bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas-Phase Pd Clusters-Modified Mesoporous Copper Oxide Hollow Spheres As Electrocatalysts for CO2 Reduction to Ethylene
Authors: Nguyen Thi Hong Trang , Sanchez Oriol Gutiérrez , Chinnabathini Vana Chinnappa , Papamichail Dimitra , Pant Deepak , Grandjean Didier , Nguyen Trang
Published: February 2024

Renewable energy-driven electrochemical CO2 conversion to value-added chemicals is a prospective strategy for addressing global carbon emission and energy consumption issues worldwide. Until today, only copper-based electrocatalysts can successfully transform CO2 into C2H4 or other desirable C2+ products, but their stability and product selectivity remain insufficient.1 Oxide-derived Cu mesoporous foam catalysts currently show the best selectivity toward C2+ product formation at particularly low overpotentials due to the availability of specific surface sites for C−C coupling in their structure and to the temporal trapping of gaseous intermediates inside the mesoporous catalyst material during CO2 electrolysis.2 To further improve their stability and product selectivity their surface can be modified with metallic clusters that can promote the adsorption of CO2 and the subsequent formation of intermediates. In particular, Pd clusters provide a favorable surface for the initial adsorption of CO2,3 while inducing a continuous restructuring of the Cu surface that maintains its catalytic properties for CO2 reduction to hydrocarbons.4

Herein, we report a novel highly efficient electrocatalyst for CO2 conversion in C2+ products based on mesoporous oxygen-rich copper hollow spheres prepared by a colloid templating method, whose surface is uniformly modified by the deposition of different loadings of well-defined Pd clusters of ca. 3 nm diameter using the laser ablation cluster beam deposition (CBD) technology.5

Primary electrochemical results show that these electrodes are able to reduce CO2 to ethylene with a faradaic efficiency of more than three times higher than that of commercial Cu2O nanoparticles under the same reaction conditions. A clear phase transition from CuO to Cu2O and metallic Cu is occurring under CO2 electro-reduction conditions as highlighted by XRD.

These remarkable performances are likely originating from the facile gas charge transport via the mesoporous structure of the oxygen-rich copper spheres as imaged by SEM (Figure 1) as well as from their high surface area, which allows a high catalytic activity and a uniform accommodation of the metallic clusters.

As CBD is a versatile technique that allows the deposition of virtually any type of well-defined cluster on a large variety of support, this work provides an attractive avenue to achieve stable selective multicarbon products via rational electrode design. References

Kuhl KP, et al., Energy and Environmental Science, 2012;5 (5):7050-7059.

Abhijit Dutta, et al., ACS Catal. 2016, 6, 3804−3814

Sichao Ma, et al., J. Am. Soc. 2017, 139, 47−50

Zhe Weng, et al., Angew. Int. Ed. 2017, 56, 13135 –13139

Chinnabathini V. C., et al., Nanoscale, 2023, DOI: 10.1039/D2NR07287D.

Figure 1
(Invited) Durable and Highly Active Fe-N-C Catalysts for PEM Fuel Cells
Authors: Wu Gang
Published: February 2024

Atomically dispersed and nitrogen-coordinated single iron sites (FeN4) embedded in carbon (Fe-N-C) catalysts are the most promising platinum group metal (PGM)-free catalysts. However, they have yet to match their Pt counterparts for oxygen reduction reaction (ORR) activity and stability in proton exchange membrane fuel cells (PEMFCs). Here, we developed viable Fe-N-C catalysts, which, for the first time, demonstrated competitive activity to that of Pt/C catalysts and dramatically enhanced stability and durability under practical PEMFC operating conditions. The most active Fe-N-C catalyst achieved a record half-wave potential (E1/2 = 0.915 V vs. RHE at 0.6 mgcatcm-2) and an ORR mass activity of 10.5 mA mgcat at 0.9 V in (RDE) tests, exceeding a Pt/C baseline catalyst (60 µgPt cm-2) by 40 mV in acidic electrolytes. This compelling activity of the Fe-N-C catalyst in aqueous acids on rotating disk electrode (RDE) was successfully transferred to fuel cell membrane electrode assembly (MEAs), generating an initial current density of 44.2 mA cm-2 exceeding the U.S. DOE 2025 target (i.e., 44 mA cm-2) at 0.9 VIR-free under O2. Under practical hydrogen-air conditions, record 151 mA cm-2 at 0.8 V and peak power density of 601 mW cm-2 were achieved. Importantly, we discovered that depositing nitrogen-carbon species on the catalyst surface via chemical vapor deposition (CVD) dramatically enhanced catalyst stability, evidenced by performance durability after accelerated stress tests (30 000 square-wave voltage cycles under H2/air) and long-term steady-state life tests (> 300 hours at 0.67 V). Innovative identical location-scanning transmission electron microscopy (IL-STEM) experiments confirmed that the CVD process leads to deposition of nitrogen-doped carbon onto the catalyst surfaces. Along with theoretical modeling, a reconstruction of the carbon structure adjacent to FeN4 sites leads to increased robustness against demetallation and carbon oxidation. This work opens new avenues for developing earth-abundant iron-based catalysts with extraordinary activity and stability, thus competing with Pt and addressing the cost barrier of current PEMFCs.
Formation of Pores on Pure Ti in Highly Concentrated Sulfuric Acids
Authors: Tsuchiya Hiroaki , Sato Ryoma , Fujimoto Shinji
Published: February 2024

TiO2 nanotubes formed by anodization in fluoride-containing electrolytes have been extensively examined due to their wide rage of applications. It is reported that fluoride ions move faster to the interface between anodic oxide layer and underlying Ti substrate, forming a fluoride-rich layer at the interface as the ionic radius of fluoride ion is smaller compared to that of oxygen ion. The fluoride-rich layer is also reported to decrease the adhesion of the anodic oxide layer to the substrate. Therefore, the formation of nanotubular oxide layer in fluoride-free electrolytes is highly desired. In the present work, we examined the formation of nanotubular oxide layers on pure Ti in highly concentrated sulfuric acids.

Specimens with the dimension of 5 mm x 80 mm x 0.6 mm were prepared from pure Ti sheet (purity ; 99.5%). Prior to anodization, the specimens were cleaned in acetone, methanol and deionized water, successively. Anodization was carried out in highly concentrated sulfuric acids at elevated temperatures using two-electrode configuration cell with platinum counter electrode. The applied voltage was increased with the sweep rate of 1 V/s to desired voltages and then kept at the voltages for various durations. After the anodization, the surface of the specimens was cleaned with deionized water and dried. The structure of the surface was evaluated using FE-SEM.

In a highly concentrated sulfuric acid, the anodic current increased with increasing the applied voltage and after switching constant voltage, decreased with time. The formation of oxide layer was confirmed at the surface, but no porous structure was visible. However, a porous structure was observed on the specimen above the electrolyte surface, indicating that the anodization occurred under the meniscus consisting of highly concentrated sulfuric acids. The optimization of water concentration in sulfuric acid and temperature led to the formation of porous structure on pure Ti. This indicates that porous oxide layers can be formed in fluoride-free electrolytes although further optimization is required to improve the ordering of pores.
A Density Potential Functional Approach for Mesoscopic Metal-Solution Interfaces
Authors: Huang Jun
Published: February 2024

Mesoscopic metal-solution interfaces (MSI) are found at nanostructured electrodes in myriad electrochemical devices. Resolving the local reaction environment for electrochemical reactions occurring in mesoscopic MSIs requires a constant-potential, computationally economic method that properly treat both quantum mechanical metal electrons and almost classical electrolyte components. We have been developing a density potential functional theory (DPFT) to meet these harsh requirements [1-4]. Our DPFT method combines an orbital-free density functional theory of quantum mechanical metal electrons, a statistical field theoretic description of classical electrolyte ions and solvent, and Morse potentials describing short-range interactions between the two parts that are parameterized using first-principles based computations. In this talk, I will introduce the theoretical framework, its relationship to other similar methods including the jellium model and implicit solvation model, its parameterization and benchmark with experimental and ab initio simulation data, and recent applications to understand solvent effects on potential of zero charge, mechanoelectrochemistry of MSIs, and supported nanoparticle catalysts. The emerging opportunities, future development needs, and important caveats of the DPFT method will be discussed.

Reference

Huang J, Zhang Y, Li M, Groß A, Sakong S. Comparing Ab Initio Molecular Dynamics and a Semiclassical Grand Canonical Scheme for the Electric Double Layer of the Pt (111)/Water Interface. The Journal of Physical Chemistry Letters. 2023 Feb 27;14:2354-63.

Huang J. Density-Potential Functional Theory of Electrochemical Double Layers: Calibration on the Ag (111)-KPF6 System and Parametric Analysis. Journal of Chemical Theory and Computation. 2023 Jan 18.

Huang J, Chen S, Eikerling M. Grand-canonical model of electrochemical double layers from a hybrid density–potential functional. Journal of chemical theory and computation. 2021 Mar 31;17(4):2417-30.

Huang J. Hybrid density-potential functional theory of electric double layers. Electrochimica Acta. 2021 Sep 1;389:138720.

J.H. is supported by the Helmholtz Young Investigators Group Leader Program.
Developing Cu-Co-Based Catalysts for Enhanced OER in Alkaline Water Electrolysis
Authors: Saei Worawee , Pasel Joachim , Scheepers Fabian , Korte Carsten
Published: February 2024

Copper, Cobalt-based (CuCo-based) catalysts are promising candidates for the anodes of alkaline water electrolyzers due to their high electrical conductivity, variable chemical state, and the potential for cost-effective large-scale production. However, the effective chemical composition and structure of these catalysts are still being explored. In this work, the focus is on the proposal CuCo-based catalysts for the oxygen evolution reaction (OER) in alkaline water electrolysis, with significant advantages for their use in anion exchange membrane (AEM) electrolyzer systems. CuCo-based catalysts with varying Cu:Co ratios were synthesized using a co-precipitation method and heat treatment, resulting in spinel type (oxides), CuCo-O, or brucite type structures (hydroxides), CuCo-OH. The catalysts were characterized using XRD, SEM, EDX, TEM and ICP-OES to confirm their morphology and composition. The OER catalytic performance of the catalysts was evaluated using rotating disk electrode (RDE) measurements with a 3-electrode system and 1 M KOH as the electrolyte.

Our results show that CuCo-OH provides lower overpotentials than CuCo-O at a current density of 10 mA/cm2. Nevertheless, CuCo-O exhibits a more consistent performance than CuCo-OH, indicating its superior properties in terms of reproducibility and reliability. Additionally, we propose a promising Cu:Co mol ratio of CuCo-OH and CuCo-O. These findings highlight the importance of the chemical composition and provides insight into the structure design of OER catalysts for alkaline water electrolysis. The results suggest a synergistic effect of Cu and Co in the catalyst composition, which could be further explored in future research.
(Invited) To Prepare 2D Au Nanoplates and Its Controlled Molecular Self-Assembly (MS) Mechanism
Authors: Guo Jian-Wei
Published: February 2024

It is very important to prepare 2D noble-metal nanomaterials, but very little is known about their chemical synthesis at molecular level. In this paper, we found the classic citric (CA) reduction method can prepare 2D Au nanoplates with a large range for 2D size (3-150nm). Furthermore, these 2D Au nanoplates exhibit thin thickness (8-20nm), along with two kinds of single crystal structure as 2D Au (110) –dominated and Au (111) –dominated nanoplates. To explore their preparation, we adjusted the CA reduction kinetic as CA additive→ acetone dicarboxylic acid (DCA) →acetone, revealing the intermediate species of DCA is crucial for nanoplate formation. Our DFT (Density-Functional-Theory) model further clarifies that the DCA has molecular interaction, preferentially transferring 2D clusters (Au3-Au7) towards Au(111) facets though accompanying with some Au (100) facets. These soft-hard interaction help us establish two kinds of controlled MS mechanisms towards (111) –dominated nanoplates and Au (110) –dominated nanoplates, revealing the cluster origination and its essential 2D growth process in nucleation-growth process. Consequently, our preparation for 2D Au nanoplates and controlled MS mechanisms open a gate towards nucleation-growth process, thus having great significance and broad impact for future studies.
Single-Impact Electrochemistry of Redox Liposomes for the Detection of Virulence Factors
Authors: Langlard Arthur , Thobie-Gautier Christine , Boujtita Mohammed , Lebegue Estelle
Published: February 2024

Early detection of pathogens is a key factor for the successful therapy of infectious diseases. Some of the pathogenic bacteria involved in diseases interact with the host by producing compounds that are toxic or disruptive to the cells. As these virulence factors can be easier to spot than the pathogen, strategies of detection can be focused on these released compounds to identify the pathogenic bacterium.[1]

Liposomes are vesicles composed of a lipid bilayer membrane, and as such are often used to mimic living cells. Here, the strategy consists in making redox liposomes by encapsulating an electroactive probe in their inner cavity, which will be detected at the electrode.[2] Virulence factors interacting with the vesicles increase the permeability of the lipid membrane and the contents of the liposomes are released over time. This redox probe is then detected with an electrode polarized at the appropriate potential. This work aims to study the single-impact electrochemistry of redox liposomes in different conditions. Previous results indicate that the addition of a surfactant to a liposomal suspension leads to their rupture when they stochastically collide with an ultramicroelectrode.[3] Similarly, virulence factors increase their release or electrolysis of contents upon impact with an ultramicroelectrode.[4] Chronoamperometry measurements recorded at the ultramicroelectrode polarized at the redox potential of the electrochemical probe show impact events (vesicle blocking) and opening events (vesicle reactor) when the encapsulated redox probe is released by the liposome, which are traced back to the presence of pathogenic bacteria.

References:

Smida, H.; Langlard, A.; Ameline, D.; Thobie-Gautier, C.; Boujtita, M.; Lebègue, E.; Anal. Bioanal. Chem.
2023, doi.org/10.1007/s00216-023-04568-z.

Smida, H.; Thobie-Gautier, C.; Boujtita, M.; Lebègue, E.; Curr. Opin. Electrochem.
2022, 36, 101141.

Lebègue, E.; Anderson, C. M.; Dick, J. E.; Webb, L. J.; Bard, A. J.; Langmuir
2015, 31 (42), 11734- 11739.

Luy, J.; Ameline, D.; Thobie-Gautier, C.; Boujtita, M.; Lebègue, E.; Angew.
Chem. Int. Ed.
2022, 134 (6), e202111416.

Figure 1
(Keynote) Polyoxometallate Functionalized Membranes for Next Generation Fuel Cells, Electrolyzers and Other Devices
Authors: Herring Andrew M. , Kuo Mei-Chen , Kim Chuloong (Christoph) , Coughlin E. Bryan , Salgado Marco
Published: February 2024

Using polyoxometalate moieties we are developing proton conducting membranes for proton exchange membrane fuel cells, electrolyzers and other devices that can solve the durability and environmental challenges and temperature limitations facing the state of the state-of-the-art perfluorinated sulfonic acid-based membranes. During recent work with perfluorinated membranes we have shown how to achieve stability enhancement that easily exceeds the Fuel Cell DOE accelerated stress tests (AST) for chemical stability and mechanical durability requirements for light duty vehicles. This indicates the potential of these For this perfluorinated polymer-HPA combination we obtained higher performance than the current state-of-the-art PFSAs under high humidity conditionsHPA moieties to give oxidative stability to hydrocarbon membranes as well. New membrane technology we are working on will utilize covalently bound heteropoly acids (HPA), inorganic super acids, that have both some of the highest proton conductivities when wet and have been proven to catalytically decompose oxygenated radicals that destroy existing membranes. We have already demonstrated similar membranes in fuel cells with high performance and some of the most stable long term durability ever demonstrated. In fuel cells, the materials always performed beyond state-of the-art when in humid conditions but struggled when the cells became dry, as electrolysis applications feeds water to the cell we have very high confidence that we will be able to easily exceed electrolyzer performance targets. We are improving upon this polymer chemistry and are now tailoring it specifically to electrolysis. When configured correctly within a hydrocarbon polymer membrane these HPA-hydrocarbon polymers will outperform perfluorosulfonic acid (PFSA) polymers. The correct HPA chemistry must be chosen, and we have shown that silicotungstic acid derivatives act as strong proton conducting moieties and also catalytically decompose oxygenated radicals. This will then enable hydrocarbon membranes with practical lifetimes and performance using the silicotungstic functionality. We are aiming to control the HPA channel morphology and allow for maximum proton conductivity with minimum water uptake. The engineered structures will facilitate proton conduction from ambient conditions to temperatures in excess of 120°C (the polymeric materials chosen are stable to 200°C when dry and potentially much higher when wet and pressurized), as well as achieving cost and durability targets for PEM membranes in electrolyzer applications. Our approach will also allow for development of an ionomer for optimal interfacing with the electrodes.
ZIF-67 Grown in Situ over Carbon Fiber Felt (CFF) for Alkaline Water Splitting
Authors: Theodoroviez Lucas Bitencourt , Graves David Alexandro , Šljukić Biljana , Gonçalves Emerson Sarmento
Published: February 2024

Aiming for clean and affordable energy through green chemistry, water splitting emerges as one of the most effective and promising methods of producing high-purity hydrogen and oxygen without emitting harmful greenhouse gases into the atmosphere. As a result, the design and construction of low-cost, highly active, and long-term stable electrocatalysts is a challenge that must be highlighted. Considering their crystalline structure, morphological feature with high surface area, well defined pores, and tunable functionality, Metal-Organic Frameworks (MOFs) have attracted attention as materials in the development of highly efficient electrocatalysts for energy conversion and storage applications. The MOF used in this case is known as ZIF-67, which is a 3D self-assembled structure with Co(II) ions interconnected with 2-methylimidazole (Hmim) and has the same ligation angle as sodalite zeolites (145°). The ZIF-67 was anchored in situ on a carbon fiber felt (CFF; a great current collector), promoting the construction of a bottom-up electrode with MOF nanoparticles, which allows the electrode surface to have greater exposure of active sites due to interaction with the polar surface of the substrate in question. Nanoparticles also allow for greater electrocatalytic impacts by having surface effects that are enhanced when compared to bulk effects. Such prepared electrode was tested for water splitting in alkaline (1 M KOH) media, i.e., for hydrogen evolution as anodic reaction and oxygen evolution as cathodic reaction. Low onset potential accompanied by high current densities was observed under anodic polarization conditions. Thus, current density of 10 mA cm-2 was reached at potential of ca. 1.6 V vs RHE and current density as high as ca. 140 mA cm-2 at 2 V vs RHE. Such high performance could be attributed to the low charge-transfer resistance observed during electrochemical impedance measurements. The charge-transfer resistance further decreased with shift of potential to more positive values. Current density of 10 mA cm-2 was recorded at -0.2 V and current density of ca. 40 mA cm-2 at -0.4 V vs RHE under the cathodic polarization conditions. High performance suggests application of the herein prepared CFF/ZIF-67 as bifunctional electrode material for alkaline water electrolyzers.

References

Zhong, D. Liu, J. Zhang, J. Mater. Chem. A 2018, 6, 1887

M. Birkholtz, DJ. Liu, Mater. Horiz. 2017, 4, 20

Li, C.; Ma, D.; Zhu, Q, Angew. Chem. 2022, 12, 848.

Figure 1
Fast and Facile Microwave Synthesis of Cubic CuFe2O4 Nanoparticles for Electrochemical CO2 Reduction
Authors: Zander Judith , Marschall Roland
Published: February 2024

Electrochemical CO2 reduction is a promising strategy for the sustainable synthesis of carbon-based chemicals or fuels such as CO, or CH4.[1] Copper-based materials are of special interest due to their broad substrate scope. While copper itself is the first known metal catalyst able to directly yield CH4, CO, methanol, or C2+ products such as ethanol can also be obtained, e.g. from oxide derived catalysts.[2][3] Another interesting copper oxide is the spinel CuFe2O4, due to its versatile electronic and magnetic properties. Those can be tuned via variations in the cation distribution between octahedral and tetrahedral sites.[4] Changes in the cation distribution, or degree of inversion, can additionally lead to a structural transformation between the cubic and tetragonal form, due to the strong Jahn-Teller effect of Cu2+. Both degree of inversion and structure are strongly dependant on the synthesis conditions.[4]

In this contribution we introduce a fast microwave-assisted solvothermal synthesis of cubic CuFe2O4. Very short synthesis times of 1 min and low temperatures of 120 °C in ethylene-glycol/water mixtures could be realised, without a loss of phase-purity and no necessity for subsequent thermal treatment.[5] The degree of inversion was found to decrease with increasing synthesis time, whereas the particle size and crystallinity was almost independent of the synthesis conditions. The influence of the synthesis conditions – and thus material properties – on the activity in electrochemical CO2 reduction to CO in 0.1 M KHCO3 was investigated. The best activity was obtained for CuFe2O4 with an intermediate degree of inversion of approx. 0.75, together with a large crystallite size and micro-strain. Since hydrogen was produced as the only side-product, CuFe2O4 can be an interesting candidate for the production of syngas.

References:

[1] Q. Lu, F. Jiao, Nano Energy
2016, 29, 439

[2] S. Nitopi, E. Bertheussen, S. B. Scott, X. Liu, A. K. Engstfeld, S. Horch, B. Seger, I. E. L. Stephens, K. Chan, C. Hahn, J. K. Nørskov, T. F. Jaramillo, I. Chorkendorff, Chem. Rev. 2019, 119, 7610

[3] D. Raciti, C. Wang, ACS Energy Lett.
2018, 3, 1545

[4] R. Zhang, Q. Yuan, R. Ma, X. Liu, C. Gao, M. Liu, C.-L. Jia, H. Wang, RSC Adv.
2017, 7, 21926

[5] J. Zander, M. Weiss, R. Marschall, Adv. Energy Sustainability Res.
2023, 2200184
Nanostructured 3D Mesoporous α-Fe2O3 Nano-Cubes As a High-Performance Electrode for Supercapacitors
Authors: Singh Umisha , Shukla Shobha , Saxena Sumit
Published: February 2024

Development of energy storage devices of high energy density and long cycle life is one of the pressing needs of electronic devices. Pseudo-capacitors with iron oxide electrodes show promising energy storage devices because they are economical and safe, but have poor conductivity and stability. To achieve an improved electrochemical performance such as shorter ion-diffusion path, faster ion accessibility, and higher conductivity, a rationally design of electrode material is highly desirable. Here, we shed the light on how three-dimensional (3D) Nano porous networked α-Fe2O3 nano-cubes serves as a supercapacitor electrode. Here we show the high specific capacitance and long-life supercapacitor anode by developing a hierarchical three-dimensional α-Fe2O3 nano-cubes. KOH is used as an aqueous electrolyte. The synthesized annealed nano-cubes (PNC) have high surface areas of 5.127m2/g. The annealed Hematite (α-Fe2O3) NC show good thermodynamic stability with high reversible redox activity. The half-cell anode based on this nanostructure give rise to a high specific capacitance value of ~520F/g at a current density of 1 A/g and ~90% of the capacitance can be retained at 2 A/g after 1000 redox cycles (indicates the good cyclic stability). The present work demonstrates that binder and conductive additive-free 3D Nano porous electrodes open up a new avenue to fabricate high surface area electrodes for improved charge storage performance. These performance features are superior among those reported for iron oxide-based supercapacitors. High specific capacitance value, stable cycling, and facile preparation make Hematite NC(α-Fe2O3) an excellent material for use as supercapacitor electrodes.
Role of Copper as Current Collectors in the Reductive Reactivity of Polymers for Anode-Free Lithium Metal Batteries - Insights from DFT and AIMD Studies
Authors: Wu Liang-Ting , Nachimuthu Santhanamoorthi , Brandell Daniel , Tsai Chia-Ni , Wang Pei-Hsuan , Li Yeh-Wei , Jiang Jyh-Chiang
Published: February 2024

Understanding the role of current collectors (CCs) in the reductive reactivity of polymers on Li metal and the resultant solid electrolyte interphase (SEI) formation is essential for improving the performance of anode-free lithium metal batteries (AFLMBs). In this study, we have examined the reactivity of three polymeric hosts: poly(ethylene oxide) (PEO), poly(ε-caprolactone) (PCL), and poly(trimethylene carbonate) (PTMC) at Li metal supported on Cu surfaces (Li/Cu) using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. In particular, the effect of copper (Cu) CCs on polymer stability, electronic structure, and their reduction reactions is investigated and compared to that of pure Li (100) surface. Through time-dependent Bader charge transfer analysis, electron transfer is identified as the triggering factor for polymer reduction. Based on the simulations, we find that the Cu CCs have a significant influence on the charge distribution of the Li metals, which increases electron transfer to the polymers and thereby accelerates polymers reduction. This thereby leads to different reaction mechanisms as compared to on Li-metal. The findings suggest that utilization of Cu CCs avoid production of CO molecules and improves the quality of the formed SEI layer.

Figure 1
High Areal Capacity Cycling of Three-Electrode Sodium/NBA/Sodium Cells
Authors: Larson Karl , Carmona Eric A , Albertus Paul
Published: February 2024

The cycling stability of Li and Na metal electrodes is influenced by the interface with the solid electrolyte. Study of the cycling behavior at areal capacities >>0.5 mAh/cm2 are uncommon, and plating and stripping behaviors remain relatively unknown for the individual electrode/electrolyte interfaces because of the difficulty of separating the individual interfaces in a two-electrode cell configuration. Because areal capacities of practical cells target >5 mAh/cm2, it is important to cycle at much higher areal capacities than typically studied. Here, we utilize a three-electrode symmetric cell of sodium metal with sodium beta alumina (NBA) electrolyte and cycled areal capacities ranging from 0.5 to 5 mAh cm-2 and achieved current densities >10 mA cm-2 at 1.0 mAh cm-2. We find that polarization increases most at the stripping electrode, and that during current density ramps the polarizations are greatly affected by the areal capacity, affecting the maximum current density that can be reached prior to either cell shorting or impedance rise that drives the voltage magnitude to well over 1 V. Additionally, we found resistance rise occurring at the Na/NBA interface during plate (reduction) as well as strip (oxidation) for the same electrode, potentially indicating voiding on plate at sufficiently high current densities and areal capacities (5 mAh cm-2, >2 mA cm-2). For two-electrode studies, the voltage evolution on the plating electrode we observe must be considered for the assumption that the plating electrode is a pseudo reference electrode. We also use our three-electrode cell configuration to study several other experimental conditions, including cycling to failure at a fixed current density and areal capacity, as well as a uni-directional current flow experiment to determine the maximum amount of plating / stripping that can be achieved in the absence of cycling. These findings will help direct future experiments and interpretation of data to quantify the limits and improve the engineering of Li and Na metal / solid electrolytes interfaces.

Jolly, D. S.; Ning, Z.; Darnbrough, J. E.; Kasemchainan, J.; Hartley, G. O.; Adamson, P.; Armstrong, D. E. J.; Marrow, J.; Bruce, P. G. Sodium/Na Β″ Alumina Interface: Effect of Pressure on Voids. ACS Appl Mater Interfaces
2019, 12 (1), 678–685. https://doi.org/10.1021/ACSAMI.9B17786.

Krauskopf, T.; Hartmann, H.; Zeier, W. G.; Janek, J. Toward a Fundamental Understanding of the Lithium Metal Anode in Solid-State Batteries - An Electrochemo-Mechanical Study on the Garnet-Type Solid Electrolyte Li 6.25 Al 0.25 La 3 Zr 2 O 12. ACS Appl Mater Interfaces
2019, 11 (15), 14463–14477. https://doi.org/10.1021/ACSAMI.9B02537/SUPPL_FILE/AM9B02537_SI_001.PDF.
(Invited) The Electric Double Layer Revisited from an Atomistic Perspective
Authors: Gross Axel
Published: February 2024

At the interface between two conducting phases, an electric double layer (EDL) forms. In interfacial electrochemistry, such an EDL is present at the interface between the electrode and the electrolyte. The structure of the EDL can be crucial for all processes that occur at such interfaces, for example in electrochemical energy conversion and storage. Yet, it is fair to say that our understanding of the structure of the EDL is still limited and mainly based on concepts that are more than one hundred years old. In this contribution, I will focus on relatively simple interfaces between metallic electrodes and aqueous electrolytes [1] from a conceptual and from a quantum chemical atomistic perspective. I will discuss how elecrochemically control parameter such as the electrode potential and pH values can enter a first-principles description of electrochemical interfaces. Furthermore, I will present examples in which the explicit consideration of the electrochemical environment is not necessary in order to faithfully reproduce adsorbate structures on metal electrodes as a function of the electrochemical control parameters [2]. In addition, I will critically discuss the properties of electrochemical interfaces that correspond to observables from an atomistic perspective.

[1] A. Groß and S. Sakong, Ab initio simulations of water/metal interfaces, Chem. Rev. 2022, 122, 10746.

[2] A. Groß, Reversible vs. standard hydrogen electrode scale in interfacial electrochemistry from a theoretician's atomistic point of view, J. Phys. Chem. C 2022, 126, 11439.
Improving Lithium Intercalation Kinetics at Nanoconfined Electrochemical Interfaces
Authors: Fleischmann Simon
Published: February 2024

Improving the performance of lithium-ion batteries (LIBs), as well as establishing alternative cell chemistries such as sodium- or multivalent-ion batteries, requires detailed understanding of ion transport processes across the electrochemical interface and within the solid-state structure of the host electrodes.To enhance the kinetics of the charge storage processes, reducing charge transfer resistance at the interface and/or reducing ion diffusion-limitations in the solid-state are required. This can be achieved, for example, by active material design, electrolyte formulation, or electrode-electrolyte matching.

In this contribution, our team’s efforts in improving the kinetics of electrochemical Li+ intercalation reactions are addressed from the electrode material side. Using layered transition metal oxides and two-dimensional transition metal dichalcogenides, we employ an interlayer-functionalization approach with organic pillar molecules to tailor the interlayer micro-environment. Changes in interlayer geometry, realized by organic pillars with different lengths, will cause changes in solid-state Li+ transport properties, with larger interlayer distance favoring Li+ diffusivity. Manipulating interlayer chemical environment is accomplished via organic pillars with different chemical backbone compositions. This can lead to changes in electrode-electrolyte/solvent interaction, impacting the charge transfer resistance. The talk will cover synthesis approaches and (electrochemical) characterization of the systems, highlighting mechanistic insights and pointing out opportunities of interlayer-functionalized materials for ion intercalation applications.
(Invited) Study of Electrochemical Interfaces Using DFT and the Classical Liquid Theory Hybrid Simulations
Authors: Otani Minoru
Published: February 2024

Understanding the properties of electrochemical interfaces leads to improving the efficiency and durability of energy and structural materials such as secondary batteries, fuel cells, catalysts, and corrosion. First-principles calculations based on the density functional theory (DFT) are useful simulation technique to those materials and are widely used to understand physicochemical phenomena such as charge and electron transfer and reaction kinetics. However, the simulation costs for the full DFT calculation are quite large. Thus, we need to reduce it to obtain as many results as possible within the limited calculation resources. Combining the DFT and the classical liquid theory is one of a possible way to reduce the costs. We have been developed a series of simulation techniques to hybridize the DFT and the reference interaction site model (RISM) [1-4]. In the presentation, after providing a brief introduction of our simulation technique, we will show the simulation results for electrolyte decompositions and battery degradation [5], a confined effect of water molecule in the MXene electrode [6], and a water dissociation reaction on Cu surface using an automated reaction path search method [7,8].

References:

Otani and O. Sugino, Phys. Rev. B, 73, 115407 (2006).

Bonnet, T. Morishita, O. Sugino, and M. Otani, Phys. Rev. Lett., 109, 266101, (2012).

Nishihara and M. Otani, Phys. Rev. B, 96, 115429 (2017).

Haruyama, T. Ikeshoji, and M. Otani, Phys. Rev. Mater., 2, 095801 (2018).

Hagiwara, J. Haruyama, M. Otani, Y. Umemura, T. Takeuchi and H. Sakaebe, Electrochemistry, 90, 107002 (2022).

Sugahara, Y. Ando, S. Kajiyama, K. Yazawa, K. Gotoh, M. Otani, M. Okubo, A. Yamada, Nat. Commun., 10 850, (2019).

S. Maeda, K. Ohio, and K. Morokuma, Phys. Chem. Chem. Phys. 15, 3683 (2013)

Hasegawa, S. Hagiwara, M. Otani, and S. Maeda, submitted to J. Phys. Chem. Lett.
Correlating Solid-Electrolyte Interface Composition to Charge Transfer Resistance for Improved Low-Temperature Performance of Lithium-Ion Batteries
Authors: Singh Triesha , McCloskey Bryan D.
Published: February 2024

The adverse impact of low temperatures on Li-ion batteries (LIBs) is a well known challenge. Currently, at subfreezing temperatures, the efficiency of conventional LIBs greatly decreases compared to their room temperature performance, which of course severely limits the performance of applications using LIBs in the colder regions on the planet. From a fundamental perspective, the causes of such performance decreases are yet to be fully understood, but are believed to be related to the ability of ions to move through the various phases (as well as move across phase interfaces) that exist in the battery.

Several studies have been conducted to improve the low-temperature performance of LIBs, most of them focusing on using solvents with lower viscosity and higher dielectric constant to promote transport through the electrolyte at the lower temperatures so as to achieve lower bulk resistance (Rbulk) of the cell. However, our Electrochemical Impedance Spectroscopy (EIS) studies at low temperatures have indicated that it is the charge transfer resistance (Rct) that grows exponentially as we go to sub-zero Celsius temperatures and is responsible for the increase in the total resistance of the cell. EIS on 3-electrode cells have shown that the anode side (Gr) is predominantly responsible for the poor cell performance, necessitating our focus on the charge transfer process in the Gr-electrolyte interface. We observe that the Rct is not only related to the Li-solvation shell but also to the composition of the Solid Electrolyte Interface (SEI). By modifying the electrolyte, such as by changing the salt concentration, adding additives, and changing the solvent, significant changes in the interface and hence in the RSEI and Rct of the cell have been observed. By combining EIS with various techniques like mass spectrometry, differential capacity analysis and SEM, we have been able to better understand the SEI composition and its impact on interfacial resistances. We specifically focus on the influence of SEI composition on the charge-transfer resistance of the cell, correlating the effect of amounts of LiF and carbonates in the SEI with the interfacial performance of the cell. Through these relations, we aim to facilitate the development of electrolytes by having a better understanding of the solvation shells and the SEI composition for low temperature performance.
Transition-Metal Interdiffusion in Solid-State Batteries Revealed By Cryo-TEM
Authors: Zhang Ruizhuo , Strauss Florian , Jiang Lin , Casalena Lee , Li Letian , Janek Jürgen , Kondrakov Aleksandr , Brezesinski Torsten
Published: February 2024

Solid-state lithium-ion batteries are being considered as a future energy-storage technology, with superior energy/power density and improved safety over conventional lithium-ion batteries. However, their commercial implementation is hampered by side reactions and electro-chemo-mechanical degradation occurring during cycling (mostly at the positive electrode side). Many efforts have been made to reveal the underlying mechanisms in order to alleviate such problems.

In the current study, the Thermo Scientific IGST workflow solution was used to enable a DualBeam to TEM workflow by protecting both bulk sample and prepared lamella under argon atmosphere with a CleanConnect transfer module. Because of the beam and temperature sensitivity of the superionic lithium thiophosphate solid electrolyte and the cathode interphases formed during cycling, the lamella preparation process (incl. bulk milling, lift out, attachment to the TEM grid, and final thinning) was carried out at cryogenic temperature (−178 °C). The lamella was then transferred to a Talos F200X CFEG for TEM analysis using an inert gas sample transfer workflow.

STEM and EELS investigations revealed Ni, Co, and Mn dissolution from a Ni-rich cathode and subsequent solid electrolyte poisoning. Transition-metal dissolution/migration during cycling operation has previously only been reported for conventional (liquid-electrolyte-based) batteries.
Improving Cycling Performance of Anode-Free Lithium Metal Batteries By Electrolyte Design
Authors: Su Wei-Nien , Wang Chia-Xin , Liao Wan-yu , Hwang Bing-Joe
Published: February 2024

The anode-free lithium metal battery (AFLMB) is gaining attention due to its straightforward yet innovative cell configuration. However, the direct plating and stripping of lithium on the copper current collector presents challenges in material design and cell fabrication. Uncontrolled lithium growth and dendrite formation are common in these challenging conditions and can result in low coulombic efficiency. In this presentation, we summarize recent efforts to develop new electrolytes for high-voltage applications based on AFLMB protocols, including concentrated dual-salt and locally concentrated electrolytes, as well as additives. The solvation structure and corresponding interfacial analysis are significant factors in this development. Additionally, we aim to establish a titration-based method to estimate dead and inactive lithium in various electrolytes, which could facilitate the quick screening of various electrolyte candidates and offer further insight into the fundamentals of lithium growth and solid-electrolyte interface formation.
Screening of First-Row Transition Metal Complexes for Aqueous Redox Flow Batteries: Experimental and Density Functional Theory Approaches
Authors: Rahbani Noura , de Silva Piotr , Bellay Corentin , Guihéneuf Solène , Godet-Bar Thibault , Baudrin Emmanuel
Published: February 2024

The development of redox flow batteries took new directions in the last decades. From initial metal-based systems, it evolved towards organic and hybrid approaches in aqueous media. Furthermore, redox targeting flow batteries are an emerging alternative to the traditional redox flow battery architecture which offer improved energy density via an added electroactive solid ‘booster’. Whatever the system, there is a need of soluble electroactive species with potentials allowing large cell potentials within the water stability window or imperative redox potentials matching between soluble redox mediator and the solid for redox targeting. Transition metal complexes are a promising class of redox electroactive centers due to the tunability of their solubility and electrochemical potential, and the ability to take into account sustainability1. Recent reports underlined for instance that either the modification of the ligand2 or using heteroleptic complexes3, can lead to iron complexes with solubilities higher than 1 M and potentials higher than 1 V vs SHE. Furthermore, reliable and time-efficient prediction tools for the redox potentials of transition metal complexes are needed to help the search for new potential systems. While density functional theory usually provides a good trade-off between computational cost and accuracy, calculations on transition metal complexes often result in large errors. We thus developed a procedure and compared different solvation methods and levels of theory using an initial experimental data set based on aqueous iron complexes with bidentate ligands (Figure 1).

In the present contribution, we will illustrate this coordination approach through a screening of new complexes based on non-toxic and affordable transition metal complexes. In this perspective, electrochemical characterization at different pH, coupled with NMR and UV-Visible studies will be presented, to screen for new candidates as electrolyte in redox flow batteries. Finally, we will show how the calculations corrected using a simple linear regression using training data yields a good prediction of redox potentials (mean average error =0.09 V).

References:

(1) Robb B.H.; Waters S.E.; Marshak M.P., Evaluating aqueous flow battery electrolytes: a coordinated approach, Dalton Trans., 2020; 49: 16047.

(2) Gao J, Amini K, George TY, et al. A High Potential, Low Capacity Fade Rate Iron Complex Posolyte for Aqueous Organic Flow Batteries. Adv Energy Mater. 2022; 12: 2202444.

(3) Li X, Gao P, Lai YY, et al. Symmetry-breaking design of an organic iron complex catholyte for a long cyclability aqueous organic redox flow battery. Nat Energy. 2021;6(9):873

Figure 1
Designing Metal Complexes for Redox Flow Batteries By High-Throughput Synthesis
Authors: Li Qiujun , Peljo Pekka
Published: February 2024

Redox flow batteries (RFBs) are an attractive device for high-capacity energy storage systems. Due to the disadvantages of vanadium RFBs such as high cost and limited temperature operability [1], researchers have been developing new redox couples to replace vanadium. The use of relatively inexpensive transition metals (Fe, Cr, Co, etc.) in combination with ligands to form metal-ligand complexes has received considerable attention [2]. The redox potential of a metal ion of a metal-ligand complex can be tuned by forming a complex with a ligand, and the metal-ligand complex form helps alleviate the crossover problem [3].

A major challenge in the discovery and development of functional materials is to find and select the most optimized candidates from millions of possible materials [4]. High-throughput Synthesis (HTSy) enables simultaneous screening, synthesis and characterization of a large number of different material classes, providing unprecedented throughput and reproducibility. Therefore, HTSy can save energy, time, and cost for more efficient discovery of advanced functional materials [5]. In this study, based on HTSy methods, we used an automatic synthesis device (OT-2 liquid pipetting robot) to mix and heat metals (Ni, Cr, Cu, etc.) and ligand liquids to automatically design metal complexes. At the same time, a robot platform is developed to perform high-throughput electrochemical tests to quickly select suitable metal complexes for RFBs, and then conduct further related RFBs performance tests.

References

[1] C. Zhang et al., “Progress and prospects of next-generation redox flow batteries,” Energy Storage Mater, vol. 15, pp. 324–350, Nov. 2018, doi: 10.1016/J.ENSM.2018.06.008.

[2] C. Noh, M. Shin, and Y. Kwon, “A strategy for lowering cross-contamination of aqueous redox flow batteries using metal-ligand complexes as redox couple,” J Power Sources, vol. 520, p. 230810, Feb. 2022, doi: 10.1016/J.JPOWSOUR.2021.230810.

[3] C. Noh, Y. Chung, and Y. Kwon, “Highly stable aqueous organometallic redox flow batteries using cobalt triisopropanolamine and iron triisopropanolamine complexes,” Chemical Engineering Journal, vol. 405, p. 126966, Feb. 2021, doi: 10.1016/J.CEJ.2020.126966.

[4] Q. Zhang, A. Khetan, E. Sorkun, and S. Er, “Discovery of aza-aromatic anolytes for aqueous redox flow batteries via high-throughput screening,” J Mater Chem A Mater, vol. 10, no. 41, pp. 22214–22227, 2022, doi: 10.1039/D2TA05674G.

[5] J. Rodriguez, M. Politi, S. Adler, D. Beck, and L. Pozzo, “High-throughput and data driven strategies for the design of deep-eutectic solvent electrolytes,” Mol Syst Des Eng, vol. 7, no. 8, pp. 933–949, 2022, doi: 10.1039/D2ME00050D.

Figure 1