bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Performance and Reliability of Hydrogen-Doped Polycrystalline Indium Oxide Thin-Film Transistors
Authors: Furuta Mamoru
Published: December 2024

High mobility and enhancement mode (E-mode) polycrystalline oxide thin-film transistor (TFT) was demonstrated by low-temperature solid-phase crystallization (SPC) of hydrogen-doped indium oxide (InO
x
:H). H2 doping during InO
x
sputtering enables the reduction of nucleation density in an amorphous InO
x
:H film. The amorphous InO
x
:H film could be converted to a poly- InO
x
:H film by SPC at 250°C for 3 min. Carrier density (N
e) of the poly-InO
x
:H film markedly decreased upon SPC in air and semiconducting poly-InO
x
:H films with N
e below 4×1018 cm−3 could be realized. Bottom-gate poly-InO
x
:H TFTs exhibited an E-mode operation with excellent uniformity of a field-effect mobility (mFE) of 32.0 ± 0.15 cm2/Vs and a threshold voltage (Vt) of 0.58 ± 0.06 V.
Enhanced Electromagnetic Wave Absorption Properties of Layer-By-Layer Films Comprising MXene@Fe3O4/Thermoplastic Polyurethane Fabricated via Spray Coating
Authors: Jeon JongYun , Kim Young-Seok
Published: December 2024

Electromagnetic interference (EMI) poses significant challenges in various fields, including automotive, military, and maritime applications, as well as concerns regarding its impact on human health. Consequently, research efforts have been directed towards developing effective electromagnetic shielding materials. While metals have traditionally been utilized for their excellent conductivity, recent focus has shifted towards 2D materials due to their lightweight and deformability. Among these materials, MXene has emerged as a promising candidate owing to its remarkable electrical conductivity. However, its application in absorption-based shielding, crucial for stealth operations, is hindered by reflection-based characteristics stemming from impedance mismatching.

In this study, we synthesized iron oxide (Fe3O4) nanoparticles, known for their magnetic properties, in conjunction with MXene via a hydrothermal synthesis method to enhance absorption properties and mitigate impedance mismatching. We employed a simple spray-coating technique to fabricate layer-by-layer films comprising Thermoplastic polyurethane (TPU) and MXene@Fe3O4 composites. This facilitated the creation of interlayer spacing, promoting multiple reflections and thereby augmenting absorption shielding properties. Our study presents a synergistic approach to enhancing electromagnetic absorption shielding through the integration of MXene and Fe3O4 nanoparticles, offering potential applications in diverse electromagnetic interference mitigation scenarios.
(Invited) Engineering Active Sites of 2D Materials for Active Hydrogen Evolution Reaction
Authors: Cho Suyeon
Published: December 2024

Hydrogen evolution reaction (HER) is a promising solution for sustainable and clean energy source with zero carbon emission. Numerous studies have been conducted with versatile low dimensional materials, and the development of highly active electrochemical catalysts for HER has been one of the most important applications of the materials in the studies. Despite such extensive research, the physical origin of active catalytic performances from low dimensional materials remains unclear, which is distinguished from classical transition metal-based catalysts. Here, we review recent studies on intrinsic catalytic activity of two-dimensional (2D) semimetals, particularly among transition metal dichalcogenides (TMDs), highlighting promising strategies for the design of materials to further enhance their catalytic performances. An attractive approach for active HER is fabricating single-atom catalysts in the framework of TMDs. While electrochemical reaction at a catalytic atom for hydrogen evolution has been discussed by the Sabatier principle, we describe the phenomenon by Gibbs free energy for hydrogen adsorption via down-sizing, alloying, hybridizing, hetero-structuring, and phase boundary engineering mostly with TMDs. Thus, unique advantage of TMDs and their derivatives for HER are summarized, proposing research directions for promising design of low dimensional electrochemical catalysts for efficient HER and their energy applications.
Effect of Pt Catalyst Instead of Pd on Switchable Ag Mirror Devices
Authors: Kageyama Yui , Aoki Atsushi
Published: December 2024

Electrochromic devices can control the transmittance of incident light between transparent state and color state under electrical bias, and has already been put into practical use in airplane windows and other applications. However, it has some drawback that the temperature rises due to absorption of light in the color state, and the heat is radiated inside. Meanwhile, the Ag mirror device that reversibly switches between transparent state and mirror state has attractive attention due to suppressing heat radiation. Since specular reflection is used in the mirror state, the Ag mirror device has an advantage over electrochromic device in that it does not emit heat and can suppress increases in room temperature.

In the previous study, Ag mirror device based on reversible silver plating on Pd-modified ITO electrodes has been reported. The Pd-modified ITO electrode is prepared by electrochemical reduction of palladium ion to get highly dispersed Pd nanoparticles on ITO surface. Pd becomes a nucleation site for Ag plating, resulting in formation of a smooth mirror surface. The Ag plating bath consists of silver nitrate, and citric acid in the mixture of acetonitrile and ionic liquid. When a negative voltage is applied in this plating liquid, the Ag⁺ is reduced to Ag metal on the ITO electrode, forming a mirror surface of Ag. Conversely, when a positive voltage is applied, the plated Ag is oxidized and dissolved in the Ag plating bath, resulting in return to a transparent state. A problem with the Pd catalyst used in this device is that Pd gradually dissolves as the number of cycles increases. In this study, in order to solve this problem and to improve cycle durability, we will consider change of the catalyst from Pd to Pt, which is a noble metal with catalytic property and electrochemical stability.

We prepared a new Pt plating bath consisting of hexachloroplatinic acid(IV) hexahydrate and hydrochloric acid in pure water. Pt modification on the ITO electrode was performed by applying a constant current of -10 mA/cm2 for 1.0 sec. Although the Pt-modified ITO electrode succeeded in switching between the mirror state and the transparent state, the switching characteristics degraded with increasing number of cycles. We assume that the degradation was caused by that the amount of modification of the Pt catalyst could not be controlled because the reducing current for Pt metal formation was also used for hydrogen generation in the acid solution. Thus we changed from acidic condition to basic condition in the Pt plating bath. We will conduct SEM image analysis and transmittance measurements to clarify the amount and form of Pt modification. After that, we will search for suitable Pt modification conditions for application to the silver mirror device, and examine whether it is possible to switch between a mirror state and a transparent state, and to improve the number of cycles.
Integration of Electrochromic Technology in Energy Applications
Authors: Moon Hong Chul
Published: December 2024

Multifunctional systems that serve simultaneously as two or more devices have attracted significant attention due to the high integration of electronic devices in cutting-edge technologies. In this work, we introduce the versatile use of electrochromism including thermal management and energy storage. In particular, we are going to describe all-in-one type, single-layer device platforms based on solid-state ionic conductors. It also covers effective strategies to tune electrochromic performance.
Modified Prussian Blue Nanoparticles with Salicylate for Electrochromic Devices
Authors: Han Jisu , Kim Tae-Youb , Ah Chil Seong , Song Juhee
Published: December 2024

Prussian blue is an important material for electrochromic devices which can act in small range of applying voltage and its various color from blue to yellow. The color changes are displayed within narrow voltage range, therefore, the specific voltage should be selected to operate the selected color. Hence, it is hard to obtain both large transition and electrochemical reaction. Modification of Prussian blue needs to be considered because of the future electrochromic devices are required either colorable or fast response.

Improving coloration efficiency of electrochromic devices is achieved in two different ways; one is to increase the optical density and the other is to lower the reacted charge. It is known that enhancing the optical properties were being researched by adding or modifying iron atom of Prussian blue structures by other metal atoms. Those are good approaches, and it effectively enhanced the optical properties. However, lowering the reacted charge is considered a property that cannot easily controlled.

In this study, we focused on lowering the reacted charges with modify the Prussian blue nanoparticles by additives as salicylate derivatives. Synthesis was done with four-type of additives, and its nanoparticle characteristics were investigated. Thin films for electrochromic measurements were deposited on the ITO electrodes. Evaluation of reacted charges was carried out by measuring electrochemical properties. Furthermore, the electrochromic properties were confirmed by its optical characteristics and calculation of coloration efficiency. The addition of salicylate into Prussian blue was achieved higher coloration efficiency compared with the regular Prussian blue by decreasing the reacted charges.

Keywords

: Prussian blue, Salicylate additives, electrochromic devices, high coloration efficiency
Optical and Plasmonic Properties of Epitaxial and Oxidative Controlled Titanium Nitride Thin Films
Authors: Chris-Okoro Ikenna , Cherono Sheilah , Kumar Dhananjay
Published: December 2024

The present study is an effort to develop negative-permittivity, high melting point, mechanically hard, and chemically stable materials beyond commonly employed plasmonic metals such as gold and silver, which are often device incompatible in terms of real operating environments. The material studied here is titanium nitride (TiN), which possess free electron gas density similar to of gold and silver, and embodies refractory metals’ characteristics. The aforementioned advantages of TiN are taken to the next level by transforming them to oxynitrides (TiON) with a precise control in oxygen composition that can, in turn, be used to tune the electronic band structure of transition metal nitrides, opening another new dimension to transition metals nitride based plasmonics and metamaterials research. This presentation will report a pulsed laser-assisted synthesis, detailed structural characterization using x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), soft x-ray absorption spectroscopy (XAS), non-Rutherford Backscattering spectrometry (RBS), and plasmonic properties of three sets of TiN/TiON thin films. The first two sets of TiN films were grown 600 and 700 °C under a high vacuum condition. The third set of TiN film was grown in the presence of 5 mTorr of molecular oxygen at 700 °C. The purpose of making these three sets of TiN/TiON films was to understand the role of film crystallinity and role of oxygen content of TiN films on their optical and plasmonic properties. The results have shown that TiN films deposited in a high vacuum are metallic, have large reflectance, and high optical conductivity. The TiN films, grown in 5 mTorr, were found to be partially oxidized with room temperature resistivity nearly three times larger than those of the TiN films grown under high vacuum conditions. The optical conductivity these films were analyzed using a Kramers-Kronig transformation of reflectance and a Lorentz-Drude model; the optical conductivity determined by two different methods agrees very well, indicative of reliable estimate of the absolute value of reflectance in the first place. Then, it allows us to determine and analyze the complex dielectric function over a broad spectral range. We notice the existence of significant spectral weight below the interband absorptions, described by two Lorentzians, one around 250 cm-1 and one around 2,500 cm-1. We discuss here the dependence of the two bands on the deposition conditions and their effect on the plasmonic performances of TiN/TiON thin films, in particular on the surface plasmon polariton (SPP) and localized surface plasmon resonance (LSPR) quality factors.
Fabrication of PbS QD-Mediated Organic-Inorganic Hybrid Swir Opds Using Azide Functional Ligand (FPA-S) and Study of Polymer Morphology Control
Authors: Park KyoBin , Chung Dae Sung
Published: December 2024

The efficiency of exciton dissociation and electron mobility in organic photodetectors (OPDs) is critically dependent on the microscale morphology of the interpenetrating network structures between electron donor and acceptor materials. Therefore, understanding the impact of phase separation within the active layer and the interactions between components is crucial for OPD performance.

In this study, we propose a hybrid Short Wavelength Infrared (SWIR) photodiode that utilizes PbS quantum dots (QDs) minimally, leveraging their exceptional SWIR absorption properties, alongside an organic semiconductor matrix to counterbalance their poor charge transport characteristics. While similar concepts of organic-inorganic hybrid photodiodes have been suggested previously, the straightforward blending of organic semiconductors and QDs has been constrained by poor miscibility due to differences in surface energy between organic and inorganic phases. This results in reduced phase stability post-film fabrication and significant phase separation. Therefore, we introduce an azide-functional ligand (FPA-S) capable of coordinating with QDs and bonding with polymers via azide groups, to induce photo-crosslinking and suppress phase separation between polymers and QDs.

Effectively separating excitons while minimizing the amount of PbS QDs, which are toxic and exhibit low charge mobility, necessitates controlling the morphology of the active layer. We optimized conditions such as solvent type, evaporation rate, volume ratio, and external humidity based on a quaternary phase diagram derived from Flory-Huggins interaction parameters. Additionally, we sought to identify the optimal condition by calculating the equilibrium state of the phase-separated structure of polymers using a phase-field model with the Ising machine.
(Invited) Optimizing the Activity of Oxygen Reduction Reaction Via Structural Engineering of Support for Fe-N-C Electrocatalysts in Proton Exchange Membrane Fuel Cells
Authors: Lee Jinwoo
Published: December 2024

The scarcity and costliness of platinum group metals in PEMFC cathodes hinder commercialization. Despite the promise of Fe-N-Cs electrocatalysts as alternatives, their oxygen reduction reaction (ORR) performance falls short. To address this, two carbon support-structural engineering methods were devised. Firstly, defect adjustment in ZIF-NC carbon support, derived from zeolitic imidazolate frameworks, via CO2 activation. Secondly, introduction of mesopores into ZIF-NC using the block co-polymer soft-template method. Controlled degree of defect sites in supports enhance intrinsic activity of Fe-N4 by modifying electronic structure such as charge distribution and spin state. Mesopores aid mass transport, improving active site accessibility. Additionally, the curved surfaces and carbon edge sites generated by mesopores alter the geometric structure of Fe-N4, optimizing the adsorption energy of oxygen species. Support-structural engineered Fe-N-Cs electrocatalysts exhibit relatively outstanding ORR performance compared to pristine Fe-N-C. MEAs with these electrocatalysts exhibit impressive peak power densities, highlighting their high activity at the MEA level.
NiMo/C Doped with Trace Precious Metals (Pt, Rh, Ru, Ir) for Enhanced Hydrogen Evolution Reaction in Anion Exchange Membrane Water Electrolysis
Authors: Lee Changsoo , Jung Chanwon , Lee Sechan , Doo Gisu , Park Hyeonjung , Kim MinJoong
Published: December 2024

Anion exchange membrane water electrolysis (AEMWE) provides a broader selection of electrocatalyst materials, including non-novel metals, due to its high pH operating condition. However, the development of transition metal-based electrocatalysts for the hydrogen evolution reaction (HER), exhibiting activity comparable to Pt/C, remains a significant challenge, aiming to reduce material costs for AEMWE. In this study, we demonstrate the remarkable activity and durability of NiMo/C electrocatalysts for HER, achieved by incorporating small amounts of precious metals (<5 at.%) such as Pt, Rh, Ru, and Ir. The effects of precious metal doping were thoroughly investigated through electrochemical and chemical state analyses. Furthermore, membrane electrode assemblies (MEAs) were fabricated using the NiMoX/C (X: precious metal) electrocatalysts, in which catalysts were coated onto membrane. Single cell tests were conducted to validate the practical feasibility of these electrocatalysts. Notably, the addition of even minute quantities of precious metals is highly effective in enhancing both the activity and stability of the HER. These findings offer valuable insights into the development of highly active HER electrocatalysts at low cost for AEMWE applications.
Optimizing Multi-Phase IrO2 Catalysts with Ti for Enhanced Oxygen Evolution Reaction for Proton Exchange Membrane Water Electrolysis
Authors: Yun Younghwa , Lee Sechan , Park Hyeonjung , Doo Gisu , Kim MinJoong , Cho Hyun-Seok , Lee Changsoo
Published: December 2024

To achieve a sustainable and environmentally benign energy paradigm shift, the utilization of renewable energy sources through water electrolysis, especially proton exchange membrane water electrolysis (PEMWE), emerges as a promising solution. Accordingly, enhancing catalytic activity and stability of the anode catalyst (IrO2), which constitutes a significant portion of the cost of PEMWE, is crucial for its practical commercialization. Notably, recent research has shed light on the pivotal role of Ir-O bond distance in IrO2-based electrocatatlysts, where doping or composite formation with foreign atoms influences oxygen evolution reaction (OER) activity and stability. Therefore, understanding these Ir-O bond distance is crucial to effectively manipulate the OER activity and stability. Herein, we developed a hybrid-phase of Ti-added IrO2 electrocatalyst, demonstrating remarkable OER activity of 233.5 mV at 10 mA/cm2 and stability for over 25 h through fundamental insights into asymmetric interatomic interactions induced by Ti adoption. Our findings reveal that optimizing the multi-phase evolution by introducing Ti into IrO2 yields compressive strains in IrO2 motifs reducing the Ir-O bond distance effectively increase the OER activity. However, In-situ X-ray absorption spectroscopy (XAS) analysis further confirms that the longer Ir-O bond distance at 1.5 V (vs. RHE) of hybrid-phase of Ti-added IrO2 indicates the facile formation of –OOH* intermediates, offering outstanding OER stability by suppressing Ir dissolution. These advancements represent a breakthrough in enhancing the OER activity and stability of IrO2, marking a significant milestone in advancing transformative energy shifts toward sustainable and environmentally integral renewable sources.
Using Operando NMR to Elucidate Degradation Mechanisms in Silicon Anodes
Authors: Wang Evelyna , Rodrigues Marco-Tulio , Park Sohyun , Dogan Fulya , Key Baris
Published: December 2024

Replacing graphite anodes with Si anodes can greatly increase the energy of current Li-ion batteries. Detailed characterization of Si lithiation reactions, SEI formation, and reversibility are therefore active areas of research. Solid-state 7Li nuclear magnetic resonance (NMR) spectroscopy is a useful for characterizing different lithium local environments within Si anodes. Here, we developed an operando NMR methodology to characterize cycle and calendar aging of Si anodes in pouch cells paired with Ni-rich cathodes in a non-destructive manner. The developed pouch cells mimic long term performance of larger scale pouch cells. We observed a new lithiation mechanism for small Si nanoparticles: direct formation of over-lithiated Li15+xSi4 (x < 0.6) phase. Furthermore, our novel operando cells maintained good performance with long-term cycle and calendar aging allowing direct identification of Li-loss and degradation mechanisms in full cells with NMR. To this end, we identified trapped lithium silicides as a major contributor to capacity fade with aging in a number of different silicon electrodes. We will discuss the new capability and the quantitative information and insights gained from full cells such as Li-inventory losses. We envision a plethora of future operando NMR work with long term aged cells, comparing the effects of cycle aging with calendar aging as well as standardized comparison of aging mechanisms in various Si anode materials and other advanced materials with new electrolytes, additives, binders etc.

Related publication: Evelyna Wang, Marco Rodrigues, Sohyun Park, Fulya Dogan and Baris Key, Journal of Power Sources, Volume 604, 2024, 234477

Figure 1
Estimating Lifetime and Degradation Analysis of PEMFC Under Harsh Load Conditions for Eco-Friendly Off-Road Heavy Equipment
Authors: Hwang Junphil , Oh Juyoung , Ryu Hoyoung , Lee Seunghyun , Kim Hee Su
Published: December 2024

The durability and lifetime are key parameters for commercial usage of Polymer Electrolyte Membrane Fuel Cell(PEMFC) in mobility industry. Off-road heavy equipment, such as excavator, loader, and dozer etcs, have severe amount of carbon emission because of its high energy density. According to California government, the air pollution contribution of off-road heavy equipment is higher than that of on-road vehicles since 2020. Therefore, it is necessary to change its power source to eco-friendly power system, such as battery or hydrogen fuel cell. However, its highly dynamic load cycles and harsh operating conditions could accelerate the degradation of Membrane-Electrode Assembly(MEA), reducing the lifetime of PEMFC and increasing the net-cost. In this work, we developed durability test protocols and model to estimate lifetime for PEMFC considering real experimental data obtained from field test results of Bobcat’s 3.8 tons compact track loader. The exact load conditions to PEMFC were obtained considering its complex movements. The 2000 hours of durability test of PEMFC single cell was conducted using newly developed protocols. The electrochemical analysis data was obtained in every 200 hours in order to analyze the degradation of MEA. The electrochemical surface area(ECSA) was decreased around 70 % with exponential decay behavior. From the electrochemical impedance spectroscopy, it was found that the Ohmic, charge and mass transport resistance were increased. According to the electrochemical analysis data, the degradation of catalyst layer was severe, which is the critical parameter for performance degradation. Using the TEM analysis, the catalyst degradation was confirmed directly.
Spatially-Resolved Characterisation of Large-Format PEMFC Electrodes: Electrochemical Impedance, ECSA and O2 Concentration
Authors: Curnick Oliver , Afra Mehran , Thirkell Alexander , Meyer Quentin , Özyalcin Can , Fleming Joe , Foster Simon
Published: December 2024

Fuel cell stacks are growing: both in numbers deployed in the field but also in terms of active electrode areas. The pursuit of higher-power applications and power densities means that cell active areas upwards of 400cm² are now commonplace. With larger electrodes comes an increased risk of non-uniform distributions of current density, temperature and reactant concentrations, which may lead in turn to locally-accelerated degradation and premature failure. Whilst detailed CFD/FEA modelling and simulation can help to refine designs, direct observations via in-situ and in-operando measurements are vital to verify model outputs and identify complex phenomena that models can fail to capture.

Our group has developed three spatially-resolved diagnostic techniques along with instrumentation, measurement systems and software tools designed to make their application as straightforward as possible for the characterisation of large-format PEMFC MEAs.

Spatially-resolved electrochemical impedance spectroscopy (SR-EIS) has been demonstrated using a commercially-available, segmented current sensor plate. A new software tool integrates a multiplexer for automated SR-EIS measurements, along with automatic equivalent circuit fitting and visualisation of spatially-resolved Ohmic, charge transfer and mass transport-related losses.

A novel technique has been developed for the measurement of distributed electrochemical surface area (dECSA), allowing localised changes in ECSA resulting from non-uniform ageing to be determined for the first time.

Finally, a chronoamperometric sensor array is demonstrated for the spatially-resolved measurement of in-plane oxygen concentration at the PEMFC cathode.

In combination, these characterisation techniques offer a significant advance in PEMFC diagnostics, providing a deeper insight into non-uniform conditions and degradation in large-format PEMFCs.
Path-Dependence and Aging Prediction of Catalyst Degradation in Polymer Electrolyte Fuel Cells
Authors: Cheng Lei
Published: December 2024

Electro-catalyst and its support play a central role in many clean energy technology applications, such as water electrolysis for green hydrogen generation and emission-free fuel cells for transportation. Electro-catalysts and the supports degrade via multiple mechanisms, depending on the exact operating conditions in its life cycles of the electrochemical device. In this presentation, we demonstrate the dependence of the catalyst layer degradation in polymer electrolyte fuel cell (PEFC) on the specific “paths” that the fuel cell takes to age. Additionally, the origin of the path dependence will be discussed. Based on the understanding, criterion is derived for determining if path dependence effect of catalyst degradation may be measurable. Furthermore, the impact of path dependence on the predication of aging in PEFC will be discussed.
Direct Use of Ammonia in Solid Oxide Fuel Cells
Authors: Bae Kiho , Park Jinsoek , Lee Kyung Min
Published: December 2024

With the global movement to suppress carbon use, hydrogen is emerging as an effective alternative to fossil fuels. However, there are difficulties in entering the energy market due to the lack of infrastructure and difficulties in storage/transportation when using hydrogen. Ammonia attracts attention as a promising solution to the hydrogen problem through well-established infrastructure around the world.

Direct use of ammonia in solid oxide fuel cells (SOFCs) offers more attractive aspects such as high efficiency and compact system size. However, instability in long-term operation has been reported in many literatures, which is mostly attributed to Ni nitridation. To overcome Ni nitridation, the current study proposes an alloy-based fuel electrode and its facile fabrication process. In this study, we intend to improve ammonia cracking in anode layer in SOFCs, contributing to improvement both fuel cell performance and long-term stability. The details on the current work will be presented.
Simulating CO2 Capture with Synthetic Microstructures in High-Temperature Mixed Conducting Membranes
Authors: Jin Xinfang , Shoukry Yasser
Published: December 2024

Composite solid oxide/molten carbonate (SO/MC) membranes [1] are gaining attention for CO2 capture due to their superior selectivity and efficiency at high temperatures, which allows them to outperform conventional methods such as wet scrubbing and pressure swing adsorption [2]. The topological characteristics of the composite material’s microstructure exert a substantial influence on the overall effective conductivity of the membrane. This influence arises from the interplay of volume fraction and tortuosity within each phase, which in turn affects the pathways of charge carrier. Quantifying the precise impact of various microstructure features is challenging through homogeneous simulations or experimental techniques alone. Consequently, the adoption of heterogeneous simulations [3] becomes imperative to gain deeper insights into how distinct microstructural attributes shape the overall macroscopic performance.

This study has developed a numerical simulation utilizing heterogeneous microstructures to optimize the performance of these membranes, capturing complex multi-phase and multi-species conducting behaviors. To enhance the simulation process, we have developed proprietary MATLAB code that imports microstructure data from Dream3D into COMSOL. This code is designed to effectively manage unconnected material segments, streamline the selection of simulation entities, and simplify the application of governing equations and boundary conditions within COMSOL. Additionally, the simulation integrates an in-situ generated Li1-xNi1+xO2 (LNO) layer within Sm0.2Ce0.8O3-δ/MC/NiO (SDC/MC/NiO) membranes. Our findings indicate that reducing the molten carbonate phase's volume fraction significantly increases the CO2 flux density across the membrane. Furthermore, this computational approach has successfully replicated experimental CO2 permeation fluxes for SDC/MC/NiO membranes, quantitatively demonstrating the advantageous impact of the in-situ generated LNO phase.

References:

[1] J. L. Wade, K. S. Lackner and A. C. West, "Transport model for a high temperature, mixed conducting CO2 separation membrane," Solid State Ionics, 2007.

[2] D. Shekhawat, D. R. Luebke and H. W. Pennline, "A Review of Carbon Dioxide Selective Membranes," US Department of Energy (US), 2003.

[3] T. W. Heo, A. Grieder, B. Wang and M. Wood, "Microstructural impacts on ionic conductivity of oxide solid electrolytes from a combined atomistic-mesoscale approach," Computational Materials, 2021.
Design of Li-Si Alloy Anodes for Enhancing Mechanical Stability and Electrochemical Performance of Sulfide-Based All-Solid-State Batteries
Authors: Jeong Yu Hong , Kim Min Ju , Lim Hyung-Tae
Published: December 2024

Li metal all-solid-state batteries, valued for their higher energy density and stability, face issues with lithium metal anodes, such as dendrite structures formation. To address these issues, alloy-based anodes such as Si, Al, and In are replacing lithium metal due to their high-capacity and lithiophilic characteristics. However, there is an issue of large volume change (~300 %) in the alloy anodes during the charge-discharge cycling Pre-lithiation, is considered one of the effective solutions to mitigate volume expansion in the alloy anode. In the present study, we prepared full cells consisting of LixSi (x = 1, 1.7, 2.3, 3.25, 4.4) anodes, argyrodite (Li6PS5Cl) electrolytes, and sulfur composite cathodes, to study the effect of the lithium concentration on the mechanical stability as well as electrochemical performance of sulfide based all-solid-state batteries. During the charge-discharge cycles, we measured the voltage profiles and electrochemical impedance spectra using an embedded Indium reference electrode. Microstructure of the solid electrolyte and distribution of lithium ions were analyzed using secondary electron microscope (SEM) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). High lithium concentrations (LixSi, x = 3.25, 4.4) exhibited high areal capacity ( ~ 3.5 mAh/cm2), however the non-uniform deposition of lithium on the anode surface during alloying led to the formation of lithium dendrite structures. For a low lithium concentration, LiSi demonstrates limited capacity due to a low lithium-ion diffusion coefficient. The medium concentration, Li1.71Si, showed comparable areal capacity to that of high lithium concentration and maintained high stability even under high cut-off voltage condition without dendrite formation. Thus, this study indicates that the medium lithium concentration (x = 1.71) alloy anode provides superior chemo-mechanical stability as well as comparable areal capacity, to the high lithium concentration (x = 3.25, 4.4).
Optimization of Synthesis Gas Composition for e-Fuel By Control of Co-Electrolysis Stack Operation Parameters
Authors: Ahn Jin Soo , Kim Sangkuk , Jeon Namgi , Ahn Kigyu
Published: December 2024

The continuous increase in greenhouse gas concentrations has manifested the impacts of climate change in all regions of the world. The development of technology for achieving carbon neutrality is now transitioning from a mere necessity to an issue of human survival. Recently, high-temperature electrolysis technology has gained significant attention as a method capable of producing clean hydrogen with high efficiency. In most regions on earth, thermal energy is cheaper than electricity. High-temperature electrolysis, which utilizes both heat and electricity simultaneously to produce hydrogen, is anticipated to be economically viable for producing clean hydrogen with minimal electrical energy. Also, high-temperature electrolysis process can be modified to accommodate CO2 gas as a reactant, allowing for simultaneous electrolysis of steam and CO2, a technique known as co-electrolysis. Utilizing low-carbon electric power in conjunction with co-electrolysis can enable the production of synthesis gas containing hydrogen and carbon monoxide (H2/CO), which can serve as a clean feed-stock for e-fuel synthesis. With this study, it has been confirmed that the existing high-temperature electrolysis 5 kW stack can be utilized for co-electrolysis reactions. Furthermore, by controlling operational conditions, it has been observed that various changes in exhaust gas composition (H2/CO/CO2) are achievable. By optimizing operational conditions, it was possible to control the composition of syn-gas to an optimal blend directly usable for Fischer-Tropsch e-fuel synthesis and methanol synthesis.
Enhancing Oxygen Catalytic Performance in Zinc-Air Batteries through Localized Micro-Interface Reconstruction of Cobalt-Manganese Spinel
Authors: Xu Nengneng , Adjah-Tetteh Christabel , Wang Yudong , He Zizhou , Zhou Xiao-Dong
Published: December 2024

Reversible zinc-air batteries are widely regarded as one of the most promising candidates for clean energy conversion and storage technology owing to their cost-effectiveness, inherent safety, wide operating temperature window and high theoretical energy density.(1) In general, the performance of zinc-air batteries is heavily dependent on highly active bifunctional electrocatalysts, which effectively accelerate oxygen reduction/evolution reaction (ORR/OER) kinetics. Among various electrocatalysts for advanced air cathodes, multivalent Co3-xMnxO4±δ oxides, as the representative mixed transition metal spinel, have attracted widespread interest because of their O2 catalytic potential and diverse properties.(2) In comparison to the state-of-the-art Pt- and Ir-based catalysts, the catalytic performances of Co3-xMnxO4±
δ remains constrained by its low electrical conductivity and inadequate ability to adsorb and activate O2.(3) Herein, we develop a unique pathway to achieve the self-reconstruction of the local micro-interface and electronic structure of Co3-xMnxO4±δ via a combustion reaction coupled with a high-temperature reduction process. The Co particles derived from the self-reconstructed Cox@Co1.5-xMn1.5O4-δ catalyst not only facilitate the formation of a metal/oxide heterojunction active interface but also improve the electrical conductivity. More importantly, Co metal precipitated from the tetrahedral site with high spin electronic configuration induces the transformation of lattice oxygen into oxygen vacancies, thereby effectively accelerating reactant adsorption. As expected, the Cox@Co1.5-xMn1.5O4-δ catalyst shows good ORR/OER activity with low overpotential. Furthermore, the zinc-air battery assembled by Cox@Co1.5-xMn1.5O4-δ catalyst demonstrates an extended charge-discharge lifespan exceeding 1000 hours, significantly surpassing that of the Pt/C+Ir/C catalyst (100 hours). The primary factor contributing to its high stability is the dimensional growth following catalyst reconstitution. This work offers novel insights into enhancing the small molecule electrocatalytic performance of typical mixed transition metal oxides, including spinel and perovskite catalysts.

References

A. Li, S. Kong, C. Guo, H. Ooka, K. Adachi, D. Hashizume, Q. Jiang, H. Han, J. Xiao and R. Nakamura, Nature Catalysis, 5, 109 (2022).

N. Xu, Y. Zhang, M. Wang, X. Fan, T. Zhang, L. Peng, X.-D. Zhou and J. Qiao, Nano Energy, 65, 104021 (2019).

C. Li, X. Han, F. Cheng, Y. Hu, C. Chen and J. Chen, Nature Communications, 6, 7345 (2015).
Redox-Mediated Electrodialysis for Recycling of Spent Lithium Ion Battery
Authors: Kim Choonsoo , Kim Hyunjin , Kim Seonghwan
Published: December 2024

Redox-mediated electrodialysis (Redox-ED) has emerged as a promising alternative for electrochemically driven desalination and ion separation. It represents a culmination of advancements in combining conventional electrochemical ion separation processes such as capacitive deionization (CDI) and electrodialysis (ED). The Redox-ED system's distinctive multi-channel design, enabling independent control of flow streams, stands out as a significant feature facilitating superior process optimization and system performance. Redox-ED offers several key advantages over conventional ED and CDI.

First, Redox-ED utilizes reversible redox couples at the end electrodes to drive deionization, resulting in minimal cell voltage requirements. This contrasts with conventional ED, which typically requires higher cell voltages for the water-splitting reaction. Second, the most notable advantage of Redox-ED is its potential for energy recovery from the redox couples employed in the process. This implies that energy expended during desalination can be partially or wholly regained when the redox reactions are reversed, similar to energy recovery in redox flow batteries. Third, Redox-ED can utilize commercially available electrodes, such as activated carbon, for redox reactions under mild conditions. In contrast, traditional ED often relies on costly metal oxide electrodes, like dimensionally stable anodes, to withstand extreme reaction conditions. Lastly, Redox-ED operates under relatively mild reaction conditions compared to traditional ED, resulting in reduced byproduct production and pH variation. This enhances the manageability of downstream processes and system operation.

Following the development of Redox-ED, this presentation aims to elucidate the basic principles of Redox-ED and recent advances, covering cell architecture, electrodes, functionality, and scale-up strategies. Additionally, potential applications in spent lithium-ion battery recycling will be explored. Finally, practical challenges and opportunities for future research directions will be discussed.
(Invited) Improvement in Dynamic Operational Stability of Alkaline Water Electrolysis
Authors: Kim MinJoong , Lee Changsoo , Lee Sechan , Doo Gisu , Seo Jongsu , Cho Hyun-Seok
Published: December 2024

The significant advantages of alkaline electrolyzers, including their maturity, large capacity, and cost-effectiveness, have garnered considerable attention as viable applications for energy storage systems linked to renewable energy sources such as wind and solar. These attributes offer economic benefits for managing fluctuations in electrical loads by storing excess energy as hydrogen, serving as an efficient energy carrier, particularly in long-term and large-scale storage systems. However, the fluctuating loads stemming from renewable power sources can impact electrolysis performance and potentially affect overall durability. Here, we will discuss improvements in the dynamic operational stability of alkaline water electrolyzers (AWE), mainly focusing on the electrodes, analyzing degradation phenomena. This analysis was conducted from the perspective of material design disciplines, combined with computational engineering and X-ray spectroscopic analysis. The dynamic operational stability of the screened electrodes in alkaline solutions was evaluated using accelerated test protocols. Importantly, no significant oxygen & hydrogen evolution reaction performance degradation was observed after the lab-scale dynamic operation tests, and no structural deformation or metal ion dissolution were found to occur. Furthermore, these electrodes were scalable up to an area of 2,500 cm2 and could be evaluated in electrolyzer stacks of 100 kW or higher. We believe that enhancing poor kinetic efficiency and mitigating component degradation would extend the system's lifetime, thereby improving the economics of alkaline water electrolysis.
Electrocatalytic CO2 Conversion to Formate Using Gas-Diffusion Electrodes with Group 12-15 Metals
Authors: Piao Guangxia , Park Hyunwoong
Published: December 2024

The group 12-15 metals of the periodic table are considered promising catalysts for the electrochemical conversion of CO2 to formate. The activities of these metals are estimated and compared using bulk metals (i.e., metal plates) in conventional aqueous CO2 electrolysis systems. Herein, five group 12–15 metals (Cd, In, Sn, Pb, and Bi) in the particulate form are hydrothermally synthesized, and their catalytic activities in formate production are examined in the gas-diffusion electrode device with continuous CO2 supply, with catalyst mass loading and applied current density as independent variables. The faradic efficiency values lower than 80% are obtained for Pb and Cd regardless of the experimental conditions. By contrast, In, Sn, and Bi show the relatively reliable faradaic efficiency values of >80% and cathodic energy efficiency values of >45% at cathodic Jof 100-300 mA cm−2 (hence partial current density for formate, J
FM ~250 mA cm-
2). Surface characterization reveals the crystalline structures of BiOCl, Cd(OH)2, In(OH)3, PbO, and SnO2. Among the metals, Sn is further modified under a reductive atmosphere to increase its energy efficiency. The figures of merit (faradaic efficiency, current, and cathodic energy efficiency) for the modified Sn are marginally higher than those for the other Sn types.

This work was supported by the Technology Innovation Program (or Industrial Strategic Technology Development Program-Alchemist Project) (NTIS-1415187362, 20025773, Development of building-Integrated Carbon Control Technologies) funded By the Ministry of Trade, Industry & Energy(MOTIE, Korea). This work is financially supported by Korea Water Cluster (KWC) as Korea Water Cluster ProjectLab.
Modeling Hydrogen Crossover in Proton Exchange Membrane Water Electrolyzers with and without Recombination Catalyst Interlayers
Authors: Arges Christopher G. , Ahluwalia Rajesh , Wang Xiaohua
Published: December 2024

Low-temperature proton exchange membrane water electrolyzers (PEMWEs) are poised to undergo rapid expansion in the coming decades for clean hydrogen production. Hydrogen has been hailed as the ‘Swiss Army knife’ of decarbonization as it can help mitigate carbon dioxide emissions from ammonia production, metal refining, and heavy-duty vehicle transportation. Proliferation of clean hydrogen production necessitates large reductions in iridium loadings in the anode while also operating at higher current density values. The latter goal can be achieved by adopting thinner proton exchange membranes (PEMs), but the use of thinner membranes exacerbates hydrogen crossover – which leads to unacceptable levels of hydrogen in the anode effluent poising safety concerns (i.e., above the lower explosion limit of 4 vol% hydrogen in oxygen). Notably, the hydrogen content in the anode effluent is high when operating the PEMWE at low current density values (0.1 to 0.5 A cm-2). A PEMWE will sometimes throttle down and operate at low current density because of the intermittent nature of renewable energy sources which are used to power the electrolyzer. Recombination catalyst (RC) interlayers, located within the PEM, can consume hydrogen and mitigate the hydrogen concentration in the anode effluent. This Talk presents our continuum-level modeling approach for hydrogen crossover in PEMWEs with membranes containing RC interlayers. The model accurately captures the hydrogen content in the anode effluent as a function of the PEMWE current density, cathode back pressure, membrane thickness, anode backpressure, RC location, and RC loading. The modeling results, as well as experimental observations in the literature, suggest that RC interlayer effectiveness is limited by oxygen availability at the RC interlayer. The low oxygen concentration at the interlayer relative to hydrogen arises from the lower solubility of oxygen in hydrated PEMs and the lower diffusivity of oxygen in hydrated PEMs. The Talk concludes with future directions to improve the model as well as suggestions for future experiments to aid the accuracy of the model.
The Effect of Pt-Skin Surfaces on Electrocatalyst Dissolution at the Atomic Scale
Authors: Fairhurst Alasdair , Haering Dominik , Stamenkovic Vojislav
Published: December 2024

Combining activity and durability in electrocatalysis is critical for successful deployment of electrochemical systems. Platinum skin surfaces are known to exhibit extraordinarily high activity towards the oxygen reduction reaction however, little is known about their dissolution characteristics. We propose that the highly uniform nature of Pt-skin surfaces protects transition metal atoms beneath and contributes to enhanced resistance to dissolution events by acting as a protective layer on the surface. The unique adsorption characteristics of skin surfaces is leveraged to confirm their existence electrochemically and dissolution behaviour is evaluated with operando ICP-MS.1,2 We apply a high precision thin film approach to electrochemical investigation to uncover the synergistic effect of platinum skin surfaces on activity and durability.