bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Electrode Blending Simulations Using the Mechanistic Degradation Modes Modeling Approach
Authors: Beck David , Dubarry Matthieu 
Published: December 2024

Blended electrodes are becoming increasingly more popular in lithium-ion batteries, yet most modeling approaches are still lacking the ability to separate the blend components. This is problematic because the different components are not likely to degrade at the same pace. In this work, we investigated a new approach towards the simulation of blended electrodes by replicating the complex current distributions within the electrodes using a paralleling model rather than the traditional constant current method.
We first investigated the impact of using a paralleling model within the mechanistic degradation modes modeling approach to replicate the current distribution more accurately within blended electrodes. Using three exemplary chemistries with electrochemical response that covers all the possible scenarios (separated, overlapping, or only partially overlapping), we demonstrated that, although the paralleling approach enhances accuracy and better replicates experimentally observed current distributions, the actual effect on the voltage response of the full cell, whether pristine or aged, was close to negligible at low rates while the computational cost was increased by two orders of magnitude and resulted in noisier results. While it might be better to use the paralleling model for simulation at higher rates or when the loss of active material on the PE is significant, the computational limitations could hinder the application of the paralleling approach in scenarios where simulation speed is crucial because of the two order of magnitude increase.
Recognizing that the constant current approach is accurate enough to provide data representative of the behavior of the individual components within a blend, we generated three publicly available synthetic datasets covering more than 260,000 different degradations to enable the development of new diagnosis techniques for blended electrodes. Such techniques must enable component specific diagnosis since we showcased a significant impact of the composition of the loss of active material on the positive electrode on the cell electrochemical response. Because these variations could be confused with the one induced by other degradation modes, overlooking them could lead to false diagnosis, potentially compromising the safety of deployed systems.
(Invited) Dynamic Impedance Spectroscopy on Batteries: From Materials to Cells
Authors: La Mantia Fabio 
Published: December 2024

Electrochemical impedance spectroscopy (EIS) is a powerful technique for analyzing and understanding electrochemical systems, which is crucial in order to improve the performance and reliability of batteries. However, it is often necessary to investigate the materials and cells under the operating conditions, i.e. outside the stationary condition. In order to do so, dynamic multifrequency analysis (DMFA) can be used to acquire dynamic impedance spectra in a large range of frequencies and with high time-resolved precision [1,2]. Starting from the physical definition of impedance and admittance, and using the concept of Volterra series, it has been shown how the concept of dynamic impedance can be interpreted as a non-stationary extension of the concept of classic impedance [3]. Here, it will be shown how the DMFA can be applied to the study of the reactions occuring at the active materials for batteries and supercapacitors, as well as its application for the investigation of full battery cells of different kind.
On one side, when investigating the reaction mechanism occuring on active materials, it is possible to fit the impedance data with physical models describing the processes occurring at the interface. The effect of the non-stationarity is manifested in the dynamic spectra only in the low frequency range and introduces a deviation from the classic behavior, which appears as an additional parallel resistance.
On the other side, when investigating full battery cells it is important to develop tools in order to analyze the impedance spectra statistically, as physical models are often too complex (overparametrized). In this case, the development of measurement models, such as the Pade’ approximants, as well as the use of statistical concepts such as the “maximum description length” or "akaike information criterion" [4], are necessary in order to obtain meaningful information. As perspective, it will be shown how the Pade’ approximants can be further used to obtain information on the complexity of the system by analyzing the extracted parameters through the concept of mutual information.
Literature:

A. Battistel, G. Du and F. La Mantia, Electroanal. 28 (2016) 2346

D. Koster, G. Du, A. Battistel, and F. La Mantia, Electrochim. Acta 246 (2017) 553

A. Battistel, and F. La Mantia, Electrochim. Acta (2019) 513

R. Chukwu, J. Mugisa, D. Brogioli, and F. La Mantia, ChemElectroChem 9 (2022) e202200109

Figure 1
Physicochemical Impedance Modelling of Porous Electrodes in All-Solid-State Electrochemical Devices
Authors: Kullmann Felix , Hauck Benjamin , Lindner Adrian , Dierickx Sebastian , Weber Andre 
Published: December 2024

Fundamental knowledge about performance limiting processes in electrochemical devices like battery-, fuel- and electrolyzer-cells is mandatory for a model-aided development. The method of choice to analyze these processes is electrochemical impedance spectroscopy, enabling a separation of electrochemical processes differing in their relaxation frequencies. In order to improve the deconvolution of these processes in the impedance spectrum, the distribution of relaxation times (DRT) analysis is a well-established method [1].
In case of porous, multiphase electrodes, the DRT usually doesn’t enable a simple correlation of a peak in the DRT with a single polarization process in an electrode. The complex coupling of electronic and ionic charge transport via charge transfer reactions, often described by a transmission line model (TLM) [2-4], induces a number of peaks in the DRT. TLM parametrization just by operating and/or electrode parameter variations is often insufficient. Since different parameter sets can result in identical spectra [3], a straightforward CNLS-fit is insufficient and a pre-parameterization by determining at least a few model parameters independently is required.
In this study, impedance spectra of two all-solid-state electrochemical devices, an all-solid-state battery and a solid oxide cell, are analyzed by the distribution of relaxation times. Physicochemically motivated impedance models based on the TLM-approach were derived, pre-parameterized and applied to quantify different loss processes in the cells. The pre-parameterization included microstructural parameters obtained by focus ion beam tomography and conductivity data. The model development and areas of application will be discussed in detail within this contribution, focusing on the differences between the two investigated all-solid-state electrochemical devices.

References:

[1] H. Schichlein, A.C. Müller, M. Voigts, A. Krügel and E. Ivers-Tiffée, J. Appl. Electrochem., 32, 875 (2002).
[2] S. Hori, R. Kanno, X. Sun, S. Song, M. Hirayama, B. Hauck, M. Dippon, S. Dierickx and E. Ivers-Tiffée, J. Power Sources, 556, 232450 (2023).
[3] F. Kullmann, M. Mueller, A. Lindner, S. Dierickx, E. Mueller and A. Weber, J. Power Sources, 587, 233706 (2023).
[4] P. Braun, C. Uhlmann, M. Weiss, A. Weber and E. Ivers-Tiffée, J. Power Sources, 393, 119 (2018).
Polarization Electric Field of Tourmaline Promotes Formic Acid Oxidation on Palladium
Authors: Zhang Xinsheng , Hu Shuozhen , Luo Guoming 
Published: December 2024

Direct formic acid fuel cells (DFAFC) use formic acid that is easy to store and transport as fuel, which has the advantages of high energy density and low operating temperature, and has shown broad application prospects in mobile power and other fields. Palladium is recognized as the most effective electrocatalyst for formic acid oxidation (FAO). Unfortunately, palladium nanoparticles are easily dissolved in the acidic environment during fuel cell operation. In addition, the d-band center of Pd is close to the Fermi level, resulting in forming a strong bond between Pd and adsorbed species (e.g., COad-like species). As a direct consequence of the above issues, Pd nanoparticles are continuously lost and poisoned, causing unsatisfactory cycling performance. However, all these previous approaches can only alleviate the issues of Pd poisoning and Pd dissolution, respectively.
In this work, by utilizing the polarization electric field of tourmaline minerals to change the adsorption state and energy of formic acid molecules, the electrocatalytic performance of palladium in FAO reactions can be improved. Tourmaline nanoparticles (TNP) are coated with resorcinol-formaldehyde (RF) resin to obtain TNP@RF support (Fig.1a), and Pd nanoparticles are uniformly and partially embedded in the RF carbon layer to generate TNP@RFC@Pd catalysts by in situ carbothermal reduction (Fig.1b). The polarized-electric field from tourmaline (Fig.1c) induces charge transfer from Pd to tourmaline, causing the d-band center to shift away from the Fermi level (Fig.1d). Both the strain effect and ligand effect cause the electron-deficient state of Pd. Consequently, breaking the O-H bond in formic acid is enhanced and the bond strength between Pd and COad is weakened. The polarized-electric field of tourmaline promotes the generation of OHad on Pd to convert COad into CO2 and release the active sites of Pd. The embedded structure of Pd nanoparticles in the carbon layer prevents the dissolution and agglomeration. Benefiting from these results, TNP6.67@RFC@Pd1 catalyst exhibits 3.9 times higher mass activity, greater CO-tolerance and better durability than those of electric-field-free catalysts (Fig.1e).

Figure 1
Biohybrid CO2 Electrolysis for the Direct Synthesis of Biomass from CO2
Authors: Lee Jae Won , Lee Hyunjoo 
Published: December 2024

Converting anthropogenic CO2 into value-added products using renewable energy has garnered significant attention in pursuit of a sustainable carbon cycle. While CO2 electrolysis has been extensively explored, the resulting products have typically been limited to simple C1-3 compounds like CO, formate, ethylene, and small alcohols. Despite their simplicity, these products can serve as feedstocks for fermenters to produce more complex chemicals. Combining electrochemical CO2 reduction with microbial fermentation has been an active area of research, albeit often hindered by low production rates.
In our study, we integrated CO2 electrolysis with microbial fermentation to directly produce biomass from gaseous CO2. Firstly, we established a biohybrid system where the electrolyte solution containing formate was continuously circulated through both the CO2 electrolyzer and fermenter. This approach facilitated efficient accumulation of poly-3-hydroxybutyrate in Cupriavidus necator cells, achieving a PHB content of 83% of dry cell weight and producing 1.38 g PHB. The biohybrid system involved the electrochemical conversion of CO2 to formate on Sn catalysts deposited on a gas diffusion electrode, with careful optimization of the electrolyzer and electrolyte solution. Subsequently, we modified the system to enable continuous PHB production at a steady state by introducing fresh cells and removing PHB.
Secondly, we developed electrochemical biohybrid system with metabolically engineered Escherichia coli (E. coli) capable of producing lactic acid solely from CO2 and formic acid. By constructing a biohybrid system comprising a CO2 electrolyzer that generates formic acid from CO2 and a fermenter housing the engineered E. coli, we achieved direct electrochemical production of lactic acid from gaseous CO2. The catholyte was optimized to support the engineered E. coli within the biohybrid system, and the formic acid production rate was controlled to ensure stable lactic acid production. These strategies employed in developing our biohybrid system hold promise for establishing other electrochemical biohybrid systems capable of producing chemicals and materials directly from gaseous CO2.
Development of a Photoelectrochemical Process for the Elimination of Trace Substances in Wastewater Treatment with an Integrated 200% Electrolysis Cell
Authors: Schanz Tobias , Bloh Jonathan Z. 
Published: December 2024

Access to clean water is one of the UN’s strategic development goals. Though often seen to target mostly the developing counties or rural regions with low infrastructure, this is an important topic even in modern industrialized countries. Here, drinking water is certainly clean by most standards, yet it is often still contaminated with micropollutants with known adverse effects even at minute concentrations which are difficult to mitigate with conventional technology. Promising technologies to tackle this challenge include electrochemical or photoelectrochemical wastewater treatment, which can effectively completely mineralize organic pollutants using in-situ generated reactive oxygen species (ROS) like hydroxyl radicals.
Photoelectrochemical wastewater treatment is an emerging technology for the removal of organic and inorganic pollutants from wastewater using sunlight as an additional or sole energy source and thereby saving on electricity costs. Since the water quality should not be subject to the intermittency of solar energy, we employ an additional conventional “dark” electrode which will operate with supplied external current in the absence of sufficient light energy. In particular, we use a BDD (boron-doped diamond) as anode in combination with a bismuth vanadate (BiVO4) based photoanode. In case of light illumination, this photoanode generates a photovoltage and current on its own without an external power supply. In both cases, ROS like hydroxyl radicals and hydrogen peroxide are formed from water oxidation. These two anodes are used in conjunction with a carbon-based gas diffusion electrode (GDE) as cathode. Here, atmospheric oxygen is reduced to form hydrogen peroxide also serving as oxidant.
In addition to the described reactions, the electrolyte ions may also play an important role. These may form other peroxo-species at the electrodes themselves or indirectly via hydrogen peroxide and hydroxyl radicals. Recently, we could show that bicarbonate in particular plays a very important role, forming the highly potent peroxomonocarbonate which was shown about 200 times as active as hydrogen peroxide itself.[1]

Overall, we show that the photoelectrochemical process can efficiently remove a wide range of recalcitrant pollutants from wastewater, including organic dyes, pesticides and pharmaceuticals. It has the advantage of being a sustainable and energy-efficient technology, as it uses sunlight as the primary energy source, meaning that a smaller amount of electricity needs to be fed in. We will further discuss the influence of the reaction parameters (light intensity, voltage, current density, pollutant concentration, flow rate) as well as the role the supporting electrolyte plays.
[1] Schanz, T.; Burek, B. O.; Bloh, J. Z. ACS Energy Lett.
2023, 8, 1463–1467.

Figure 1
Bipolar Membrane Polarization Governed By Interfacial Ionic Species
Authors: George Thomas Young , Brimley Paige N , Smith Wilson A , Aziz Michael J. 
Published: December 2024

Bipolar membranes (BPMs), consisting of an anion exchange polymer membrane layer, a cation exchange polymer membrane layer, with a catalytic interfacial layer in between, enable electrolysis cells with large difference of pH between adjacent chambers. This pH gradient is a working principle of a number of devices for energy and sustainability: acid/base batteries store and release energy by building and depleting a pH difference; BPM electrodialysis reactors capture CO2 in alkaline electrolytes and release CO2 by acidifying; CO2 and H2O electrolysis devices may employ pH-decoupled electrodes to avoid precious metal electrocatalysts while maintaining low electrode overpotentials. For all of these devices the most efficient operation - in terms of extracting maximum voltage from a battery or driving electrolysis with minimum overpotentials - is achieved when the BPM selectively transports H+ and OH- ions in the cation and anion exchange layers respectively. But in practical devices, salt impurities may be present in the electrolytes, or supporting salt may be intentionally added to improve electrolyte conductivity. In this work, we explore how ion exchange processes in bipolar membranes in impure electrolytes affect the ion composition at the bipolar junction - the interfacial layer where the two membrane layers meet. We propose that the ion composition at this interface determines the voltage measured across the membrane at open-circuit, as well as the polarization behavior of the membrane under applied current.
We investigate the proposed mechanism using a model system comprising electrolytes with KOH, HCl, and KCl at various relative concentrations with a commercially available BPM (Fumasep FBM). We combine analysis of polarization experiments in a four-electrode setup with a 1D continuum model of water dissociation and multi-ion transport. We report that increased relative salt concentration in the electrolytes erodes the open-circuit voltage across the membrane, yielding voltages significantly lower than expected based on the measured pH difference, indicating that H+ and OH- ions within the BPM exchange with ions from the added salt to occupy membrane fixed charges at the bipolar junction. This phenomenon penalizes the energy efficiency of BPM acid/base batteries. Additionally, we find that during polarization, impure electrolytes exhibit salt crossover at low current density and that the magnitude of this crossover depends on the relative concentration of the salt versus H+ and OH- ions. We utilize the 1D continuum model to visualize concentration profiles of ions in the BPM at both open-circuit and applied current conditions.
This work illustrates the importance of electrolyte species on interfacial BPM phenomena and provides guidance both for designing new BPM materials and for choosing electrolytes and operating conditions in electrochemical cells.

Figure 1
Life Cycle Assessment of Liquid Alkaline Electrolyzers Comparing Environmental Performance across Various Design, Operation, and End-of-Life Scenarios
Authors: Zaki Mohammed Tamim , Breunig Hanna 
Published: December 2024

Alkaline water electrolysis (ALK) is a demonstrated technology, used for over 100 years primarily for ammonia production, and later advanced for oxygen production for nuclear submarine applications. With a new focus on the expansion of renewably-powered hydrogen production, ALK systems hold great promise for commercialization. Recent research may further drive-down costs by addressing challenges related to electrodes, electrolytes, bubble formation, and impact of operation patterns. However, literature studies on ALK often lack a comprehensive model that can capture the impact of such deployment nuances on overall greenhouse gas emissions and environmental impacts. For example, an analysis of the effect of hourly or sub-hourly operation of ALK based on electricity generation profiles on required heat management, shutdowns, hydrogen leakage, safety, and cell degradation are lacking. Additionally, details on the manufacturing of critical components of the ALK cell stack are missing, although material contributions by weight are available. Materials at their end-of-life may have unique requirements for recycling or disposal, and these factors are also not well understood.
Herein, we present an overview of life cycle assessments (LCA) of ALK, as well as novel modeling of environmental impacts associated with ALK supply chains in the United States. Details and impacts of component manufacturing is included, along with the uncertainties of the raw materials production. We will then present our dynamic ALK model that includes cell voltage degradation, effects of the input power load on the electrolyzer temperature, purity, and associated hydrogen leakage at the electrolyzer facility itself. Finally, we present findings on plausible recycling and landfilling of the raw materials. We use the NREL United States Life Cycle Inventory database supplemented by Ecoinvent in the OpenLCA platform to evaluate embodied emissions. We compare the environmental performance for different scenarios of stack design (baseline versus advanced based on reduced diaphragm thickness and improved catalyst material), operation (low versus high pressure and scales such as 50 versus 500 ton/day), end-of-life cases (landfilling versus combination of landfilling and recycling). Finally, we make a comparison of these different scenarios to identify environmental impact hotspots along the life cycle of a liquid alkaline electrolyzer and guide future research on cell stack development.
Influence of Electrodes Surface Area Ratio on Titanium Electrorefining Process
Authors: Woo Hwa-young , Ri Vladislav , Kim Ki-hong , Lee Byoung-gun , Kim Ga-min , Ryu Hong-youl 
Published: December 2024

Most titanium is commercially produced by the Kroll process, which was developed in the 1960s. Recently, it has been criticized for its high energy consumption, toxicity, significant greenhouse gas emissions, and the generation of iron-contaminated titanium scrap. Consequently, numerous attempts to develop alternative methods for titanium production have been widely studied in the past few years, electrorefining is one of these methods.
The titanium electrorefining process is based on the transfer of titanium from an impure electrode (CuTi anode) to another electrode (cathode) in an electrolyte environment. The configuration of the electrodes is highly important for the electrorefining process, as it can limit conditions for efficient electrorefining and reduce the quality of the produced titanium deposits.
Titanium electrorefining tests were conducted in molten LiCl-KCl-NaCl with 7.5 mol.% of TiCl2, in an argon atmosphere at 600 °C. A CuTi ingot was used as the anode, and a steel electrode served as the cathode. The influence of the electrodes' surface area was studied to improve the efficiency of the electrorefining process and the quality of titanium deposits. The surface area ratio of the anode to cathode was varied from 2.28 to 7.84, and the current density applied to the cathode ranged from 12.5 to 104 mA/cm².
Electrode potentials, cell voltage, and maximum current density were measured using a data logger and DC power supply for experimental setups with various surface area ratios of the electrodes. The experimental results indicated that current efficiencies ranged from 69 to 82.5% based on weighing the leached titanium deposits. Typically, lower current densities resulted in higher current efficiencies and improved quality of titanium deposits. Higher cell voltages and potentials were observed in setups with lower surface area ratio.
Morphology and chemical analysis of titanium deposits were obtained through SEM/EDS analysis and N/O analysis. It was found that higher current densities resulted in finer titanium deposits and increased oxygen content in the deposits. The optimal surface area ratio was estimated to be 2.84 at a current density of 62.5 mA/cm² for producing large dendritic titanium with oxygen as low as 963 ppm, and as 5.21 at current density of 104 mA/cm2 for production of fine titanium powders with oxygen of 3163 ppm.