Cell Performance Stability Research Articles

Compact Solid Electrolyte Interface Realization Employing Surface-Modified Fillers for Long-Lasting, High-Performance All-Solid-State Li-Metal Batteries.

The implementation of polymer-based Li-metal batteries is hindered by their low coulombic efficiency and poor cycling stability attributed to continuous electrolyte decomposition. Enhancement of the solid electrolyte interface (SEI) stability is key to mitigating electrolyte decomposition. This study proposes surface-functionalized silica mesoball fillers to fabricate a composite polymer electrolyte (MSBM-CPE). As a result of surface modification, the polyethylene oxide matrix benefits from the uniform distribution of the filler, which provides a large surface area and Lewis acid sites. Molecular dynamics simulations reveal that the dissociation energy of lithium bis(trifluoromethanesulfonyl)imide in the filler is fourfold higher (-1.95eV) than that of the filler-free electrolyte. Consequently, the MSMB-CPE diffusivity is 30 times higher than its filler-free counterpart. The MSMB-CPE of ionic conductivity of 1.16 × 10-2Scm-1 @60 °C and a venerable Li-ion transference number of 0.81. The excellent compatibility of MSMB-CPE with the Li anode is demonstrated by its stable symmetric cell performance under high current density (200µA cm-2 @60 °C) for over 5000h. Approximately 85.60% retention capacity of the [Li/MSMB-CPE/LiFePO4] full cell after 700 cycles. Furthermore, compositional analysis reveals that the SEI layer in MSMB-CPE is smooth with fewer by-products at the electrolyte/Li interface.

Exploration of proton exchange membrane fuel cell performance under dynamic humidification conditions

Controlling the relative humidity is crucial for improving fuel cell performance in self-humidifying fuel cells. In light of this, this study investigates the influence of humidity variation on Proton Exchange Membrane Fuel Cells (PEMFC) performance through single-cell testing and a two-dimensional two-phase model. In the experiment, different humidity conditions are achieved by adjusting the inlet air temperature, and the effect of relative humidity on cell performance is observed. The research findings indicate that as the relative humidity increases, the performance of the fuel cell gradually improves. Increasing humidity reduces voltage fluctuations, particularly at low flow rates, demonstrating more stable performance. Under different humidity conditions, when the inlet air flow rate exceeds a certain value, the voltage non-uniformity of the cell remains within 1, indicating insignificant voltage fluctuations, attributed to the effects of inlet air flow rate on performance improvement and alleviation of flooding phenomena. Analysis of the two-dimensional two-phase model reveals that liquid water impedes gas mass transfer, with gas transport under the rib particularly affected. Increasing the flow rate helps remove liquid water under the rib, promoting cell performance stability.

Advanced composite membranes based on multifunctional fillers constructed by covalently linking phosphotungstic acid with mesoporous carbon nitride for high-performance and durable fuel cell under low humidity

Two-dimensional (2D) nanosheets possessing large specific surface area and high aspect ratio can serve as proton-conduction accelerators owing to their continuous proton transport feature. Herein, phosphotungstic acid (HPW) is chemically grafted to mesoporous carbon nitride nanosheets (CN) via a hydrothermal process to produce water-insoluble HPW/CN (PCN) nanofillers, and subsequently embedded into sulfonated poly(arylene ether sulfone) (SPAES) to develop a long-range proton transport channels for high-performance composite membranes. The loading of hydrophilic HPW enhances the dispersivity and compatibility with the SPAES polymer and improves the mechanical-dimensional-chemical stability of the composite membranes. The formed hydrogen-bonding networks and acid-base interactions between fillers and polymers could endow the SPAES/PCN membranes with favorable water-absorption ability and proton-conducting performance. Besides, the excellent interfacial interactions working as a “bridge” facilitates the formation of well-defined phase-separation structure and constructs long-range ionic/water channels at the SPAES-PCN interface. Moreover, the strong acidic HPW on surface and mesoporous structure of CN enhance effectively water-retention ability of the composite membranes, which is specially contribute to rapid proton transport at low humidity. The proton conductivity of the SPAES/PCN-7.5 membrane reaches up to 250 mS cm−1 at 90 °C, hydrous condition, and 46 mS cm−1 at 80 °C, 50 % RH, which are 42 % and 84 % higher than those of the control SPAES membrane, respectively. The SPAES/PCN-7.5 membrane achieves highest maximum power density of 404–824 mW cm−2 at 80 °C and 50%–100 % RH, exceeding that of the SPAES membrane (207–546 mW cm−2) and Nafion® 112 (359–723 mW cm−2). It still remains stable cell performance, as well as undergoes lower voltages loss and hydrogen permeation after the durability test (144 h, 80 °C/60 % RH). In addition, molecular dynamics simulation analysis is performed to offer new insight into elucidating the structure-property relationships of the composite membrane. These results indicate that the SPAES/PCN composite system is an advanced membrane for the practical applications of fuel cells.

Unlocking the Potential of A-Site Ca-Doped LaCo0.2Fe0.8O3-δ: A Redox-Stable Cathode Material Enabling High Current Density in Direct CO2 Electrolysis.

Massive carbon dioxide (CO2) emission from recent human industrialization has affected the global ecosystem and raised great concern for environmental sustainability. The solid oxide electrolysis cell (SOEC) is a promising energy conversion device capable of efficiently converting CO2 into valuable chemicals using renewable energy sources. However, Sr-containing cathode materials face the challenge of Sr carbonation during CO2 electrolysis, which greatly affects the energy conversion efficiency and long-term stability. Thus, A-site Ca-doped La1-xCaxCo0.2Fe0.8O3-δ (0.2 ≤ x ≤ 0.6) oxides are developed for direct CO2 conversion to carbon monoxide (CO) in an intermediate-temperature SOEC (IT-SOEC). With a polarization resistance as low as 0.18 Ω cm2 in pure CO2 atmosphere, a remarkable current density of 2.24 A cm-2 was achieved at 1.5 V with La0.6Ca0.4Co0.2Fe0.8O3-δ (LCCF64) as the cathode in La0.8Sr0.2Ga0.83Mg0.17O3-δ (LSGM) electrolyte (300 μm) supported electrolysis cells using La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) as the air electrode at 800 °C. Furthermore, symmetrical cells with LCCF64 as the electrodes also show promising electrolysis performance of 1.78 A cm-2 at 1.5 V at 800 °C. In addition, stable cell performance has been achieved on direct CO2 electrolysis at an applied constant current of 0.5 A cm-2 at 800 °C. The easily removable carbonate intermediate produced during direct CO2 electrolysis makes LCCF64 a promising regenerable cathode. The outstanding electrocatalytic performance of the LCCF64 cathode is ascribed to the highly active and stable metal/perovskite interfaces that resulted from the in situ exsolved Co/CoFe nanoparticles and the additional oxygen vacancies originated from the Ca2Fe2O5 phase synergistically providing active sites for CO2 adsorption and electrolysis. This study offers a novel approach to design catalysts with high performance for direct CO2 electrolysis.

Composite Membrane for Sodium Polysulfide Hybrid Redox Flow Batteries.

Non-aqueous redox flow batteries (NARFBs) using earth-abundant materials, such as sodium and sulfur, are promising long-duration energy storage technologies. NARFBs utilize organic solvents, which enable higher operating voltages and potentially higher energy densities compared with their aqueous counterparts. Despite exciting progress throughout the past decade, the lack of low-cost membranes with adequate ionic conductivity and selectivity remains as one of the major bottlenecks of NARFBs. Here, we developed a composite membrane composed of a thin (<25 µm) Na+-Nafion coating on a porous polypropylene scaffold. The composite membrane significantly improves the electrochemical stability of Na+-Nafion against sodium metal, exhibiting stable Na symmetric cell performance for over 2300 h, while Na+-Nafion shorted by 445 h. Additionally, the composite membrane demonstrates a higher room temperature storage modulus than the porous polypropylene scaffold and Na+-Nafion separately while maintaining high Na+ conductivity (0.24 mS/cm at 20 °C). Our method shows that a composite membrane utilizing Na+-Nafion is a promising approach for sodium-based hybrid redox flow batteries.

Development of a Zn-Mn aqueous redox-flow battery operable at 2.4 V of discharging potential in a hybrid cell with an Ag-decorated carbon-felt electrode

The Zn-Mn redox pair has great potential as a next-generation redox flow battery (RFB) because of its economic strength and capability to conduct safe reactions. However, because of the potential window restriction of the aqueous system, maximizing the performance of the system with a Zn-Mn redox pair is difficult. Hence, in this study, a hybrid RFB cell with three-electrolyte chambers is designed to expand the potential window using different electrolytes with varying pH values in the anolyte and catholyte. In the three-electrolyte chamber cell, a buffer electrolyte is utilized between the anolyte and catholyte, and the system exhibits a high discharge potential of approximately 2.4 V. Despite this success, stability problems still arise because of MnO2 precipitation in the electrolyte. Therefore, the cathode is further modified using an Ag-based metal-organic framework (MOF). The stability of the carbon-felt electrode is also improved when the cathode is decorated with an Ag electrocatalyst. The potential plateau during the discharge sustained at 2.3–2.4 V, while the cell is maintained over 550 mAh/gMnO₂ of specific capacity. Accordingly, the system design with a three-electrolyte chamber cell and cathode modification can enable the Zn-Mn redox reaction to provide stable and superior cell performance during charge-discharge cycles.

Performance evaluation of TiN/Ti coatings on the aluminum alloy bipolar plates for PEM fuel cells

In this study, different coatings were applied to the bipolar plates (BPs) of proton-exchange membrane fuel cells (PEMFCs). The studied BPs materials include graphite, uncoated Al6061, Al6061 coated with single TiN (0.5 μm) layer, and different composite TiN/Ti layers. Experimental results show that the BP with TiN coating has a higher corrosion potential than those with TiN/Ti coatings, which implies TiN/Ti may have shorter operating life than TiN. The Al6061 with TiN (0.5 μm) has the lowest water contact angle among all the materials. As the Ti proportion on TiN increases, the water contact angle becomes greater, leading to better water removal ability and better fuel cell performance stability. The PEMFC performance with the Al6061 BPs coated with TiN/Ti (0.5μm/0.125 μm) is slightly better than that only coated with TiN. The appropriate thickness of Ti coating improves the PEMFC performance. The BPs made of uncoated Al6061 show the worst performance. After 480-h testing, the cell with uncoated Al6061 BPs has a significant performance degradation due to the increase of the ohmic resistance. The performance degradation rates with TiN/Ti and TiN coated BPs are slightly different, but both coatings significantly improve of the PEMFC life with Al6061 BPs.

The influence of sulfur impurities in industrial COx gases on solid oxide electrolysis cell (SOEC) degradation

High-temperature solid oxide cells (SOC) offer unrivaled Faradaic and energetic efficiencies during carbon dioxide electrolysis. However, it is still unclear which gas quality and impurity level is required for low degradation rates in their commercial application. Here, it is shown that the polarization resistance of electrolyte-supported cells (ESC) with Ni/Gadolinia-doped ceria (Ni/CGO) degrades strongly over time periods of up to 72 h when operated in CO/CO2 gas mixtures. X-ray photoemission spectroscopy (XPS) and high-resolution secondary ion mass spectrometry (SIMS) imaging techniques were used to show that this degradation effect is related to sulfur impurities in the feed gas and their poisoning of the Ni surface. Variation of the inlet gas composition showed that impurities are present in both CO and CO2. The degradation was significantly less pronounced for Ni/CGO fuel electrodes compared to Ni/Yttria-stabilized zirconia (YSZ) and also when hydrogen was introduced into the feed gas. Generic natural gas cleaning desulfurization units were not able to remove the impurities from the feed gases. After initial electrode deactivation, stable cell performance was obtained for >900 h. The results clearly underline the importance of feed gas purity and the necessity for advanced cleaning units for the commercialization of high-temperature CO2 electrolysis.

Development of polybenzimidazole modification with open-edges/porous-reduced graphene oxide composite membranes for excellent stability and improved PEM fuel cell performance

In this research work, we have investigated effect of microwave exfoliated open-edges containing porous-reduced graphene oxide nanosheets (rGO NSs) as nanofillers in polybenzimidazole (PBI) membrane electrolyte assembly for high-temperature proton-exchange membrane fuel cell (PEMFC). PBI/rGO composite membranes were formed by incorporating different amounts (1, 2, and 3 wt%) of rGO NSs into the PBI membrane. Among the three rGO-modified PBI membranes, the optimized amount of 2 wt% rGO NSs in PBI/rGO (PBI/rGO-2) composite membrane shows high ionic conductivity and stable cell performance, with superior maximum power density of 372 mW cm−2 at 150 °C. The PBI/rGO-2 composite membrane reveals excellent stable performance for fuel cells and contains 98.3% stable cell voltage after 32 h of measurement. The proposed tentative mechanism shows the attachment of oxygen-containing functionalities with rGO NSs in the PBI membrane to form the PBI/rGO composite membrane. The rGO NSs play a crucial role in the PBI membrane, assisting in improving proton conductivity, mechanical stability, thermal stability, and easy phosphoric acid (PA) intake without PA electrolyte leaching at higher temperatures, resulting in a high-temperature PEMFC with high power density and stability.

Co-generation of gas and electricity on liquid antimony anode solid oxide fuel cells for high efficiency, long-term kerosene power generation

Kerosene, as a widely used liquid hydrocarbon fuel, is difficult to convert directly in solid oxide fuel cells (SOFCs) due to the coking issue. Liquid antimony anodes (LAAs) are promising for converting complex hydrocarbon fuels, but the intrinsic low open circuit voltage (0.72 V at 750 °C) limits the energy efficiency of LAA-SOFCs. In this paper, we propose a method using LAA-SOFCs as an electrochemical partial oxidation reformer of kerosene, which has the potential to co-generate electricity and syngas. The conversion processes for kerosene in the different components of LAAs were investigated. In liquid Sb2O3, kerosene was partially oxidized into gaseous products with an oxygen/carbon ratio of 1.3–2 at 750–900 °C, which can be directly used as reforming feedstock to produce syngas. We also measured an LAA-SOFC with sulfur-containing kerosene as the fuel for 650 h at 750 °C, and the stable cell performance demonstrated the good durability of the cell. Comparison between the gas-electricity co-generation method and conventional fuel processing methods demonstrates that LAA-SOFCs are attractive as a primary gas-electricity co-generation module for high-efficiency, long-term kerosene-fuelled series power generation systems.

An industrial scale solution to achieving light-induced degradation (LID) free silicon solar systems: &gt;5% performance gain at system level with advanced hydrogenation technology

Light-induced degradation (LID) and light- and elevated-temperature induced degradation (LeTID) effects in p-type monocrystalline silicon (Si) passivated emitter and rear contact (PERC) cell structure have been extensively studied in recent years. Various advanced hydrogenation techniques were previously reported, and aimed to eliminate or at least minimize the effect of LID/LeTID on solar cell performance stability. However, there are limited reports on the long-term performance of solar modules which comprise of these treated solar cells and deployed in typical outdoor conditions. This work aims to provide quantified outdoor performance data for comparing solar modules that are comprised of either hydrogenated or non-hydrogenated reference p-PERC silicon solar cells. A total of 1150 solar modules (>82,000 p-PERC silicon solar cells) were deployed on a commercial building rooftop with identical placement and real-time performance monitoring over an extended period of 12 months under standard outdoor conditions. The results showed that effective advanced hydrogenation is achievable with process time as short as 5 s, although a longer process time of 10–15 s delivered optimal results. The advanced hydrogenation technology in this work can effectively address the LID and LeTID issues on the cell, module, and system levels, with >5% higher power generation capability on hydrogenated solar arrays as compared to the non-hydrogenated reference. Solar cell and module manufacturers strive to produce products with long-term stability, and the successful demonstration of the advanced hydrogenation technology in this work could serve this demand. A future perspective for advanced hydrogenation technologies is also presented.

Anodic polarization characteristics in hydrogen and methane oxidations at nickel-cobalt yttria-stabilized zirconia cermet relating to prolonged cell performance stability

The conventional solid oxide fuel cell (SOFC) anode, which consists of metallic Ni and yttria-stabilized zirconia (YSZ), is liable to deactivation when a carbon-containing gaseous fuel is directly supplied. To retard the degradation due to a direct supply of CH4, the Ni/YSZ has been modified with the incorporation of Co into the Ni matrix, forming a substitutional solid-solution alloy. As a result, the porous anode exhibits well-connected compositional grains owing to the Co3O4 precursor as a sintering aid. The 25 mol% Co incorporation producing the Ni0.75Co0.25/YSZ anode significantly improves the cell performance and prolonged stability. In addition, the Ni0.75Co0.25/YSZ anode provides the apparent activation energy of the charge transfer reaction to a lower value in the electrochemical oxidation of CH4 at the triple-phase boundary. However, the apparent activation energy decrease is not identified for H2. The Co alloying effect on catalyzing the electrochemical oxidation of CH4 is caused by suppressing the carbon deposition originating from the thermal dissociation of adsorbed CH4 on the Ni1-xCox alloy surface.

Dendrite Issues for Zinc Anodes in a Flexible Cell Configuration for Zinc-Based Wearable Energy-Storage Devices.

A key application of aqueous rechargeable Zn-based batteries (RZBs) is flexible and wearable energy storage devices (FESDs). Current studies and optimizations of Zn anodes have not considered the special flexible working modes needed. In this study, we present the Zn accumulation on the folded line and curve areas of flexible anodes. The correlation between the bending radius and the lifespan of symmetric cells is proposed. The interface contact of hydrogel electrolytes when working in a bending mode is another key factor affecting cell lifespan. After detailed analysis, the ideal cell configuration is shown to be hydrogel electrolytes with suitable chemistry, satisfactory mechanical properties, and high adhesivity. Thus a water in salt (WIS) hydrogel is proposed that demonstrates a highly stable cell performance. This work provides a new perspective in Zn anode research for the development of FESDs.

Dendrite Issues for Zinc Anodes in a Flexible Cell Configuration for Zinc‐Based Wearable Energy‐Storage Devices

AbstractA key application of aqueous rechargeable Zn‐based batteries (RZBs) is flexible and wearable energy storage devices (FESDs). Current studies and optimizations of Zn anodes have not considered the special flexible working modes needed. In this study, we present the Zn accumulation on the folded line and curve areas of flexible anodes. The correlation between the bending radius and the lifespan of symmetric cells is proposed. The interface contact of hydrogel electrolytes when working in a bending mode is another key factor affecting cell lifespan. After detailed analysis, the ideal cell configuration is shown to be hydrogel electrolytes with suitable chemistry, satisfactory mechanical properties, and high adhesivity. Thus a water in salt (WIS) hydrogel is proposed that demonstrates a highly stable cell performance. This work provides a new perspective in Zn anode research for the development of FESDs.

Quantification of Microbial Robustness in Yeast.

Stable cell performance in a fluctuating environment is essential for sustainable bioproduction and synthetic cell functionality; however, microbial robustness is rarely quantified. Here, we describe a high-throughput strategy for quantifying robustness of multiple cellular functions and strains in a perturbation space. We evaluated quantification theory on experimental data and concluded that the mean-normalized Fano factor allowed accurate, reliable, and standardized quantification. Our methodology applied to perturbations related to lignocellulosic bioethanol production showed that the industrial bioethanol producing strain Saccharomyces cerevisiae Ethanol Red exhibited both higher and more robust growth rates than the laboratory strain CEN.PK and industrial strain PE-2, while a more robust product yield traded off for lower mean levels. The methodology validated that robustness is function-specific and characterized by positive and negative function-specific trade-offs. Systematic quantification of robustness to end-use perturbations will be important to analyze and construct robust strains with more predictable functions.

Comparative Study of Different Activation Procedures of High Temperature Proton Exchange Membrane Fuel Cells

Herein, the objective is to investigate the activation mechanism and activation process in high‐temperature proton exchange membrane fuel cell under different activation procedures from multiple perspectives. The effects of galvanostatic, temperature cycling, current step cycling, and increasing back pressure on cell performance were investigated by current density distribution test, electrochemical impedance spectroscopy, and distribution of relaxation times analysis. The results show that galvanostatic activation was the optimal activation mode. Current step cycling and elevating back pressure activation increase the voltage growth rate, but make the difference in the optimization of each parameter become greater, and do harm to cell performance stability and long‐term durability. Temperature cycling activation increases the charge transfer resistance and makes the uniformity of current density distribution deteriorate due to the thermal and mechanical stresses. It emphasizes the fact that different activation modes had great influence on the uniformity of current density distribution, and the optimization speed and change trend of each key parameter are not synchronized during the activation process. It is insufficient to focus only on voltage reaching steady state, and factors such as voltage, impedance, and uniformity of current density distribution should be considered comprehensively.

Anodic Polarization Characteristics in Hydrogen and Methane Oxidations at Nickel-Cobalt Yttria-Stabilized Zirconia Cermet Relating to Prolonged Cell Performance Stability

Anodic Polarization Characteristics in Hydrogen and Methane Oxidations at Nickel-Cobalt Yttria-Stabilized Zirconia Cermet Relating to Prolonged Cell Performance Stability

Anode biofilm maturation time, stable cell performance time, and time-course electrochemistry in a single-chamber microbial fuel cell with a brush-anode

For accurate and reproducible MFC experiments, it is important to know when MFCs produce stable cell performance. Herein, four replicate single-chamber MFCs were tested for 17 weeks by using polarization and cyclic voltammetry (CV) tests. The strong MFCs (#2,4,3) showing continuous performance enhancement initially (3rd–9th week) produced good subsequent performance (9th–17th week). The weak MFC-1 experienced a performance drop initially and showed bad subsequent performance. All the MFC performance became stable after 9 weeks. The strong MFCs produced power 2.8–3.6 times higher and anode resistance 7.5–23.9 times lower than the weak. However, their cathode resistances were similar. CV results showed anodic current production increased continuously in all MFCs, indicating anode biofilms kept growing;, MFC performance did not increase accordingly. Anodic CVs had a typical S-shape curve, but those of MFC-1 showed straight lines from the 9th week. The weak MFC-1 showed smaller CV currents and thinner CV curves than those of the strong MFCs. In MFC-1, at the 17th week, the anode resistance reduced by 47%, anodic current and cell performance increased. Regression analysis showed anode resistance was a limiting factor of the weak MFC and cathode resistance was that of the strong MFCs. This result suggests one operating principle: improve anodes in weak MFCs and cathodes in strong MFCs to achieve better MFC performance.

Ultrafast ion-transport at hierarchically porous covalent-organic membrane interface for efficient power production

Highly ordered free-standing membranes are challenging to fabricate using conventional polymeric material. Additionally, several organic-inorganic materials have been studied to develop a stable free-standing membrane for energy applications. Still, fragile structural issues under realistic conditions remain one of the most significant barriers to making them commercially viable. Here, we have prepared a series of large-area 10 × 10 cm2 free-standing, proton-conducting covalent organic membrane (COM) for reverse electrodialysis. COM possesses a hierarchical nanoporous stable structure formed with a highly crystalline organic framework. The random arrangement of layered micropores with a pore size of 1.16 nm plus mesopores and macropores provides a hierarchical porous structure in COM. However, the crystalline arrangement is highly ordered with fixed pores in COF, a pore size of 1.34 nm. The determined surface porosity of cross-sectional COM is ~66%. The pore size distribution is ~1.2 nm, and the estimated surface area of COM is up to ~33 m2 g-1. The prepared free-standing structure is stable at elevated temperatures under 100% hydrated conditions. COM structure is also mechanically stable ~2 MPa with elongation up to 4% and maintains its free-standing structure under acidic conditions. Besides robust hierarchical porous structure and chemical stability under stress conditions, acid-treated COM offers better ion selectivity with enhanced ion transport at elevated temperatures. It is only possible because of low membrane swelling density while maintaining the high ion-exchange capacity, which are crucial factors for implementing it in an electrochemical application. The free-standing COM combined with FAA-3 membrane for assembling the reverse electrodialysis's stack for power production. The obtained power density of reverse electrodialysis is ~1.44 W m-2 at a fixed flow rate of 2 mL min-1. With negligible hydrodynamic loss and maintaining stable cell performance.

High-performance poly(fluorenyl aryl piperidinium)-based anion exchange membrane fuel cells with realistic hydrogen supply

Anion exchange membrane fuel cells (AEMFCs) have advanced rapidly in the past four years, while the majority of the state-of-the-art AEMFCs relies on unrealistic and uneconomical operating conditions, particularly a high hydrogen flow rate (>1000 mL min −1 ). Here, we report a poly(fluorenyl aryl piperidinium) (PFAP) ionomer that enables high power of AEMFC with low hydrogen flow rate (≤100 mL min −1 for 5 cm 2 cell). The high water permeability of the ionomer is beneficial to prevent anode flooding under moderate relative humidity. The relationship between hydrogen flow rate and limiting current density is revealed based on PFAP copolymers. Specifically, the peak power density of AEMFC is 1.77 W cm −2 with a H 2 flow rate of 75 mL min −1 , retaining >70% power density from the H 2 flow rate of 1000 mL min −1 (2.42 W cm −2 ). Importantly, the present AEMFCs display much higher hydrogen utilization efficiency above 90% and hydrogen fuel power (∼30 W cm −2 L −1 ) than previously reported AEMFCs (<30% and 0.4–3.5 W cm −2 L −1 ). Moreover, the present AEMFCs show stable cell performance with a low hydrogen flow rate at 70 °C for >110 h. • Limiting current density and H 2 utilization efficiency are elucidated in AEMFCs. • AEMFCs using realistic and low H 2 flow rate reach the power density >1.9 W cm −2 . • Present AEMFCs display outstanding hydrogen fuel power of 10–34 W cm −2 L −1 .