validated the accuracy of our proposed *** most influential(111)surface with highest percentage in electrocatalyst determined the trend of ammonia *** specific,the onset potential of ammonia production at 0.1 V and emergence of yield rate peak at−0.3 V in experiments precisely located in the predicted potentials on Cu(111).Four critical factors for the high ammonia yield and selectivity on Cu surface via NO3RR are summarized,including high NO3RR activity towards ammonia on the dominant Cu(111)facet,more possibilities to produce ammonia along different pathways on each facet,excellent ability for HER inhibition and suitable surface size to suppress di-nitrogen species formation at high nitrate cove

关键词： Nitrate reduction to ammonia Copper surface Density functional theory Constant electrode potential method Experimental validation

Large specific surface area S-doped Fe–N–C electrocatalysts derived from Metal–Organic frameworks for oxygen reduction reaction

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Progress in Natural Science:Materials International 2020年第6期30卷 896-904页

作者： Xiaohui Yan Xiaolin Li Cehuang Fu Chen Lin Huanming Hu shuiyun shen Guanghua Wei Junliang Zhang Institute of Fuel Cells School of Mechanical Engineering Shanghai Jiao Tong University Central Research Institute Shanghai Electric Group SJTU-Paris Tech Elite Institute of Technology Shanghai Jiao Tong University MOE Key Laboratory of Power Machinery and Engineering Shanghai Jiao Tong University

It is highly desired but challenging to develop platinum group metal-free electrocatalysts for oxygen reduction reaction(ORR), which can promote the commercialization of fuel cell technology. To achieve this target, we report a one-step doping method to prepare S-doped Fe–N–C catalysts using zeolite imidazole framework(ZIF-8)and iron(III) thiocyanate(Fe(SCN)3) as precursor. Different from conventional doping approach, i.e. physical mixing, Fe(SCN)3is in-situ added during ZIF-8 formation which would encapsulate Fe(SCN)3molecules inside ZIF-8 to avoid structure destruction and create potential replacement of Zn ions by Fe ions to form uniform Fe–N4 complexes. As a result, the prepared S-doped Fe–N–C catalysts own large specific surface areas with a maximum value of 1326 m2g-1and a dual-scale porous structure that benefits mass transport. Significantly, the composition-optimized catalyst exhibits superior ORR activity in both 0.1 M HCl O4electrolyte and 0.1 M KOH electrolyte, in which the half-wave potential reaches 0.81 V and 0.92 V(vs. RHE), respectively. Remarkable stability is also attained, which loses 2 m V only after 10000 potential cycles in O2-saturated 0.1 M HCl O4and remains almost constant in O2-saturated 0.1 M KOH, surpassing commercial Pt/C catalyst in both acidic and alkaline medium.

关键词： Fuel cells Oxygen reduction reaction Non-precious metal catalyst Co-doping Acidic and alkaline medium