bluuebunny/crossref_metadata_2025 huggingface dataset:
High-Performance Optimised Porosity Iron Electrode for Hybrid Battery Electrolyzer
Authors: Pal Santosh K. , Mulder Fokko M.
Published: August 2024

The growing demand for efficient, cost-effective and sustainable energy systems has prompted significant research into the development of advanced electrochemical devices. Hybrid battery electrolyzer, integrating the capabilities of both battery and electrolyzer, is a groundbreaking technology aiming to enhance both energy conversion efficiency and storage capacity. [1] Iron with large earth-abundance, low-cost, robustness, and high capacity is a promising electrode material for such hybrid energy systems. [2-4]

This study focuses on the design, fabrication, and performance evaluation of a novel porous iron electrode tailored for use in a hybrid battery electrolyzer system. The proposed electrode exhibits superior electrocatalytic activity, enhanced mass transport properties, and increased surface area, contributing to improved overall performance. The electrode's porosity and pore structure are tuned to facilitate efficient mass transport and electrolyte penetration, addressing common challenges associated with conventional electrodes. The electrochemical performance of the optimised porosity iron electrode is investigated through comprehensive characterization techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and charge-discharge cycling tests. Results indicate superior electrochemical properties, showcasing enhanced specific capacity, faster charge/discharge kinetics, and prolonged cycle life compared to conventional electrodes. The incorporation of conducting nanocarbon and sintering at optimized temperature of 800 ℃ led to the achievement of a stable and elevated capacity exceeding 500 mAh/g for these advanced iron electrodes. The iron electrodes exhibit outstanding porosity (65 - 70%), along with a pore size of 5-10 µm. This configuration results in exceptional current rate performance, achieving a discharge capacity of 350 mAh/cm2 at a current density of 35 mA/cm2 and 245 mAh/cm2 at 50 mA/cm2. Furthermore, the iron electrodes exhibit superior performance in high-current electrolysis, showcasing an HER potential of -1.25, -1.34, and -1.50 V (vs Hg/HgO) at a current density of 200, 500 and 1000 mA/cm2 respectively.

These findings highlight the potential of optimised porosity iron electrodes as a key component in the development of high-performance and cost-effective hybrid battery electrolyzer systems. The integration of such advanced materials holds promise for unlocking new frontiers in energy storage and green hydrogen technology, contributing to the realization of efficient and sustainable energy systems.

References:

F. M. Mulder, et al., Energy Environ. Sci., 2017, 10, 756.

K. Manohar et al., J. Electrochem. Soc. 2012, 159, A2148.

H. Weinrich, et al., Batteries & Supercaps 2022, 5, e202100415.

Möller-Gulland, et al. submitted.

Figure 1
4D-STEM and Eels Analysis of Complex C-Based Sensor Architectures
Authors: Ogolla Charles Otieno , Hepp Marco , Butz Benjamin
Published: August 2024

Transforming high-carbon precursors into open-porous carbon foams and coatings via thermal processes is gaining attention as a sustainable method for various applications, including catalysis, energy utilization, and sensing [1]. In this research, we adopt a one-step laser patterning approach to selectively pyrolyze doctor-bladed ink coatings on flexible PET substrates, thereby producing highly porous, intricately designed CO2 sensor structures with a thickness of about 50 µm. Our ink formulation includes glucose as a pore-forming agent and adenine as a nitrogen source to enhance sensing capabilities.

Laser processing in an oxygen-rich setting results in flexible, highly porous sensor heterostructures characterized by distinct areas enriched with nitrogen and oxygen functionalities. The laser intensity’s attenuation with depth leads to the development of a distinctly porous graphitic surface layer (serving as the electrical transducer layer) and a denser nitrogen-enriched lower sensor layer, linked by a narrow transitional region [2].

To understand the formation and functionality of these sensors, we conducted an in-depth TEM analysis of cross-sections of the complete device, prepared through ultramicrotomy cross-sectioning. STEM-EELS elemental distribution maps distinctly show the chemical composition differences between the upper and lower layers of the sensor. Principal component analysis was utilized to separate the complex sensor structures into their constituent crystalline and amorphous carbon and nitrogen-containing phases. 4D-STEM analysis exposed the arrangement of the crystalline graphitic phase and the orientation of graphite basal planes adjacent to the pores of the open-porous sensor. Analyzing these structural parameters is essential for understanding the electrical performance of the sensor, as depicted in Figure 1 [3].

Figure 1: A (top)) SEM micrograph of sensor embedded in epoxy, (bottom) depth-dependent thermal laser intensity attenuation; B (left)) HA ADF-STEM micrograph showing different sensor layers, (middle) STEM-EELS nitrogen distribution map, (right) PCA bond analysis, C) HRTEM images of sensor from transducer (top) and sensor (bottom) layers with SAED image of respective ROIs (inset); D) 4D-STEM analysis depicting misalignment angle between graphitic carbon basal plane normal relative to the pore surface normal

References

[1] M. Hepp, et al. npj Flexible Electronics 6, 1-9 (2022)

[2] H. Wang, et al. Advanced Functional Materials 32, 2207406 (2022)

[3] C. Ophus, et al. Microscopy and Microanalysis 28, 390-403 (2022)

Acknowledgements: We acknowledge use of the DFG-funded Micro-and Nanoanalytics Facility (MNaF) at the University of Siegen (INST 221/131-1).

Figure 1
Design and Additive Manufacturing of Electrodes for Electrochemical Energy Storage
Authors: Reale Batista Mariana Desiree , Chandrasekaran Swetha , Moran Bryan , Salazar de Troya Miguel A , Pinongcos Anica , Wang Zhen , Hensleigh Ryan , Carleton Adam , Zeng Manhao , Roy Thomas , Lin Dun , Xue Xinzhe , Beck Victor A , Tortorelli Daniel , Stadermann Michael , Zheng Rayne , Li Yat , Worsley Marcus Andre
Published: August 2024

Supercapacitors exhibit rapid charge/discharge times and have attracted considerable attention within the automotive, aerospace, and telecommunication industries. The high electrical conductivity and surface area of porous carbons have been attractive for supercapacitor electrodes. Fabricating thick electrodes is one strategy to further increase energy density due to a higher volume fraction of active material. However, thick electrodes suffer from sluggish charged species transport. In this work, we investigate the use of computational optimization and additive manufacturing to design and fabricate thick porous electrodes with improved performance. Electrode performance was maximized by designing their morphologies via topology optimization and printing by projection micro stereolithography (PµSL) using commercial resin (PR48). The PR48 resin was then pyrolyzed (PR48-P) to create the final conductive electrode. The optimized PR48-P electrodes exhibited 99% improvement in capacitance compared to control electrodes printed with cubic lattice morphologies. To further improve performance, we formulated a resin combining graphene oxide (GO) and trimethylolpropane triacrylate (TMPTA). Electrodes printed with 3 wt% GO in TMPTA exhibited improved capacitance retention after pyrolysis compared to the PR48-P electrodes. This work demonstrates the enormous potential of leveraging topology optimization and additive manufacturing to resolve many challenges in the electrochemical storage and renewable energy regimes. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC

Figure 1
Developing and Testing Standards to Assess Atmospheric Corrosion of Silver Witness Coupons
Authors: Johnson Alexander , Sanders Christine E. , Santucci Raymond , Policastro Steven A , Hammond Mark H.
Published: August 2024

Silver witness coupons are used to assess the corrosivity and chemistry of an ambient environment. The formation of silver corrosion products such as silver chloride is highly dependent on local conditions. However, the mechanisms that are responsible for these corrosion products are not well-understood, and there is a lack of standards used to compare and assess the quality of observations.

The goal of this study is to synthesize silver corrosion film standards with known thickness and morphology. Compounds of interest include silver chloride, silver oxide, silver sulfide, silver sulfite, and silver sulfate. These compounds were generated electrochemically by oxidizing the silver in the presence of the anion of interest (chloride, sulfite, or sulfate), chemically by submerging the silver in a solution containing the anion, and chemically by dipping the silver in molten silver salts. The surface chemistry of these films was then analyzed using galvanostatic reduction, x-ray diffraction, x-ray photon spectroscopy, Raman spectroscopy, and energy dispersion spectroscopy. The films generated from each method were compared against each other to determine the optimal film thickness and morphology. In the future, these results will be compared against the surface chemistry of silver films formed by testing in laboratory chambers or by exposure in field environments.

Figure 1
Monitoring the Corrosion Resistance of Cold-Spray Coatings with Membrane-Based Sensors
Authors: Rendon Arnaldo , Belarbi Zineb , Eden Timothy J , Dogan Omer , Hall Derek M.
Published: August 2024

Ensuring the management of gas transportation infrastructure requires the monitoring of internal corrosion within pipelines. The utilization of membrane-based electrochemical sensors is a promising advancement in corrosion risk monitoring. These sensors demonstrate an ability to operate within humidified gas environments, previously inaccessible to conventional electrochemical monitoring methods. Simultaneously, ongoing research is delving into novel sacrificial coatings and application methods to prolong the lifespan of existing pipeline structures and minimize associated repair costs. In this context, we broaden the application of membrane-based electrochemical sensors to investigate the response of electrodes equipped with cold-spray coatings. This examination encompasses a range of fluids exhibiting varying levels of corrosivity pertinent to natural gas pipelines. Multiple sensors with 316 stainless steel working electrodes were coated with cold spray sacrificial coating then exposed to humidified gases with differing relative humidities (RH) (5 %, 50 %, and 95 %) and condensed phases with differing salt content (deionized water and 0.1 mol kg-1 NaCl solution). Three electrochemical techniques (potentiometry, impedance spectroscopy and potentiodynamic scans) were used to monitor the corrosive environment and probe the extent of coating coverage. For the conditions studied, impedance values were extremely sensitive to changes in water content through changes in the membrane resistance (from ~1 kΩ in deionized water to ~5 MΩ with 5 % RH). Polarization resistances (Rp) consistently decreased with increasing corrosivity (~3 kΩ in deionized water to 15 GΩ with 5 % RH). Scanning electron microscopy and energy dispersive X-ray spectroscopy were used to identify the extent to which corrosion products permeated the membrane after major corrosion events.
Modification of the Structure and Protectiveness of Rust Layers on Carbon Steel Utilizing Reactive Actions of Metallic Cations
Authors: Tsuchiya Hiroaki , Kim Kyung-Tae , Hanaki Koushu , Yamashita Masato , Fujimoto Shinji
Published: August 2024

Carbon steels are widely used as structural material for infrastructures due to their superior mechanical properties such as strength and toughness. However, infrastructures made of steels suffer from degradation due to atmospheric corrosion when they are used in atmospheric environments. It is well-known that rust layers formed on steel in atmospheric environments mainly consist of alpha-, beta-, and gamma-FeOOH and Fe3O4. Among the constituents of rust layers, alpha-FeOOH has been reported to be electrochemically stable compared to the other types of FeOOH and Fe3O4, suppressing atmospheric corrosion. Weathering steels exhibit superior atmospheric corrosion resistance compared to carbon steel due to enhanced growth of alpha-phase in rust layers. It has been reported that the growth of alpha-phase can be enhanced by alloying elements such as Cu and Cr in weathering steels. This implies that the introduction of such metallic cations into rust layers modifies their structure and protectiveness. In the preset work, we examine the effects of various metallic cations on the structure and protectiveness of rust layers on carbon steel.
Assessing the Corrosion Rate of Carbon Steel in Steam Cycle Chemistries Using X-Ray Computed Tomography and Electrochemical Methods
Authors: Ganesan Akash , Howell Andrew , Hall Derek M. , Burns Brad
Published: August 2024

Corrosion management and mitigation from steam cycle contaminants are top priorities for power plant operators. As such, accurate estimation of corrosion rate dependencies on steam cycle chemistry contamination levels are of critical importance. While electrochemical methods can detect corrosion rate increases due to known corrosion agents, like chloride or sulfates, they often underrepresent the danger they present to power plant operations due to their inability to quantify localized corrosion values and the extent of under-deposit corrosion (UDC). High resolution X-ray computed tomography (CT) scans can bridge this gap and provide a means of measuring of localized corrosion rates to better inform the risks associated with specific steam cycle contaminants. If combined with conventional electrochemical monitoring, these methods provide a more comprehensive picture of the corrosion risk associated with particular steam cycle chemistry environments. Herein, we compare corrosion rates obtained from these methods for carbon steel samples exposed to steam cycle chemistries at 300 °C and 124 bar for 60 hours in a laboratory setting. Both linear sweep voltammetry (LSV) and linear polarization resistance (LPR) were used to estimate corrosion rate throughout the exposure test. After the exposure test, X-Ray CT scans were done at a resolution of 710 nm over a sample region of 1.4 mm to determine general and localized corrosion rates. The highest rates calculated for the localized corrosion were all an order of magnitude higher than the general corrosion values calculated from LSV and LPR. The largest discrepancy between the general and localized corrosion rate was observed for chloride contamination. For this case, general corrosion rates were between 0.21 and 0.57 mm y-1, whereas localized corrosion rates were as large as 5.55 mm y-1.
EIS Investigation of a Single Pit on Cantor Alloy in Acidic Environment
Authors: Hou Yaojun , Sun Fan , Ogle Kevin , Gharbi Oumaïma , Turmine Mireille , Vivier Vincent
Published: August 2024

High-entropy alloys (HEA) are an emerging class of materials with promising properties such as high strength and ductility, improved fatigue resistance, fracture toughness, and thermal stability. They show considerable potential for use as corrosion resistant alloys to support our infrastructure especially for use in extreme environments. In this work, we mainly focused on the typical Cantor alloy, which consists in a mixture of 5 elements CrMnFeCoNi in equimolar proportion. A huge amount of works has already been devoted to the study corrosion resistance of alloys in sulfuric acid [1] or in chloride containing solutions [2,3]. For the latter, the study of the pitting propagation remains challenging since this kind of corrosion initiates as a stochastic process.

Electrochemical impedance spectroscopy (EIS) is intensively used as a tool for corrosion research and is well suited for the identification of complex mechanisms. However, data analysis remains difficult in the case of pitting studies, which can be described schematically as n anodic sites in parallel at different states of evolution. In this work we report on EIS analysis performed on a single pit (Fig. 1a) in order to describe the various step of its evolution as a function of time, but also as a function of various parameters such as the chloride ion concentration or the corrosion potential. Single pits were obtained by studying the breakdown of the passive film using the pumped-micropipette delivery/substrate collection (Pumped-MD/SC) mode of scanning electrochemical microscopy (SECM). A detailed mechanism is proposed to account for EIS results obtained on a single pit (Fig. 1b) in order to explain results on usuals EIS measurements.

[1] J. Yang, J. Wu, C. Y. Zhang, S. D. Zhang, B. J. Yang, W. Emori et J. Q. Wang, « Effects of Mn on the electrochemical corrosion and passivation behavior of CoFeNiMnCr high-entropy alloy system in H2SO4 solution », Journal of Alloys and Compounds, 819, avril 2020, p. 152943, https://doi.org/10.1016/j.jallcom.2019.152943

[2] Camila Boldrini Nascimento, Uyime Donatus, Carlos Triveño Ríos et Renato Altobelli Antunes, « Electronic properties of the passive films formed on CoCrFeNi and CoCrFeNiAl high entropy alloys in sodium chloride solution », Journal of Materials Research and Technology, 9, no 6, novembre 2020, p. 13879-92, https://doi.org/10.1016/j.jmrt.2020.10.002

[3] Mengjiao Li, Qingjun Chen, Xia Cui, Xinyuan Peng et Guosheng Huang, « Evaluation of corrosion resistance of the single-phase light refractory high entropy alloy TiCrVNb0.5Al0.5 in chloride environment », Journal of Alloys and Compounds, 857, mars 2021, p. 158278, https://doi.org/10.1016/j.jallcom.2020.158278

Figure 1
A Data-Driven Approach for Predicting the Lifetime of Lithium-Metal Batteries
Authors: Uppaluri Maitri , Ma Wenting , Ha Sara , Aliahmad Nojan , Saatchi Alireza , Littau Karl , Onori Simona
Published: August 2024

Lithium-metal batteries (LMBs) are promising candidates for accelerating the implementation of electric vehicles in our society. LMBs comprise of a lithium-metal anode that possesses the highest theoretical specific capacity (3860 mAh/g) and the lowest redox potential (-3.04V vs standard hydrogen electrode).1 LMBs undergo repeated plating and stripping of lithium ions on the anode surface. The non-homogenous stripping process leads to the isolation of metallic lithium from the anode surface, forming dead-lithium.2 The parasitic reaction between the lithium-metal anode and the electrolyte leads to the formation of the solid electrolyte interphase (SEI) layer. These phenomena lead to the reduction of available lithium and a rise in cell impedance, causing a rapid reduction of lifetime for these batteries.3
,
4

In this talk, we present a diverse dataset collected from different LMBs of different capacities and voltage ranges, that includes features from the initial formation cycle, rest voltages and CV charging during cycling. A data-driven model from the LMB cycling data is presented to predict the remaining useful lifetime (RUL) of these cells. Insights from the model can be used to determine the bad cells in a batch, improve the designs of the cells and derive optimal charging protocols for their implementation in the BMS.

References

Lin, D., Liu, Y. & Cui, Y. Reviving the lithium metal anode for high-energy batteries. Nat. Nanotechnol.
12, 194 (2017).

Xu, S., Chen, K.-H., Dasgupta, N. P., Siegel, J. B. & Stefanopoulou, A. G. Evolution of Dead Lithium Growth in Lithium Metal Batteries: Experimentally Validated Model of the Apparent Capacity Loss. J. Electrochem. Soc.
166, A3456–A3463 (2019).

Liu, G. & Lu, W. A Model of Concurrent Lithium Dendrite Growth, SEI Growth, SEI Penetration and Regrowth. J. Electrochem. Soc.
164, A1826–A1833 (2017).

Gao, N. et al. Fast Diagnosis of Failure Mechanisms and Lifetime Prediction of Li Metal Batteries. Small Methods
5, 1–11 (2021).
Sr and Fe-Substituted LaMnO3 Perovskite for High-Rate Asymmetric Hybrid Supercapacitors
Authors: Shim Jae-Jin , Parasseeri Muhammed Shafi , Shagar Md Mahmudul Hasan , Brousse Thierry , Tuma Dirk
Published: August 2024

Perovskite has been getting significant attention in solar cells, photocatalysts, and hybrid supercapacitors. The symmetry or structural stability of ABO3-type perovskite oxides depends mainly on the size of ‘A’ and ‘B’ cations, which determines the material properties. The partial substitution of these cations may be used to tune these properties. The ionic sizes and valence states of the cations play an important role in improving the properties of perovskite. In this study, the substitution of La3+ with Sr2+ with a larger ionic radius and Mn3+ with Fe3+ with a similar ionic radius favored both the crystal symmetry and the mixed ionic-electronic conductivity of the perovskite. Electrodes based on La0.7Sr0.3Mn0.5Fe0.5O3 (LSMFO55) exhibited a faradaic behavior with a specific capacity of 330 C g-1 (92 mAh g-1) at a 12C rate, while this electrode maintained a capacity of 259 C g-1 at 240C (charge or discharge in 15s). Additionally, exohedral carbon nano-onions (CNO) were introduced as a negative electrode to design an asymmetric hybrid supercapacitor (AHS) with a widened cell voltage. The use of CNO as a negative electrode in the AHS improved the rate capability drastically compared to rGO. This device maintained a good energy density even at an extra-high charging rate (600C), owing to its outstanding rate capability. The high-rate performance of the LSMFO55//CNO AHS can be elucidated by successful fabrication with a mixed ionic-electronic conductive positive electrode and a CNO negative electrode. Tuning the electronic and ionic conductivities by cationic substitution and introducing CNO negative electrodes can provide a practical high-rate hybrid device using various perovskites.
(Dielectric Science and Technology Division Poster Award, 3rd Place) Radical Oxidation for Enhancing Polishing-Rate and Improving Slurry Stability in Ag-Film Chemical–Mechanical-Planarization
Authors: Park Jea-Gun , Han Manhyup , Kim Myung-Hoe , Park Jin-Hyung
Published: August 2024

Recently, Ag-film has been utilized as a reflective layer in organic-light-emitting- diode on silicion(OLEDoS). The formation of a reflective Ag-film layer was conducted by Ag-film deposition and following Ag-film chemical-mechanical planarization (CMP). The Ag-film has ductility property (i.e., hardness of 0.3 GPa) so that a reletively soft CMP pad should be used to minimize the generation of the CMP induced scratches. However, using a soft CMP pad, it is notably difficult to achieve a high Ag-film polishing-rate (i.e., 300 nm/min). Thus, to enhance Ag-film polishing-rate, a Fenton reaction between ferric ions and H2O2 has been applied. Although, a Fenton reaction enhancing dissolved oxygen concentration can increase remarkably the Ag-film polishing-rate, the CMP slurry using Fenton reaction has produced a detrimental slurry stability after mixing with H2O2 (i.e., extremely low H2O2 pot life time. In this study, as a solution, the Ag-film CMP slurry was designed via radical oxidation on the Ag-film surface during CMP, without using Fenton reaction (i.e., mixing ferric ions with H2O2). The radical oxidation was achived by using halide oxidant (i.e., H5IO6), which radical oxidation degree principally depended on halide oxidant concentration and slurry pH, showing a notable high Ag-film polishing-rate (i.e., 400 nm/min) without the precence of corrosion. Without using Fenton reaction, the secondary diameter of colloidal abrasives in the designed Ag-film CMP slurry was not changed for several months. In our presentation, we will prove the mechanism of the radical oxidation on the polished Ag-film surface. In addition, we will present the dependencies of the chemical dominant polishing properties (i.e., OH radical, chemical oxidation degree of the Ag-film surfcae, chemical composition of chemical oxidation, slurry adsortion degree, and corrosion potential and current) as well as the mechanical dominant polishing properties (i.e., electrostatic force between abrasives and Ag-film surface) on the halid oxidant concentration.
Impact of Thermal Properties of Pad Materials on CMP Process Stability
Authors: Khanna Aniruddh Jagdish , Ramos Jonathan J , Wang You , Menk Gregory , Kim Jaeseok , Mamidana Avinash , Tham Benjamin , Fung Jason , Jewett Jason , Madhusoodhanan Sudhakar , Pathak Srikant , Jayanath Shiyan , Chen Ying , Lu Xinyi , Hong Qing , Chockalingam Ashwin , Ali Mahmood
Published: August 2024

Chemical mechanical planarization (CMP) remains a pivotal step in the fabrication of devices for upcoming technology nodes. The optimal performance of a CMP process hinges on a precise combination of pad, slurry, and pad conditioner. Utilizing engineered pads and cutting-edge slurries proves instrumental in enhancing CMP performance to align with the stringent process demands of advanced technology nodes. This study underscores the indispensable role of thermal stability in CMP pad materials for ensuring process stability. Our research demonstrates that by modifying the thermal properties of CMP pad materials, we successfully mitigated the exponential increase in platen motor torque (indicative of friction) and pad temperature. Additionally, we explore the stability challenges associated with different wafer films such as thermal oxide and TEOS, offering effective solutions to address them. Furthermore, our investigation sheds light on the substantial impact of slurry flow rate on motor torque, emphasizing how the thermal instability of the pad material significantly influences process stability. Notably, we observed a direct correlation between the glass transition temperature of the CMP pad material and the ramp rate of motor torque and pad temperature. These foundational insights are invaluable for the design of advanced CMP pads for meeting the stringent requirements of future technology nodes, providing a comprehensive understanding of the intricate interplay between thermal stability and CMP process performance.
SiC CMP Process Sensitivities
Authors: Rhoades Robert , Currier Ian
Published: August 2024

Single-crystal silicon carbide (SiC) is a wide bandgap semiconductor with physical and electrical properties that provide superior performance compared to silicon or almost any other semiconductor material in high-voltage and high-power applications. It is also extremely hard, second only to diamond, and chemically almost inert which makes the CMP process step quite challenging. In recent years, a great deal of effort has been expended on advancing this process, particularly with regard to slurry formulations that can provide reasonable removal rates and damage-free final surface finishes. In this presentation, we will review a number of these developments for SiC CMP slurries. We will present data highlighting their process responses to standard CMP parameters, interactions with pad conditioning, and describe some of the requirements for production process controls.
High Throughput Manufacturing of Highly Ordered Mesoporous Thin Film Oxides for Hybrid-Polymer Nanocomposite Dielectrics
Authors: Colburn Thomas William , Collinson David William , Dauskardt Reinhold Horst
Published: August 2024

Highly ordered mesoporous metal oxide thin films have potential to become integrated into widely impactful dielectric materials due to the tunable properties of the oxide and its polymer filling; however, current manufacturing techniques to form the mesoporous oxide greatly limit scalable fabrication. Sol-gel mesoporous metal oxides generated via traditional processes require multi-day aging and high temperature, prolonged curing processes to yield controlled porosity at the expense of manufacturability. Moreover, high cost and unstable alkoxide precursors require precision over the solution precursor pH and subsequent thin film aging humidity after deposition.

Solution combustion synthesis (SCS) is a next-generation method of generating metal oxides at reduced process temperatures (often <300 ºC) and using green precursors compared to the sol-gel approach. The metal oxide is typically produced from a metal nitrate, which provides both the metal cation and oxidant and an organic chelator fuel. The fuel acts to stabilize the cation against hydrolysis and to participate in the exothermic redox reaction that results in the metal oxide.

Here, we present porogen integrated rapid oxidation (PIRO) which utilizes the principles of SCS to fabricate large-area mesoporous thin films of AlOx in less than 1 hour and at a temperature of 230 ºC. The PIRO method uses low-cost precursors to generate micelles with a controllable open-cell porosity ranging from ~30 – 60% and with varying degrees of closed-packed cubic ordering at a nearly 95% reduction in overall processing time. We show the precursor chemistry can be deposited via ultrasonic spray or blade coating at up to 6 m/min to manufacture large area mesoporous oxides and demonstrate filling of the porous AlOx with TOPAS® polymer to generate a hybrid nanocomposite with a dielectric constant of 6.26.
Porous Dielectric Structure and Response Speed of Moisture Sensors
Authors: Ali Ronak , Swartz Aaron , Badhan Riasad Azim , Ilka Reza , Wang Yiju , He Jiangbiao , Chen Zhi , Ren Ning , Zhang Z George , Wu Gefei , England Roger
Published: August 2024

Humidity sensors are typically made of alpha-alumina films as porous dielectric materials deposited through the anodic spark deposition (ASD) technique, a unique anodic oxidation method to deposit ceramic coatings on the exterior of metals. Close attention to the precise composition of electrolyte solution is crucial when mixing chemical compounds. Moreover, the ASD process, which happens during dielectric breakdown at the anode surface in an electrochemical cell, is clearly followed by visible sparking at the anode/electrolyte interface, leading to the formation of various ceramic coatings on metal substrates. Electrical breakdown happens over an anodized barrier layer, typically amorphous aluminum oxide, which has been produced on the metal anode. The local high temperature (>2000°C) produced by electrical sparks melts the amorphous aluminum oxide and converts it to alpha-aluminum oxide, forming the stable foundation for a reliable humidity sensor.

In this study, we produced a variety number of small pores to investigate the response speed of moisture sensors. The ASD current can be adjusted to control the number of small pores. The smaller current gives a greater number of small pores. We focused on low-humidity sensors, often referred to as dew-point sensors. In fabrication of dew-point sensors, Scanning Electron Microscopy (SEM) was used to examine and determine the size of pores. Three different currents, 30 mA, 25 mA, and 10 mA, have been tried for comparative analysis of small pores existing within large pores. Two pores have been measured for current 10 mA, resulting in sizes of 47 nanometer (nm) and 71 nm, respectively. Similarly, three small pores for current 30 mA were measured with sizes of 32 nm, 42 nm, and 31 nm respectively. After the testing of low-humidity (dew-point) sensors, we found that the number of small pores does not significantly affect the response speed of the sensors.
Exploring Anion Exchange Phase Transformations in 1D Solid Systems
Authors: Kosicek Martin , Zavašnik Janez , Baranov Oleg , Cvelbar Uros
Published: August 2024

Phase transformations through ion exchange reactions represent a relatively new strategy, offering a promising route for synthesizing complex and metastable morphologies and phases in nanoscaled solid ionic materials, which are challenging or even impossible to achieve through standard bottom-up approaches. Moreover, they provide a unique opportunity to investigate the mechanisms and new, yet unexplored phenomena accompanying the chemical modifications in the solid state. These mechanisms remain largely unknown and unexplored, thereby limiting the full potential of ion exchange reactions as one of the primary synthesis or modification strategies for complex ionic nanomaterials. In this study, copper oxide (CuO) nanowires were prepared via thermal oxidation method and used as a template material to explore oxide-sulfide anion exchange transformation mechanism. Following the synthesis, CuO nanowires underwent treatment with sulfur-containing gases in both thermal and non-thermal environments under various conditions to achieve a controllable exchange of oxygen anions with sulfur. The mechanisms underlying these transformations were unraveled with the use of electron microscopy. The copper oxide–sulfide system is particularly intriguing due to the promising properties of copper oxide and sulfide in gas sensing, solar cells, energy storage systems, and photocatalysis. The full or partial transformation between the two phases can therefore represent a route to manipulate and enhance the properties desired for each application.
Unraveling Morphology and Chemistry Dynamics in Fluoroethylene Carbonate Generated Silicon Anode Solid Electrolyte Interphase across Delithiated and Lithiated States
Authors: Yao Koffi , Mou Rownak Jahan , Barua Sattajit , Abraham Daniel P.
Published: August 2024

The silicon (Si) solid electrolyte interphase (SEI) faces cyclical cracking and reconstruction due to the ~350% volume expansion. Understanding the SEI dynamic morphology and chemistry evolution from delithiated to lithiated states is thereby paramount to engineering a stable Si anode. Fluoroethylene carbonate (FEC) is a preferred additive with widely demonstrated enhancement of the Si cycling. Thus, insights into the dynamics of the FEC-SEI may provide hints toward engineering the Si interface. Herein, complementary ATR-FTIR, AFM, tip IR, and XPS probing reveal the presence of an elastomeric polycarbonate-like matrix in the FEC-generated SEI which is absent from the FEC-free SEI. Adding FEC to the baseline 1 M LiPF6 in EC:EMC (1:1) electrolyte promotes formation of a thinner and more conformal SEI, and subdues morphology and chemistry changes between consecutive half-cycles. From AFM, morphological stabilization of the FEC-SEI occurs earlier. Furthermore, conventional SEI biproducts such as Li2CO3 and LiEDC appear in reduced quantities in the FEC-SEI implying a reduced quantity of Li-consuming species. The thin polymeric FEC-SEI enables deeper (de)lithiation of silicon. In conclusion, the enhanced mechanical compliance, chemical invariance, and reduced Li inventory consumption of the FEC-SEI are logically the key features underlying the Si cycling enhancement by FEC.
Operando and Ex-Situ Studies of Columbite Electrode Materials
Authors: Friskey Matthew Harry , Keenan Luke , Amboage Monica , Payne Julia Louise
Published: August 2024

Storing and utilising electricity from renewable sources is of growing importance as we move away from our reliance on fossil fuels. Batteries and supercapacitors are becoming ever more present in our day to day lives; in order to improve the next generation of batteries and supercapacitors, we must understand on an atomic scale what happens to electrode materials upon charge and discharge. In order to do this, we must combine structural and electrochemical studies, using techniques which use both different length scales and different timescales. These experiments are known as operando experiments and are a valuable tool in analysing new materials for energy storage.

Transition metal niobates of the columbite structure (MNb2O6, M = transition or alkali earth metal) have previously been studied for their photocatalytic and magnetic properties but recently have garnered interest as negative electrode materials for batteries and supercapacitors.1 In this study, a series of columbite materials have been studied using a range of operando and ex-situ techniques. Samples were prepared using both solid-state synthesis2 and solution methods. Ex-situ X-ray diffraction and scanning electron microscopy were used to characterise the columbites prior to electrochemical testing. Operando X-ray absorption spectroscopy and operando Raman studies have been used to probe the changes in oxidation state of the transition metals and local structure upon charge/discharge.

References

Yang, X. Zhao, F. Liao, Q. Cheng, L. Mao, H. Fa and L. Chen, Sustain. Energy Fuels, 2021, 5, 3039

Garía Alvarado, A. Orera, J. Canales-Vázquez, and J. T. S. Irvine, Chem. Mater., 2006, 18, 3827-3834

Figure 1
Understanding the Origin of Voltage Hysteresis in Disordered Rocksalt Cathodes
Authors: Kim Byunghoon , Ceder Gerbrand
Published: August 2024

Lithium-rich cathodes are regarded as promising energy storage materials due to their high energy densities. However, voltage hysteresis presents challenges to maximizing their energy efficiency and practical implementation. Voltage hysteresis has generally been associated with transition metal migration and oxygen dimer formation within the structure. To understand the contribution of specific structural disorder to voltage hysteresis, one needs to consider the kinetics of the formation and recovery of each of these.

In this work, we clarified the mechanism by which oxygen dimerization and transition metal migration induce voltage hysteresis using lithium-rich disordered rocksalt cathodes as a model compound. We identify the type of structural transformations that occur at an exceptionally rapid rate, potentially saturating during room-temperature ab-initio molecular dynamics simulations lasting several hundred picoseconds. This clarification indicates that the formation of certain structural disorder is not always directly linked to hysteresis. Furthermore, we confirm a correlation between oxygen dimerization and transition metal migration, demonstrating that they mutually promote each other. Our work provides a mechanistic understanding of how structural disorder induces voltage hysteresis in lithium-rich cathodes, thereby reconciling the debate over the cause of hysteresis.
Phase-Field Modeling of Electrolyte Transport Properties and Elasticity Modulus in Suppression of Dendrite Growth in Solid-State-Lithium-Ion-Batteries
Authors: Pala Raj Ganesh , Kankani Komal , Chakraborty Pritam
Published: August 2024

Dendrite formation in batteries is a critical issue that affects battery performance and lifespan. Solid-state electrolytes have gained attention due to their advantages such as compactness, higher energy density, and enhanced safety. This study investigates dendrite growth in batteries via phase field simulations utilizing a grand potential-based phase field model. The simulations are executed using the MOOSE (Multiphysics Object-Oriented Simulation Environment) framework, a Finite Element Method (FEM) based solver known for its modular approach and proficiency in handling complex multi-physics problems.

Initially, the study considers a pure lithium anode and a 1M LiPF6 electrolyte for the liquid case. To explore the benefits of solid electrolytes, a fictitious solid electrolyte with transport properties similar to the liquid electrolyte but having different mechanical properties is considered. The mechanical impact resulting from the volume changes due to lithium deposition is not accounted for in the liquid electrolyte model. However, the solid electrolyte model addresses this by modifying the Butler-Volmer kinetics and incorporating the influence of stresses on the localized lithium deposition. Sensitivity analysis is performed for various parameters in both the liquid and solid electrolytes. The results indicate that dendrite growth is reduced with decreased applied over-potential and interfacial energies. For solid electrolytes, an additional parameter, increased Young’s modulus, contributes to reduced dendrite growth.

The evaluation of dendrite growth involves quantifying surface roughness using the root mean square (RMS) approach. The elasticity modulus significantly influences dendrite formation, with higher values in materials like LLZO, and glass Li3PS4 exhibiting lower dendrite growth, while lower values in polymer-based materials like P(VDF-HFP) and PVDF/CAB/PE exhibit higher dendrite growth. The solid electrolyte acts as a crucial mechanical barrier, influencing the dendrite tip growth rate and ensuring uniform electrodeposition throughout the dendritic structure. Furthermore, the work investigates the impact of the cathode on dendrite growth. The contraction of the cathode provides additional space for dendrites to move, leading to reduced compressive stresses and increased dendrite growth. Conversely, higher compressive stresses suppress dendrite growth.
Transient Chemo-Mechanical Model of Lithium Plating Impacted by External Pressure
Authors: Meyer Julia , Mukherjee Partha P. , Roberts Scott A.
Published: August 2024

To meet the ever-growing need for high capacity, fast-charge batteries, lithium anodes have been considered a direct upgrade to previous commercial anode materials thanks to their high gravimetric density and low coulombic efficiency. However, their implementation into crucial applications such as electric vehicles has been hindered by safety issues during and at the end of their operational lifetime. Over hundreds of cycles, nonhomogeneous plating and stripping of lithium on the anode surface encourages the growth of dendrites, which eventually lead to capacity loss, cell failure, and fire. The application of stack pressure has been found to mitigate dendrite growth to an extent; however, the impacts of long-term pressure application on lithium deposition, and subsequent lithium plastic deformation and creep, are not well understood. In this work, we present a novel method for accurately modeling the interplay between mechanical deformation and electrochemical deposition. We develop a 3D, finite-element, transient model of lithium plating and stripping at the mesoscale. A stack pressure is applied to a lithium anode in contact with a polymer separator, and the electrochemical response to an applied current density is evaluated. The lithium protrusion is then reshaped to model incremental plating or stripping, thus simulating the cumulative interfacial movement over a full charge-discharge cycle. Mechanical complexities of the materials, such as lithium plastic deformation and separator porosity, are accounted for. The interfacial response is studied with respect to applied stack pressure and assumed lithium yield strength. Through this work, the impacts of stack pressure on dendrite growth at the microscale are explored. The lithium yield strength assumption is found to be crucial for accurately predicting deposition behavior.

Supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA-0003525.
Evaluation of Electrochemical Techniques for Characterizing the Kinetics of Porous Insertion-Type Electrodes
Authors: Moon Seongbak , Chagnot Matthew , Kamboj Ishita , Augustyn Veronica
Published: August 2024

The composite-type porous electrode remains the most commonly used electrode for a wide variety of electrochemical energy storage devices, including lithium-ion batteries, electrochemical capacitors, Li-S/Li-air batteries, and even all-solid-state batteries. This is due to its ease of manufacturability and ability to maintain a high electrochemical surface area with adequate ion and electron transport. Understanding porous electrode kinetics is essential to maximize the active material utilization at high rates. A variety of electrochemical techniques exist to characterize the kinetic behavior of porous electrodes. The most popular ones include electrochemical impedance spectroscopy, galvanostatic charge/discharge, galvanostatic intermittent titration technique, and cyclic voltammetry. The purpose of this work was to evaluate which of these four techniques provides the most relevant kinetic information for understanding porous electrode kinetics. To do this, we utilized porous electrodes composed of LiCoO2 as a model insertion-type material, and with varying thicknesses (10 - 40 µm). We find that GITT is an accessible and reliable method for obtaining the effective diffusion coefficient of the porous electrode. It yields consistent results, regardless of electrode thickness and component ratio. On the other hand, the cyclic voltammetry peak current behavior can be easily compromised, even at slow scan rates of 0.01 - 0.1 mV/s, and when using a high conducting domain ratio. When comparing the dQ/dV plot and cyclic voltammetry for observing peaks indicating phase transitions in the insertion material, the dQ/dV plot is less kinetically limited. We utilized the differential relaxation time (DRT) method to analyze electrochemical impedance spectroscopy data. Our findings demonstrate that as thickness increases, charge transfer resistance decreases, while diffusion resistance increases. This study provides a comprehensive evaluation on the differences between electrochemical methods to characterize the kinetics of composite porous electrodes.
(Invited) Tuning the Optoelectronic Properties of Inorganic and Carbon-Based Quantum Dots for Highly Efficient Luminescent Solar Concentrators
Authors: Ibrahim Kassa Belay , Hassan Mahnoor , Shifa Tofik Ahmed , Vomiero Alberto
Published: August 2024

Luminescent solar concentrators (LSCs) are an old class of devices based on semitransparent windows, in which luminophores are embedded in a transparent matrix.[1] The luminophores can absorb and re-emit solar light and are able to generate electric power by collecting the re-emitted light at the borders of the slab. In the past, lab-to-fab transition of such devices was impeded by intrinsic limitations of the luminophores in terms of low quantum yield, strong resorption due to small Stokes shift, low optical and photoconversion efficiency of the final device. In the last years, a renaissance of such devices has been driven by the development of new 0-dimensional nanostructures, with tunable optical properties, which can guarantee good performance of LSCs.[2,3] Specifically, high quantum yield can be obtained; resorption losses can be limited by modulating the Stokes shift; final color of the window can be tuned by tuning light absorption properties; UV and IR parts of solar spectrum can be exploited without affecting window transparency. We will give examples of different 0-dimensional systems, which have been developed toward high efficiency LSCs, among which inorganic quantum dots and carbon dots.[4,5] Several strategies will be illustrated to tune the optoelectronic properties of the luminophores, including doping, core-shell structuring, and surface treatments.

References

[1] R. Mazzaro, A. Vomiero. Advanced Energy Materials, 2018, 8 (33), 1801903.

[2] Y. Zhou et al. Advanced Energy Materials, 2016, 6 (11), 1501913.

[3] H. Zhao et al. Energy & Environmental Science, 2021, 14 (1), 396-406.

[4] X. Gong et al. Materials Chemistry Frontiers, 2021, 5 (12), 4746-4755.

[5] G. Liu et al. Journal of Materials Chemistry A, 2023, 11 (16), 8950-8960.