bluuebunny/crossref_metadata_2025 huggingface dataset:
Screening the Dynamic Behavior of the Electrode-Electrolyte Interphase on Hard Carbon Via Scanning (Electrochemical) Probe Microscopy
Authors: Kranz Christine , Daboss Sven , Saleh Salimeh , Palanisamy Krishnaveni
Published: December 2024

Hard carbon is an attractive anode material for alkali-ion batteries, particularly for sodium-ion batteries (SIBs), due to the high storage capacity and the fact that HC can be produced from renewable bio-resources1. Similar to lithium-ion batteries (LIBs), the performance and operational stability of SIBs is dependent on the electrode electrolyte interface (SEI)2. Although, the SEI on graphite anodes (LIBs) and HC anodes (SIBs) have similar chemical properties, it has been shown that the SEI of SIBs is less stable and its stability is strongly dependent on the experimental conditions3. For example, we have recently investigated the SEI formation on spray-coated HC composite anodes in half-cell configurations in dependence of the electrolyte (ester and ether based including studies in the presence or absence of fluoroethylene carbonate (FEC) as an additive). Using scanning (electrochemical) probe microscopy (SEPM), such as scanning electrochemical microscopy (SECM), atomic force microscopy (AFM) and hybrid AFM-SECM, we could characterize the electrochemical and nanomechanical properties of the SEI4
-6.

In this contribution, we present SEPM such as scanning electrochemical cell microscopy (SECCM)7, which has been used as attractive SPM technique for battery research8,9. SECCM is used to locally form SEI layers under different experimental conditions at the surface of HC composite anodes. The advantage of this approach is that on the same electrode surface e.g., different number of charge and discharge cycles can be performed forming localized SEI spots. These spots are then investigated by AFM and AFM-SECM to study the electrochemical and nanomechanical properties as well as dynamic behaviour such as the dissolution or possible swelling. Advantages and challenges of this in situ characterization of the formed interphases at post-Li battery electrodes are discussed.

Acknowledgement

This work contributes to the research performed at CELEST (Center for Electrochemical Energy Storage Ulm - Karlsruhe) and was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy – EXC 2154 – Project number 390874152 (POLiS Cluster of Excellence).

References

[1] A. Baldinell et al., Green Chem.
,

20
, 1527-1537, 2018.

[2] E. Peled, S. Menkin, J. Eelectrochem. Soc.
164, A1703-A1719, 2017.

[3] L. A. Ma, A. J. Naylor, L. Nyholm, R. Younesi, Angew. Chem. Int. Ed.
60, 4855–4863, 2021.

[4] K. Palanisamy et al.,Batt. & Supercaps 7, e202300482, 2024.

[5] K. Palanisamy et al.,Batt. & Supercaps 7, e202300402, 2024.

[6] S. Daboss, T. Philipp, K. Palanisamy, J. Flowers, H.S. Stein, C. Kranz, Electrochim. Acta 453, 142345, 2023.

[7] D.Martín-Yerga, M. Kang, P. R. Unwin, ChemElectroChem 8, 4240 – 4251, 2021.

[8] S. Daboss, F. Rahmanian, H. S. Stein, C. Kranz, Electrochem. Sci. Adv. 2, e2100122, 2021.

[9] E. Ventosa, Curr. Opinion Electrochem. 25, 100635, 2021.
Complementary Analysis on the SEI of Thin Film Siox Using X-Ray Photoemission Spectroscopy and X-Ray Reflectivity Methods
Authors: Nakamoto Mitsunori , Lu Zijie , Zrikem Khawla , Le Cras Frédéric , Tanaka Masatomo , Benayad Anass , Tardif Samuel , Van Roekeghem Ambroise
Published: December 2024

Silicon materials are expected as a high-capacity anode material for lithium-ion batteries. However, the life of the cell with such silicon materials tends to be short due to the pulverization of silicon associated with its large volume change, and electrolyte consumptions associated with the continuous growth of solid electrolyte interphase (SEI). Compared to pure silicon anodes, silicon oxide (SiOx) has been reported to mitigate such issues and extend the life of the battery1,2. In this study, we combined ex situ XPS (X-ray photoemission spectroscopy) and operando XRR (X-ray reflectivity) methods to investigate the phase transformations in the thin-film SiOx and the nature of SEI during the first lithiation/delithiation cycle to obtain the insights to improve the cycle performances.

Using ex situ XPS, we examined the depth profile of the thin-film SiOx sample (Figure 1) at some representative potentials during the first cycle. This elucidated the evolution of chemical nature and thickness of the SEI, and simultaneously the irreversible phase changes in the SiOx. In recent years, the operando XRR method has been successfully applied to the pure silicon thin films3,4, revealing the nature (like thickness and electron density) of top and bottom SEI layers in early cycles. In this study, XRR was applied to thin-film SiOx for the first time. The insight from XPS and that from XRR were integrated for a comprehensive understanding on the evolution of the SEI layer and the SiOx electrode. A systematic comparison was made using the electrolytes with FEC and without FEC to better understand the importance of FEC. It was found out that the SEIs in both systems commonly show breathing behaviors, but the thickness of the SEI is almost always smaller in the FEC containing system. These findings can be a foundation for the high-performance batteries.

1. Chen, T.; Wu, J.; Zhang, Q.; Su, X. Recent Advancement of SiOx Based Anodes for Lithium-Ion Batteries. J Power Sources
2017, 363, 126–144.

2. Hsu, C.-H.; Chen, H.-Y.; Tsai, C.-J. Stoichiometry Dependence of Electrochemical Behavior of Silicon Oxide Thin Film for Lithium Ion Batteries. J Power Sources
2019, 438, 226943.

3. Cao, C.; Steinrück, H.-G.; Shyam, B.; Stone, K. H.; Toney, M. F. In Situ Study of Silicon Electrode Lithiation with X-Ray Reflectivity. Nano Lett
2016, 16 (12), 7394–7401.

4. Cao, C.; Steinrück, H.; Shyam, B.; Toney, M. F. The Atomic Scale Electrochemical Lithiation and Delithiation Process of Silicon. Adv Mater Interfaces
2017, 4 (22), 1700771.

Figure 1
Multiscale Modeling of Oxygen Interfacial Transport Resistance in Proton Exchange Membrane Fuel Cell Catalyst Layer
Authors: Wang Shiyi , Weber Adam Z.
Published: December 2024

As lower catalyst loading is required to maintain cost efficiency for PEMFCs, O2 transport becomes pivotal due to the spontaneously increased pressure-independent transport resistance. While O2 transport occurs from nanoscale to macroscale, emerging evidence suggests that the interfacial region at atomistic level near catalyst surface dominates the total transport resistance. Extensive experimental efforts have been taken to understand the transport resistance contributions from each level. However, due to the complexity of the multiscale porous structure and the triple-phase interfaces in catalyst layer, coupled with the limited laboratory techniques for probing the interface at nanoscale in MEA, no conclusive correlation has been established across the scales. Mathematical modelling is a promising approach to connect nanoscale interactions with macroscopic phenomena in a computationally efficient manner. In this work, a multiscale modeling study is presented to understand the effect of platinum interfacial transport resistance on cell performance. The Pt interfaces are separately considered as exterior and interior to represent solid carbon and porous carbon situations. Ionomer and SO3
- coverage are considered for the exterior Pt interfaces, and interior Pt is correlated with pore water uptake in terms of Pt utilization, O2 transport, and proton transport. The interface-dependent properties are up-scaled to a 2D MEA cell-level model through a modified agglomerate model framework. The model reasonably predicts the MEA measurements using Pt/Vulcan and Pt/KB with varying interior Pt loading. The ionomer poisoning not only attributes to the site blocking from SO3
- (reducing ECSA) but also from the low O2 solubility at Pt-ionomer interface compared to the water-covered exterior Pt interface. As for the Pt loaded inside the high surface area carbon (HSC) pores, we found a similar O2 interfacial permeability with the Pt-ionomer interface. Possible explanation includes ionomer penetration, confined water structure inside nanopore that hinders the O2 diffusion, or the long diffusion pathway because of the tortuous pore network. We also performed parametric studies to understand how transport at different scales—interface, ionomer film, and agglomerate—affect the total transport resistance. Lastly, a HSC pore water uptake model was integrated into the cell-level model to address the effect of RH and pore size distribution. We examined the optimal HSC pore size distribution that can balance the Pt utilization, proton transport, and oxygen transport at given operation conditions. The model offers guidance for catalyst design by optimizing ink interaction and CL multiscale porous structure.
Quantifying Individual Electrode Polarization and Elucidating Interactive Phenomena in PEM Fuel Cells
Authors: Li Lulu , Wang Yudong , Xu Nengneng , Zhou Xiao-Dong
Published: December 2024

Fuel cells (FCs) that utilize hydrogen as fuel represent a clean and advanced energy conversion technology[1]. In the past two decades, FCs have achieved significant breakthroughs through the development of key materials and components. Nevertheless, quantifying the polarization and dynamics of individual electrodes and components under operating conditions remains a challenge for FC systems, which involve multiple physical and electrochemical processes. Electrochemical impedance spectroscopy (EIS), a widely used non-invasive technique, provides extensive information about the charge transport and reaction kinetics in the frequency domain[2]. The distribution of relaxation times (DRT) method further increases the resolution of the impedance in the relaxation domain[3]. In general, various physical and electrochemical processes occurring on the two electrodes manifest as peaks in the DRT plot. The areas corresponding to these peaks quantify the resistance contributed by each respective process. However, the DRT peaks are still highly convoluted, and additional efforts are required to assign the peak contributions and further separate the resistances of cathode processes and anode processes.

In this work, we designed a Pt-wire (Au-wire) micro-reference electrode/ probe (MRE), which is laminated between two PEMs (Nafion® 212), and positioned centrally within the active area. The artifact-free impedance spectra of the cathode and anode under operating conditions were recorded by utilizing the pseudo-reference electrode. The DRT functions of the cathode and anode can add up to the total DRT function of the cell. Under these conditions, The ion conduction resistance, capacitance of the electrode, and contact resistance at the electrode∣∣MRE interface can be quantified. Multiple operation conditions including relative humidity of both electrodes, back pressures, and gas compositions are studied to verify the reliability of the DRT method in PEMFC research. Hence, this study offers a novel approach to guiding the development of high-performance PEMFC by quantifying the resistance associated with various processes in PEMFC components.

Reference:

[1] F. Xiao, T. Chen, Y. Peng, R. Zhang, Fault diagnosis method for proton exchange membrane fuel cells based on EIS measurement optimization, Fuel Cells, 22 (2022) 140-152.

[2] J. Kwon, P. Choi, S. Jo, H. Oh, K.-Y. Cho, Y.-K. Lee, S. Kim, K. Eom, Identification of electrode degradation by carbon corrosion in polymer electrolyte membrane fuel cells using the distribution of relaxation time analysis, Electrochim. Acta, 414 (2022).

[3] Y. Wang, N. Xu, X.-D. Zhou, Quantifying individual electrode polarization and unraveling the interactive phenomenon in solid oxide fuel cells, Next Energy, 1 (2023).
Durability Study of Membrane Electrode Assembly for Heavy-Duty Fuel Cells
Authors: Quesada Calita Maria , Wang Xiaojing , Komini Babu Siddharth , Gawas Ramchandra , Mukundan Rangachary , Borup Rod L.
Published: December 2024

Polymer electrolyte membrane fuel cells (PEMFCs) are a zero emission replacement for heavy duty applications due to their range, energy density and fast refueling times.[1] In 2020, the U.S. Department of Energy (DOE) lunched the Million Mile Fuel Cell Truck (M2FCT) consortium to fund fuel cell R&D to meet heavy duty truck standards.[2] Durability studies focusing on heavy-duty applications for advanced materials testing under the M2FCT consortium have been extensively explored and continue to be analyzed to standardize the evaluation of next generation fuel cell materials.

This study combines in situ electrochemical characterization with ex situ analysis of single cell PEMFCs membrane electrode assemblies (MEAs) to predict long-term durability for heavy-duty applications. Various accelerated stress test (AST) parameters were analyzed to determine the stressors affecting the long-term durability. Local degradation resulting from repeated high voltage to low current cycles was analyzed by testing state-of-the-art materials. High potential holds at various conditions were analyzed to determine membrane chemical degradation. Repeated wet and dry cycles were performed to test the membrane mechanical durability. In situ electrochemical analysis include mass activity, electrochemical surface area, hydrogen crossover, and polarization curves were collected and compared among the MEAs. Ex situ analysis includes quantification of membrane thinning at end of life and fluoride emission rate measurement for water effluent throughout the test was conducted to study the membrane degradation.

Acknowledgement:

This work was supported by the Hydrogen and Fuel Cell Technologies Office (HFTO), Office of Energy Efficiency and Renewable Energy (EERE), US DOE through the Million Mile Fuel Cell Truck (M2FCT) consortium, technology managers G. Kleen and D. Papageorgopoulos.

References:

David A. Cullen, K. C. Neyerlin, Rajesh K. Ahluwalia, Rangachary Mukundan, Karren L. More, Rodney L. Borup, Adam Z. Weber, Deborah J. Myers, and Ahmet Kusoglu, New roads and challenges for fuel cells in heavy-duty transportation. Nat. Energy, 2021. 6(5): 462-474.

DOE Launches Two Consortia to Advance Fuel Cell Truck and Electrolyzer R&D. 2020; Available from: https://www.energy.gov/eere/articles/doe-launches-two-consortia-advance-fuel-cell-truck-and-electrolyzer-rd.
Enhanced Low-Humidity Performance of Polymer Exchange Membrane Fuel Cells via Membrane Surface Engineering
Authors: KIM Taehyo
Published: December 2024

Polymer electrolyte membrane fuel cells (PEMFCs) have emerged as a promising and eco-friendly energy source for portable devices and mobile power systems. However, the commercialization of PEMFCs for high-power operations, such as construction and agricultural machinery, faces challenges related to cost and low-humidity environments. This study introduces a novel approach to address these challenges by utilizing a polymer template for pattern transfer onto Nafion membranes. The patterned membrane exhibited increased surface area, leading to superior catalyst activity and improved water management. Performance evaluations of the patterned membrane electrode assembly (MEA) demonstrated enhanced efficiency, even in fully humidified conditions, and notably outperformed under low humidity (60%, 30% relative humidity) conditions. The increased surface area and three-phase interface improved catalyst efficiency and water generation and discharge, showcasing the potential of utilizing generated water as a valuable resource. The introduction of a cost-effective, patterned membrane not only enhances PEMFC performance but also offers a dual advantage by potentially reducing costs associated with humidification maintenance. Addressing critical issues hindering PEMFC commercialization, our study aims to pave the way for widespread utilization in demanding applications, including construction and agricultural machinery, while simultaneously enhancing their sustainability and economic feasibility.
Manufacturing Novel Cathodes for Improved Fuel Cell Performance
Authors: Allen Jabari , Mukundan Rangachary , Rockward Tommy
Published: December 2024

In Proton Exchange Membrane Fuel Cells (PEMFCs) water generation and management can become a difficult challenge for sustained operation. In short, too much water can flood the electrodes and block the reactant gases, while too little water can induce membrane dehydration and decreased protonic conductivity, highlighting the necessity for optimized hydration of the electrodes. To address this challenge, our efforts are directed toward the refinement of the cathode architecture, to improve the overall mass transport of the reactants and management of product water. The experimental design includes varying the Pt-loading, while optimizing the degree of porosity within the electrode structure. The cathode is fabricated by using an ultrasonic spray-coating method and its loading is determined by X-Ray Fluorescence (XRF). Porosity is managed by the pore size distribution of the additives and unique layering techniques. The performance of these cathodes is isolated by keeping all other materials, components, and parameters identical (e.g., anode loading, membrane, etc.), allowing us to elucidate the performance.
Understanding PEMFC Catalyst Ink Component Interactions Using Rheo-Impedance Measurement
Authors: Mora Joy Marie , Chuang Po-Ya Abel
Published: December 2024

Optimizing electrode performance remains a grand challenge for fuel cell researchers, particularly in proton exchange membrane fuel cell (PEMFC) catalyst layers (CLs). These layers are typically fabricated from inks containing carbon-supported platinum catalyst particles and ion-conducting polymer material, dispersed in a solvent solution. Variations in catalyst ink formulations result in distinct interactions among ink components, shaping the microstructure and performance of CLs. Additionally, fabrication processes play a crucial role in determining the final properties and microstructure of these CLs. Therefore, understanding the correlation between precursor ink, catalyst morphology, and performance is essential in materials and design optimization for fuel cell technology.

This study investigates the interactions within PEMFC catalyst ink using various ink component formulations. We employ a combination of rheological and electrical impedance spectroscopy measurements (rheo-EIS) to probe the static and dynamic nature of catalyst ink. The observed properties, coupled with zeta (ζ) potential and dynamic light scattering (DLS) measurements, provide insights on ink agglomeration levels and microstructure evolution. The experimental approach and findings offer a deeper understanding of ink component-CL structure relationships, guiding the engineering of catalyst inks tailored for practical and optimal performance.
Exploring the Impact of Contamination and Ageing on Proton Exchange Membrane Fuel Cells: Insights from Transmission Electron Microscopy
Authors: Pourrahmani Hossein , Ferriday Thomas B. , Oveisi Emad , Bettex Jeremie , Van herle Jan
Published: December 2024

This paper presents a thorough investigation into the multifaceted impacts of contamination and ageing on the performance and structural integrity of proton exchange membrane fuel cells (PEMFCs) utilizing advanced Scanning Transmission Electron Microscopy (STEM). The study scrutinizes three distinct membrane electrode assemblies (MEAs): pristine, contaminated, and aged over an extensive operational period of 900 hours. Through meticulous analysis encompassing morphology and chemical composition, the intricate alterations induced by these factors are elucidated, providing invaluable insights into PEMFC degradation mechanisms.

While contamination exhibited a seemingly minor influence on carbon distribution, profound effects were discerned on the ionomer and membrane constituents. Notably, a reduction in the perfluorinated backbone of polytetrafluoroethylene (PTFE) was evident, quantified by the ratio , standing at 2.07. This degradation significantly impeded the binding of catalysts and hindered ionic charge conduction, thereby fostering agglomeration and impeding ionic conductivity within the catalyst layer. Moreover, the aged MEA endured substantial carbon corrosion, resulting in the structural compromise of the carbon support layer.

The repercussions of carbon corrosion were manifold, manifesting in a discernible decrease in the electrochemical active surface area (ECSA) attributable to platinum dissolution and re-deposition. Consequently, this led to an uneven distribution of platinum, forming clusters and exacerbating activation overpotential. These findings underscore the intricate interplay between contamination, ageing, and the ensuing structural and electrochemical alterations in PEMFCs, shedding light on critical degradation pathways.

Furthermore, a comprehensive analysis of the aged MEA revealed notable changes in the microstructural characteristics, including an increase in pore size and surface roughness, indicative of progressive degradation mechanisms. These structural alterations were found to directly correlate with deteriorating performance metrics, emphasizing the pivotal role of microstructural integrity in PEMFC functionality.

In conclusion, this study offers valuable insights into the intricate interplay between contamination, ageing, and structural degradation in PEMFCs, highlighting the urgent need for effective mitigation strategies to prolong lifespan and enhance performance. The findings presented herein serve as a crucial foundation for the development of advanced materials and design strategies aimed at enhancing the durability and efficiency of PEMFCs for diverse applications.

Figure 1
Hydrogen Limiting Current Test Diagnostic Tool for Analyzing PEMFC Durability in Accelerated Stress Tests
Authors: Baricci Andrea , Casalegno Andrea , Colombo Elena , Grimaldi Amedeo , Mora Daniele
Published: December 2024

The durability of Polymer Electrolyte Membrane Fuel Cells (PEMFC) is a crucial factor for enhancing their competitiveness in the heavy-duty vehicle sector thus it is essential to assess the impact of the major degradation mechanisms on the performance and lifetime of the technology. To this end, accelerated stress tests have been standardized over the years with the aim of expediting the development of durable materials and being able to evaluate the durability in MEA. In this framework, it is extremely important to be able to separate different sources of voltage loss. Specifically, the degradation of mass transfer loss is extremely important because impacts the maximum power density available, efficiency and thermal management of the stack. Mass transfer loss is correlated at the material level, to the loss in electrocatalyst active surface (ECSA) being a consequence of the limitations in oxygen transport across the ionomer thin film. In this work mass transfer degradation is analyzed by ASTs that accelerate real-world ageing [1]. In this work, in addition to standard diagnostic tools, hydrogen limiting current test are investigated. Previous work reported that using hydrogen as reacting gas for limiting current test can give additional information on the sources of mass transfer loss compared to oxygen, specifically information on the ionomer thin film resistance [2]. In this work, limiting current tests were carried out as diagnostic tools during ASTs for electrocatalyst durability and novel ASTs that better mimick real-world vehicle operation within the IDFAST H2020 project and in the Italian project PERMANENT to investigate the degradation [2]. Correlation between mass transfer resistance in ionomer between oxygen and hydrogen limiting current test is found. Additional effects in the high potential region are observed and attributed to platinum oxide formation by means of a 1D MEA model that is adopted to investigate this effect.

[1] Spingler F.B., Phillips A., Schuler T., Tucker M.C., Weber A.Z. (2017) International Journal of Hydrogen Energy, 13960-13969

[2] Colombo E., Baricci A., Mora D., Guetaz L., Casalegno A., (2023) Journal of Power Sources, 580 , art. no. 233376
Effects of Gravity on Water Transport in PEM Fuel Cells Via Synchrotron X-Ray Radiography
Authors: Chadwick Eric Alexander , Schulz Volker Paul , Bazylak Aimy
Published: December 2024

To mitigate the effects of anthropogenic climate change caused primarily by CO2 emissions, sustainable energy technologies must be advanced to eliminate our reliance on CO2-emitting energy sources. Polymer electrolyte membrane (PEM) fuel cells are a promising technology for producing power without carbon emissions and with high efficiencies and scalability [1]. However, the commercial adaptation of PEM fuel cells has been sluggish due to high material costs [2]and inefficiencies caused by liquid water accumulation [2,3]. While major improvements have been made to PEM fuel cell components to improve water management, recent studies have shown that macroscopic changes such as cell orientation and flow direction can have profound effects on fuel cell performance and two-phase flow [3-5].

In this study, to determine the optimal orientation for industrial applications of fuel cells and provide insights on water accumulation as a result of external body forces, we performed operando synchrotron X-ray radiography while varying orientation and reactant flow direction of a PEM fuel cell (Fig. 1a). We observed lower water content in the anode GDL when the flow of reactants was gravity-assisted (45º and 90º), and significantly more water content was observed when reactant flow opposed the force of gravity (315º and 270º). Furthermore, placing the cathode on top (180º) resulted in dramatic increases in anode GDL water accumulation compared to placing the cathode on the bottom (0º). Similar trends in cathode GDL water accumulation were observed but were less pronounced compared to the anode GDL. Electrochemical impedance spectroscopy and analytical modelling revealed that mass transport resistances are strongly correlated to water accumulation in the cathode GDL and especially the anode GDL. Our findings suggest that gravity and flow orientation significantly affect two-phase transport and therefore long-term performance in PEM fuel cells (Fig. 1c).

References:

D. A. Cullen et al., Nat Energy, 6, 462–474 (2021).

J. Wang, Appl Energy, 157, 640–663 (2015).

M. Pan, X. Meng, C. Li, J. Liao, and C. Pan, Int J Green Energy, 17, 603–616 (2020).

M. Ashrafi and M. Shams, Appl Energy, 208, 1083–1096 (2017).

H. Guo, X. Liu, J. F. Zhao, F. Ye, and C. F. Ma, Energy, 112, 926–934 (2016).

Figure 1: a) Experimental schematic showing the fuel cell in the 45°/315° position. b) Liquid water saturation levels in the Anode (top) and Cathode (bottom) GDLs at 0.7 . c) Mass transport resistance of every orientation at each tested current density obtained via electrochemical impedance spectroscopy.

Figure 1
Balancing Performance and Pressure Drop in Ni Foam Flow Fields Via Embedded Channel Design
Authors: Chadwick Eric Alexander , Briand Axel , Seip Tess , Auvity Bruno , Bazylak Aimy , Schulz Volker Paul
Published: December 2024

To curb the effects of anthropogenic climate change, advancements in sustainable energy storage technologies are needed. Hydrogen storage has proven to be more reliable and scalable compared to other storage technologies due in large part to the high efficiencies and energy density of polymer electrolyte membrane (PEM) fuel cells used to extract energy from hydrogen [1]. However, due to high material costs and performance limitations [2,3], commercial adaptation of PEM fuel cells has been relatively slow [4]. In particular, the flow fields in PEM fuel cells account for 70-90% of the weight and volume, and 18-28% of stack costs, making the optimization of flow field function and weight particularly desirable [5]. Porous metal foams have shown promise as a light-weight alternative to conventional flow fields that can achieve competitive performance to baffle and interdigitated designs, but often suffer from high pressure drops [6].

In this study, we demonstrate the capabilities of porous Ni foams with embedded channels as light-weight flow fields for improving fuel cell performance via enhanced reactant distributions and water management while also reducing the pressure drop. Fuel cell performance using gold coated Ni foams with and without embedded channels was compared to a baseline serpentine flow field. All flow field designs were evaluated at wet and dry RH conditions and at two different compression conditions. We reveal that thick Ni foam flow fields without channels improved performance notably compared to the baseline serpentine flow field due to enhancements in reactant delivery and water removal at both wet and dry RH conditions. Further, the use of embedded channels in both thick and thin foam improved performance at both RH conditions by providing larger pathways for water removal while retaining porous lands for efficient reactant delivery. Thick foams significantly reduced pressure drop and achieved lower variability over the course of the test while thin foams only slightly reduced pressure drop with high variability due to local water droplet buildup. The improved performance, reduced pressure drop, and inherent light-weight design of these foams can significantly reduce energy capacity and power density of next generation fuel cells.

References:

X. Luo, J. Wang, M. Dooner, and J. Clarke, Appl Energy, 137, 511–536 (2015).

J. Wang, Appl Energy, 157, 640–663 (2015).

M. Pan, X. Meng, C. Li, J. Liao, and C. Pan, Int J Green Energy, 17, 603–616 (2020).

D. A. Cullen et al., Nat Energy, 6, 462–474 (2021).

Y. Wang, D. F. Ruiz Diaz, K. S. Chen, Z. Wang, and X. C. Adroher, Materials Today, 32, 178–203 (2020).

W. Yuan, Y. Tang, X. Yang, and Z. Wan, Appl Energy, 94, 309–329 (2012).
(Invited) Lithium Ion Conduction by Molecular Vibrations in Ion-Conducting Glasses
Authors: Ohara Koji , Yamada Hiroki , Hiroi Satoshi , Sakuda Atsushi , Ohkubo Takahiro , Hayashi Akitoshi
Published: December 2024

Controlling Li ion conduction in glasses at atomic and molecular levels is key to realizing all-solid-state batteries, a promising technology for electric vehicles. In this context, Li3PS4 glass, a promising solid electrolyte candidate, exhibits dynamic coupling between the Li+ cation mobility and the PS4
3− anion libration, which is commonly referred to as the paddlewheel effect1. In addition, it exhibits a concerted cation diffusion effect (i.e., a cation–cation interaction), which is regarded as the essence of high Li ion conduction. However, the correlation between the Li+ ions within the glass structure can only be vaguely determined, due to the limited experimental information. We report that the Li ions present in glasses can be classified by evaluating their valence oscillations via Bader analysis to topologically analyse the chemical bonds2. We found that three types of Li ions are present in Li3PS4 glass, and that the more mobile Li ions exhibit a characteristic correlation at relatively long distances of 4.0–5.0 Å. Furthermore, reverse Monte Carlo simulations combined with deep learning potentials that reproduce X-ray, neutron, and electron diffraction pair distribution functions showed an increase in the number of more mobile Li ions for partially crystallised glass structures with improved Li ion conduction properties. Our results show order within the disorder of the Li ion distribution in the glass by a topological analysis of their valences.

References

J. G. Smith, D. J. Siegel, Nature Communications, 11 (1), 1483 (2020).

H. Yamada, K. Ohara, S. Hiroi, A. Sakuda, K. Ikeda, T. Ohkubo, K. Nakada, H. Tsukasaki, H. Nakajima, L. Temleitner, L. Pusztai, S. Ariga, A. Matsuo, J. Ding, T. Nakano, T. Kimura, R. Kobayashi, T. Usuki, S. Tahara, K. Amezawa, Y. Tateyama, S. Mori, and A. Hayashi, Energy & Environmental Materials, e12612 (2023).
(Invited) Evaluation and Characterization of NaCl as an Electrode for Sodium-Ion Batteries
Authors: Moeez Iqra , Park Jae-Ho , Susanto Dieky , Kim Ji-Young , Jung Hun-Gi , Lim Hee-Dae , Chung Kyung Yoon
Published: December 2024

Sodium-ion batteries (SIBs) have attracted considerable attention as a promising alternative for large-scale energy storage due to their remarkable benefits in terms of resource availability and cost-effectiveness. However, there is still a big difference in energy density between SIBs and lithium-ion batteries (LIBs) that are commercially available, which makes it hard to meet the needs of practical applications. The fabrication of high-energy cathodes has become a successful approach for increasing the energy density of SIBs. This often involves using cathodes that can operate in high-voltage regions.

Herein, we used table salt (NaCl) as a novel cathode material for SIBs, where this electrochemically inactive NaCl was activated by introducing structural defects that induce a phase transition from B1- to B2-type NaCl. It was demonstrated that B2-NaCl could exhibit a high initial capacity of 260 mAh g−1; however, poor cycle stability with unsatisfactory capacity retention was a major challenge for its practical application. For this, additional Na-vacancies were introduced by controlling the upper limit of the cut-off voltage, which helped to accommodate more sodium ions during the next discharge, resulting in increased capacity. Meanwhile, Cl-ions, which are released during NaCl decomposition at high voltage of 4.5 V, are oxidized to form Cl-based organic species at the active material interfaces, which helps to enhance the cycle stability. XPS, SEM, and TOF-SIMS characterizations helped to understand the crucial role of these Cl-based species in protecting the NaCl electrode from undesired side reactions at high voltage. Additionally, the in-situ XRD and XAS studies investigated the relationship between the degree of electrochemical activation and the structural stability of metallic NaxCl. We believe that this study could help in exploring a novel method for generating low-cost and high-capacity electrode material for future energy-storage devices.
Detangling Ion Transport and Lithium Dendritic Growth Using Stimulated Raman Scattering Microscopy
Authors: Cheng Qian
Published: December 2024

Ion transport is one of the fundamental processes in batteries, directly impacting energy density, power density, and cycling lifetime. However, ion concentration in electrolyte is usually low (0.01 M to 1 M), while ion diffusion coefficient is extremely high (10^-6 cm^2/s), making characterization of this process extremely difficult. Conventional characterization techniques such as transmission electron microscopy, nuclear magnetic resonance, and synchrotron radiation have encountered significant challenges on this topic, leaving ion transport process inside working batteries largely unknown.

Stimulated Raman Scattering microscopy (SRS) is a recently emerging imaging technique, offering a speed approximately 10^8 times faster than conventional Raman spectrometers. It provides extremely high concentration, time, and spatial resolution, along with high selectivity and non-invasiveness. In our study, SRS was employed for the first time to dynamically image ion depletion within batteries and the growth of lithium dendrites in situ, providing visualization and quantitative analysis of ion distribution in liquid electrolytes. A three-stage lithium deposition process is uncovered, corresponding to no depletion, partial depletion, and full depletion of lithium ions. Further analysis reveals a feedback mechanism between the lithium dendrite growth and heterogeneity of local ionic concentration on lithium metal electrode, which can be effectively suppressed by artificial solid electrolyte interphase.

We further explored lithium dendrite growth in PEO solid polymer electrolyte, but found unexpected opposite behaviors in solid polymer electrolytes: concentration polarization can induce phase transformation in a PEO electrolyte, forming a new PEO-rich but salt-/plasticizer-poor phase at the lithium/electrolyte interface, as unveiled by SRS. The new phase has a significantly higher Young’s modulus (1–3 GPa) than a bulk polymer electrolyte (<1 MPa). We hereby propose a design rule for PEO electrolytes: their compositions should be near the boundary between single-phase and two-phase regions in the phase diagram so that the applied current can induce the formation of a mechanically rigid PEO-rich phase to suppress lithium whiskers.

This study revealed the growth mechanism of lithium dendrites and proposed solutions to suppress metallic lithium dendrites. SRS offers unprecedented ability over conventional characterization tools in studying reaction mechanisms, and is going to play a crucial role in research fields such as batteries, supercapacitors, and catalysis in the future.
Comparative Study of Irreversible Lithium Formation Mechanisms in Various Silicon Anode Materials for Li-Ion Secondary Batteries
Authors: Yu Yong-Hyun , Kim Dong-Young , Shim Jae-Hyun
Published: December 2024

Lithium-ion secondary batteries play a crucial role in mobile power storage systems, supplying energy for electronic devices and electric vehicles. However, compared to current carbon-based anode materials, they suffer from limitations in energy density and cycle stability . The application of silicon materials is emerging as a promising alternative to overcome these limitations due to its high theoretical capacity, approximately 10 times higher than that of graphite (4200mAh/g compared to 372mAh/g). However, the structural instability caused by volume changes during charging and discharging poses a challenge in the application of silicon materials.

Various silicon anode materials that can be applied to lithium-ion secondary batteries include crystalline silicon, amorphous silicon, silicon alloys, and oxide-based silicon. These diverse silicon materials each possess different capacities and electrochemical properties. The composition of lithium-silicon compounds formed during charging varies with different silicon materials, leading to differences in electrochemical properties. Additionally, the crystal structures formed during charging differ, influencing their irreversible lithium formation and affecting the battery's cyclability and expansion characteristics. Therefore, it is essential to compare and analyze the irreversible lithium formation and charging/discharging mechanisms of silicon anode materials.

In this study, we will observe the crystallographic structural changes occurring during charging and discharging of crystalline silicon, amorphous silicon, silicon alloys, and oxide-based silicon anode materials using ex-situ X-ray diffraction (XRD) and transmission electron microscopy (TEM). Furthermore, we will examine how these crystallographic changes affect the electrochemical properties and volume expansion.
Unraveling the Composition Effects in Chemo-Mechanical Behavior for Single-Crystal Ni Rich Cathodes
Authors: Wang Jing , Liu Tongchao , Meng Shirley , Amine Khalil
Published: December 2024

Nickel-rich lithium layered oxides (LiNi
x
Mn
y
Co
z
O2 (NMC), x + y + z = 1, x ≥ 0.6) with high accessible capacity, have received tremendous attention as the most promising cathode candidate for next-generation lithium-ion batteries1. To obtain cathode materials with superior electrochemical performance, substantial efforts have focused on optimizing materials’ chemical compositions. However, regardless of chemical compositions, most commercial NMC materials are typically agglomerates composed of primary nanograins (polycrystalline (PC) NMC) which suffer from severe anisotropic expanding or shrinking and thus rapid mechanical failure in the form of intergranular cracking2. To enhance the structural stability, single crystal (SC) NMC with pore-free and high-strength micron-scale particles have received considerable attention3. Owing to the changes in mechanical properties and degradation mechanisms, uncertainties persist regarding the applicability of established compositional design principles and structural degradation indicators in PC Ni rich cathodes to the newly developed SC counterparts4-5. Here we elucidate the intricate correlation between chemical composition and structural properties in SC Ni-rich cathodes using Co-free and Mn-free cathodes as the models. In this case, Mn and Co exhibit significantly different roles for SC cathodes in electrochemical behaviors compared to their PC analogues. By leveraging multi-scale and high dimensional characterization techniques, we reveal the composition effects in lattice strain generation, phase evolution and microcrack formation. This study deepens understanding of the relationship between chemical composition and chemo-mechanical behaviors for SC Ni rich cathodes, contributing to relevant development of rational design strategies and refined characterization methodology.

References

M. Li, J. Lu, Z. Chen, K. Amine. Adv. Mater.
2018, 30, e1800561.

T. Liu, L. Yu, J. Lu, T. Zhou, X. Huang, Z. Cai, A. Dai, J. Gim, Y. Ren, X. Xiao, M. V. Holt, Y. S. Chu, I. Arslan, J. Wen, K. Amine. Nat. Commun.
2021, 12, 6024.

J. Langdon, A. Manthiram. Energy Storage Mater.
2021, 37, 143-160.

T. Liu, L. Yu, J. Liu, J. Lu, X. Bi, A. Dai, M. Li, M. Li, Z. Hu, L. Ma, D. Luo, J. Zheng, T. Wu, Y. Ren, J. Wen, F. Pan, K. Amine. Nat. Energy
2021, 3, 277-286.

A. Aishova, G-T. Park, C. S. Yoon, Y-K Sun. Adv. Energy Mater.
2020, 10, 1903179.
From Cradle to Grave: In-Situ Imaging of Microstructural Changes in Commercial Cells during Formation and after Long-Term Cycling
Authors: Bond Toby Mishkin , Gauthier Roby , Dressler Reid Andrew , James Abraham Jeffin , Dahn Jeff R.
Published: December 2024

Electrode microstructure changes occur at many different timescales: from irreversible changes during formation to gradual microcracking and pulverization of electrodes after months of cycling2. These changes are generally characterized using either destructive sampling or purpose-built in-situ cells2, which may not always represent the real operating environment of a commercial cell.

Over the past three years, we have developed in-situ imaging methods that use synchrotron-based computed tomography to non-destructively image the microstructure of electrodes inside unmodified commercial-form-factor cells.3,4 This has allowed us to capture changes occurring within a single charge/discharge cycle, such as irreversible changes in porosity and anode thickness occurring during formation in Si-graphite-containing pouch cells. On a larger timescale, we can characterize and quantify the extent of microcracking for pouch cells containing Ni-rich cathodes like NMC622. These methods even allow us to study high-rate cycling behavior, such as the effect of gravity on electrolyte motion in 18650 cells. Taken together, these methods allow us to understand what's happening inside real-world cells on a timescale of minutes to years.

References:

[1] R. Gauthier, A. Luscombe, T. Bond, M. Bauer, M. Johnson, J. Harlow, A. Louli, and J. R. Dahn, J. Electrochem. Soc., 169, 020518 (2022).

[2] T. Waldmann, A. Iturrondobeitia, M. Kasper, N. Ghanbari, F. Aguesse, E. Bekaert, L. Daniel, S. Genies, I. Jimenez Gordon, M. W. Loble, E. De Vito, and M. Wohlfahrt-Mehrensa, J. Electrochem. Soc. 163, A2149 (2016).

[3] T. Bond, R. Gauthier, A. Eldesoky, J. Harlow, J.R. Dahn, J Electrochem Soc. 169, 020501 (2022)

[4] T. Bond, R. Gauthier, S. Gasilov, J. R. Dahn, J Electrochem Soc. 169 (2022) 080531. doi:10.1149/1945-7111/AC8A22.

Figure 1
Investigating Low Temperature Degradation and Its Impact on the Performance and Safety of Lithium-Ion Batteries
Authors: Kirchner-Burles Charlie Rodney , Johnson Michael , Buckwell Mark , Hinds Gareth , Shearing Paul Robert , Jervis Rhodri , Robinson James B
Published: December 2024

Lithium-ion batteries are at the forefront of facilitating the modern-day industrial revolution: a transition from petrochemical energy storage to specialised carbon-free energy storage. Batteries hold a crucial role in storing energy generated by renewables outside of peak energy demands, whilst also enabling an extended portable energy supply for applications such as electronic devices, aerospace applications and electric vehicles. Increasing the energy densities of our batteries is one of the main avenues these technologies are taking to ensure the demands of the green transition are met. In recent years, numerous high-profile failures of lithium-ion batteries have been reported1, contributing to wider concerns about the safety of high energy density cells. Inadequate management of such systems can be costly for both human health and financial damages. To accommodate these more energy-dense cells, manufacturers need to provide better assurances in safe cell operations.

Apprehensions in cell safety can mainly be attributed to a cell’s ability to enter thermal runaway, a process that is most often caused by an internal short circuit (ISC). Such an event can be triggered by three different modes of abuse: thermal, mechanical, and electrical. At the anode, metallic lithium can precipitate onto the surface via three main conditions: overcharge, high charging currents, and low charging temperatures. Each of which creates a saturation of intercalated lithium-ions in the crystallographic active sites near the anode surface. This lowers the anodes surface potential until it is sufficiently low enough for lithium plating to occur. This work investigates cell function at low temperatures and how the resulting degradation affects their response to abusive conditions.

Various ageing regimes were applied to a set of commercial lithium-ion cells and, by monitoring their electrochemical behaviour, carrying out ex-situ characterisation of the aged negative electrodes, and employing X-ray computed tomography (CT), this work evaluates the decline in performance observed at low temperatures. Subsequent accelerated rate calorimetry (ARC) and operando ultra-high-speed synchrotron tomography studies highlight the diminished thermal stability these aged cells possess as the states of degradation become more advanced and reveal the mechanisms through which failure occurs. These findings demonstrate why improved cell architecture and real-time management systems are necessary to realise commercial success in future battery applications.

Figure 1