bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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.

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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.

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(Invited) Characterization of Catalyst Layers in Polymer Electrolyte Membrane Electrolyzers
Authors: Stelmacovich Genevieve , van Eijk Lonneke , Foster Jayson , Pylypenko Svitlana 
Published: December 2024

Polymer electrolyte membrane water electrolyzers (PEMWEs) play a vital role in promoting the widespread adoption of renewable hydrogen. To successfully fabricate and integrate components, develop scalable manufacturing techniques, understand degradation mechanisms, and devise strategies to mitigate degradation, it is essential to thoroughly characterize materials and components in these devices. Due to the complexity of these systems and various interconnected problems, as well as the multitude of relevant scales, the use of multi-technique characterization and the development of novel characterization approaches and methods are crucial.
This talk will highlight the complementary nature of electron and X-ray microscopy and spectroscopy methods for investigating surfaces, interfaces, and interactions with focus on catalyst layers (CLs) with an emphasis on analysis of as-prepared, tested and degraded samples. Micro X-ray computed tomography (XCT) provides both 2D and 3D analysis, but its resolution is not sufficient to identify catalyst layer features with enough detail, especially when Pt PTL coatings and low Ir-based catalyst loadings are used. On the other hand, Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-Ray Spectroscopy (EDS) provides superior resolution and enables the differentiation of PTL coatings and catalysts. Although SEM-EDS provides only 2D information, by employing a combination of top-down and cross-sectional analysis, a comprehensive understanding of catalyst distribution within the PTL can be attained, facilitating the initial assessment of PTLs and PTEs. The parameters extracted from SEM-EDS data can be used for a comprehensive quantitative assessment of the composition and distribution of catalysts, highlighting the differences between fabricated samples across a wide range of fabrication variables. Transmission Electron Microscopy (TEM) in tandem with EDS is also essential for nanoscale analysis of CLs, and PTEs. However, it is limited by its focus on small areas and necessitates complex sample preparation, especially for degraded samples. To complement these techniques, Time-of-Flight Secondary Mass Spectrometry (ToF-SIMS) has been developed as a promising complementary method to offer chemical insights, particularly valuable in analyzing protective coatings, catalyst layers, and interfaces between different layers. Furthermore, X-ray photoelectron spectroscopy (XPS) has high sensitivity in discerning catalyst evolution and subtle variations at the catalyst-ionomer interface, highlighting its complementary role in elemental and chemical composition analysis, especially in the context of tested and degraded samples.
A “Ship-in-a-Bottle” Method for Hydrogen Crossover Mitigation in PEM Water Electrolyzers
Authors: Yang Fan , Sun Qiang , Mittelsteadt Cortney 
Published: December 2024

This work presents a new approach to address hydrogen crossover in proton exchange membrane water electrolyzers (PEMWEs), a pivotal challenge that not only compromises safety but also affects the system’s compatibility, especially when integrated with fluctuating renewable energy sources like wind turbines and solar panels. Platinum (Pt), a critical component for recombination reaction in PEMWEs, is traditionally integrated into ionomers through mechanical processing methods such as ball milling, sonication, or inline milling. These processes disperse Pt particles directly within ionomer dispersions1, but they have limitations in terms of efficiency and cost. Our "ship-in-a-bottle" method involves introducing Pt ions into the ionomer substrate, which are subsequently chemically reduced to form Pt nanocrystals within the polymer matrix. It offers numerous benefits over traditional routes, including a more uniform distribution of Pt nanocrystals within the hydrogen channels of the polymer network. This leads to significantly enhanced recombination efficiency and allows for the use of thinner membranes, production of high-pressure H2, reducing the quantity of platinum required, and consequently lowering the cost of the PEMWE technology.
Moreover, our research delves into the creation of a unique recombination layer within membrane electrode assemblies (MEAs), significantly curtailing hydrogen crossover, especially at low turn-down ratio—a persistent issue in PEMWE industry. Utilizing the non-conductive PTFE backbone of PFSA ionomers to isolate well dispersed Pt nanocrystals from areas of high voltage, our approach markedly increases efficiency of hydrogen crossover mitigation. The result not only improves the safety and operational flexibility of PEMWEs but also underscores a shift towards a more economical, safe, and adaptable hydrogen production methodology. By addressing key challenges associated with hydrogen crossover, this study lays the groundwork for transformative changes in the green hydrogen sector, emphasizing a sustainable future powered by renewable energy sources.

Klose et al 2018 J. Electrochem. Soc. 165 F1271
From Structure to Performance: Insights into the Role of Porous Transport Layers in PEM Water Electrolysis via Electrode Engineering
Authors: Goswami Navneet , Diaz-Abad Sergio , Komini Babu Siddharth , Spendelow Jacob S. , Kort-Kamp Wilton 
Published: December 2024

Proton Exchange Membrane Water Electrolyzers (PEMWEs) are a promising technology to combat the deleterious effects of climate change [1]. It uses intermittent electricity from sustainable energy sources to electrochemically generate green hydrogen – a carbon-free energy carrier. Most importantly, the integration of water electrolyzers with fuel cells into a single reversible system is an enabler to achieving hydrogen-based long-duration energy storage. To make PEMWE systems more cost-competitive and technologically viable, it is essential to control the ohmic and mass transport limitations, a significant contribution of which stems from the fibrous porous transport layers (PTLs). In this work, we present a multiscale framework to investigate the effect of PTL electrode parameters on the electrochemical response of the PEMWE. Our starting point is stochastically generated PTL configurations with a host of microstructural features such as fiber diameter, porosity, fiber orientation, etc. The salient morphology-dependent transport properties like tortuosities, effective electronic conductivities, and two-phase permeabilities are then evaluated by employing pore-network modeling [2]. These are subsequently deployed to a physics-based multiphase reactive transport model [3] of the electrolyzer to quantify the concomitant overpotential modes. The interplay of operating regimes and PTL structural parameters on the resistive signature is further delineated. An optimization of the PTL architecture along with its pore size distribution investigated in this study can guide the design of experiments towards high-performing PEMWEs with enhanced catalyst utilization and mass transport.
References:
[1] Pham, Chuyen Van, et al. "Essentials of high performance water electrolyzers–from catalyst layer materials to electrode engineering." Advanced energy materials 11.44 (2021): 2101998.
[2] Gostick, Jeff, et al. "OpenPNM: a pore network modeling package." Computing in Science & Engineering 18.4 (2016): 60-74.
[3] García-Salaberri, Pablo A. "1D two-phase, non-isothermal modeling of a proton exchange membrane water electrolyzer: An optimization perspective." Journal of Power Sources 521 (2022): 230915.
Fibrous Electrodes for Alkaline Electrolysis
Authors: Russo Andrea , Jensen Jens Oluf , Kraglund Mikkel Rykær , Zhang Wenjing (Angela) , Cho EunAe 
Published: December 2024

The development of thin alkaline ion-conducting membranes with low internal resistance has highlighted the potential to reach high current densities in conventional alkaline electrolyzers. As membrane resistances drop with new novel separators, the necessity of using high surface area 3D porous electrodes without inactive regions in the form of large holes becomes evident, to be able to reach performances comparable to PEM or AEM systems.
To improve electrodes many researchers are moving towards high surface area nickel foams, as opposed to more conventional mesh or perforated plate-based electrode materials. While nickel foams have more surface area compared with their mesh counterparts, the specific surface areas are is still relatively low unless further surface enhancements are carried out in the form of rough coatings. Additionally, the total electrode thickness remains substantial, potentially resulting in mass transport issues, gas entrapment, and additional ionic ohmic losses within the porous structure. However, the absence of blind spots should lead to a significant increase in active catalytic area, corresponding to a higher performance.
This work demonstrates how to take the supporting structural morphology to the next step, by developing finely porous electrodes based on a polymer skeleton, coated with a thin homogenous layer of nickel phosphorous. This approach both enhances the accessible electrochemical surface area and reduces the environmental impact as the amount of nickel used is significantly decreased. The developed finely porous structures result in an order of magnitude larger surface area, at approximately one-tenth of the electrode thickness.
As an additional benefit, the diffusion path length for the evolved gasses is reduced, promoting mass transport properties, and helping to avoid commonly labeled bubble resistances, as well as potentially suppressing supersaturation effects.
Anion Exchange Membrane Water Electrolyzer Accelerated Durability Assessment Using Potential Cycling
Authors: Ul Hassan Noor , Volk Emily K. , Kreider Melissa , Dinh Huyen N , Pivovar Bryan S. , Alia Shaun M 
Published: December 2024

Anion exchange membrane water electrolyzers (AEMWEs) have shown remarkable progress in terms of voltage efficiency and achievable current density in the past few years. Various methods are employed to assess the durability of AEMWEs at component and cell level, and include constant and cycled current/potential, start/stop cycles, and open-circuit-voltage (OCV) holds. Each technique may impose different levels of stress on individual components, and in cases have aimed to accelerate polymer degradation or to stress the catalyst or catalyst layer integrity. Particularly due to the more fundamental technology readiness level of AEMWE, it is essential to understand the degradation mechanism and failure modes at membrane electrode assembly (MEA) level.
In this study, commercial AEM, ionomer, Co3O4 as anode and PtC as cathode catalysts were employed for fabricating MEAs. Square-wave and triangular-wave potential cycling were applied as operational-based stress tests to understand the impact of load cycling on degradation. Square-wave potential cycling appeared to accelerate catalyst layer degradation through ionomer oxidation, which lessened catalyst site-access and enhanced kinetics. On the other hand, triangular-wave potential cycling seemed to stress membrane (thinning) reducing the high frequency resistance (HFR). In both cycling patterns, the dissolution of cobalt (catalyst) and nickel from the porous transport layer (PTL) were observed by inductively coupled plasma-mass spectrometry (ICP-MS) analysis of the feed liquid. Moreover, a slight decrease in double layer capacitance supports degradation of catalyst layer. The motivation of this investigation was to mimic closely representative operation when directly integrated with renewable energy sources. The results discussed here may provide insight as to lifetime differences between different electrolysis technologies and provide pathways to develop stress tests for AEMWE systems and improve cell level durability.

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