Effects of various operating conditions and optimal ionomer-gradient distribution on temperature-driven water transport in cathode catalyst layer of PEMFC

Xu, Yiming; Chang, Guofeng; Fan, Ruijia; Cai, Tao

doi:10.1016/j.cej.2022.138924

Cited by 55 publications

(1 citation statement)

References 92 publications

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“…Excess water directly affects the performance and operational durability of PEMFC in different ways, including voltage drop caused by mass transfer limitations at high current densities, [9] voltage instability at low current densities, and unreliability during cold start. [10][11][12][13] For hydrogen-oxygen PEMFCs, the dead-ended anode and cathode (DEAC) operation strategy is usually adopted with an auxiliary gas purging scheme to achieve proper water management. [14,15] However, when the PEMFC is operated in the DEAC mode for a long time, the accumulation of liquid water can lead to electrochemical degradation of the catalyst caused by gas starvation of the fuel cell.…”

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Performance Evaluation and Degradation Mechanism for Proton Exchange Membrane Fuel Cell with Dual Exhaust Gas Recirculation

Liu

Chan

2023

Adv Energy and Sustain Res

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With growing energy and environmental challenges, clean energy technology has received worldwide attention and importance. [1] Proton exchange membrane fuel cells (PEMFCs) have the advantages of high-energy conversion efficiency, nonpolluting emissions, a wide range of fuel sources, low operating temperatures, and rapid startup steps. Therefore, PEMFCs can be used in transportation, stationary power stations, and underwater navigation. [2][3][4][5] Water generated at the cathode of a PEMFC can lead to fuel cell flooding if not purged efficiently, resulting in catalyst loss and degradation. [6][7][8] Therefore, water management is a key factor in improving the performance of PEMFCs. Excess water directly affects the performance and operational durability of PEMFC in different ways, including voltage drop caused by mass transfer limitations at high current densities, [9] voltage instability at low current densities, and unreliability during cold start. [10][11][12][13] For hydrogen-oxygen PEMFCs, the dead-ended anode and cathode (DEAC) operation strategy is usually adopted with an auxiliary gas purging scheme to achieve proper water management. [14,15] However, when the PEMFC is operated in the DEAC mode for a long time, the accumulation of liquid water can lead to electrochemical degradation of the catalyst caused by gas starvation of the fuel cell. [16] In addition, pressure fluctuations during gas purging can shock and damage the membrane electrode assembly (MEA) of PEMFCs, causing physical degradation. [17] An exhaust gas recirculation operating strategy is usually adopted for either anode or cathode systems to ensure the stable operation of the PEMFC. [18] Numerous studies on anode recirculation in PEMFCs have shown that different recirculation subsystems, such as recirculation pumps and ejectors, improve gas utilization and enable sufficient self-humidification. [19][20][21][22] Ejectors are structurally simple and do not suffer from parasitic power, but they are difficult to adapt to changes in the operating strategy of the PEMFC. [23] Recirculation pumps have the advantages of a wide operating range and simple control, but the efficiency of the entire system is low. [24] Much of the research on exhaust gas recirculation in fuel cells has focused on hydrogen recirculation, and only a few studies have been conducted on PEMFC systems with dual gas recirculation.The oxygen recirculation subsystem also plays a critical role in the economy of the entire PEMFC system, internal water balance of the stack, and lifetime of the MEA. Zhang et al. [25] established a dynamic mechanism model for the cathode recirculation of

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confidence: 99%

Performance Evaluation and Degradation Mechanism for Proton Exchange Membrane Fuel Cell with Dual Exhaust Gas Recirculation

Liu

Chan

2023

Adv Energy and Sustain Res

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Accelerating Hydrogen Desorption of Nickel Molybdenum Cathode via Copper Modulation for Pure‐Water‐Fed Hydroxide Exchange Membrane Electrolyzer

Yang,

Zhang,

Oliveira

et al. 2024

Adv Funct Materials

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The more sluggish kinetics of hydrogen evolution catalysts in base as compare to that in acid to some degree restricts hydrogen production performance of hydroxide exchange membrane electrolyzers, especially when using earth‐abundant catalysts. Here a ternary nickel–copper–molybdenum hydrogen evolution catalyst is reported that exhibits ≈5 times higher turnover frequency than without copper doping. The X‐ray absorption near‐edge structure and valence band spectrum demonstrate that the light doping of copper into nickel–molybdenum alloy modulates the electronic structure and downshifts the d‐band center, resulting in accelerated hydrogen desorption, as consolidated by H2 temperature programmed desorption and theoretical calculation. An electrolyzer employing this cathode catalyst and a nickel–iron anode, gives a current density of 1.7 A cm−2 at 2.0 V with a pure‐water feed through the anode, which outperforms the 2025 target proposed by the United States Department of Energy, and even is operated continuously for over 1000 h with a decay rate of as low as 0.5 mV h−1. Post‐mortem analysis discloses that hydroxide exchange ionomer migration is one of the key factors affecting long‐term durability. This work demonstrates the feasibility of a low‐cost, water‐fed hydroxide exchange membrane electrolyzer achieving industrial‐level performance and lifetime.

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Effects of Ionomer Content on Transient Response Characteristics of PEMFCs Under Dynamic Loading Conditions

Fan,

Chang,

2024

Springer Proceedings in Physics

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Effects of various operating conditions and optimal ionomer-gradient distribution on temperature-driven water transport in cathode catalyst layer of PEMFC

Cited by 55 publications

References 92 publications

Performance Evaluation and Degradation Mechanism for Proton Exchange Membrane Fuel Cell with Dual Exhaust Gas Recirculation

Performance Evaluation and Degradation Mechanism for Proton Exchange Membrane Fuel Cell with Dual Exhaust Gas Recirculation

Accelerating Hydrogen Desorption of Nickel Molybdenum Cathode via Copper Modulation for Pure‐Water‐Fed Hydroxide Exchange Membrane Electrolyzer

Effects of Ionomer Content on Transient Response Characteristics of PEMFCs Under Dynamic Loading Conditions

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