bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exploring Ion Transport Dynamics in Liquid Electrolytes: Insights from in-Situ FTIR Imaging of Lithium Electrodes
Authors: Porter Jason Morgan , Dick Schuyler 
Published: December 2024

While solid-state batteries have demonstrated potential in enhancing metal electrode stability, achieving the same stability in liquid electrolytes remains elusive. The instability of the SEI plays a pivotal role in the stability of metal electrodes in liquid electrolytes. Despite several promising strategies to stabilize metal electrodes in liquid electrolytes, the intricate relationship between the composition of the liquid electrolyte and the formation and stability of the SEI is still not fully understood.
This study delves into the constraints of ion transport in liquid electrolytes, specifically focusing on the process of lithium plating and stripping on metal electrodes. A customized short pathlength transmission flow cell, equipped with symmetric lithium electrodes, is employed to simultaneously image lithium deposition, capture electrochemical measurements, and perform in-situ Fourier Transform Infrared (FTIR) imaging. This methodology illuminates the complex relationship between electrolyte transport, local composition, and the morphology of lithium plating.
The research utilizes quantitative analysis of electrolyte components, Li+, PF6-, EC, and EMC, through spectral analysis with chemometric methods and machine learning. The composition of the local electrolyte, which undergoes significant changes under rapid charge conditions, impacts SEI composition, and by extension lithium plating morphology. In situ FTIR imaging, with a resolution of five microns, is used to evaluate the role of preferential diffusion and/or migration of solvent and ionic species. Synchronized optical imaging, with a superior resolution of one micron, providing visual images of lithium structures that are correlated with solvent and ion concentration distributions measured in the infrared. The findings establish a link between ion transport dynamics and the efficiency of lithium plating and stripping, which has far-reaching implications for the performance and safety of electrochemical systems.
Analytical Electron Microscopy Investigation of PEM Electrolyzer Degradation Mechanisms Under Different Durability Test Protocols
Authors: Yu Haoran , Padgett Elliot , Li Kui , Cullen David A. , Alia Shaun M , Komini Babu Siddharth , Mukundan Rangachary 
Published: December 2024

Hydrogen as an energy carrier is a promising solution to reduce carbon emissions and fight climate change. The US Department of Energy (DOE) announced the Hydrogen Shot initiative to reach $1 per 1 kilogram of hydrogen in 1 decade (by 2031). Although millions of metric tons of hydrogen are produced each year by industry, cost-effective approaches such as steam methane reforming involve the release of carbon dioxide. Water electrolysis is one of the key technologies of producing hydrogen from renewable energy sources which has zero carbon emission, but significant and rapid innovations are required to reach the Hydrogen Shot cost target.
Here we focus on low temperature proton exchange membrane (PEM) electrolyzers which have demonstrated high efficiency and high capacity recently. Successful deployment of PEM electrolyzers requires reducing cost while simultaneously improving performance and lifetime. To evaluate and project electrolyzer performance and lifetime more effectively, accelerated stress test (AST) protocols are being developed. The primary goal of this work is the identification of key stressors of degradation and their related degradation mechanisms. Parameters of interest, such as upper and lower potential limit, dynamic vs constant load, temperature, start-up/shut-down procedures, etc., are varied in different AST protocols to elucidate their effect on membrane electrode assembly (MEA) degradation.
Electron microscopy offers an in-depth examination of the MEA after AST. In this presentation, we will discuss the following findings that shed light on the degradation mechanisms of electrolyzer MEAs. Firstly, the crystalline structure of the Ir oxide catalyst was compared before and after degradation, showing a structural change from amorphous Ir oxide to nano-sized crystallites. Then, through energy dispersive X-ray spectroscopy (EDS), a correlation is found between type of AST protocol, performance loss, and degree of Ir lost from the anode due to Ir dissolution and migration toward the membrane. We will also show the migration of Ir and Ti to the cathode forming Ir-coated Pt particles and Ti oxide, respectively, for long term tests. Lastly, we find that cathode degradation occurs if a start/stop protocol is employed where Pt particle coarsening and dissolution into the membrane can be observed. [1]
References
[1] Funding for this work was provided by U.S. Department of Energy Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office through the H2NEW Consortium. Electron microscopy research conducted as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory.
Quantifying H2 Crossover in PEM Water Electrolyzers Operating at High Differential Pressure
Authors: Gawas Ramchandra , Wang Guanzhi , Rudnicki Paul E. , Dizon Arthur , Kushner Douglas I. , Peng Xiong , Mukundan Rangachary 
Published: December 2024

Large-scale deployment of proton exchange membrane water electrolyzers (PEMWEs) is crucial for producing clean and economically viable hydrogen to create hydrogen-based energy ecosystems that can replace existing carbon-intensive processes. Efficient operation of PEMWEs requires the use of thinner membranes to reduce ohmic losses as well as the differential pressure operation to increase the overall system efficiency. The high differential pressure operation of PEMWEs with thin membranes results in significant hydrogen crossover from cathode to anode. This crossover-H2 has considerable implications on PEMWE performance, durability, as well as operational safety.
In this work, we develop a method to accurately quantify hydrogen crossover rates in PEMWEs operating at high differential pressure. Our analysis shows that crossover-H2 is oxidized at the anode catalyst layer resulting in measurable hydrogen oxidation reaction (HOR) currents. We combine this HOR current measurement with online gas chromatography with thermal conductivity detector to determine H2 concentration in the anode outlet and also calculate H2 crossover rates at various operating current and differential pressures (up to 30 bar). Further, we use this methodology to evaluate the effect of porous transport layer (PTL) coatings (Pt, Ir, and Au) on the HOR current as well as the hydrogen crossover rate in PEMWEs.
Acknowledgment: This research is supported by the U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office (HFTO) through the Hydrogen from Next-generation Electrolyzers of Water (H2NEW) consortium.
Compression of Porous Transport Layers Enhanced Bubble Transport in Polymer Electrolyte Membrane Water Electrolyzers
Authors: Zhu Lijun , Lee Jongmin , Ham Chaeyoung Tina , Chadwick Eric Alexander , Parmar Harsharaj Birendrasingh , Trtik Pavel , Bazylak Aimy 
Published: December 2024

At high current densities, oxygen bubble formation limits the performance of polymer electrolyte membrane (PEM) water electrolyzers, particularly due to bubble accumulation at the porous transport layer (PTL)/catalyst layer (CL) interface. Efficient bubble removal from the PTL/CL interface is therefore crucial for PEM water electrolyzers1,2. Bubble transport at the PTL/CL interface is dominated by mechanical compression 3,4. However, it is still unclear how mechanical compression impacts bubble transport at the PTL/CL interface, due to difficulties in capturing the multiphase flow and differentiating liquid/gas in the pores of the titanium PTL. Thanks to its spatial resolution and high transmissivity for titanium, neutron imaging enables visualization of the bubble distribution in the PTL hence allowing for the identification of the role of compression in the bubble transport.
We conducted operando neutron imaging for PEM water electrolyzers and examined the relationship between compression ratio and electrochemical performance. Neutron imaging results showed that the through-plane bubble distributions became more homogeneous as compression increased. Additionally, pore network modelling simulations indicated that compression-induced catalyst coated membrane intrusion homogenized the bubble distribution in the PTL. We identified an optimal compression condition for enhanced interfacial bubble transport that can contribute to the next-generation material development to improve the efficiency of PEM water electrolyzers at high current densities with low mass transport losses.

References

J. K. Lee and A. Bazylak, Joule, 5, 19–21 (2021).

S. Yuan et al., Prog.
Energy Combust.
Sci., 96, 101075 (2023).

T. Schuler, T. J. Schmidt, and F. N. Büchi, J. Electrochem.
Soc., 166, F555–F565 (2019).

A. Martin et al., J. Electrochem. Soc., 169, 014502 (2022).
Electrospun Micro Porous Layer for Enhanced Proton Exchange Membrane Water Electrolysis
Authors: Diaz-Abad Sergio , Komini Babu Siddharth , Spendelow Jacob S. 
Published: December 2024

Current porous transport layers (PTLs) utilized in proton exchange membrane water electrolyzers (PEMWEs), suffer from limited interfacial contact area with the catalyst layer which reduces the performance. Although high anode catalyst loadings can mitigate this issue, it contradicts the objective of reducing the loading of precious metals in PEMWEs to lower costs. The combination of poor in-plane conductivity of the anode catalyst and the poor interfacial contact results in increased contact resistance and reduced catalyst utilization which leads to accelerated catalyst degradation due to non-uniform exposure to the applied voltage or current in the catalyst. Micro-porous layers (MPLs) can alleviate the interfacial contact problem. MPLs provide with high surface areas and low pore size, facilitating enhanced contact with the catalyst layer and improving catalyst utilization. Furthermore, the hierarchical MPL morphology can aid in efficient oxygen removal and enhanced water transport to the anode catalyst layer.
In this study, titanium-based MPLs were fabricated via electrospinning employing a titanium precursor and a carrier polymer. Electrospun offers a superior control on the morphology of the resulting fibers. The electrospun fibers were subsequently calcined to yield TiO2 fibers, forming the MPL. The MPL was then integrated into a commercial felt based PTL substrate through hot-pressing and sintering to enhance the improved integration between the MPL and substrate. We will present the electrochemical performance evaluation including polarization curves, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry. Surface characterization of the MPL and catalyst layer surface was performed via scanning electron microscopy (SEM) and laser profilometry before and after electrolyzer testing.
Acknowledgement
This research is supported by the U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office through the Hydrogen from Next-generation Electrolyzers of Water (H2NEW) consortium. Program manager Dave Peterson and Mackenzie Hubert.
(Invited) Pathways Toward Efficient and Durable AEM Water Electrolyzers
Authors: Tricker Andrew , Ertugrul Tugrul , Lee Jason Keonhag , Lang Jack Todd , Zenyuk Iryna , Weber Adam Z. , Peng Xiong 
Published: December 2024

Green hydrogen will play a key role in decarbonization efforts, especially for heavy industries.[1] Durable, efficient, and low-cost electrolyzers are critical to realize economical and green hydrogen production. Anion exchange membrane water electrolyzer (AEMWE) is an emerging technology that combines the benefits of low components cost of conventional alkaline electrolyzers and the high efficiency of proton-exchange membrane (PEM) electrolyzers.[2] Although promising, a significant hurdle to commercial deployment of AEMWEs is the durability under industrially relevant conditions. Here, we demonstrate how porous transport layers comprised of natively active materials (PTL electrodes) can be used to achieve efficient and durable AEMWEs.[3] Specifically, stainless-steel fiber PTLs were used as anodes, without the addition of a catalyst layer. When comparing the PTL electrode to traditional catalyst layers, electrolyzer cells with several commercial anion-exchange ionomers (AEI) were subjected to current cycling. This accelerated stress testing (AST) of the electrolyzer cells showed that no significant degradation in the PTL electrode, while cell using traditional catalyst layers exhibited a loss in performance and the complete degradation of the ionomer functional group. When assessing the industrial applicability, the active area of the electrolyzer was increased up to 50 cm2, which showed the same performance as the 5 cm2 cell. The durability of the electrolyzer was tested at 2 A cm-2 in 0.1 M KOH for 660 h. During this period, the cell exhibited a degradation rate of 5 µV h-1, which was comparable to typical PEM electrolyzers. The use of experiment and modeling was used to investigate the role of the structure of the PTL in influencing cell performance. The inclusion of a denser layer on the membrane side increased the utilization of the electrode by decreasing the bubble coverage on the fiber surfaces and increasing the effective electrolyte conductivity within the electrode. Finally, we demonstrate a facile etching method to modify the surface of the PTL fibers to increase the active surface area of the anode and achieve a cell current density of 2.3 A cm-2 at 1.8 V.
References:
[1] D. S. Mallapragada, Y. Dvorkin, M. A. Modestino, D. V Esposito, W. A. Smith, B.-M. Hodge, M. P. Harold, V. M. Donnelly, A. Nuz, C. Bloomquist, Joule
2023, 7, 23–41.
[2] L. Wan, Z. Xu, Q. Xu, M. Pang, D. Lin, J. Liu, B. Wang, Energy Environ Sci
2023, 16, 1384–1430.
[3] A. W. Tricker, T. Y. Ertugrul, J. K. Lee, J. R. Shin, W. Choi, D. I. Kushner, G. Wang, J. Lang, I. V Zenyuk, A. Z. Weber, X. Peng, Adv Energy Mater
2023, 2303629.
Liquid Alkaline Water Electrolysis: Are the Reports of Its Demise Premature?
Authors: Leonard Daniel , Maurya Sandip , Kang Sun Young 
Published: December 2024

The future for hydrogen is bright. There is a widely recognized need to produce large quantities of emissions-free hydrogen to achieve the decarbonization goals expressed in national climate change ambitions. Electrolysis has attracted more attention as the most viable near-term process to meet that need. From the research community’s perspective, the course of electrolytic hydrogen production technology is expected to be led by proton exchange membrane (PEM) technologies. PEM will eventually be supplanted by anion exchange membrane (AEM) technologies, which are expected to maintain all of the PEM capabilities without the precious metal drawbacks. Liquid alkaline (LA) water electrolyzer systems will fall by the wayside as they are based on century-old technology and should not meet the high H2 production needs of the future.
The source of LA’s poor reputation is due to the materials used as catalysts. While low cost, they are mainly designed with simplicity and longevity in mind. Simply opening the door to the possibility of using Pt and Pt alloy catalysts as the hydrogen evolution electrodes can lead to increases in hydrogen production without substantially increasing the cost of the electrolyzer stack. We show that using a reasonable Pt loading of 0.3 mg/cm2 at the cathode and a standard Ni foam anode results in a ten-fold increase in hydrogen production. The cell remains stable without a quantifiable loss in performance after 250 h at a current density of 2 A/cm2 in 30 wt% KOH at 80 oC. This result exceeds the 2026 performance and durability targets for liquid alkaline electrolysis set by the U.S. Department of Energy (DOE). When the Ni foam anode modified by the electrodeposition of an NiFe layered double hydroxide (LDH), the performance is identical to the current PEM benchmark, FuGeMEA. The result is within 100 mV of DOE’s ultimate technical target for LA performance, 2.0 A/cm2 at 1.7 V. The degradation rate using the NiFe LDH anode system is too high at present (461 mV/kh rather than the 2.1 mV/kh target).
From a cost perspective the use of Pt at the cathode results in only a small increase at the system level, extrapolating from the International Renewable Energy Agency’s 2020 “Green hydrogen cost reduction” report. While the ultimate goal is to remove the need for precious metal catalysts entirely, in the near-term their adoption in liquid alkaline may speed the cost reductions necessary to meet the hydrogen cost goals. They are simply too promising to be ignored.
The authors would like to acknowledge the support of the DOE Hydrogen and Fuel Cell technology Office and the Hydrogen from Next-Generation Electrolyzers of Water (H2NEW) Consortium.
Optimization of Porous Transport Layers in PEM Electrolyzers Using Pore Network Modeling with Combinations of Fiber Size and Volumetric Fractions
Authors: Ghosh Amit , Uddin Aman 
Published: December 2024

Polymer Electrolyte Membrane (PEM) electrolyzers as a promising technology in addressing climate change challenges and facilitating the development of renewable energy sources at lower costs. They offer clean operation and scalability, making them a valuable tool for harnessing energy without leaving any carbon footprint. However, a key challenge to widespread PEM electrolyzer adoption is the cost of the porous transport layer (PTL). In this study, we address this challenge by utilizing stochastic modeling to develop 3D PTL models numerically. To optimize the structural and transport properties of the PTL, we explored a range of combinations for the radius (2, 3, 4, 5 µm) and volumetric fraction (20%, 40%, 60%, 80%, 100%) of small fibers dispersed within a matrix of large fibers (6 µm) (Figure 1). The structural properties (e.g., mean surface roughness, specific surface area) were analyzed numerically, whereas transport properties (e.g., thermal conductivity, electrical conductivity, and diffusivity) were analyzed via pore network modeling. Before further analysis, our model was validated against both experimental and numerical results from previous research works. In our study, we observed that increasing the volumetric fraction of small fibers, while decreasing their radius, led to reduced surface roughness and higher thermal and electrical conductivity. However, this came at the cost of increased tortuosity, which hindered the diffusion and permeability of the material. Conversely, PTLs with a higher volumetric fraction of large fibers exhibited the opposite trend.
By combining these insights, we developed customized multi-layer PTLs. These PTLs have a small fiber radius at the catalyst side and a large fiber radius at the flow-field side. This design leverages the advantages of both small and large fiber radii. Our customized multi-layer PTLs demonstrated improved gas removal, higher electrical conductivity, and better heat dissipation while maintaining good surface contact area and reduced roughness. To utilize the benefits of our modeled multi-layer PTL in an electrolyzer cell, the volumetric fractions of the fiber radius should be adjusted based on operating conditions. By tailoring the fiber characteristics and PTL geometries, we can develop optimized PTL models that can be scaled to real-time PEM electrolyzer setups for renewable energy generation, paving the way for a better future.

Figure 1
Effect of Cations Contamination on Durability of Proton Exchange Membrane Water Electrolyzer
Authors: Rodriguez Mayra , Diaz-Abad Sergio , Spendelow Jacob S. , Komini Babu Siddharth 
Published: December 2024

Cation contamination in proton exchange membrane water electrolyzers (PEMWE) presents a significant challenge for industrial applications impacting both performance and durability. Common sources of cation contamination include salts present in the feed water or those resulting from corrosion of components and balance of plant systems. The cations ion-exchange with the protons in Nafion® membrane, leading to a significant reduction in proton conductivity of the membrane.1 This decrease in conductivity directly affects the performance of electrolyzers resulting in increased energy consumption, and reduction in lifetime of the PEMWE, which places a significant economic and operational barrier on commercial hydrogen production.2 The cation can accelerate the degradation of the catalyst and the membrane. However, the effect of cation on the durability are not well understood.
In this work, the effects of cation contamination, originating from various sources, on the performance and durability were investigated. Specifically, we investigated cations that are present in feed water (Na+, K+, Mg2+) and metal cations (Fe2+, Ti+, Al3+, Cu2+) that are introduced as the result of corrosion of the PEMWE components. In this study, cations were introduced by soaking the catalyst coated membranes (CCMs) in a solution with a known concentration of cation. The effect of PEMWE performance as a function of the cation concentration was studied. Subsequently, accelerated stress tests (AST) were performed to evaluate how cation concentrations affect the degradation of the membrane and the catalyst.
Acknowledgement
This research is supported by the U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office through the Hydrogen from Next-generation Electrolyzers of Water (H2NEW) consortium. Program manager Dave Peterson and Mackenzie Hubert.
LA-UR-24-23217
References
(1) Li, N.; Araya, S. S.; Cui, X.; Kær, S. K. The effects of cationic impurities on the performance of proton exchange membrane water electrolyzer. Journal of Power Sources
2020, 473. DOI: 10.1016/j.jpowsour.2020.228617.
(2) Becker, H.; Murawski, J.; Shinde, D. V.; Stephens, I. E. L.; Hinds, G.; Smith, G. Impact of impurities on water electrolysis: a review. Sustainable Energy & Fuels
2023, 7 (7), 1565-1603. DOI: 10.1039/d2se01517j.