bluuebunny/crossref_metadata_2025_split huggingface dataset:
Redox Behavior of Quinones Bearing Ionic Liquid Moiety for Electrochemical CO2 Capture
Authors: Fujisawa Takuma , Tsuzuki Seiji , Watanabe Masayoshi , Ueno Kazuhide 
Published: December 2024

CCUS (Carbon dioxide Capture, Utilization and Storage), is attracting attention as an effective method for reducing carbon dioxide (CO2) emissions toward carbon neutrality by 2050. Currently, chemical absorption followed by thermal desorption using liquid amine is employed as the CO2 capture and concentration technology. However, low energy efficiency and high cost of the thermal swing process remain to be addressed. CO2 capture driven by renewable electricity represents a promising alternative approach to mitigate CO2 emissions and address climate change. Electrochemically mediated carbon capture can be achieved by developing redox-active CO2 adsorbents, such as quinones. In aprotic electrolytes, reduced quinone species can selectively uptake CO2 from a dilute feed upon electro-reduction via a nucleophilic addition reaction and release a concentrated CO2 upon electrochemical oxidation. However, the low solubility of quinones in nonaqueous solvents limits their total CO2 carrying capacity in the system. We synthesized a salt of imidazolium modified anthraquinone with ionic liquid-like structure to address the solubility issue. The synthesized cationic quinone derivatives showed more than 100 times higher solubility and high ionic conductivity as well as electrochemically reversible CO2 adsorption-desorption. In addition, we synthesized anionic quinone derivatives, anthraquinone with sulfonate (SO3
−) moiety, by one-step salt metathesis reaction, and confirmed that the negatively charged quinones is also applicable to the electrochemical CO2 capture. We report the electrochemical CO2 capture-release behaviors of the ionic quinones and its monitoring using in situ spectroscopic analysis with the aid of density functional theory calculations.
Reference:
Iida, S. Kondou, S. Tsuzuki, M. Tashiro, N. Shida, K. Motokura, K. Dokko, M. Watanabe, K. Ueno, J. Phys. Chem. C, 2023, 127, 10077.
Electrochemical Studies on CO2 Reduction at Liquid Gainsn Alloy Electrodes
Authors: Bogdanoff Peter , Mohamed Aya , Lörch Daniel , Euchner Holger , May Matthias , van de Krol Roel 
Published: December 2024

The electrochemical reduction of CO2 (CO2RR) offers a sustainable technology for converting CO2 into valuable products when using electricity generated from renewable sources. Application-oriented research is currently focused mainly on the electrolysis of CO2 to hydrogen-rich fuels or chemical feedstock materials. In contrast our project aims to form solid carbon or carbon rich products (e.g. oxalate), which can finally be disposed in geological repositories. This negative emission technology is developed for a long-term and thereby sustainable CO2 removal from the global CO2 cycle 1. The continuous electrochemical formation of solid carbon from CO2 has so far only been reported on liquid GaInSn-M alloys (M: Ce, V) in water-containing DMF 2,3. Liquid electrodes have the advantage over solid electrodes that solid products do not adhere at the interface and therefore deactivate the catalytic properties of the electrode (coking effect). In first experiments, we studied GaInSn without additional metal alloying in DMF/H2O/ TBAPF6 electrolyte and got differing results to the previously published data. In our experiments, even pure GaInSn shows a significant activity for CO2RR to carbon monoxide and formic acid accompanied by lower quantities of H2. The product distribution (faradaic efficiencies) depends strongly on the water content in the DMF electrolyte. The production rate of CO increases significantly even with small amounts of water. First DFT simulations of the CO2RR provide possible explanations of this effect. Furthermore, it was observed that, depending on the applied cathodic potential, metallic nano particles are released from the GaInSn surface into the organic electrolyte (expulsion effect) which indicates a possible change in the surface composition during CO2 electrolysis 4. In accordance with the literature, our findings confirm the production of carbon flakes from CO2 on cerium modified GaInSn. However, we observe it even independently from the addition of water to the DMF electrolyte. DFT calculations enable us to conclude that the high affinity of cerium to oxygen is responsible for the change in product selectivity, as it can extract oxygen from CO2.
1: May, M. M. and Rehfeld, Earth Syst. Dynam., 10, 1–7.
doi.org/10.5194/esd-10-1-2019, 2019.
2: Dorna Esrafilzadeh, NATURE COMMUNICATIONS | (2019) 10:865.
doi.org/10.1038/s41467-019-08824-8
3: Mehmood Irfan, J. Mat. Chem. A, Issue 27, 2023
doi.org/10.1039/D3TA01379K
4: Mahroo Baharfar, Chemistry of Materials
2022
34 (23), 10761-10771
doi.org/10.1038/s41467-019-08824-8

Figure 1
Large-Scale DFT Calculations on Size and Site Dependences of Atomic and Electronic Structures in Metallic Nanoparticle Catalysts
Authors: Nakata Ayako , Li Shengzhou , Miyazaki Tsuyoshi 
Published: December 2024

Size control of Pt nanoparticle catalysts is one of the key challenges in fuel cell development. Miniaturization of Pt nanoparticles is expected to increase activity and save the amount of Pt, while very small particles (e.g. sub-nano particles or clusters) have different electronic structures and stabilities from “nano” particles. To investigate the atomic and electronic structures of materials, first-principles density functional theory (DFT) calculation is a powerful tool. However, because of its high computational cost, the DFT applications have been limited mainly for small particles and clusters of tens to hundreds of atoms. In this study, by using our own large-scale DFT calculation method, we investigate the size and site dependences of atomic and electronic structures in Pt nanoparticles with the diameters of several nanometers, which are comparable to the sizes of the particles in practical use.
The computational cost of the conventional DFT calculation methods scale cubically to the system size, i.e., the number of the atoms in the target system and the number of local functions for each atom, which are used to express electronic density. We have developed the multi-site support function (MSSF) method [1,2], in which local functions are constructed as the linear combinations of the atomic orbital functions belonging to not only the target atom but also its neighboring atoms. The MSSF method enables us to reduce the number of local functions to be the minimal-basis size, leading the dramatical computational cost reduction. The MSSF method is implemented in our large-scale DFT code CONQUEST [3,4].
We optimized the structures of Pt nanoparticles with the diameters of 0.5 nm (13 atoms) - 5.5 nm (3871 atoms) and found that the Pt-Pt bond lengths inside the nanoparticle converge to those in bulk Pt when the nanoparticle size becomes large. The similar trend is found also in the electronic structures as shown in the figure. In the presentation, we compare the size dependence of the stability and atomic and electronic structures of Pt nanoparticle with other metallic nanoparticles. Site dependence of the electronic structures and reactivity with molecules are also investigated by using large-scale DFT together with statistical analysis.
[1] A. Nakata, D. R. Bowler, T. Miyazaki, J. Phys. Soc. Jpn., 91, 091011 (2022). [2] A. Nakata, D. R. Bowler, T. Miyazaki, Phys. Chem. Chem. Phys. 17, 31427 (2015). [3] http://www.order-n.org/ [4] A. Nakata, J. S. Baker, S. Y. Mujahed, J. T. L. Poulton, S. Arapan, J. Lin, Z. Raza, S. Yadav, L. Truflandier, T. Miyazaki, D. R. Bowler, J. Chem. Phys., 152, 164112 (2020).

Figure 1
Electrode-Level Modeling of Silicon Anodes for Improved Design
Authors: Shumway Edmund McKay , Hamedi Amir Sina , Wheeler Dean 
Published: December 2024

Silicon is an ideal active material for lithium-ion battery anodes, due to its low potential and high theoretical capacity. However, extreme volume changes during lithiation and delithiation make reversibility and long cycle life difficult challenges. To properly understand these volume changes, a detailed electrochemical model is needed. Much previous modeling work has focused on particle-level effects such as intra-particle diffusion and cracking. Beyond this, some efforts have successfully utilized pseudo-2-dimensional (P2D) models to evaluate electrode-level phenomena — such as stress distribution and changes in electrode thickness and electrochemical potential. Nevertheless, some essential physics is still missing.
Here, we present a new P2D model with improvements that provide a deeper level of understanding of porous silicon anode property changes during lithiation, to enable improved electrode design. Important among these improvements are the use of local state of lithiation as opposed to electrode average state of lithiation to better capture porosity and ionic conductivity changes; an effective electrolyte reservoir that properly addresses electrolyte volume-change requirements; advection of electrolyte and solid-state Li; and an extensive electrode-level plastic deformation model that has a dramatic effect on the model’s predictions.
We use this model to test the efficacy of various electrode and cell design decisions. The model can make recommendations on casing design such as rigidity and thickness and the effect of other cell sandwich components e.g. different layers thickness on the electrochemical performance of the cell. Furthermore, using the revised swelling behavior predictions given by the mechanical model, we can provide recommendations for initial electrode porosity and binder volume fraction. Finally, the model as a whole allows us to provide recommendations that will accommodate particle expansion with the least detriment to ionic conductivity at various C-rates.

Figure 1
State of Charge When Cycling LiFeO4/Graphite Cells Affects Lifetime
Authors: Zsoldos Eniko , Thompson Daphne , Black William , Azam Saad , Dahn Jeff R. 
Published: December 2024

Lithium iron phosphate (LFP) battery cells are used ubiquitously in electric vehicles and stationary energy storage because they are cheap and have a relatively long lifetime, but they have low energy and power density1. This work compares the LFP / Graphite pouch cells undergoing charge-discharge cycles over three state of charge (SOC) windows: 0 – 25%, 0 – 100%, and 75 – 100%. Cycling LFP cells across a lower average SOC provides longer cell lifetime than a higher average SOC, regardless of depth of discharge. There are two capacity fade degradation mechanisms that are prominent at high SOC: iron dissolution and deposition onto the negative electrode, and lithiated graphite reactivity with electrolyte increasing incrementally with SOC and with the amount of deposited Fe. It is commonly known that cell voltage and depth of discharge should be minimized to improve lifetime, but this is based on cell types that operate at higher voltages than 3.65 V in LFP/AG cells. Our results show that even low voltage LFP systems have this trade-off between state of charge and lifetime. We show that the average SOC of operation is more critical for capacity fade than the variables of electrolyte salt choice (LiPF6 vs LiFSI), graphite choice or temperature (40°C vs 55°C). This work employed isothermal microcalorimetry to investigate the heat flow from lithiated graphite-electrolyte reactivity2, scanning micro-xray fluorescence to quantify iron deposition on the negative electrodes3, and liquid electrolyte analysis techniques NMR and GC-MS to investigate electrolyte degradation products.
Figure 1: LFP/AG pouch cell cycling capacity fade across different SOC ranges in long term cycling over 2500 hours. For best comparison, only the C/20 checkup cycles are plotted, where all cells cycle 0-100% every 100 cycles or every ~300 hours. The regular cycles are at C/3 rate, and only 60 mAh out of 240 mAh nominal are cycled. Discharge capacity vs cycling time is plotted for (a) 40°C and (b) 55°C testing of LFP/AG cells with LiPF6 and LiFSI electrolyte salts at various SOC operation windows. The cell barcode IDs are indicated in the legends. The normalized discharge capacity fade per hour at (c) 40°C and (d) 55°C is summarized after 2500 hours of cycling for the different SOC windows cycled. Electrolyte is EC:DMC 3:7 2VC 1.5M LiFSI or LiPF6.

References:

[1] Safari, M. & Delacourt, C. Aging of a Commercial Graphite/LiFePO4 Cell. J. Electrochem. Soc.
158, A1123 (2011).
[2] Logan, E. R.; Dahn, J. R. Measuring Parasitic Heat Flow in LiFePO 4 /Graphite Cells Using Isothermal Microcalorimetry. J. Electrochem. Soc.
2021, 168 (12), 120526. https://doi.org/10.1149/1945-7111/ac405b.
[3] Eldesoky, A., Logan, E. R., Johnson, M. B., McFarlane, C. R. M. & Dahn, J. R. Scanning Micro X-ray Fluorescence (μXRF) as an Effective Tool in Quantifying Fe Dissolution in LiFePO 4 Cells: Toward s a Mechanistic Understanding of Fe Dissolution. J. Electrochem. Soc.
167, 130539 (2020).

Figure 1
A Discrete Element Analysis of the Mechanical Properties of Lithium-Ion Electrode Layers Linked to Mechanical Degradation
Authors: Lundkvist Axel , Larsson Per-Lennart , Olsson Erik 
Published: December 2024

Lithium-ion batteries are a key player in the electrification of the transport sector. One of the main challenges of today’s lithium-ion batteries is the degradation of charge capacity over time. This capacity degradation stems from several phenomena, and chemical degradation has historically been the main focus of investigation. However, the mechanical degradation of the cell also contributes considerably to the charge degradation and is, therefore, a topic of interest. In this work, a framework for modelling the mechanical behaviour of a positive electrode layer within a lithium-ion battery cell has been developed. This framework uses the discrete element method (DEM), which accurately resolves the granular microstructure of the electrode's active layer. This study aims to characterize the electrode layer’s mechanical response, stemming from the active particles’ elastic-plastic nature and the viscoelastic binder domain. The DEM framework links the local contact behaviour of the particles and the binder and the global mechanical response of the full electrode layer. Understanding this link between length scales is a central first step to fully understanding the mechanical degradation behaviours of the electrode. The model is verified against experimental measurements of the electrode layers’ mechanical properties, measured through U-shape bend tests, by Gupta et al. [1]. The in-plane unloading stiffness and the relaxation of the layer were determined in the experiments, both in compression and tension. The experiments indicated that the in-plane stiffness of the layer differed in compression and tension, with an increasing stiffness at increased compression levels. The relaxation of the layer is also measured over a six-hour period. Through our modelling framework, we were able to capture the pressure-sensitive in-plane stiffness and relaxation of the electrode layer. This work lays an excellent foundation for further investigations of the mechanical properties of the active layer and its mechanical degradation mechanisms, such as swelling and fracture of the active particles due to charge cycling.
[1] P. Gupta, I. B. Üçel, P. Gudmundson, and E. Olsson, “Characterization of the Constitutive Behavior of a Cathode Active Layer in Lithium-Ion Batteries Using a Bending Test Method,” Exp. Mech., vol. 60, no. 6, pp. 847–860, 2020, doi: 10.1007/s11340-020-00613-5.
Evaluation of an Ag/AgF Reference Electrode for Electrochemical Measurements of Molten 2LiF-BeF2
Authors: Pickarski Timothy Ryan , Williams Haley , Scarlat Raluca O. , Borrello Michael 
Published: December 2024

Despite the wide application of molten fluoride salts, such as 2LiF-BeF2 (FLiBe), as heat transfer fluids, fuel solvents, and fusion blanket materials in advanced nuclear power concepts, the mechanisms of ion transport, speciation, and reaction kinetics in these systems have not been comprehensively characterized. Though electrochemical methods are powerful tools for probing these properties of molten fluorides, current studies are limited by the lack of a reliable thermodynamic reference electrode (TRE) compatible with the fluoride environment. The reference electrode designs used in fluorides can be classified into three main categories: quasi-reference electrodes (qREs), dynamic reference electrodes (DREs), and thermodynamic reference electrodes. qREs and DREs are not well suited to in-line measurements of molten fluorides since the reference redox couple of the noble qRE material cannot be assumed to be constant and the time scale of the DRE’s relaxation of the transient redox system is too short.
Therefore, explorations of the FLiBe system have pursued the development of a TRE which can hold a thermodynamically stable reference potential for an extended time. Current designs using the H2/HF or Ni/Ni2+ couples suffer from either difficult handling of gas electrodes at high temperatures [1] or long equilibriation times. Since pure NiF2 does not melt at reactor operating temperatures (~500-1000°C), the NiF2 used must dissolve into a reservoir of supporting FLiBe, a process which takes over 30 hours. In this study, the performance of a reference electrode using the Ag/Ag+ redox couple is assessed for long-term electrochemical stability. The Ag/AgF system was chosen to address the limitations of the Ni/Ni2+ TRE, as the low melting point of AgF (Tmelt = 435°C) allows for the direct use of the pure salt in the electrode, eliminating the time-consuming dissolution step required for NiF2.
The Ag/AgF TRE was constructed by melting AgF salt into a boron-nitride crucible fitted with a LaF3 fluoride membrane and inserting a silver wire into the salt reservoir. The stability and reproducibility of the electrode potential were evaluated through long-term open circuit potential measurements against a platinum qRE in a FLiBe melt at 600°C. The reversibility of the Ag/Ag+ reaction was assessed using a linear polarization study. Finally, the location of the redox potential was found by comparing the open circuit potential of the Ag/AgF TRE against a beryllium rod electrode. The development of a reliable and easy-to-operate thermodynamic reference electrode will facilitate future studies on the thermochemical properties of molten FLiBe while laying the foundation for advancing in-line monitoring and redox control in nuclear technologies.
[1] Jenkins, Howard W., "Electrochemical Measurements in Molten Fluorides. " PhD diss., University of Tennessee, 1969. https://trace.tennessee.edu/utk_graddiss/3072
Al Electroplating on Etched CFRP Surfaces in AlCl3-EmImCl Ionic Liquids
Authors: Kishi Naoki , Matsushima Hisayoshi , Ueda Mikito 
Published: December 2024

Carbon fiber-reinforced plastics (CFRP) are composite materials of carbon fibers and resin. Since it is low in density, high in strength, and high in rigidity, it is used in many applications such as sports fields and automobiles. However, its surface wear resistance is not enough, and it is limited to using it as a material for friction. To improve wear resistance, CFRP surface modification by Al electroplating and surface anodizing were used in this study. Electroplating is one of the low-cost Al plating methods with easy control of plating film thickness. Since the surface consists of highly conductive carbon fibers and low conductive resin, only the carbon fibers are electroplated. In this study, to increase the occupancy of carbon fibers on the surface, the resin in CFRP was dissolved and removed by acid treatment. Then, Al electrodeposition experiments in ionic liquids were also conducted for the surface.
CFRP (PEEK resin) was cut into 2 cm x 5 cm pieces and used as substrates. Surface etching treatments were performed under 5 molL-1 sulfuric acid at 373 K for 10 to 120 seconds. The ionic liquid used in the electrodeposition experiments was a mixture of 1-ethyl-3-methylimidazolium chloride (EmImCl) and AlCl3 at a molar ratio of 1: 2. As an additive, 1,10-phenanthroline was added to the ionic liquid to a concentration of 20 mmolL-1. In the Al electrodeposition experiments, a CFRP plate (before and after surface etching) was used as the working electrode; Al mesh and Al wire were used as the counter and reference electrodes, respectively. For electroplating, the condition was current pulse electrolysis at 20 mA cm-2, duty ratio 0.83, and temperature at 333 K. In the electroplating, applied electric charge corresponds to a targeted theoretical film thickness of 20 µm. The surface morphology of the electrodeposit before and after electrodeposition was observed by Scanning Electron Microscopy (SEM). Surface roughness was also measured using Confocal Laser Scanning Microscopy (LSCM).
In surface observation after the etching of CFRP in 5 molL-1 sulfuric acid at 373 K, the surface became rougher as the etching time was increased. The surface roughness showed little change when the etching time was 60 and 120 s. The Al electrodeposits on the untreated CFRP surface were smooth with a roughness of 0.43 μm. Al deposits on the surface after etching treatment were 2.25 μm for 60 s treatment and 2.27 μm for 120 s treatment. From the SEM observation of the Al electrodeposits, the electrodeposits were formed along the carbon fibers. In addition, some parts with large gaps between carbon fibers were not covered by Al electrodeposits. It was considered this was due to the difficulty of electrolytes with high viscosity to penetrate into the gap.