bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatially Resolved Analysis of the Influence of Three-Dimensional Flow Field Structures on Loss Processes in PEMFCs
Authors: Oppek Philipp , Raab Sebastian , Weber Andre 
Published: December 2024

During operation of large-area polymer electrolyte membrane fuel cells (PEMFCs) under high loads, strong gradients occur along the gas channel and mass transport becomes the performance limiting factor. Towards the gas outlet the concentration of the reactants decreases, while the relative humidity increases and liquid water is formed. Despite these high gradients, the aim is to achieve a high performance over the entire channel length.
The flow field geometry, which controls the distribution of the reactant, the removal of excess liquid water and the electrical contact, has a significant influence on the overall performance and the power density distribution along the channel. Conventionally, channel-rib structures are used, but these are limited in terms of the distribution and transportation of the reactants, especially under high loads.
Due to their specific structure and open geometry, three-dimensional flow structures have an optimized transport of reactants to the active layer as well as removal of water and thus a strongly improved mass transport. At the same time, such structures have a highly reduced contact area, which leads to increased ohmic losses. In order to fully understand the impact on the performance of the cell under different operating conditions, a quantification of the local performance as well as resistances distribution and their dependencies is essential.
For this purpose, we are examining both channel-rib and three-dimensional flow structures using a segmented cell. The performance distribution is determined by the local measurement of current and voltage. The measurement of electrochemical impedance spectra of each segment and impedance data analysis by the distribution of relaxation times (DRT) [1,2,3] enables the local deconvolution of the loss processes.
In this contribution, an experimental analysis of the influence of three-dimensional meshes compared to a channel-rib flow field design on cell performance is presented. In particular, the effects of high loads, high humidities and low oxygen concentrations on the performance and resistances and their distribution along the gas channels are discussed. Based on the physical interpretation of the results, consequences and conclusions for the further development of three-dimensional flow field geometries are drawn.
References:

H. Schichlein et al., J. Appl. Electrochem. 32, pp. 875-882 (2002).

E. Ivers-Tiffée et al., J. Ceram. Soc. Japan 125, pp. 193-201 (2017).

M. Heinzmann et al., J. Power Sources 558, 232540 (2023).
Novel Design of Corrugated Columns for Water Management in a Proton Exchange Membrane Fuel Cell
Authors: Shahzad Hasan , Garcia-Salaberri Pablo A. , Duque Luis , Diaz-Álvarez Ester , Folgado M. Antonia , Chaparro Antonio M 
Published: December 2024

Fuel cells have become increasingly acknowledged as an important and sustainable source of energy in recent years. Proton exchange membrane (PEM) fuel cells, which use hydrogen to generate power, are closer to a wide use in stationary, transport, and portable devices. However, water management significantly influences the efficiency and long-term reliability of PEM fuel cells in both convective and passive configurations. This study focuses on investigating a novel cathodic plate design with helicoidally corrugated columns to optimize the water removal from a PEM fuel cell. The plate is equipped with a series of helicoidally corrugated columns to enhance the movement and removal of water droplets from the cathode surface. The analysis is carried out using computational modeling and experimental research for both convective as well as passive PEM fuel cells. The preliminary outcomes of our research demonstrate substantial enhancements in the efficacy of water management, which contributes to the prolonged operational lifespan and improved overall performance of air-breathing PEM fuel cells. The results provide a valuable contribution to enhance the expandability and practicality of air-breathing fuel cell technologies, which has diverse applications for portable electronics.
This work was supported by projects PORHYDRO1 TED2021-131620B-C21/AEI and PORHYDRO2 TED2021-131620B-C22/AEI European Union NextGenerationEU/PRTR, of the Ministry of Science and Innovation of Spain, Spanish Research Council.
Water Transport, Diffusion and Drag in Intermediate Temperature Proton Exchange Fuel Cells
Authors: Nikolic Nikola , Lindbergh Goran , Eriksson Björn , Lindström Rakel Wreland , Lagergren Carina 
Published: December 2024

Low-temperature proton exchange membrane fuel cell (PEMFC) systems operating at <80 °C show limitations such as requirements for large cooling systems, employment of expensive catalysts and challenging water management. Operating the PEMFC at intermediate temperatures (80 - 120 °C) would reduce these limitations. As water is a product in the oxygen reduction reaction on the cathode it is important to understand its management at elevated temperatures to avoid flooding or drying out, especially due to exceeding water boiling temperature.
In this work the water transport in PEMFC at 80 – 120 °C is examined by measuring the water content at anode and cathode during operation with sensors at inlets and outlets. This is examined under ambient and pressurized conditions and at relative humidities (RHs) of 40 % and 70 %. The results show that water content at the cathode always increases with rising current due to water production (Figure 1 a). However, the water content at the anode is dependent on the operating condition and is always lower compared to the cathode. Due to water diffusion from the cathode water is also slightly increased on anode at 80 °C, but at 100 and 120 °C negative values at the anode are noted. This means that the water dragged from the anode to the cathode by the migration of protons is larger than the water diffused from cathode to the anode at higher temperatures. This was further evaluated by performing hydrogen pump measurements and elucidated through a physics-based model using COMSOL Multiphysics software. The divergence due to temperature is smaller when the cell is pressurized (Figure 1 b), and negative values at the anode are observed only at 120 °C. Even though the water content is decreasing, the decrease of RH or drying out is never observed at either ambient or pressurized conditions. Water distribution was shown to be unaffected by changing RH of inlet gases, however, the divergence of RH between cathode and anode was not observed at 70 % RH as it is observed at 40 % RH. Overall, it is possible to run the cell at elevated temperatures without danger of drying out at tested pressures and RHs.

Figure 1
Quantitative Chemical State Analysis of Silicon-Based Anodes for Lithium Ion Battery Using X-Ray Emission Spectroscopy
Authors: Takahara Hikari , Shoji Takashi , Kawahara Naoki , Doui Makoto , Kobayashi Hironori 
Published: December 2024

The advancement of lithium-ion batteries for electric vehicles has prompted the utilization of diverse materials, including substances like amorphous and sulphated materials, which may lack inherent stability. Consequently, employing various analytical techniques, spectral analysis, and in-operando cell testing becomes imperative for their characterization. We assess the potential of X-ray Emission Spectroscopy (XES) to integrate chemical state and quantitative analysis, capitalizing on its bulk analysis capabilities with large analytical area and deep analytical depth.
Silicon-based anodes offer high theoretical capacities and hold promise for lithium-ion batteries in electric vehicles. However, their practical application is hindered by poor cycling performance and mechanical failure attributed to significant volume changes during lithiation. Understanding the formation of amorphous and crystalline lithium silicon alloy phases, crucial for capacity degradation analysis, underscores the importance of quantifying the x value in the Li
x
Si phase. SiO emerges as a compelling anode material with potential to enhance energy capacity and mitigate degradation. Demonstrating this property involves the complex conversion of SiO to amorphous Si and lithium silicates during charging.
While electrochemical reaction mechanisms and structural changes in silicon-based anodes have been explored using various techniques such as 7Li and 29Si solid-state NMR, Si K XAS, and Si-L2,3 soft X-ray emission spectroscopy, accurately quantifying reacted components remains challenging.
In this study, Si Kβ X-ray emission spectroscopy (XES) is employed to quantify the composition of lithium-silicon alloys and lithium silicates during charging and discharging processes. The Si Kβ spectrum evolves with the reaction progression, and linear combination fitting (LCF) proves instrumental in estimating material quantities based on the reaction formula. The quantitative results of the XES analysis are shown and the accuracy, validity and findings are discussed.
Degradation and Safety Analysis of Large Format LiFePO4/Graphite Battery
Authors: Matsuda Keisuke , Shono Kumi , Kobayashi Yo , Nakamura Tomoyuki 
Published: December 2024

Large format LiFePO4/Graphite (LFP/Gr) Lithium-ion battery (LIB) have been developed for electric vehicles (EV) and stationary use. In case of large surface electrodes, intrinsic two-phase reaction of LFP has a risk to induce inhomogeneous reaction in planar electrode surface. We applied >200 Ah class LFP/Gr LIBs and cycled them around 80-65 % SOH levels. Among them, we applied non-destructive differential voltage analysis (dV/dQ) to three cells (Cell1:SOH 80.9 %, Cell2:SOH 73.5 %, Cell3:SOH 68.4 %), and determined the degree of inhomogeneity of the electrodes by disassembly of the cell in the Ar-filled glove box.
We could obtain dV/dQ peak corresponds to Gr 2nd stage single phase by charge curve analysis between SOC 0 and 100 % at C/20. Based on the assumption that Gr capacity is twice of the Gr 2nd stage peak capacity, Gr capacity was sufficiently larger than cell capacity. Therefore, cell capacity fade was not related to the capacity fade of Gr but caused by the shift of the cathode / anode operation window (SOW) due to loss of lithium inventory (LLI) and/or capacity fade of LFP.
After dV/dQ analysis with capacity check, cells were disassembled at 2.5 V, and confirmed LFP and Gr capacity by reassembling coin cells with Li counter electrode. Reassembled LFP/Li cells was discharged to 2 V, and Gr/Li cells were deintercalated to 2.5 V. The subtracted value of these residual capacities, we could estimate SOW capacity. The obtained estimated cell capacity by LFP-SOW showed strong correlation with SOH of cells before disassembly (R=0.98). Therefore, we confirmed that capacity fade of the cell was due to increase in SOW and/or capacity fade of LFP.
To determine the degree of inhomogeneity in electrode planar, we applied XRD to LFP. As LFP reaction proceeds typical two-phase reaction, we can indirectly estimate Li content by estimating ratio of LFP and FePO4(FP). The LFP/FP ratio was optimized by Rietveld refinement of the diffraction peaks in various sampling points of the electrode sheet. We confirmed several macroscale inhomogeneous Li distributions in planar LFP electrode. Li poor area was observed at the beginning and the final edge of the roll electrode. The correlation details between cell SOH and degree of inhomogeneity will be discussed in the presentation.
In addition, we applied two kinds of abuse test, overcharge and forced internal short circuit test by laser spot heating to three cells with different SOH. In case of overcharge, cell was charged at 0.78 C from SOC 100 %. In case of laser heating, pulse laser with 0.5 sec supply / 0.1 sec rest at 2000 W applied to the cell. The difference of the obtained parameters, and correlation with SOH will be discussed in the presentation.
Forecast Li Plating in LiFePO4/Graphite Cells: Proposal and Issues
Authors: Shono Kumi , Kobayashi Yo , Matsuda Keisuke , Nakamura Tomoyuki 
Published: December 2024

Lithium-ion battery (LIB) for stationary use is required non-destructive degradation and SOH estimation in operation with sufficient safety and long-term use. We have developed non-destructive and post-mortem analysis for large format batteries. In case of non-destructive analysis, differential voltage analysis (dV/dQ) have been applied for the detection of lithium (Li) plating in operation. In addition, we have introduced Ar-filled glove box specially designed for large format battery disassembly to confirm the capacity fade of cathode / anode materials including Li plating on the anode.
We selected 20 conditions as acceleration tests using cylindrical 26650 type LiFePO4/Graphite (LFP/Gr) cells with nominal capacity of 3.4 Ah. We applied the following four non-destructive approaches to the cells with under 90% SOH to forecast Li plating; i) slope of open circuit voltage (OCV) during galvanostatic interruption of titration technique (GITT), ii) gap of charge end voltage and OCV, iii) Gr capacity estimation using dV/dQ peak to peak (Gr 4th and/or 3rd to 2nd stage) capacity or Gr 2nd stage dV/dQ peak position, and iv) peak height and/or width of dV/dQ at Gr 2nd stage.

In case of OCV monitoring, we focused on OCV trend at Gr 2nd and 1st stage coexisting region (0.5<
x
<1 in Li

x

C6). In the normal reaction, OCV at the region is almost flat due to the two-phase reaction of Gr and also LFP. However, we found the cell with OCV slope at the corresponding region was an indicator to forecast Li plating.

In addition, the gap of charge end voltage and OCV during GITT was also an indicator to forecast Li plating. In such case, we could forecast Li plating by using two charge end voltage and subsequent OCV values at D10% SOC at the region of 0.5<
x
<1 in Li

x

C

On the other hand, Li plating forecast using dV/dQ peak positions (used as an indicator of Gr capacity) could be applied in some cycle conditions but could not be applied other conditions including inhomogeneous capacity fade in operation.

Then we focused on peak height and width of dV/dQ at Gr 2nd stage and found that the trend of its peak shape will be an indicator to forecast Li plating. Furthermore, such forecast can grasp at limited SOC range operation including Gr 2nd stage region. Therefore, it will be a possibility to forecast Li plating in a short time using single dV/dQ profile.

We will report merits and issues of the procedure to forecast Li plating including the evidence of Li plating by post mortem analysis.
In Situ Insights into Cathode Calcination for Predictive Synthesis: Kinetic Crystallization of LiNiO2 from Hydroxides
Authors: Tayal Akhil 
Published: December 2024

Calcination is a solid-state synthesis process extensively employed in the industrial manufacturing of cathode materials for batteries. However, achieving predictive control of the process to synthesize high-performance cathodes faces complexities associated with the formation of kinetic intermediates that are often elusive and tend to structurally and chemically evolve towards equilibrium phases.
Herein, we use a combination of correlated in situ synchrotron X-ray diffraction (XRD), X-ray absorption spectroscopy (XAFS) and multiscale modeling to investigate the synthesis of the archetypical nickel-based cathode LiNiO2
via calcination from hydroxides. A multistage non-equilibrium crystallization of intermediates is uncovered, with the process dynamically driven by lithiation. Specifically, Li-intercalation occurs concomitantly with dehydration, resulting in the early emergence of Li-containing layered and rocksalt motifs upon the decomposition of Ni(OH)2 precursor. During the subsequent phase progression, crystal growth of the layered LiNiO2 goes slowly due to lithiation-limited sluggish mass transport, then abruptly accelerates upon full lithiation, while experiencing Li/O loss and structural degradation. These findings have immediate implications for the synthetic optimization of Ni-based cathodes, offering opportunities to tune their structural properties through lithiation control intentionally[1]. Figure 1. shows XRD and XAFS data of nickel hydroxide calcined at different temperature with and without Li source (LiOH.H2O).
Reference:
[1] A. Tayal et al. Adv. Mater. 2024, 2312027

Figure 1
Operando Raman Microscopy Studies on Next Generation Positive Electrode and Electrolyte Materials
Authors: del Campo Eva Maria , Marcinek Marek , Hardwick Laurence J. , Neale Alex R. , Żukowska Grażyna Zofia 
Published: December 2024

The growing demand for high-performance Li-ion cells nowadays has encouraged researchers to deeply understand the evolution of the various battery’s components over time. Ageing mechanisms have a great impact on the battery life performance; therefore, a better understanding of these complex processes may allow the prolongation of their useful cycle life. Monitoring the cathode material during battery operation is crucial since it represents the performance-limiting component in most of the LIBs [1]. Particularly, cobalt free lithium transition metal oxides are currently gaining interest as active materials for enabling higher energy density cells. Among them, LiNiO2 presents relatively high capacity and long durability. However, this material suffers from capacity loss and thermal instability at highly de-intercalated states due to its non-stoichiometric composition [2]. The mechanisms involved in the capacity fade remain still unclear making it crucial to understand these processes throughout cycling.
Among the methods available to perform operando measurements for Li-ion electrodes, Raman spectroscopy is well stablished to track structural evolution and chemical composition during charge and discharge [3,4]. With this work, an optimised electrode configuration [5] is presented which enables the monitoring of the different electrode phase transitions over several cycles. The developed methodology is applied for the investigation of LiNiO2 active material as a benchmark to understand the evolution of lithium metal oxides among time. The spectra collection obtained was rapidly analysed via the analysis tool PRISMA [6]. Overall, the ability of operando Raman as a pertinent diagnostic tool to follow electrodes behaviour during commercially relevant cycling conditions is demonstrated.
[1] Matteo Bianchini et al. Angew. Chem. Int. Ed. (2019), 10434-10458, 58 (31).
[2] Edgar Bautista Quisbert et al. Small. (2023) 2300616 19 (30).
[3] Hui et al. J. Am. Chem. Soc.(2022) 9434-9442, 144 (21).
[4] Sole et al. Faraday discussions (2016) 223-231, 72.
[5] Timothy E. Rosser et al, J. Electrochem.
Soc. (2021), 070541 (168).
[6] Flores E et al. Chemistry-methods (2022) 2 (10).
Understanding Local Structure-Activity Relation in Lithium-Ion Cathodes with Solid State NMR: Effect of Dopants, Synthesis and Electrochemical Cycling
Authors: Mallick Subhadip , Park Sohyun , Badami Pavan , Gim Jihyeon , Garcia Juan , Iddir Hakim , Abraham Daniel P. , Croy Jason R. , Dogan Fulya 
Published: December 2024

As the need for research and development efforts to enable alternative, sustainable lithium-ion cathode material is increasing, fine-tuning of the cathode composition and local structure has been focused on the use of dopants/ coatings and varying synthesis conditions such as annealing temperature and time. While changing these parameters has been shown to have significant effect on materials performance, the relation of synthesis parameters with local structure and composition and electrochemical activity is an ongoing focus area1. Solid state NMR is an important characterization technique for LIB systems as 6Li and 7Li solid state NMR can directly “see and follow” the Li cations within the structure, providing crucial information on domain structures, lithium local order changes and metal segregation. A multinuclear NMR approach is also crucial to track the dopants and study how/ if the dopants are diffusing into the bulk or remain on the surface as unintended coatings. This work covers an overview of how multinuclear solid-state NMR can be utilized to understand cathode local structure changes with synthesis, and electrochemical cycling, how dopants play a role in transition metal segregation and cathode interphase, and they affect materials performance. The NMR characterization studies focus on lithium-ion cathodes systems including lithium and manganese rich transitional metal oxide cathodes, lithium nickel oxide and nickel manganese cobalt oxides and are assisted by density functional theory calculations in providing a better understanding of the experimental characterization data and therefore local environments, domain structures and dopant effects.
References:

Brandon R., Long, Jason R. Croy, Fulya Dogan, Matthew R. Suchomel, Baris Key, Jianguo Wen, Dean J. Miller, Michael M. Thackeray, Mahalingam Balasubramanian, Chem.Mater.2014, 26, 3565−3572

Dogan F., Long B. R., Croy J. R., Gallagher K. G., Iddir H., Russell J. T., Balasubramanian M., Key B., Journal of the American Chemical Society (2015), 137(6), 2328-2335

Figure 1
Visualizing Solid Electrolyte Interphase Formation in Carbon Nanotube-Based Lithium-Ion Batteries: A Comparative in-Operando Electrochemical Atomic Force Microscopy Study
Authors: Frost Brandon Henry , Miller Thomas Samuel 
Published: December 2024

Reducing the impact of the climate crisis is this centuries greatest challenge and requires a global effort. Renewable energy sources are the key to decarbonising our energy systems. Lithium-ion batteries (LIBs) have played a key part in tackling the climate crisis and their continued development is imperative to further reducing the impact. More than ever, researchers are incorporating additives and components into battery electrode materials to enhance their electrochemical behaviour, such as their cyclability, conductivity and capacity retention. Carbon nanostructures as additives have been envisioned to offer solutions to problems associated with volumetric fluctuations as well as low conductivities in some next-generation LIBs.
Carbon nanotubes (CNTs) have been researched since 1991 and are essentially rolled up single or multiple sheets of graphene to produce single-walled CNTs or multi-walled CNTs respectively. The incorporation of CNTs into LIBs enhances conductivity and improves mechanical properties, enabling better tolerance to volume expansion. Despite these benefits, CNTs contribute to an initial irreversible capacity charge loss in the first cycle. Unlike the capacity loss seen in graphitic anodes, the high surface area of CNTs leads to increased electrolyte decomposition, forming the solid electrolyte interphase (SEI). This is essential for stable, long-term cycling. Given the limited understanding of SEI formation and growth in conventional LIBs, the introduction of CNTs further complicates this process.
In this work, in-operando electrochemical atomic force microscopy (EC-AFM) is employed to investigate the evolution of the electrode surface morphology. It can provide real-time information about the changing topography of the electrode surface as the electrochemical environment changes. Thus, processes leading to SEI formation on CNT and CNT:graphite electrodes will be visualised. A comparison is made with graphite:CNT electrodes, revealing a rapid SEI formation on the CNT electrode and a slower one on the graphite:CNT electrode. This demonstrates that the graphite:CNT ratio significantly influences SEI formation and, consequently, electrochemical performance. EC-AFM proves powerful in real-time probing of the effects of changing potential on an electrode surface, highlighting where SEI first nucleates and subsequently grows. This technique facilitates a direct correlation of electrochemical analysis with topographical images, offering invaluable insights into how initial electrochemical processes impact the electrode surface at micro- and nano-scales, applicable across various battery chemistries.