bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquid Metal as a “Self-Healing” Agent for Phosphorus in Li-Ion Batteries
Authors: Park Zachary , Colvard Rex Edward , Dickey Michael D , Fedkiw Peter S.
Published: December 2024

The demand for energy storage in applications such as electric vehicles, consumer electronics and grid storage is ever increasing. Lithium-ion batteries (LIBs) are currently the state-of-art in electrochemical energy storage and are extensively used in electric vehicles and consumer electronics. To advance the state-of-art in LIBs, we propose to use gallium-based liquid metals (GLMs) as a “self-healing” agent for phosphorus in anodes. Phosphorus has a significantly larger theoretical capacity for Li+ ions (2596 mAh g-1
, Li3P) than graphite (372 mAh g-1, LiC6). However, phosphorus suffers from pulverization due to a high-volume expansion during charging (~300%) which results in delamination of phosphorus from the anode and rapid capacity fade.1 To address this issue, we use GLMs to fill in or “heal” defects formed from the large volume expansion of phosphorus and maintain electrical contact with any pulverized phosphorus particles. A similar strategy with GLMs has been reported in the literature with silicon which also suffers from large volume expansion.2–6 However, to the best of our knowledge, we are the first to report the use of GLMs as a “self-healing agent” for phosphorus in LIB anodes. In our work, we fabricate a composite film electrode comprising eutectic gallium indium nanoparticles and red phosphorus nanoparticles in a carbon polymer matrix. We electrochemically characterize the electrode in coin cells with a Li half-cell configuration. Additionally, we conduct material characterizations of the electrode before and after galvanostatic charge discharge cycling. Our GLM and red phosphorus strategy may help develop effective approaches for designing anodes with high volume expansion active materials.

Zhou, J. et al. Phosphorus-Based Composites as Anode Materials for Advanced Alkali Metal Ion Batteries. Adv. Funct. Mater.
30, 2004648 (2020).

Yang, J. et al. Self-Healing Silicon Anode via the Addition of GaInSn-Encapsulated Microcapsules. ACS Appl. Energy Mater.
5, 12945–12952 (2022).

Zhao, Z. et al. Liquid Metal Remedies Silicon Microparticulates Toward Highly Stable and Superior Volumetric Lithium Storage. Adv. Energy Mater.
12, 2103565 (2022).

Han, B. et al. Spontaneous repairing liquid metal/Si nanocomposite as a smart conductive-additive-free anode for lithium-ion battery. Nano Energy
50, 359–366 (2018).

Hapuarachchi, S. N. S. et al. Interfacial Engineering with Liquid Metal for Si-Based Hybrid Electrodes in Lithium-Ion Batteries. ACS Appl. Energy Mater.
3, 5147–5152 (2020).

Hapuarachchi, S. N. S. et al. Utilizing Room Temperature Liquid Metals for Mechanically Robust Silicon Anodes in Lithium-Ion Batteries. Batter. Supercaps
1, 122–128 (2018).
Investigating the Dissolution ‐ Redeposition Kinetics of Transitions Metals in Alkaline Media for Application in Advanced Material Processes
Authors: Promi Anika Tabassum , Lin Feng
Published: December 2024

The dynamic dissolution/redeposition (D/R) equilibrium of transition metals (TM) in alkaline media governs particle growth and morphological properties, impacting the diverse domains of catalyst longevity, metal recovery, coprecipitation of cathode precursors, nanoparticle engineering, semiconductor processing, wastewater metal extraction etc. D/R equilibriums exist in many chemical systems where they can affect how efficiently transition metals reversibly interact with their surrounding alkaline media, ultimately controlling reaction rate and properties of the final product. Understanding the D/R kinetics can help achieve control over particle size, shape and distribution which further impacts many properties of these particles such as the electrochemical, magnetic, optical or catalytic properties. One such system is the coprecipitation reaction used to synthesize mixed metal hydroxides materials. In this reaction, different transition metal ions simultaneously precipitate with the aid of a chelating agent in an alkaline reaction medium. The equilibrium between the precipitated hydroxide particles and the chelating agent solution leads to the growth of the embryonic agglomerates into spherical particles. In this study, we examine the D/R kinetics of this coprecipitation reaction as it can help investigate the comparative behavior of multiple transition metals in one system. Studying this dynamic D/R equilibrium under different reaction conditions will provide a platform to visualize and quantify this phenomenon in real time, which can aid in understanding reaction mechanisms and guide material design in many fields of application.
NMR Insights into Designing Safe and Efficient Lithium-Ion-Batteries with Solid Electrolyte
Authors: Shin Yoonju , Han Ji-Hoon , Kim Dokyung , Cho Young Whan , Ahn Sangdoo , Lee Young Joo
Published: December 2024

The inherent risk of explosion in widely used lithium-ion-batteries has ignited greater interest in the development of more efficient and safer energy storage. Notably, there is growing attention on all-solid-state batteries for their ability of providing both safe and efficient energy storage. Among the promising candidates, we focused on argyrodite-type electrolytes exhibiting high ionic conductivity on the order of some mS/cm at room temperature.

In this study, we compared dual-substituted argyrodite-type electrolytes to observe the effect of the anion substitution on the physical properties of the solid electrolytes using solid state NMR. We investigated the correlation between anion substitution and the local dynamics of lithium ions through NMR relaxometry. We measured 7Li spin-lattice relaxation times (T1) in various temperature, fitted the T1 values into the Arrhenius equation and calculated the activation energy. Furthermore, by comparing the peak intensity of NMR 1D spectra before and after cycling, we confirmed the movement of Li ions between cathode and electrolyte.

In short, our findings, obtained via solid-state NMR, deepen our insights on electrolytes down to the atomic level. This work gained ground for future research to develop the efficient and safe energy storage systems and drive innovation in all-solid-state batteries.
Unraveling Ion Conduction and Interfacial Processes in Sulfide Electrolytes for Emerging Sodium Batteries
Authors: Shreyas Varun , Chertmanova Sabina Zakhidovna , Li Yang , Halacoglu Selim , Wang Hui , Narayanan Badri
Published: December 2024

Solid-state sodium (Na) batteries(SSSBs) using sulfide-based solid electrolytes (SEs) has been attracting a lot of attention due to their high theoretical specific capacity, enhanced safety, and abundant resources. Especially, Na3SbS4 shows tremendous potential as a SE owing to its good Na+ ion conductivity of ~1 – 3 mS cm-1. Despite its promise, electrochemical performance of SSSBs based on Na3SbS4 SE remain far from commercialization. The major roadblock thwarting progress in SSSBs is the lack of fundamental understanding of atomic-scale mechanisms underlying (a) interfacial reactions with Na anode, and (b) Na+ ion conduction (especially in the presence of dopants). Here, we employ ab initio molecular dynamics (AIMD) simulations to identify key reactions occurring at the Na|Na3SbS4 interface. Our AIMD simulations indicate that addition of an ionic liquid interlayer results in a stable solid-electrolyte-interphase (SEI) composed mainly of NaF, in excellent agreement with our synthesis and characterization experiments. Similarly, our DFT studies show that Se doping increases the electrochemical stability window of Na3SbS4. In terms of Na+ conduction, we employ AIMD simulations, and nudged elastic band calculations to understand the effect of (a) valence, and (b) size of cation dopants that partially replace Na in Na3SbS4. These cations introduce charge compensating Na-vacancies in the SSE, which in turn, enhance Na+ ion conduction. However, size of the cation dopant has a profound impact on the extent of increase in Na+ ion conductivity. For instance, Ca-doped Na3SbS4 (Na2.75Ca0.125SbS4) showed Na+ conductivity of ~10 times that of pristine Na3SbS4 (rCa2+ / rNa+ = 0.98). On the other hand, larger Ba2+ as dopant (rBa2+ / rNa+ = 1.35) in Na2.75Ba0.125SbS4 hinders Na-ion hops owing to local strain, thereby, yielding a Na+ conductivity ~5 times that of Na3SbS4.We will discuss these findings in the context of developing solid-state electrolytes for emerging SSSBs.
Mechanical Analysis of Lithium-Ion Batteries via Acoustic Impedance Spectroscopy
Authors: Soulen Charles Edward , Sherrit Stewart , Brandon Erik , Liu Ping
Published: December 2024

Current state-of-charge (SOC) and state-of-health (SOH) estimation techniques for commercial Li-ion batteries (LIB) rely almost exclusively on voltage measurements and current integration, which produce large errors. Recently, acoustic techniques, primarily ultrasonic time-of-flight (US-ToF) have been used to reduce these errors, though cost, size, and voltage limitations prevent widespread use. Here, we introduce a practical alternative acoustic technique based on acoustic impedance spectroscopy (AIS). Using thin, cheap piezoelectric resonators, we can identify the acoustic resonances of commercial LIBs by measuring the complex electrical impedance of the resonator. In-operando AIS shows that these resonances are dependent on the bulk mechanical properties of the LIB, which change reversibly with SOC. Moreover, these mechanical changes induce unique responses in the resonance frequencies based on the modal structure of each resonance. Utilizing these changes, we can obtain a multi-dimensional trace of the SOC and SOH of a LIB. The application of AIS to LIBs represents a major step forward in practical acoustic characterization techniques.
Fabricating Solid-State Batteries for Electric Aviation
Authors: Dornbusch Donald A , Usie Griffin , Huddleston William , Lin Yi , Viggiano Rocco P.
Published: December 2024

All-solid-state lithium batteries are widely reputed as the next major step in energy storage technology on account their drastically improved safety over wet cells, as solid electrolytes lack the volatile compounds in wet electrolytes that make them combustible. This enhanced safety enables a far wider range of products and vehicles to go fully electric and aligns with future NASA missions that require high performing, reliable, and safe batteries. However, they currently face issues with implementation in both aeronautical and consumer products due to the often-poor mechanical properties of the solid electrolyte and relative difficulty to manufacture [1].

Typical solid-state electrolyte challenges were bypassed by incorporating a range of polymeric binders into a solid electrolyte suspension and cast onto a composite carbon-sulfide cathode to create a single bilayer film. The resulting films display superior flexibility and durability compared to solid-electrolyte films typically discussed in literature without compromising the thinness of the films. The bilayer film was then punched into 12.7 cm diameter discs and 4 cm by 5 cm sheets, pressed, and assembled into coin cells and pouch cells respectively.

[1] Donald A. Dornbusch, Rocco P. Viggiano, John W. Connell, Yi Lin, Vadim F. Lvovich. Practical considerations in designing solid state Li-S cells for electric aviation, Electrochimica Acta, 2021, 139406, ISSN 0013-4686, https://doi.org/10.1016/j.electacta.2021.139406.
Modifying Intermolecular Interactions of Single-Ion Conducting Polymer Electrolytes through Salt Additives for Stable and High Performance Lithium Metal Batteries
Authors: Yun Susung , Handayani Puji Lestari , Kim Naehoon , Choi U Hyeok
Published: December 2024

Lithium metal batteries (LMBs) are emerging as a crucial breakthrough in energy storage systems due to their lowest electrochemical redox potential at -3.04V (vs. the standard hydrogen electrode) and highest theoretical capacity of 3860 mAh g-1. However, the irregular deposition on the lithium metal anode during the cycles may lead to the formation of lithium dendrites, adversely affecting the safety and performance of LMBs. Furthermore, concentration polarization can cause lithium depletion at the electrode-electrolyte interface, increasing overpotential and thereby accelerating dendrite growth. Single-ion conducting polymer electrolytes (SIPEs), in which the anion is immobilized, possess the ability to mitigate concentration polarization. Herein, we prepared a salt-in-SIPE (SiSIPE) by incorporating a salt additive (LiTFSI) into SIPEs. Spectroscopy analysis (FT-IR and Raman) and density functional theory (DFT) calculations indicated that NMA, a plasticizer that has crystallinity at 25 ℃, can form a solvation structure with LiTFSI. The intermolecular interactions inhibit the SiSIPE from crystallizing even at -80 ℃, ensure high ionic conductivity (7.0×10-4 S cm-1) at 25 ℃, and lead to a high tLi
+ (0.67) comparable to that of the SIPE (0.71, 2.2×10-4 S cm-1 at 25℃). Additionally, while NMA is easily decomposed above 4.0 V, the interactions ensure that the SiSIPE possesses a wide electrochemical stability window up to 4.4 V. To suppress the decomposition of the electrolyte and achieve stable cycle performance at high voltage, the electrolyte's HOMO level should be lower than that of the cathode. The DFT calculation results showed that the HOMO level of the solvation structure was found to be lower than when NMA forms hydrogen bonds with each other, which implies that it can suppress the decomposition of NMA at high voltages. Additionally, since the solvation structure has a lower LUMO level than NMA, it is preferentially used for forming the solid electrolyte interphase (SEI) layer. As a result, as shown in the X-ray photoelectron spectroscopy results, due to the salt additive, the SiSIPE forms a more stable SEI layer compared to the SIPE. This leads to improved cycle stability in both Li symmetric cell (0.1 mAh cm-2, 700 hours) and LiFePO4 full cell tests (1 C-rate, 400 cycles, 80% retention). The intermolecular design through the salt additive can not only effectively suppress lithium dendrites but also enhance stability at high voltages and improve the cycle performance of LMBs. These strategies could significantly provide a new perspective in achieving high stability and high-performance LMBs.

Figure 1
Growth of Anodic Oxide Layers on Titanium Alloys Including Noble Metal and Transition Metal
Authors: Kim Jongwon , Tsuchiya Hiroaki , Fujimoto Shinji
Published: December 2024

Anodic TiO2 nanotubes have attracted attention, especially in the field of photocatalysis, enabling the generation of hydrogen from water. It has been reported that the hydrogen production can be enhanced by decorating co-catalysts onto nanotubes, and that, nanoparticles consisting of noble metal alloys can be deposited onto TiO2 nanotubes by anodization of Ti alloys containing noble metals at reducing reliance on noble metals. In this study, we studied the anodization behavior and oxide layer formation on titanium alloys containing both noble and transition metals to reduce the amount of noble metals used.

Titanium alloys containing noble metals (Au, Pt) and transition metals (Cu, Fe, Co) were fabricated via the arc melting method. Anodization was conducted in ethylene glycol solutions containing fluorides and water using a two-electrode cell with a Pt plate serving as the counter electrode. Current generated during anodization oxidation was monitored, and the surface and cross-section of the oxide layers formed were observed with FE-SEM.

In the present work, ammonium fluoride and hydrofluoric acid were used as fluoride source. In the case of the electrolyte containing ammonium fluoride, SEM observations confirmed the formation of TiO2 nanotubes, along with the decoration of co-added metal nanoparticles on their surfaces and cross-sections. In contrast, in the electrolyte containing hydrofluoric acid, the formation of nanograss was confirmed. A significant number of co-added metal nanoparticles were observed on the surface and cross-sections of the formed nanograss. In this presentation, the effect of water content in the organic electrolytes on the formation of TiO2 nanotubes decorated with nanoparticles will be discussed.
Reduction and Oxidation Behavior of Rust Layers Under Aqueous Solution Films with Different Thicknesses
Authors: Kurooka Hayato , Tsuchiya Hiroaki , Hanaki Koushu , Yamashita Masato , Fujimoto Shinji
Published: December 2024

It is well known that steel materials widely used in infrastructures corrode rapidly in atmospheric environments. As a result of corrosion, rust layers form on steel surfaces exposed to repeated wet and dry environments. In such wet and dry environments, redox reactions of rust layer may occur and accelerates the corrosion of steels. Such redox behavior can strongly depend on the composition of rust layer and the thickness of the solution film that is present on the surface in the wet stage. In this study, we investigated the effect of solution film thickness on the redox behavior of two types of rust layers with different compositions, i.e. FeOOH-rich and Fe3O4-rich rust layers.

Specimens used were carbon steels, on the surfaces of which either of rust layers was present, that is, FeOOH-rich or Fe3O4-rich rust layers. FeOOH-rich rust layers were produced though atmospheric exposure of carbon steel for 3 months. On the other hand, Fe3O4-rich rust layers were produced by dipping of FeOOH-rich rust layers in 0.1M Na2SO4 solution of pH 5 at 50 ℃ for 24 h. The specimens were subjected to the solution film test in which the rust layers were covered with 0.1M Na2SO4 solution film with various thicknesses. To avoid evaporation of the solution film, the specimens were put into tightly sealed container and kept in a thermostatic chamber at 50 ℃ for 24 h. After the test, the solution films on the specimen surfaces were removed and then dried at 60 ℃ and 50% R.H. for 6 h.

X-ray diffraction pattern obtained for the specimens indicated that main rust constituents in each specimen were Fe3O4, α-FeOOH, and γ-FeOOH. The mass fraction of each rust constituent was calculated from the peak intensity of the X-ray diffraction and based on the calculation, the Fe2+/Fe3+ ratios in the rust layers were estimated. The Fe2+/Fe3+ ratio in the FeOOH-rich rust layer increased after the solution film test and the increase varied depending on the solution film thickness. In the thinner range than 200 µm, the increase of the Fe2+/Fe3+ after the test was relatively low whereas in the thicker range than 200 µm, the increase was significantly large, indicating that the reduction of FeOOH predominantly occurred under thick solution film. The Fe2+/Fe3+ ratio in the Fe3O4-rich rust layer tended to decrease with decreasing the solution film thickness. These imply that the reduction and oxidation of rust layers depend not only on the thickness of the solution film present above rust layer but also its composition.
X-Ray Fluorescence Measurements of Elements in High Matrix Solution Using Solid Substrate Having Nanoporus Structure
Authors: Hibino Nozomi , Hagiwara Kenta , Asoh Hidetaka
Published: December 2024

X-ray fluorescence (XRF) analysis can determine directly and non-destructively the elemental composition of various materials such as solid samples and water. For multi-elemental analysis of low volume (sub-milliliter levels) solution, XRF analysis combining with a droplet method is effective. In general, a dried droplet on a filter paper is analyzed in the droplet method. For measurements on high matrix solution, however, the sensitivity is reduced, resulting in large spread of values. In this study, to improve the sensitivity and repeatability of determination values of elements in high matrix solution by an XRF analysis with a droplet method, a silicon substrate having nanoporous structure was used instead of conventional filter paper. Two methods ((i) anodic etching using a hydrofluoric acid, (ii) metal-assisted chemical etching using gold and silver particles) were applied to silicon for introducing nanoporous structure on the surface of silicon. Different nanoporous structures were formed on the surface reflecting each etching condition. In the case of anodic etching, the silicon surface had spongy nanoporous structure. A dried residue containing 1 mg of the element was prepared on the etched silicon to investigate the effect of the nanoporous structure on the thickness and area of the dried residue. The size, shape and thickness of the dried residue were affected by the surface morphology of the silicon prepared by various etching conditions. Among them, the dried residue formed on anodic etched porous silicon was most circular and uniform. As compared with a flat silicon, the sensitivity and repeatability of energy dispersive XRF analysis by droplet method were improved by using a substrate having nanoporous structure. Especially, the intensity of Mg Kα increased by 11 times, and relative standard deviation (n = 5) of X-ray intensity of Mg Kα decreased by 1/5.
Effect of Ketjenblack Content on Ammonia Electrolytic Synthesis Ability of Ru/Ketjenblack/TiO2/Carbon Paper Catalysts at Low Temperature and Atmospheric Pressure
Authors: Yasuda Taketoshi , Shiroishi Hidenobu , Matsumoto Haruka , Nishitani-Gamo Mikka
Published: December 2024

Introduction

Realizing a hydrogen society is a promising solution to the problem of global warming. Ammonia has attracted attention as a hydrogen carrier, and electrolytic synthesis of ammonia at low temperature and atmospheric pressure is a useful method for generating hydrogen carriers utilizing intermittent renewable energy. Employing a three-phase interface as the reaction field can potentially achieve practical electrosynthesis rates. We previously reported that a Ru/Ketjenblack-TiO2/Carbon paper catalyst exhibits ammonia electrosynthesis activity with a high Faraday efficiency of 26% under ambient conditions, compared to conventional catalysts. In this study, we investigated the effect of Ketjenblack (KB) loading amount in the catalyst on ammonia electrosynthesis performance using a half-cell with a three-phase interface.

Experimental

Catalyst Preparation: TiO2 (P25, Degussa) and Ketjenblack (KB, ECP-600JD, Lion) pastes with varying volume ratios were spray-coated onto hydrophobic-treated carbon paper (TGP-H-060, Toray). The carbon paper was heat-treated at 500°C for 1 h under 5 vol% O2 atmosphere to obtain KB/TiO2-modified carbon paper (KB/TiO2/CP) with a TiO2 loading of 0.5 mg cm−2. The KB loading was determined by the volume percentage (100×KB/(KB+TiO2)) and used as the catalyst name. Ru nanoparticles were electrodeposited onto KB/TiO2/CP (hereafter Ru/KB/TiO2/CP) in a RuCl3-0.1 M KCl solution using Pt wire counter electrode.

Electrochemical Measurements: The modified catalyst carbon paper was hot-pressed (135°C) with a Nafion® membrane (NR212, Dupont) to fabricate a membrane electrode assembly, which was incorporated into a half-cell with a three-phase interface, as shown in Fig. 1(a). Electrochemical measurements were performed using 0.1 M Na2HPO4-0.02 M KH2PO4 electrolyte, with N2 gas flowing. Ammonia electrolytic synthesis was carried out under N2 atmosphere using a square wave potential (5 s at electrolysis potential, 0.1 V for 1 s) for an actual electrolysis time of 1 h. The generated ammonia was collected in a 4 mM methanesulfonic acid solution and quantified using ion chromatography (column: Shodex IC YS-50, eluent: 4 mM methanesulfonic acid solution).

Results and discussion

Fig. 1(b) shows the ammonia electrosynthesis rates, Faraday efficiency, and energy conversion efficiency at −0.3 V vs. RHE with varying mixing ratios of KB and TiO2. The addition of KB increased the ammonia synthesis rate compared to KB-free catalysts, however it led to decrease in Faraday efficiency. Moreover, a further increase in the amount of KB addition resulted in a decrease in the ammonia production rate.

Figure 1
Study on Pressurized Diesel Reforming with Electrophoretic Deposition Coated Structural Catalyst
Authors: Kim Yeongwoo , Bae Joongmyeon
Published: December 2024

Storing hydrogen in gas, liquid and hydrogen carrier form requires the continuous use of energy for conversion and storage. Therefore, on-site hydrogen production using liquid fuel reforming has a great advantage in a condition that must be stored for a long time. Diesel is the most attractive source for emergency generators or mobile power unit, because of its high volumetric and gravimetric energy density, storage stability, and its accessibility. For diesel reforming, precious metal catalysts has been commonly used for high fuel conversion and reforming efficiency. However, reforming high-carbon liquid fuels causes a number of difficulties, including catalyst deactivation due to coke formation, active metal aggregation due to high-temperature reforming, cracks and delamination in structural catalysts. To address these challenges, in this study, electrophoretic deposition (EPD) coating method is used to make a structural catalyst for pressurized reforming. This coating achieved high dispersion and sufficient porosity to promote the reforming performance. By comparing the fuel conversion rate and reforming efficiency of metal foam structural catalysts and monolith catalysts, the performance of EPD coated catalyst shows the higher performance. Furthermore, at the condition of SCR: 2.0, OCR: 0.55, GHSV: 3,000 h-1, T: 800ºC, and P: 8 bar(g), the EPD-coated catalyst lasted 196 hours. Therefore, we achieved high conversion to hydrogen while reducing the amount of precious metals, leading to enhanced cost-effectiveness of diesel-reforming catalysts.
Synchrotron X-Ray Micro Computed Tomography Investigation of in-Situ Deformation of PFSA Membranes for Water Electrolyzers
Authors: Bergeson-Keller Anyka , Sabharwal Mayank , Kusoglu Ahmet
Published: December 2024

Proton exchange membrane water electrolysis (PEMWE) is an electrochemical energy conversion technology that splits water molecules to produce hydrogen gas. PEMWE, when powered by renewable electricity sources, offers a promising solution to generate clean hydrogen fuel as well as for storing energy [1]. One barrier to the wide-scale commercialization of PEMWEs is their durability, which is compromised in part by mechanical damage to the membrane. It has been hypothesized that the rough surface of the PTL causes damage to the surface of the membrane in the form of pinholes and interfacial fractures under PEMWE operating conditions, which lead to increased degradation of the membrane and reduced performance and longevity of the PEMWE cell [3]. Furthermore, the extent of damage and deformation to the membrane can be related to the morphology (i.e. the feature and pore size/distribution) of the PTL. Thus, characterizing the interfacial contact between the PEM-PTL and the stresses induced in the membrane during operation is of great importance for understanding and mitigating the mechanical aspects of failure in PEM electrolyzers.

To investigate this phenomenon, we conducted X-ray micro computed tomography (MCT) at the advanced light source (ALS) at Lawrence Berkeley National Laboratory (LBNL) on a PTL/membrane stack being pressed together at 2.2, 4.4, 8.9, and 22.2 MPa using a custom compression stage. We tested the effect of two different standard PTL morphologies: a sintered Ti from Mott® and a fibrous Ti from Bekeart® on both wet and dry membrane specimens (Nafion 115). By carefully segmenting the X-ray MCT images, we were able to construct 3D strain mappings across the membrane to highlight areas of concentrated stress due to prominent features of the PTL protruding into the membrane and portions of membrane extruding into the pores of the PTL. Based on these results, we find that prominent features on the PTL surfaces lead to increased membrane surface roughness and strain, and indeed can pierce the hydrated membrane surface at elevated pressures. In summary, our study offers a unique insight into the deformation mechanisms that occur at the membrane surface as it interfaces with the PTL under standard PEMWE operating conditions of high compressive stress and hydrated states. This work will guide researchers within the PEMWE community to develop material and integration strategies that mitigate mechanical degradation and improve the system lifetime.

References

[1] Wang, Y.; Pang, Y.; Xu H.; Martinez, A. S.; Chen, K. S., Energy and Environmental

Science 2022, 15, 2288–2328.

[2] Hoppe, E.; Holtwerth, S.; Müller, M.; Lehnert, W., Journal of Power Sources 2023, 578

[3] L. Shi et al., Journal of The Electrochemical Society, vol. 167, no. 14, p. 144506, Nov.

2020. doi:10.1149/1945-7111/abc4bd
(General Student Poster Award Winner, 3rd Place) Biomimetic Auxiliary Channels for Enhanced PEM Fuel Cell Performance
Authors: Chadwick Eric Alexander , Shrestha Pranay , Parmar Harsharaj Birendrasingh , Bazylak Aimy , Schulz Volker Paul
Published: December 2024

The bipolar plate of polymer electrolyte membrane (PEM) fuel cells is responsible for reactant delivery, liquid product water removal, and mechanical stability of PEM fuel cell stacks. Bipolar plates account for 70-90% of the weight and volume and 18-28% of the production costof stacks [1]. Improving the function of the flow fields embedded in the bipolar plates can significantly impact the energy density of PEM fuel cells by improving liquid water management and reactant distribution. Researchers have modified conventional flow fields by adding baffles or partially narrowed channels as semi-obstructive structures in the channels, exploiting Forchheimer’s intertial effect to locally increase gas velocity, thereby increasing oxygen diffusion and water removal in the GDL [2,3]. However, adding obstructions such as baffles or narrowed channels inherently increases the overall pressure drop across the flow fields, thus increasing the power required to supply reactant gases. In other attempts, biomimetic channel architectures have been shown to enhance preferential water flow; however, these designs have not been tailored to control water accumulation for improved reactant distribution [4,5]. Therefore, there is still a need to investigate flow field land-channel architectures that both enhanced inertial gas diffusion to the catalyst layer reaction sites and efficiently remove excess liquid water.

In this work, PEM fuel cell flow fields were laser-cut to enhance the liquid water removal and reactant distribution in the under-land region of the GDL. Operando synchrotron X-ray radiography revealed reduced GDL water accumulation when using our novel flow fields. The reduced mass transport overpotential and corresponding power density increase were attributed to enhanced liquid water removal and reactant distribution due to the flow field design. Ultimately, this work can be used to further optimize the design of bipolar plates for more efficient stacks and accelerate the commercialization of PEM fuel cells.

References:

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

H. Guo, H. Chen, F. Ye, and C. F. Ma, Int J Energy Res, 43, 2737–2755 (2019).

H. Chen, H. Guo, F. Ye, and C. F. Ma, Int J Hydrogen Energy, 46, 2990–3007 (2021).

N. Guo, M. C. Leu, and U. O. Koylu, Int J Hydrogen Energy, 39, 21185–21195 (2014).

S. Feng et al., Science, 373, 1344–1348 (2021).
Facile, Fast, and Cost-Effective Fabrication of Iron-Based Electrocatalysts on Nickel Foam: Towards Highly Efficient, Stable, and Sustainable Water Splitting Performance
Authors: Lahrichi Amina , El Issmaeli Youness , Pollet Bruno Georges
Published: December 2024

The development of effective, economical, and ecologically friendly catalysts for the oxygen evolution reaction (OER) is essential to advancing the production of hydrogen via electrolysis. Non-precious metal catalysts, known for their cost-effectiveness, abundance, lack of toxicity, stability, and efficiency, are at the cutting edge of this research field. Iron (Fe), the second most abundant metal on Earth, shows promise as a cost-effective alternative to traditionally used OER catalysts made from ruthenium (Ru), iridium (Ir), and cobalt (Co). Fe-based catalysts have typically shown limited OER activity, which has limited their practical use, despite their potential advantages.

This study presents a facile, fast, and unique approach to prepare iron-based transition metal phosphate films on nickel foam (TM-Fe-Pi/NF) for OER. The TM-Fe-Pi/NF electrocatalyst has been optimized to exhibit outstanding performance, with a remarkably low overpotential of +267 mV at a current density of 10 mA cm-2 in a 1.0 M KOH solution. Remarkably, this catalyst maintains its OER efficiency without significant degradation even after continuous operation for more than 10 hours, as confirmed by chronoamperometry measurements at a current density of 10 mA cm-2. In addition, the synthesis method used in this study produces catalysts that have exceptional uniformity, highlighting its potential for the efficient and cost-effective production of high-performance catalysts for industrial use.

Keywords: Iron phosphate; transition metals; KOH; water splitting; oxygen evolution reaction
Nature Derived Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells
Authors: Parmar Harsharaj Birendrasingh , Bazylak Aimy
Published: December 2024

The adverse effects of global warming have accelerated the push for sustainable energy sources to meet the global energy demand. Renewable energy can be stored in the form of hydrogen to continuously produce clean power using a proton exchange membrane fuel cell (PEMFC). A typical PEMFC consists of a proton conductive membrane coated with platinum-based catalyst layers, which promote the hydrogen oxidation (anode) and oxygen reduction (cathode) reactions. Moreover, these catalyst layers are supported by gas diffusion layers, which supply reactants and facilitate the removal of water generated from the reduction reaction. While membrane hydration is necessary for maintaining protonic conductivity, excess water in the gas diffusion layer can severely inhibit the chemical reaction. Thus, efficient water management not only enhances reactant delivery but also substantially reduces the required platinum catalyst content in PEMFCs to ensure cost-effective power generation.

Interestingly, the simultaneous transport of water and oxygen is precisely optimized in trees, which are all around us. Thus, the hypothesis is that exceptional mass transport characteristics can be obtained using the organized microchannels of a novel nature-based basswood gas diffusion layer. First, basswood was carbonized to establish high electrical conductivities, and this was achieved while preserving their microstructure. Next, the microstructure of the carbonized basswood blocks was characterized using scanning electron microscopy. Finally,electrochemical testing of the carbonized basswood gas diffusion layer was performed to compare its performance with a conventional carbon paper gas diffusion layer. The mass transport behavior was characterized using electrochemical impedance spectroscopy. Through the application of our novel basswood gas diffusion layer, we provide new insights into the potential for high performance wood-based materials for clean energy, guiding the design of next generation sustainable fuel cell materials.
Tailoring Electrolyzer Catalyst Layer Morphology Via Pore Network Modelling
Authors: Seip Tess , Lee Jason Keonhag , Shaigan Nima , Dinu Marius , Fatih Khalid , Bazylak Aimy
Published: December 2024

Polymer electrolyte membrane (PEM) water electrolysis is a key technology to produce clean, high purity hydrogen, which can serve as an alternative to carbon-based fuels. However, PEM electrolyzer uptake has been sluggish due to high catalyst costs, which can contribute to up to 47% of total stack costs [1]. Thus, to lower stack costs, the morphology of the catalyst layer must be optimized towards lower precious metal loadings. However, catalyst layer morphology optimization remains a challenge, as the mechanisms linking catalyst morphology to mass and charge transport remain ambiguous in the literature [2], [3]. While the morphology of porous transport layer (PTL) has been extensively explored via stochastic material generation and pore network modelling techniques [4], such an analysis must also be extended to the catalyst layer to design efficient, low-cost materials.

In this work, we introduce a method to replicate the pore structure of commercially available PEM electrolyzer catalyst layers using stochastic generation techniques. Our method employs a custom divider to combine regions of varying pore sizes and effectively replicate the range of catalyst layer pore sizes observed in commercial materials. Moreover, we demonstrate that the pore size distribution of stochastically generated materials is statistically indistinguishable from imaged catalyst samples. Pore network modelling techniques were further applied to stochastically generated morphologies to evaluate electrical and mass transport properties. We not only reveal that the transport properties of our stochastically generated materials fall within experimentally measured ranges, but also reveal how tailoring pore size distributions can enhance these properties. The findings from our analysis can be used to identify desirable catalyst morphology targets for manufacturing and enhance the accuracy of electrolyzer transport models via the estimation of catalyst layer transport properties.

[1] A. Mayyas, M. Ruth, et al., Manufacturing Cost Analysis for Proton Exchange Membrane Water Electrolyzers, United States (2019).

[2] Z. Taie, X. Peng, et al., ACS Appl. Mater. Interfaces, 12, 47, 52701–52712 (2020).

[3] J. Lopata, Z. Kang, et al., J. Electrochem. Soc., 167. 064507 (2020).

[4] J. K. Lee, C. H. Lee, and A. Bazylak, J. Power Sources, 437, 226910 (2019).
Effect of Surface Fluorination on LaNiO3 Perovskite-Type Oxides for Oxygen Evolution Reactions
Authors: Sugimura Ayane , Shibata Daisuke , Inada Yasuhiro , Zhong Chengchao , Shimoda Keiji , Okazaki Ken-ichi , Orikasa Yuki
Published: December 2024

The technology of hydrogen production by alkaline water electrolysis using renewable energy has the advantages of abundant energy sources and minimal environmental pollution. However, the oxygen evolution reaction (OER) catalyst in water electrolysis faces several challenges. One problem is the unstable supply of renewable energy, which leads to frequent starting and stopping of the electrolyzer. This intermittency exposes the anode catalyst to drastic potential changes that generate reverse currents, resulting in anode catalyst degradation. Therefore, there is a critical need for research on more durable electrocatalysts. In this study, we attempted to improve the stability of perovskite-type oxides by using fluorination chemistry for surface treatment. We prepared fluorine-treated LaNiO3 by calcination with polyvinylidene fluoride (PVDF) and analyzed the electronic structures of the prepared samples by X-ray absorption spectroscopy.

LaNiO3 and PVDF, a fluorine additive, were mixed using a mortar. The mixture was then pelletized and sintered in a sealed vessel at 350 °C for 12 hours. This experimental condition was based on the fluorination reaction of HfO2
[1]. Four different PVDF-to-LaNiO3 mixing ratios were synthesized: 0% (pure LaNiO3), 2.5%, 5%, and 10% by weight. To confirm whether the catalyst surfaces were fluorinated, XRD and XAFS measurements were performed to analyze the changes in the crystal structure and the valence changes by the introduction of fluorine. For electrochemical measurements, a measuring cell for electrolysis was used[2], which is reported to be analyzable only with powder catalysts.

A comparison of the X-ray diffraction (XRD) patterns of pure LaNiO3 and LaNiO3 treated with PVDF showed that the addition of PVDF shifted the XRD peak to lower angles. This shift confirms a structural expansion in the LaNiO3 crystal lattice due to the PVDF treatment. For a more detailed investigation, XAFS measurements were performed. Analysis in the F K-edge XAFS identified a distinct fluorine peak in the PVDF-treated LaNiO3 sample, indicating successful introduction of fluorine into the structure. In addition, in the Ni K-edge X-ray absorption near edge structure, the spectrum of the PVDF-added sample shifted to a lower energy compared to pure LaNiO3, indicating a reduction in nickel valence, likely due to fluorine incorporation. However, electrochemical measurements indicated a decrease in the initial OER activity of LaNiO3 treated with PVDF.

[1] Steven Flynn, Chi Zhang, Kent J. Griffith, Jiahong Shen, Christopher Wolverton, Vinayak P. Dravid, and Kenneth R. Poeppelmeier, Inorganic Chemistry, 60(7), 4463-4474 (2021)

[2] K. Nagasawa, T. Ishida, H. Kashiwagi, Y. Sano, and S. Mitsushima, Int. J. Hydrogen Energy, 46, 36619 (2021)
Evaluation of the Anode Characteristics of a Solid Oxide Fuel Cell for Electric Aircraft Propulsion
Authors: Wada Shuya , Nakajima Hironori , Okai Keiichi , Kojima Takayuki
Published: December 2024

We focus on the characteristics of a pressurized solid oxide fuel cell for a hybrid system with gas turbine (jet engine) electric generation for the propulsion of electric aircraft1). In this study, we electrochemically characterize the anode, evaluating the dependence of the exchange current density on hydrogen partial pressure2). The exchange current density is used for numerical modeling as an electrochemical kinetic parameter3). Such numerical models are useful for optimizing the cell/stack designs and operating conditions4). An electrolyte-supported

(YSZ) symmetrical cell with Ni-YSZ electrodes was prepared to measure the single-electrode reaction resistance, which gives the exchange current density, by using electrochemical impedance spectroscopy under various partial pressures of humidified hydrogen. The hydrogen partial pressure with diluting nitrogen under atomospheric pressure gave a different reaction order for the exchange current density from that without nitrogen under pressurized conditions.

Acknowledgement

Thanks are offered to Professor Kohei Ito and Associate Professor Tatsumi Kitahara of Kyushu University for their valuable discussions.

References

1) T. Kojima and K. Okai, AIAA (2023) 2023-1325. https://doi.org/10.2514/6.2023-1325

2) Yonekura, Y. Tachikawa, T. Yoshizumi, Y. Shiratori, K. Ito, K. Sasaki, ECS Trans, 35 (1) (2011) 1007-1014. https://doi.org/10.1149/1.3570081

3) Ö. Aydın, T. Ochiai, H. Nakajima, T. Kitahara, K. Ito, Y. Ogura, and J. Shimano, Int. J. Hydrogen Energy, 43 (36) (2018) 17420-17430. https://doi.org/10.1016/j.ijhydene.2018.07.030

4) H. Nakajima, J. Yamashita, K. Okai, and T. Kojima, 243rd ECS Meeting with the 18th International Symposium on Solid Oxide Fuel Cells (SOFC-XVIII) (2023). https://doi.org/10.1149/MA2023-01562726mtgabs
Chemical Versus Electrochemical Oxidation of Triclosan: Reaction Yield and Selectivity
Authors: Lewis Tyra , Martic Sanela
Published: December 2024

Phenolic compounds are generally known for their benefits toward human health. Triclosan (5-chloro-2-(2,4-dichlorophenoxy) phenol) plays a role as an antibacterial agent and is often found in personal care products such as toothpaste, disinfecting products, and cosmetics amongst others.1 However, despite the named health benefits, several concerns have arisen due to the compound’s potential environmental toxicity, for instance, as a result of its transportation to wastewater treatment plants.1-2 Therefore, the development of methods for efficient removal of triclosan from such streams is vital for maintaining environmental health. A variety of methods including adsorption, photolysis, chemical oxidation and biodegradation processes have been used for removing or degrading the wastewater pollutant. However, these techniques may require highly trained, sample preparation, specialized reagents etc. As an alternative solution, the electrochemistry offers multiple advantages. 1 Herein, we utilized electrochemical methods for selective electrochemical oxidation/reduction of triclosan toward the formation of dechlorinated and oxidized products.3 The electrochemical reactions and were monitored by UV-Vis spectroscopy and GC-MS which suggested that the reaction yield and selectivity was potential-dependent. The electrochemical conversion of triclosan was also compared to the traditional chemical conversion method. Data indicate that the electrochemical process allows for higher yield of the products within a shorter reaction time. Hence, electrosynthesis provides an alternative way of bond breaking and bond making, with applications in green chemistry, synthesis of value-added chemicals or bioremediation.

1 Knust K.N., Foley M.P., Mubarak M.S., Skljarevski S., Raghavachari K., Peters D.G. Electrochemical reduction of 5-chloro-2-(2,4-dichlorophenoxy)phenol (triclosan) in dimethylformamide, J. Electroanal. Chem., 2010, 638, 100-108.

2 Zhang H., Huang C-H. Oxidative transformation of triclosan and chlorophene by manganese oxides, Environ. Sci. Technol.,
2003, 37, 2421-2430.

3 Zabik, N et al. Selective Electrochemical versus Chemical Oxidation of Bulky Phenol. J. Phys. Chem. B.
2016, 120, 8914-8924.

Figure 1
(Invited) Tailoring Molecular Interaction in Solid-State Polymer Electrolytes for High-Performance Supercapacitors
Authors: Choi U Hyeok , Je Ji Hyang , Park Seon Min , Handayani Puji Lestari , Lee Dawoon , Kim Jaekyun
Published: December 2024

In the development of the next-generation safe solid-state supercapacitors with high energy density, durability, and flexibility, the synthesis of high ion-conducting solid-state electrolytes with electrochemical and mechanical stabilities is a great challenge. Solid-state polymer electrolytes (SSPEs) are of great interest as materials in energy storage devices because ion-conducting SSPEs enable good adherence to electrodes and excellent processability for being made into a thin film. The key challenge facing the SSPE development for all-solid-state supercapacitors is to achieve high mechanical performance without sacrificing the requisite ionic conductivity. To overcome the issue, we synthesized networked polymer electrolytes in both aqueous- and non-aqueous forms, using UV or thermal cross-linking methods. The aqueous versions comprise nanohybrid polymer electrolytes (NPEs), salt-in-polyampholoytes (SIPAs), and triple-network polymer electrolytes (TNPEs). Meanwhile, the non-aqueous type features branched network structures endowed with hierarchical nano-canyon characteristics. To tune and understand the SSPE physical and electrochemical properties, the effects of electrolyte type and concentration on morphologic, dielectric, and mechanical properties were thoroughly explored by microstructural, dielectric relaxation, and mechanical measurements. We found that intermolecular interactions within the electrolyte play a vital role in the formation of a nanoscale ion channel confined in the polymer matrix, allowing for a simultaneous increase in the ionic conductivity and mechanical modulus. Tuning the SSPE morphology can also control the microscopic ion migration rate as well as the macroscopic flexibility of the SSPE. To further introduce multifunctional properties, nanocomposite SSPEs were also prepared by combining aqueous SSPEs with inorganic nanoparticles, and their physical properties were investigated using dielectric relaxation spectroscopy, oscillatory shear, and DFT calculation. The principal focus of this presentation is on the insight about our understanding of ion and polymer dynamics of the SSPEs for high-performance supercapacitors.