bluuebunny/crossref_metadata_2025 huggingface dataset:
Insights on Solid-electrolyte/electrode interfaces of All-solid-state Batteries: Multiscale Framework
Authors: Mamme Mesfin Haile , Bekaert Lieven , Gebregeorgis Tewelde , De Proft Frank , Hubin Annick , van Duin Adri
Published: September 2023

The harmonious transition of society towards carbon-free technologies, from fossil fuel to renewable energy sources only, including transition from combustion engined cars to electrical vehicles, requires efficient and safe energy storage technologies [1-3]. Among the various battery technologies being available today, all-solid-state batteries (ASSBs) have garnered a lot of attention, due to their many advantages, including the high thermal stability, non-flammability, long lifetime. Moreover, they enable the use of lithium metal anode (theoretical specific capacity 3862 mAh g-1), which would increase considerably the performance of the ASSBs [4,5]. However, the realization of ASSBs is hampered by a limited understanding of the nanometer-thin solid-state electrolyte/electrode buried interfaces. In this talk, we present our recent findings and theoretical developments on the nanometer-thin solid-state electrolyte and electrode interfaces of solid state electrolyte in combination with different anode and cathode electrode interfaces. By combining a multiscale framework (DFT, reactive force field to continuum scale) with surfaces and electrochemical techniques (including Electrochemical Impedance Spectroscopy), the structural origin of interfacial resistance, the degradation mechanisms, and the lithium-ion transport mechanism at the cathode interfaces at different working/environmental conditions (Electric field, temperature, state of charge, etc.) are now better understood. As a result, the strategy of a hybrid multiscale experimental and computational framework paves the way towards further understanding and (re-)designing highly compatible and stable

electrolyte/electrode interfaces, which can be extended to other energy conversion and storage devices. Some of the findings will be discussed during the presentation.

References

1. K. Dahal, et al., Sustain. Cities and Soc., 2018, 40, 222.

2. V. Stamenkovic, et al., Nat. Mater., 2017, 16, 57.

3. M. Whittingham, MRS Bull., 2008.

4. K. Takada, et al., ACS Energy Lett., 2018, 3, 98.

5. A. Zhamu, et al., Energy Environ. Sci., 2012, 5, 5701.
(Invited) Unification of Bulk Storage and Supercapacitive Storage
Authors: Xiao Chuanlian , Usiskin Robert , Maier Joachim
Published: September 2023

In typical insertion electrodes for batteries, the capacity is determined by bulk storage within the electroactive particles, which is comparatively well investigated and understood. In contrast, supercapacitor electrodes are dominated by interfacial storage at interfaces, which is well addressed experimentally. However the charge carrier chemistry (defect chemistry) especially in the latter case is not taken seriously. Consequently a bridge between the two important fields is absent. Following and extending our quantitative concept of job-sharing storage, a generalized description that includes bulk and space charge storage (electrochemical and supercapacitive storage) is possible. In other words the treatment of defect chemistry as a function of the degree of storage as well as of position is key to a unification.

The experimental part of our research uses TiO2 and Nb2O5 thin films. The precise measurement of the storage capacity of thin films as a function of thickness allows us to deconvolute bulk and interfacial contributions. We discuss the results in terms of bulk and space charge capacitance. The generalized treatment that comprises both contributions shows also how the ratio of both varies with the degree of storage. Meanwhile exploiting various techniques (bias dependent impedance, TEM and EELS) electric field and charge distributions from bulk to the interface region are investigated. In the same context we study the space charge behavior in a discretized manner rather than by using the analytical Poisson-Boltzmann function. In this way a more precise definition and demarcation of electrode and double layer capacity is achieved. In terms of application we expect this work to provide a better understanding of energy and power densities of storage devices which becomes particularly important for nanoionic systems.
Operando Measurement of Lithiation Gradients in NMC111-Argyrodite All-Solid-State Composite Cathodes
Authors: Stavola Alyssa M. , Guida Dominick P. , Bruck Andrea M. , Sun Xiao , Zhu Hongli , Gallaway Joshua W.
Published: September 2023

Achieving the high energy density targets in all-solid-state batteries (ASSBs) will require thick cathodes optimized for full utilization of active material. In composite cathodes with sulfide SSEs, the exclusion of carbon additives makes cathode design to balance ionic and electronic conductivities all the more important. Li-Ni1/3Mn1/3Co1/3O2 (NMC111) is a widely studied cathode material for its high energy density and high working voltage. The lattice parameters of this well-studied structure directly correlate to the amount of Li in the material, allowing for very accurate measurements of lithium-ion concentration gradients (lithiation gradients) throughout the cathode depth.

Spatially resolved lithiation gradients in thick NMC111/ Li6PS5Cl composite cathodes were measured using operando energy dispersive X-ray diffraction (EDXRD) on sealed and pressurized ASSBs with varying relative amounts of cathode active mass (CAM) and SSE. Electrochemical impedance spectroscopy (EIS) and transmission line modeling were employed to test the ionic and electronic conductivities of composite cathodes with similar varied CAM and SSE ratios. The balance of ionic and electronic conductivities was found to influence not only the lithiation gradients and utilization of active material in the cell, but also the NMC structural change throughout the depth of the cell resulting in peak bifurcation in the NMC (003) diffraction pattern.

Sulfide ASSBs suffer from a large capacity loss on the first cycle due to formation of the cathode electrolyte interface (CEI). To study this interface formation and capacity loss, in situ EIS was performed during the first charge and discharge of the full cell (Li/In| Li6PS5Cl| NMC111/Li6PS5Cl). This piecewise EIS allows us to analyze both time dependent and state-of-charge dependent interfacial processes while the battery cycles with no modifications to cell design.

Acknowledgments

We acknowledge financial support from the National Science Foundation under Award Number CBET-ES- 1924534. This research used resources of the Advanced Photon Source beamline 6-BM, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
(Invited) Critical Electrochemical Limits before Dendrite Penetration in Li-Ion-Conducting Electrolytes
Authors: Bai Peng
Published: September 2023

Rechargeable metal anodes hold the promise to nearly double the energy density of available metal-ion batteries by removing the ion-intercalation anodes. However, metal dendrites that may form during recharging can even penetrate hard and stiff ceramic electrolytes, causing irreversible damage or short-circuit risks. While lithium dendrites formed in liquid electrolytes are distinctively different from those formed in ceramic electrolytes, the ion polarization process before the onset of dendrite formation show similarities. However, due to the limited number of samples, inconsistent sample properties, and inaccurate interfacial current densities, rigorous analyses of the critical electrochemical limits in ceramic electrolytes have been difficult. In this presentation, we will first introduce a rigorous analysis of the system-specific limiting current, Sand’s capacity, and their dependence on the electrolyte thickness, to reveal the role of transport limitation in lithium dendrite formation in liquid electrolytes, via the combined operando microscopy and mathematical models. By performing two types of one-way polarization experiments with hundreds of highly consistent Li|LLZTO|Li miniature cells (LLZTO: Li7-xLa3Zr2-xTaxO12), we discover for the first time the development and relaxation of a significant transient impedance at the critical current density (CCD) that cannot be attributed to interfacial void formation but to the polarization of mobile ions, which were confirmed by electrochemical impedance diagnosis and scanning electron microscopy focused ion beam (SEM-FIB) characterizations. The similar electrochemical limits identified in this study suggest that the empirical CCD in ceramic electrolytes may be interpreted as a transport-limited electrochemical phenomenon, despite that void formations would apparently exacerbate the dynamics.
(Invited) Stable Anode-Free All-Solid-State Lithium Battery through Tuned Metal Wetting on the Copper Current Collector
Authors: Mitlin David , Wang Yixian , Liu Yijie
Published: September 2023

It is demonstrated that a standard copper foil current collector with appropriately modified surface chemistry will allow for stable lithium cycling in an anode-free all-solid-state lithium battery (AF-ASSB). An argyrodite solid electrolyte Li6PS5Cl (LPSCl) is employed without any modifications or secondary interlayers. The tuned lithophilic copper surface allows for stable plating and stripping, reducing the overpotentials and significantly improving the Coulombic efficiency (CE). During continuous plating experiments using half-cells (1 mA cm-2), the accumulated thickness of electrodeposited Li on Li2Te-Cu is more than 70 μm, which is the thickness of Li foil counter-electrode. Full AF-ASSB with NMC811 cathode delivers an initial CE of 83% at 0.2C, with a cycling CE above 99%. Post-mortem cryo-FIB-SEM analysis demonstrates uniform electrodeposited metal microstructure, with no signs of voids or dendrites at the collector-SE interface. The same copper current collector but unmodified leads to inhomogeneous Li plating, with “dead metal” formation and an irregular honeycomb-like solid electrolyte interphase (SEI) interspersed with pores. Density functional theory and mesoscale calculations provide complementary insight regarding nucleation-growth behavior. Unlike for conventional liquid-electrolyte metal batteries, the role of current collector/support lithiophilicity has not been explored for emerging AF-ASSBs.

Figure 1
Operando Quantification and Visualisation of Dendrite-Induced Stresses in Ceramic Electrolytes Via Photoelasticity
Authors: Athanasiou Christos E. , Fincher Cole D. , Gilgenbach Colin , Carter W. Craig , Chiang Yet-Ming , Gao Huajian , Sheldon Brian W.
Published: September 2023

The measurement of stress fields around lithium metal dendrites in solid electrolytes in operating conditions is critical for the design of next-generation, dendrite-resistant solid electrolytes. Prior work, both experimental and theoretical, indicates that the developed stresses in the in the electrolyte can be significantly high. However, direct stress measurements are still missing as they entail inherent experimental difficulties associated with probing stress fields at small scale brittle specimens operando.

By employing the principle of photoelasticity combined with electrochemical cycling in a plan-view cell the aforementioned challenges are bypassed, allowing not only to track the stress field as the dendrite events progress, but also to obtain whole-field stress information on a propagating dendrite in an LLZTO electrolyte. This new experimental methodology allows for direct stress measurements around the dendrite tip. The experimental data demonstrate that the dendritic events at such current densities can be understood by the classic Griffith - Irwin fracture theory.
Operando X-Ray CT Analysis of Composite Electrode in All-Solid-State Battery Using Silicon Anode
Authors: Orikasa Yuki , Matsumoto Mao , Watanabe Ayaka , Sakka Yuya , Zhong Chengchao , Yamashige Hisao
Published: September 2023

As a next-generation rechargeable battery, all-solid-state battery is expected for used in practical applications, in which electrolyte solution of the current lithium-ion battery is replaced with a solid electrolyte. To further increase the capacity of all-solid-state batteries, silicon is used as the anode active material forming an alloy with lithium. However, in the charge and discharge reaction using silicon anode, poor cycle capability due to the volume change of the silicon alloying reaction has been known. Many reports are limited to the analysis of the volume change of the whole electrode, and there are few reports on the quantitative analysis of the volume change of the silicon active material itself. In this study, X-ray computed tomography (X-ray CT) was used to analyze the expansion and contraction of silicon-active materials in all-solid-state battery. X-ray CT analysis can provide the contacted state information between electrode active materials and solid electrolytes [1]. By operando X-ray CT analysis, the expansion and contraction behavior of silicon particles during charging and discharging on the electrode was studied.

Nb-coated LiNi1/3Co1/3Mn1/3O2(NCM), Li10GeP2S12(LGPS), acetylene black (AB) mixed at a weight ratio of 1:1:0.2 were used as the cathode composite. Silicon, LGPS, AB mixed at a weight ratio of 1:1:0.1 were used as the anode composite. All-solid-state battery, Si | LGPS | NCM was assembled in a cylinder with an inner diameter 1 mm. The cell was brought into SPring-8 BL20XU beamline, and the operando X-ray CT measurement was carried out. From the obtained X-ray CT images, the three-dimensional analysis of silicon particles was performed.

Mean expansion coefficients of silicon‐particles traced during charging and discharging were calculated. The expansion of silicon particles by charging (lithiation) and the contraction of silicon particles by discharging (delithiation) are confirmed. Furthermore, the volume expansion rate of the silicon particles after the charging is average exceeded 300%. After discharge, silicon shrinkage is observed with delithiation, but the solid electrolyte cannot follow the volume change, and the silicon/solid electrolyte interface is broken. However, the contact is not completely failed, maintaining the partial contact between silicon and the electrolyte.

[1] Y. Sakka, H. Yamashige, A. Watanabe, A. Takeuchi, M. Uesugi, K. Uesugi and Y. Orikasa, J. Mater. Chem. A, 10 16602–16609 (2022).

Acknowledgement: This work was partially supported by the New Energy and Industrial Technology Development Organization (NEDO), JPNP20004.
(Invited) Pragmatic Approach and Challenges of All Solid State Batteries: Hybrid Solid Electrolyte for Technical Innovation
Authors: Choi Kyoung Hwan , Yi Eunjeong , Kim Kyeong Joon , Lee Seunghwan , Park Myung-Soo , Lee Hansol , Heo Pilwon
Published: September 2023

For the growth of electric vehicle market, lithium-ion batteries (LIBS) used in the EVs still requires safety and reliability. Unfortunately, large-scale application of the LIBs is being challenged due to the fact that the use of flammable liquid electrolytes has caused safety issues such as leakage and fire explosion. In this respect, all-solid-state batteries (ASSBs) have been intensively studied to ensure the safety and mileage that are superior to the current LIBs. In terms of solid electrolytes, oxide electrolytes not only shows high ionic conductivity (10-4 ~ 10-3 S/cm) but also high mechanical strength to suppress surface dendrite formation. In addition, the oxide electrolytes possess advantages such as non-flammability, high thermal stability, and excellent electrochemical stability (~ 6 V), enabling high temperature/high voltage operations of oxide-based ASSBs. However, most of oxide materials require a sintering process at high temperatures to form a planar solid electrolyte. And a lack of flexibility results in non-uniform electrolyte/electrode contact in the battery, which makes it difficult to apply the rigid oxide electrolyte directly. On the other hand, solid polymer electrolytes have also been actively investigated due to no leakage, good electrolyte/electrode contact, easy processing, flexibility, and good film formability. However, the solid polymer electrolytes have critical disadvantages such as low ionic conductivity at room temperature and low thermal/mechanical stability, which precludes commercialization of solid polymer-based ASSBs despite their advantages. To overcome each disadvantages of oxide and polymer electrolytes, we developed hybrid electrolytes for improved ionic conductivity, easy processing, and formation of continuous electrolyte/electrode interface. In this presentation, pragmatic approach and current challenges related to solid batteries will be discussed including innovative manufacturing process. Hybrid electrolytes and their synergistic effect on the battery performance as a promissing solution will be presented [Fig. 1]
(Invited) Polymer Blends As Electrolytes in All-Solid-State Batteries
Authors: Dolle Mickael , Caradant Lea , Verdier Nina , Foran Gabrielle , Nicolle Paul , Lepage David , Prébé Arnaud , Aymé-Perrot David
Published: September 2023

Advantages of polymer electrolytes include material flexibility, good interfacial compatibility and easy processability. However, these materials typically possess room temperature ionic conductivities, oxidation stability windows and mechanical strengths that are too low for them to be useful electrolyte materials in all-solid-state batteries (ASSB). One reason for this is that polymer properties that favor improved ionic conductivity such as high polymer chain mobility are generally not compatible with good mechanical strength making these properties difficult to optimize simultaneously. One strategy that has been investigated to this effect is polymer blending. The idea is that polymers with good ionic conductivity can be blended with thermoplastic or elastomeric materials that have high mechanical resistance to create a new electrolyte material with the properties of its combined parts. In this work, polymers with good ionic conductivity were combined with thermoplastic materials with high mechanical strength via melt processing methods to yield solid polymer electrolytes. The resultant electrolyte materials show promising results when implemented in composite electrodes and electrolytes for use in ASSB which will be discussed in this talk.
The Zircon Structure As a Prototype Host for Fast Monovalent and Di-Valent Ionic Conduction
Authors: Chen Qian , Sari Dogancan , Rutt Ann , Kim Jiyoon , Ceder Gerbrand , Persson Kristin A.
Published: September 2023

"Beyond Li-ion" energy storage solutions based on ions such as Na, Mg, Ca and Zn-ion have attracted increasing attention due to growing concerns about the cost, resource availability and safety of the currently dominant Li-ion batteries. One of the greatest challenges for beyond-Li systems, especially multivalent ones, is the lack of materials with high ionic mobility.

In this study, we find that zircon-type framework presents a unique structural environment that enables superior conduction of multiple species including Na+, Ca2+, Mg2+ and Zn2+, even in the dilute carrier concentration regime. Nudged elastic band (NEB) calculations show very low diffusion barriers for Na/Ca/Mg/Zn in pristine YPO4 and ab initio molecular dynamics (AIMD) simulations confirm the 1D percolating diffusion channel in the zircon-type framework. These 1D percolating channels of adjacent, distorted octahedral sites result in a smoothly varying coordination environment thus correspondingly low activation barriers. The phase stability of doped compositions is examined when both carrier ion and subvalent dopants are introduced into the system and confirm good stability through low decomposition energy of compositions with different carrier-dopant combinations. Among these compositions, we found Na0.0625YSi0.0625P0.9375O4 exhibiting a high Na+ conductivity of 0.99 mS/cm at 300 K with an activation energy of 220 meV. Finally, we identify dopant-carrier association in doped YPO4 as a key challenge for long-range diffusion in this structure family.
Electric Vehicle Battery Replacement Costs Under Realistic Fast Charging Behaviors
Authors: Morin Hannah , Whitacre Jay , Michalek Jeremy
Published: September 2023

Fast charging networks are being constructed in the United States based on the assumption that electric vehicles can sustainably fast charge. However, fast charging has been shown to shorten calendar and cycle life across multiple lithium-ion battery chemistries. Public information on degradation is limited for realistically fast charged commercial cells and extensions from academic work on commercial-adjacent chemistries is difficult. Here, we model realistic consumer charging behavior by cycling commercial NCA 21700 and LFP 26650 cells under 20 different fast charging behaviors, mixing fast charging (2C) and Level 2 charging (C/6|C/5) under different voltage bounds and under well-ventilated thermal conditions. The degradation observed in these tests were used in an economic model to estimate the number and present value cost of battery pack replacements over an electric vehicle’s lifetime, in which results map to a worst case, upper bound scenario. Overall, the tested LFP cells showed extremely low rates of degradation compared to the tested NCA cells. Cycling the NCA cells under the most aggressive charging scenario (2.5-4.2V, 100% of charging at 2C) showed more than 100 pack replacements over 8 years and a present value cost of more than $1M. Cycling the LFP cells under equivalent conditions (2-3.65V, 100% of charging at 2C) showed only 0-1 pack replacements.
Multifaceted Effects of Ring Fusion in Charged Dialkoxyarene Redoxmers
Authors: Li Zhiguang , Jeong Heonjae , Fang Xiaoting , Zhao Yuyue , Zhang Jingjing , Shkrob Ilya A. , Wei Xiaoliang , Cheng Lei , Zhang Lu
Published: September 2023

Redox flow batteries (RFBs) hold promises for long-duration energy storage, with various chemistries demonstrated by academia and industry. However, their practical applications remain limited due to high active material cost, low energy density, narrow voltage window, and limited cyclability. Improving the performance of redox active materials (redoxmers) in RFBs is crucial for addressing these challenges. In this study, to better understand the impact of π-conjugation of aromatic redox cores on the redoxmers’ electrochemical behavior, we systematically investigated a series of dialkoxy benzene based redoxmers, including 1,4-dimethoxy benzene (DMB), 1,4-dimethoxynaphthalene (DMN), 2-ethyl-9,10-dimethoxyanthracene (EDMA). As the conjugation increases from DMB to DMN, we observed a lower redox potential, improved kinetic stability, and longer cycling life. However, further expanding the conjugation as in EDMA resulted in rapid O-dealkylation of the radical cation, possibly due to increased strain in methoxy groups. For DMN, the radical cation is observed to be prone to neutralization (likely via disproportionation) and can be recharged, suggesting a longer cycling life than the calendar life. Our study indicates that extending the π-system alters reactivity in multiple ways, and lowering the oxidation potential through π-conjugation to improve redoxmer stability should be cautiously pursued.
Aggregation and Capacity Limiting Effects in Anthraquinone-Based Flow Battery Negolytes
Authors: Pasadakis-Kavounis Alexandros , Baj Vanesa , Hjelm Johan
Published: September 2023

Anthraquinone-based molecules constitute promising electroactive materials for use in aqueous organic flow batteries. It has been observed that in high concentration in aqueous solutions these molecules tend to aggregate. It has been speculated that the aggregation causes a decrease in capacity as the number of electrons partaking in the electrochemical processes gets smaller. Three water-soluble anthraquinones were studied in different electrolytes in order to have a more meaningful insight into the possible causes, aggregation phenomena and electrochemical performance. 1H-NMR and PGSTE measurements were performed in non-deuterated solvents. Single cell testing was performed to assess the number of electrons. The aggregation constants have been determined using data from both 1H-NMR and PGSTE at different concentrations. Those data were fit into the Isodesmic model wherein the diffusion coefficient of the monomers and aggregation constants were extracted and compared. In all cases NMR signals showed aggregation taking place but it did not translate to reduced number of electrons. Capacity retention was very profound in the case of disodium anthraquinone-2,7-disuflonate (AQDS) in carbonate solution, wherein a reduced amount of electrons from 2 to 1 was observed. 2,6 dihydroxyanthraquinone (DHAQ), to a less extent, also showcased a reduced amount of electrons in carbonate solution.
Insights into Electrolyte Reactivity and Solid Electrolyte Interphase Formation at the Li Metal Anode Surface from DFT Simulations
Authors: Agarwal Garvit , Brock Casey Neil , Rao Karun Kumar , Fonari Alexandr , Tiwari Subodh , Gavartin Jacob L , Kwak H Shaun , Leswing Karl , Halls Mathew D
Published: September 2023

Solid electrolyte interphase (SEI) is a critical component of lithium ion batteries, yet is poorly characterized and not well understood. We use plane wave density functional theory simulations to perform a comprehensive study of the degradation reaction mechanisms of four electrolyte solvents and additives, ethylene carbonate (EC), propylene carbonate (PC), fluoroethylene carbonate (FEC), and vinylene carbonate (VC), at the Li (001) metal anode surface. The calculations provide fundamental insights into electrolyte decomposition and spontaneous SEI formation. Utilizing automated workflows implemented in the Schrödinger Materials Science Suite, we compute the adsorption energies and calculate the reaction energies for each decomposition pathway. Furthermore, we employ nudged elastic band calculations to compute the decomposition reaction barriers and provide mechanistic insights into the onset of SEI formation. We analyze trends in decomposition reaction energies and the relationships between the reaction energies and the activation barriers for the various electrolyte molecules as a function of applied bias potential. We find that the preferred decomposition pathways are different for the solvent molecules (EC and PC) than for the additives (FEC and VC). Calculations also suggest that applied bias reduces decomposition reaction barriers thus enhancing SEI formation. Such a comprehensive dataset of reaction energies and activation barriers provides useful benchmarks for the development and validation of reactive machine learned force fields for modeling advanced battery chemistries at a larger scale.
Macroporous Carbon Films Support Vs. Conventional Carbon Particles with FeN4 Sites for Oxygen Reduction in Gas-Diffusion-Electrodes
Authors: Kellner Simon , WANG Mengnan , Heutz Sandrine , Stephens Ifan E L , Titirici Magda
Published: September 2023

Novel synthetic approaches have been developed to maximize the active site density of atomically dispersed Fe sites coordinated to nitrogen in carbon matrix. (Fe-N-C) (1,2) Nevertheless, the realistic maximum for single iron sites in these catalysts is deduced to be limited to 1021 sites per gram. (3) Therefore, for the application these Fe-N-C catalysts at the cathode for the oxygen reduction reaction in fuel cells, the catalyst material loading has to be increased to be able compete with the performance of Pt/C catalysts. Due to the resulting increased thickness of Fe-N-C catalyst layers, the oxygen available for the ORR at high current densities is dependent on the insufficient transport of oxygen across the catalyst layer. Freestanding catalyst nanostructured films, whose porosity is controlled across the entire thickness of the catalyst layer are expected to improve the mass transport at high current densities. Carbon nanostructures could provide the support substrate for such freestanding catalyst films. For instance, mesophase pitch-based films have been templated by silica (SiO2) nanoparticles have favourable morphologies for supporting Pt. (4) However, harsh conditions and long reaction times are required to etch away the SiO2. In our work, SiO2 nanoparticles are substituted by polystyrene nanoparticles, which decompose and tracelessly evaporate during the carbonization process. We have fabricated carbonized films of multiple thicknesses. We found 100 µm to be optimal, substantially thicker than Pt based electrodes to accommodate the lower density of sites and cheaper catalyst material. which is a usual thickness for Fe-N-C-based cathodes. Iron phthalocyanine (FePc) as a model active site is adsorbed on the freestanding carbon film. Gas-Diffusion-Electrodes (GDE) enable us to investigate the performance of such freestanding thin film catalysts at high current densities relevant for fuel cells. (5) A comparison of the ORR performance of catalyst layers, based on carbon films support (A) and conventional carbon particle support (B) are presented. We discuss the effect of adjusting the thickness of the two types of catalyst layers on the performance.

1 Barrio J, Pedersen A, Feng J, Sarma S. C., Wang M, Li A. Y. , Luo, H. Ryan M. P., Titirici M.-M., Stephens I. E. L. J. Mater. Chem. A, 2022;10: 6023-30

2 Mehmood A, Pampel J, Ali G, Ha H Y, Ruiz-Zepeda F, Fellinger T P Adv. Energy Mater., 2018; 8: 11649-55

3 Mehmood A, Gong M, Jaouen F, Roy A, Zitolo A, Khan A, Sougrati M.-T., Primbs M., Martinez Bonastre A, Fongalland D, Drazic G, Strasser P, Kucernak A Nat. Cat., 2022;5, 311-23

4 Atwa M, Li X, Wang Z, Dull S, Xu S, Tong X, Tang R, Nishihara H, Prinz F, Birss V 2021;8: 2451-62

5 Inaba M, Jesen A W, Sievers G W, Escudero-Escribano M, Zana A, Arenz M Energy Environ. Sci,2018;11: 988-94
(Invited) Two-Dimensional Materials-Based Structure Design for Energy Conversion and Storage
Authors: Luo Zhengtang , Hossain Md Delowar , LI Yuyin , Goddard William A
Published: September 2023

We have investigated activity correlations with catalysts, electronic structure based on DFT calculations, in order to clarify the origin of reactivity for a series of transition metals supported on two-dimensional material, such as nitrogen-doped graphene as single atom catalysts (SACs) for hydrogen evolution reaction (HER), CO2 reduction reactions and for batteries. For example, we applied the grand canonical potential kinetics (GCP-K) formulation of quantum mechanics to predict the kinetics as a function of applied potential (U) to determine faradic efficiency, turn over frequency, and Tafel slope for CO and H2 production for all three sites. With this method, we are able to predict an onset potential and current at of different structures. We have also used MD simulation to visualize metal nucleation and morphological evolution at the atomistic level in batteries when graphene-based material is used support. The corresponding materials are synthesized and used to verify the computational results.
(Invited) Interface Engineering of Nanocarbon-Supported Catalysts for Direct Ethanol Fuel Cells
Authors: Yang Yang
Published: September 2023

A new strategy to controllably regulate the local bonding states and local coordination environment (LCE) in the classic carbon-supported metal catalysts for direct ethanol fuel cells will be discussed. Particularly, we use F-doped Pd-X-C (X = N, P, S, B) as model systems to study the LCE effects on oxygen reduction reaction (ORR) and ethanol oxidation reaction (EOR). The N-rich Pd surface with regulated LCE not only boosts the activity of Pd but also enhances the catalyst stability by inhibiting the migration and agglomeration of Pd as well as endowing carbon support with long-term anti-corrosion properties. As a result, an unbeatable power density of 0.57 W cm-2 with more than 5,900 hours of operation was achieved in direct ethanol fuel cells using the proposed LCE-regulated catalysts, remarkably outperforming benchmarking catalysts. In an extended study, the concept of F-induced LCE regulation can be applied to other Pd-X-C catalysts (X = P, S, B) with drastically improved activities and stabilities
Nanoelectrical Mapping of Carbon Nanofibers By Means of Peakforce Tunneling Atomic Force Microscopy
Authors: Borowec Julian , Selmert Victor , Kretzschmar Ansgar , Fries Kai , Tempel Hermann , Hausen Florian
Published: September 2023

Electrospun polyacrylonitril (PAN) based carbon nanofibers (CNFs) are promising candidates for applications in energy conversion and storage. This originates from their electrical properties,[1] and their relatively easy manufacturing from abundant and cheap material.[2] However, the utilization of PAN CNF mats in devices such as electrolyzers is currently limited by their low conductivities. Advanced nanoelectrical characterization methods, such as Conductive Atomic Force Microscopy (C-AFM),[3] give insights into nanoscale limitations of the CNF’s conductivity. Revealing the limitations will help tailoring CNF’s conductivity. Thereby, a rational CNF design for applications in energy devices will be enabled.

In this work, morphology, structure and nanoelectrical properties of electrospun PAN CNF mats, which were carbonized at different temperatures, are investigated by means of PeakForce Tunneling Atomic Force Microscopy (PF TUNA, Bruker). Next to the fundamentals of PF TUNA, topography and current maps of PAN CNF networks are presented and critically discussed. Topography maps reveal relatively homogeneous CNFs, which are in line with the homogeneous currents detected across the CNF network. The detected current signals indicate electrically well-interconnected fibers within the mats. Consequently, poor fiber interconnections or heterogeneities are not the limiting factor for an ideal macroscopic conductivity. High resolution maps of CNFs show that a large fraction of the surface area is non-conductive and that the fraction of conductive domains depends critically on the carbonization temperature. The nanoelectrical currents detected by PF TUNA on CNFs carbonized at different temperatures correlate strongly to the respective macroscopic conductivities measured by the four point method.

The obtained results show that PF Tuna is a powerful tool to correlate nano- and macroscale conductivities. Future investigations, especially with CNFs containing integrated additives, will provide significant insights into nano- and macroscale relations and pave the way towards CNFs with desired electrical properties.

Literature:

[1] Gehring et al., RSC Adv. 2019, 9 (47), 27231–27241.

[2] Kretzschmar et al., ChemSusChem 2020, 13 (12), 3180–3191.

[3] Butnoi et al., JMR&T 2021, 12, 2153–2167.
Selenized Binary Transition Metals-Mxene Composite for the High-Performance Asymmetric Supercapacitors
Authors: Li Hui , Ko Min Jae
Published: September 2023

The exploration of novel and efficient energy storage materials is crucial for the development of high-performance supercapacitors. Herein, we develop a new composite with multilayered MXene (Ti3C2Tx) nanoparticles and porous NiCo2Se4 nanosheets. The unique accordion-like nanostructure and strong interfacial interactions of MXene introduce the favorable nanocomposite with a larger surface area and reasonable cycling stability. The substitution of Se for the oxyhdryl in the Ni-Co based hydroxides modulates the orbital hybridization with the corresponding metallic cations, which effectively improves the electrochemical activity of Ni/Co and reduces the adsorption/desorption energy barrier of electrolyte ions. Based on the above considerations, we proposed a new Ni-Co TMSe and multilayer Ti3C2Tx MXene nanocomposite on NF (denoted as MXene-NiCo2Se4@NF) that could act as a binder-free electrode for SCs. In this regard, compared with the directly grown pure NiCo2Se4 electrode, the composite electrode exhibits a larger surface area, higher mass-loading, and lower internal resistance by the introduced MXene particles. The well-designed hierarchical structures make it possible for facilitated electrolyte diffusion, more active sites, fast electron transport, and improved nanostructure stability for a longer lifespan. Owing to such multifold attributes, the fabricated composite electrodes enable to attain a specific capacity of 786.25 C/g and 589.22 C/g at the current density at 1 A/g and 20 A/g with a good rate capability, respectively. The selenization improved the inherent conductivity of active materials and contributed to the lower deprotonation energy barrier, resulting in facile electron transfer in the Faradaic reaction process. Furthermore, the composite structure retained over 90% of capacity after 8000 cycles. The assembled asymmetrical device displays a high specific energy density of 64.36 Wh/kg, at a power density of 0.8kW/kg. These results suggest that the proposed composite structure can potentially be used as active material in various practical applications.
(Invited) 2D Mxenes for Energy Storage Applications
Authors: Matthews Kyle , Gogotsi Yury
Published: September 2023

MXenes are a family of two-dimensional (2D) transition metal carbides and nitrides, with a general structure of Mn+1XnT
x
, where M is the transition metal, X is carbon and/or nitrogen, and T represents the surface terminations (F, O, OH). MXenes have attracted attention in a multitude of energy storage applications due to their high electronic conductivity, tunable interlayer spacing, redox-active transition metals, and hydrophilic surface groups. In this talk, we discuss the use of MXene electrodes in supercapacitor applications, including aqueous, non-aqueous, and water-in-salt electrolytes. The variability of MXenes is demonstrated with each electrolyte system showing unique electrochemical responses, not limited to redox and/or intercalation pseudocapacitance, and hydrated cation intercalation. Furthermore, the versatility of the hydrophilic, 2D morphology of MXenes is demonstrated through its use in multiple form factors, not limited to flexible free-standing films, multilayer powder electrodes, interdigitated microsupercapacitors, knitted textiles, and more. New directions and perspectives for MXenes in energy storage are discussed, including MXenes’ use as passive components (separators, current collectors, binders, scaffolds, conductive additives) in energy storage systems.

Figure 1 (A) Schematic illustration showing MXenes’ electrochemical properties for ion storage applications. (B) Cyclic voltammetry (CV) data collected at scan rates from 10 to 100,000 mV·s−1 for a 90-nm-thick Ti3C2T
x
film. (C) Influence of an electrolyte’s solvent on the lithium-ion storage capacity of Ti3C2T
x
; CV curves of microporous Ti3C2T
x
electrode in 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in DMSO, acetonitrile (ACN), or propylene carbonate (PC) electrolytes. (D) A digital photograph showing the wafer scale fabrication of an array of 143 MXene microsupercapacitors. (E) Photograph of a knitted textile with an interdigitated pattern made using Ti3C2T
x
MXene-coated cotton yarn to produce electrodes for wearable textile supercapacitor.

Reference

[1] A. VahidMohammadi, J. Rosen, Y. Gogotsi, Science,
2021, 372, eabf1581.

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(Invited) Harvesting Energy from Freestanding Graphene Thermal Fluctuations
Authors: Thibado Paul M , Kumar Pradeep , Singh S , Neu J , Bonilla L
Published: September 2023

Highly flexible, electrically conductive freestanding graphene membranes hold great promise for vibration energy harvesting applications. In this study, we present numerical results for a graphene ripple treated as a Brownian particle coupled to an energy harvesting circuit. When circuit and particle are at the same temperature, the second law forbids harvesting energy from the thermal motion of the Brownian particle, even if the circuit contains a rectifying diode. However, when the circuit contains a junction followed by two diodes wired in opposition, a special ultraslow convergence to equilibrium may be imposed. Detailed balance is temporarily broken as current flows between the two diodes and charges two storage capacitors. The harvested energy is taken from the surrounding thermal environment, and we show that the system obeys the first and second laws of thermodynamics. Experimental results will also be presented for a custom designed integrated circuit built by TSMC combined with post-processing lithography on bare die followed by graphene suspension.

Figure 1
Tetracene Dimers: A Platform for Balancing Intramolecular Up- and Down-Conversion
Authors: Guldi Dirk Michael
Published: September 2023

Photon energy conversion can be accomplished in two opposing manners, down conversion (i.e., singlet fission, SF), and up-conversion (often referred to as triplet-triplet annihilation up-conversion, TTA-UC), both of which have the potential to help overcome the Shockley-Queisser limit of single-junction solar cells. Inter-chromophore electronic coupling plays opposing roles in these two processes. The energies of the lowest singlet excited state and twice the triplet excited state are comparable in tetracene dimers, which exhibit both up- and down-conversion. Here, we have designed meta-phenylene- and 1,3-diethynyladamantyl-linked tetracene dimers with different electronic coupling to probe the interplay between intramolecular SF (intra-SF) and intramolecular TTA-UC (intra-TTA-UC) viasteady-state and time-resolved absorption and fluorescence spectroscopy. In addition, temperature-dependent measurements are carried out to shed light on the thermal effects on intra-SF and intra-TTA-UC. We have also used a Pd-phthalocyanine as photosensitizer to enable intra-TTA-UC in the two dimers via indirect photo-excitation in the near-infrared. These results not only reveal the interplay between intra-SF and intra-TTA-UC, but also provide guidelines and strategies for the design of photon down- and up-converting materials.
(Second Place Poster Award) Improving Oxygen Reduction Reaction ORR Fuel Cell Efficiency with Carbon Nano Onions
Authors: Steiger Florian , Kaiser Pascal , Assebban M'hamed , Hirsch Andreas , Abellán Gonzalo , Echegoyen Luis , Mayrhofer Karl J. J. , Cherevko Serhiy , Pérez-Ojeda Rodríguez Maria Eugenia , Lloret Segura Vicent
Published: September 2023

Hydrogen Fuel cell innovations are cutting-edge clean power solutions highly demanded nowadays. Since the oxygen reduction reaction (ORR) in fuel cells needs to be catalyzed heterogeneously, conductive substrates such as carbon materials are critical for the construction of electrocatalysts. Thus far, the research has been focused on commercially available carbon supports such as the well-known Vulcan, and the high-surface area Ketjenblack.[1] Thanks to the fast development of material science, other carbon supports such as graphite, graphene oxide, and carbon nanotubes have been also studied in a lesser extent, mainly due to their novelty and underdeveloped scale up syntheses.[2,3] This work focuses on utilizing a relatively new and, as of yet, largely unexplored carbon nanomaterial: carbon nano onions (CNOs).

CNOs are spherical nanoparticles of about 5 nm diameter composed of concentrical multi-layered fullerenes, first discovered by Ugarte in 1992. CNOs exhibit outstanding properties such as low density, high thermal stability, and a graphitic multilayer morphology, which makes them excellent candidates for a wide variety of applications. Furthermore, the onion’s large surface area and high conductivity make them particularly interesting as catalyst support for electrochemical applications as they have already been demonstrated to be a superior Pt support alternative thanks to a higher cycling stability compared to carbon black, since their particle size and morphology suppress catalyst agglomeration and avoid its ripening.[4] However, despite their excellent long-term stability, the few available studies using CNOs were performed using the rotatory disc electrode (RDE) method, reaching only modest performance in the mA / cm2 range. Thus, our work aims to further extend upon this research by measuring the ORR performance with a gas diffusion electrode (GDE), to reproduce realistic fuel cell conditions.[5] The catalyst layer, obtained by growing Pt nanoparticles on CNOs, is characterized by electrochemical measurements such as ORR polarization curves, electrochemical active surface area (ECSA) by the CO-stripping method, and O2-mass transport. The utilization of GDE cells allows for higher current densities and a realistic catalyst mass transport compared to the RDE method, thus better representing an applied ORR fuel cell test.[6]

[1] Electrochem. Solid-State Lett.
2005, 8, A320-A323

[2] Carbon
2013, 58, 139-150

[3] Energy Environ. Sci.
2010, 3, 1286-1293

[4] ACS Appl. Mater. Interfaces
2017, 9, 28, 23302–23308

[5] Angew. Chem. Int. Ed.
2021, 60, 8882-8888

[6] ACS Energy Lett.
2022, 7, 2, 816–826

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(Digital Presentation) Self-Discharge Study of Carbon-Based Supercapacitors with Tunable Pore Size
Authors: Zhang Qing , Wang Yuru
Published: September 2023

Electrochemical double-layer capacitors (EDLCs), as a major type of energy storage devices besides rechargeable batteries such as lithium-ion batteries, holds excellent properties such as high power density and ultra-long cycling stability[1-3]; however, its fast self-discharge process has become the major issue that impedes its development and application. Even though research on EDLCs’ self-discharge has demonstrated that the fast self-discharge rate can be tuned even repressed through modifying certain structural properties of electrodes or electrolytes[4-9], to the end of realizing full control over the self-discharge process requires unveiling the fundamental relation between structural parameters (i.e., the pore structure, the surface functionalities, the electrolytic ion size and shape, and etc.) and the self-discharge performance.

Carbon, due to its superior chemical stability, high surface area, natural abundance, etc.[4,10], has become one of the main types of electrode materials under extensive research interest for developing advanced EDLCs. Herein, we focus on tuning the pore size, one of the major structural properties of carbon materials relating to its electrochemical performance, to study its effects on self-discharge process and to learn how to construct the optimal pore structure with respect to certain application requirements.

In this work, porous carbon materials with designed pore structure are prepared via soft-template method to analyse the self-discharge performance. Through investigating the effects of pore size, as the single variable, on the self-discharge process, as well as on the micro-electrochemical process on the electrode/electrolyte interface, underlying mechanism between pore size and the self-discharge performance has been constructed. These findings should provide guidance on how to locate the optimal pore size for a chosen electrolyte and to realize control over self-discharge, which will serve as solid references for designing the next-generation EDLCs with high performance and controllable self-discharge rates.

Reference

[1] X. Chen, R. Paul, L. Dai, Natl. Sci. Rev., 2017, 4(3), 453-489.

[2] G. Wang, L. Zhang, J. Zhang, Chem. Soc. Rev
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2012, 41, 797-828.

[3] Y. Liu, Y. Shen, L. Sun, J. Li, C. Liu, W. Ren, F. Li, L. Gao, J. Chen, F. Liu, Y. Sun, N. Tang, H. Cheng, Y. Du, Nat. Commun., 2016, 7, 10921.

[4] Q. Zhang, C. Cai, J.W. Qin, B.Q. Wei, Nano Energy., 2014, 4, 14-22.

[5] T. Tevi, H. Yaghoubi, J. Wang, A. Takshi, J. Power Sources., 2013, 241, 589-596.

[6] L. Chen, H. Bai, Z. Huang, L. Li, Energy Environ. Sci., 2014, 7, 1750-1759.

[7] G. Shul, D. Bélanger, Phys. Chem. Chem. Phys., 2016, 18, 19137-19145.

[8] M. Xia, J. Nie, Z. Zhang, X. Lu, Z.L. Wang, Nano Energy., 2018, 47, 43-50.

[9] J. Menzel, E. Frackowiak, K. Fic, Electrochimica Acta, 2020, 332, 135435.

[10] D.P. Dubal, O. Ayyad, V. Ruiz, P. Gomez-Romero, Chem. Soc. Rev., 2015, 44, 1777–1790.

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