bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Bipolar Membrane Electrolysis for CO2 to Ethylene
Authors: Hatzell Marta , Song Hakhyeon
Published: September 2023

Carbon dioxide conversion systems are important to drive down the cost of carbon capture through the creation of valuable products. However, how to integrate carbon capture with carbon conversion devices is not yet clear. Bipolar membrane electrolyzers have attracted significant interest as a device which is compatible with carbon capture, as these systems can operate with bicarbonate and carbonate-based solutions. In a bipolar membrane electrolyzer, carbonate is converted to carbon dioxide through a pH swing process driven by water dissociation within the bipolar membrane. However, balancing the rate of water dissociation, carbon dioxide production, and carbon dioxide electrocatalysis remains a critical challenge. Furthermore, steering carbon dioxide electrocatalysis toward a specific high value product such as ethylene is unclear.

Here, we set out to examine the activity of Cu, Ag and CuAg catalyst in a carbonate electrolysis system. Cu is a unique metal catalyst and has previously shown the capacity to generate multi-carbon products such as C2H4 and C2H5OH within gas phase anion exchange membrane electrochemical cell. Cu-based catalysts are however known to suffer sluggish C–C coupling kinetics which is a requirement for C2+ product formation. To overcome this challenge, bimetallic are used. For instance, through introducing a known CO-producing catalyst such as Au and Ag with Cu one can perform a cascade reaction. This tandem strategy can enhance performance of multi-carbon products by increasing the coverage of *CO intermediates, known as an important intermediate for C–C coupling, on the Cu surface. Thus, here we will detail a set of experiments aimed at discerning the selectivity of a bipolar-membrane electrode assembly cell which contains Cu, Ag, and Cu-Ag bimetallic electrocatalyst. We examine the impact of temperature, catalyst loading, and system operations. We also will briefly discuss technoeconomic considerations.
Effect of Cations on Electrocatalytic CO2-to-Methanol Conversion by Heterogenized Molecular Catalyst
Authors: Yu Sunmoon , Yamauchi Hiroki , Shao-Horn Yang
Published: September 2023

Catalytic benefit and role of electrolyte cations for electrochemical CO2 reduction reaction have recently received significant research attention. It has been experimentally and theoretically demonstrated that cations can stabilize the key intermediate species, for example, *CO2
–, through mid- or short-range electrostatic interactions, facilitating the CO2 activation step.1-2 However, to date, these discussions are mostly limited to CO2-to-CO conversion (a two electron/proton transfer reaction) and electrostatic stabilization of reaction intermediate species.

In present work, we show that cations play a crucial role in further reducing CO2 to methanol. We found that cations engage as a promoter in the rate determining step of the CO2-to-methanol conversion, which involves a proton-coupled electron transfer, beyond the first CO2 activation step. For this study, heterogenized molecular catalyst with a cobalt single site (Co-N4) was employed, achieving ~25% methanol selectivity at –0.78 V vs. RHE. Through an isotope labeling experiment (13CO2 reduction reaction), we validated that methanol is produced by the CO2 reduction reaction. Furthermore, electrolytes with different cation species and concentrations were tested in a systematic manner to investigate the promoting effect of cations on methanol production. In addition, using deuterated electrolytes, we studied kinetic isotope effect, proposing a reaction pathway for CO2-to-methanol conversion on the cobalt single site. Our findings offer new insights into the beneficial effect of cations on electrochemical CO2 reduction reaction kinetics besides their widely acknowledged stabilizing effect. Our discovery also opens up new research directions where non-covalent interactions between electrolyte species and reaction intermediates are utilized to enhance electrocatalytic production of a desired product in CO2 reduction reaction beyond two-electron transfer products.

In this talk, I will discuss the promoting effect of cations on the electrochemical reduction of CO2 to methanol and conclude by proposing potential strategies to further improve the electrocatalytic CO2-to-methanol conversion.

References

Monteiro, M. C. O.; Dattila, F.; Hagedoorn, B.; García-Muelas, R.; López, N.; Koper, M. T. , Absence of CO2 electroreduction on copper, gold and silver electrodes without metal cations in solution. Nature Catalysis
2021,
4 (8), 654-662.

Resasco, J.; Chen, L. D.; Clark, E.; Tsai, C.; Hahn, C.; Jaramillo, T. F.; Chan, K.; Bell, A. T., Promoter Effects of Alkali Metal Cations on the Electrochemical Reduction of Carbon Dioxide. Journal of the American Chemical Society
2017,
139 (32), 11277-11287.
(Invited) Development of Energy-Efficient and Scalable Electrochemical Devices for CO2 to Formate Conversion
Authors: Hu Leiming , Intia Fry , Wrubel Jacob A , Baez-Cotto Carlos , Saha Prantik , Lou Kun , Neyerlin Kenneth C.
Published: September 2023

CO2 electrochemical reduction to useful chemicals has drawn significant interest over the past decade, as the technology shows promising potential for coupling with renewable energies and helping reduce the overall CO2 emission.1 Among different CO2 reduction (CO2R) end products, formate has some economic advantages because it is easier for downstream separation as a liquid product, and has many applications, such as hydrogen storage 2 and biomass conversion3. Several studies have shown that using SnO2 or Bi-based catalyst, the Faradaic efficiency (FE) for CO2 to formic acid/formate can be high (>80%).4,5 However, many literature-reported CO2 to formic acid/formate systems either has very high cell voltage during operation or contain complex chamber structures that induces large Ohmic drops or make it very hard for scaling up.

In this study, we explored different pathways for CO2 to formate electrochemical conversion that are both energy-efficient and scalable. Several cell configurations were investigated regarding cell voltage, energy consumption, and FE. As shown in Figure 1a, by optimizing the cell configuration, we can get the cell voltage 50% lower compared to the previous reported bipolar membrane with catholyte chamber configuration. The FE is 80.1% at 400 mA/cm2 and 79.5% at 500 mA/cm2. The overall energy consumption of the formate production is < 0.2 kWh/mol. We will talk about the advantage of different cell configurations we explored and the stability of each of those systems.

Figure 1
Optimizing the Design and Fabrication of Membrane Electrode Assemblies for High Performance CO2 Electrolyzers
Authors: Kabir Sadia , Ye Nancy , Waldrup Mark , Kuhl Kendra
Published: September 2023

The electrode layer is a critical component of low-temperature polymer electrolyte membrane electrochemical devices such as fuel cells and CO2 electrolyzers. The electrode has a major impact on the device’s efficiency, high current density performance and long-term durability. As such, the rational design and fabrication of electrode structures and interfaces with optimal component interactions, ionic and gas phase accessibility, as well as water management properties is crucial for advancing the performance, durability and economic viability of these electrochemical devices.

Typically, membrane electrode assemblies are manufactured using fabrication techniques such as roll to roll, electrospinning or ultrasonic spray coating. These methods rely on homogenizing the catalysts, ionomers, solvents, and any other polymeric additives into a colloidal ink and depositing them onto a substrate. At the microscopic level, the combination of electrostatic repulsion and Van der Waals attraction between the individual constituents (solvent, catalyst, polymer) can alter the macroscopic properties (i.e. viscosity, surface tension, rheology) of the colloidal inks. These properties are relevant for coating and MEA manufacturing processes, as the net interparticle interaction potentials determine the tendency of particles to aggregate or disperse which impacts tortuosity, density and porosity of the deposited layer. .

As such, optimizing component interactions is crucial for improving particle dispersion, drying behavior and stability of inks to fabricate high performance defect-free electrodes. Its imperative to expand our understanding of structure-property relationship between MEA composition and electrochemical characteristics (i.e. CO selectivity, HFR, mass/charge transport) to fabricate electrodes with high CO2 conversion efficiencies. Elucidating how composition (loading/thickness) morphology (porosity, surface roughness) and architecture (ionomer coverage, additives) of the catalyst layer and in turn its resulting impact on short term and long term performance will determine the commercial viability of CO2 electrolysis systems. This talk will highlight current R&D advancements in understanding of component interactions (i) for integrating high performance materials in electrodes for industrially relevant CO2 reduction applications, ii) improving electrode structure to maximize active site utilization and iii) mitigating mass transport limitations at catalyst-ionomer interface with a focus on understanding decay mechanisms.
Enhancing Electrocatalytic Conversion of Bicarbonate to Formate by Via Bismuth Alloys
Authors: Wong Andrew Barnabas
Published: September 2023

The bicarbonate reduction reaction has been emerging as a promising approach for converting CO2-riched medium to profitable products. However, the reduction of bicarbonate to formate still requires further development to achieve a moderate faradic efficiency. Herein, we introduced a low hydrogen-affinity metal (indium) into bismuth-based materials for BRR. It shows a favorable FEformate of 84.81%, a considerable formate partial current density of 241 mA∙cm-2, and a superior formate generation rate of 56 mmol∙L-1∙cm-2∙h-1.

Comprehensive ex-situ XRD characterization suggests that the incorporation of indium will inhibit the phase transformation from metallic bismuth to a bismuth subcarbonate species, which leads to the enhanced performance for bicarbonate reduction to facilitate improved cathodic formate production from the In-Bi alloy as compared to pure Bi.
Intercalation of Potassium Ions in Molybdenum Sulfide as Catalyst for CO2 Reduction
Authors: Mádai Eszter , Mol Arjan , Hartkamp Remco , Taheri Peyman
Published: September 2023

The increasing CO2 emission during the last decades highly contributed to global warming and as a consequence, we are facing the disruption of nature and more and more extreme weather conditions nowadays [1]. One way of dealing with the emitted excess CO2 is to create a synthetic carbon cycle, where the emitted CO2 is captured and turned into fuel using electrocatalysis and green energy. However, in order to achieve this, the exploration of new electrocatalysts is needed for the sake of cost and process efficiency and environmental friendliness.

Two dimensional materials have a promising future as catalysts due to their high surface-to-volume ratio. A potential catalyst material for CO2 reduction is molybdenite (MoS2), a cheap, layered semiconductor which already showed selectivity towards CO2 reduction in non-aqueous media [2,3]. Its layered structure allows not only to have a high specific surface area but also makes the intercalation of different ions possible. These features enable us to enhance the conductivity of the material via electron donation by the intercalated species [4]. The improved conductivity and the changed band gap can contribute to a higher efficiency of electrochemical processes.

Our research investigates the intercalation mechanism of potassium ions into MoS2 layers and the effects of the intercalated potassium on the CO2 reduction efficiency. The intercalation process is studied experimentally through electrochemical impedance spectroscopy (EIS) and confirmed by X-ray diffraction (XRD). Furthermore, the Gibbs free energy profile of the intercalation is obtained by Molecular Dynamics (MD) simulations using umbrella sampling. The electronic properties are measured with X-ray photoelectron spectroscopy (XPS) and the products of the CO2 reduction reaction is measured with gas chromatography (GC). The results suggest that the potassium intercalation improves the conductivity of the MoS2 and consequently the CO2 reduction efficiency.

[1] McCrystall et al. New climate models reveal faster and larger increases in Arctic precipitation than previously projected. Nat. Commun. 12:6765, 2021.

[2] Asadi et al. Robust carbon dioxide reduction on molybdenum disulphide edges. Nature Communications, 5(1), 2014.

[3] Asadi et al. Nanostructured transition metal dichalcogenide electrocatalysts for CO2 reduction in ionic liquid. Science, 353(6298):467–470, 2016.

[4] Wang et al. Atomic-scale clarification of structural transition of MoS2 upon sodium intercalation. ACS Nano, 8(11):11394– 11400, 2014.
Scalable Membrane-Free Electrolyzers for Electrochemical CO2 Conversion
Authors: Pang Xueqi , Lin Zhexi , Verma Sumit , Liu Chao , Esposito Daniel V.
Published: September 2023

Bicarbonate electrolysis offers an attractive approach to conducting electrochemical carbon dioxide (CO2) conversion within the same working fluid used in commonly considered carbon capture processes. However, conventional membrane-based electrolyzers face significant challenges related to scale-up, durability, and CO2 utilization. Here, we present a scalable packed bed membraneless electrolyzer (PBME) design for which liquid bicarbonate electrolyte flows sequentially through alternating porous flow-through anodes and cathodes. Within this design, hydrogen oxidation at porous anodes is used to produce protons that trigger in situ CO2 release immediately upstream of porous cathodes, where electrochemical CO2 reduction generates the desired product and returns the solution pH back towards its inlet value. By using the sequential flow-cell arrangement, the PBME offers the ability to mitigate large concentration overpotentials and non-uniform current distributions that naturally arise during scale-up of conventional membrane-based electrolyzers that rely on lateral flow of catholyte parallel to the surface of the electrodes. This study uses in situ colorimetric imaging to highlight the ability of PBME to rebalance pH across adjacent electrodes. In addition, results obtained with a multi-cell PBME demonstrate the scalability of this concept and reveal the ability to increase CO2 utilization from 12.9% for a single-cell PBME up to 20.5% for a four-cell PBME operated under baseline conditions. With operating the PBME at elevated pressure, the performance can be further improved by increasing the concentration of CO2 in the dissolved phase, which results in higher CO partial current density.
Large-Scale and Highly Selective Electrochemical CO2 to C2H4 Conversion Based on the Giner Water Management GDL
Authors: Zhang Tianyu , Pupucevski Max , Ding Shuo , Lattimer Judith
Published: September 2023

C2H4 is a key building block in the chemical industry to produce a wide range of plastics, solvents, cosmetics, etc. On average, the production of 1 MMT of C2H4 generates 1.5 MMT of CO2, coming from fuel combustion, decoking, and utilities. Globally, C2H4 production by steam cracking is ranked as the second-largest contributor of energy consumption (2.8 EJ/year) and greenhouse gas emissions (300 MMT of CO2-e/year) in the chemical industry. Electrochemical CO2 reduction reaction (CO2RR) to produce C2H4 at ambient conditions, when coupled with renewable electricity, could reduce dependence on fossil fuels and decarbonize the chemical sector associated with C2H4 production. However, more efforts are needed to improve selectivity, productivity, and durability before the CO2 electrolyzer can be deployed commercially.

State-of-the-art continuous CO2 electrolyzers utilize gas diffusion electrodes (GDEs) to achieve CO2-to-C2H4 conversion at industrially relevant current density. However, managing the flooding of liquid electrolytes into the porous structure of GDE remains a critical practical challenge for stable and efficient CO2 transport. To date, most CO2 electrolyzers used commercial gas diffusion layer (GDLs) designed for polymer electrolyte membrane fuel cells (PEMFC), which operate under different conditions than CO2RR. The conventional GDL is generally made of carbon paper coated with 5-30 wt.% of polytetrafluoroethylene (PTFE) to protect against flooding. These GDLs still lose hydrophobicity fast during CO2 electrolysis at highly negative potentials due to the electrowetting of carbon materials, salt precipitation, and chemical degradation. As a result, the electrolyte even penetrates the micropores of the GDL, blocking CO2 transport to catalyst sites.

Giner has designed an innovative structure, the water management GDL (WM-GDL), providing a breakthrough solution for water management under the operational conditions of a CO2 electrolyzer. The WM-GDL has dedicated mass transport pathways for gas and electrolyte, which allows durable and efficient mass transport of both over long-term operation. The utilization of WM-GDL will assist in the scale-up of electrochemical CO2-to-C2H4 conversion. Currently, the state-of-the-art WM-GDL achieved 60% C2H4 selectivity at 500 mA cm-2 and 3 V in a 50 cm2 MEA electrolyzer. Larger-scale demonstration of the CO2-to-C2H4 conversion with high selectivity and durability will be carried out in stacks.

Acknowledgment: The project is financially supported by the Department of Energy’s Office of EERE under the Grant DE-EE000942l
Higher Alcohol Synthesis from CO2 Hydrogenation through a CO2/H2O Co-Transport Membrane Reactor
Authors: Zhang Kangkang , Sun Shichen , Huang Kevin
Published: September 2023

With the rapid development of renewable energy, direct CO2 hydrogenation (CHR) to liquid fuels and value-added chemicals has attracted considerable attention worldwide. Among them, converting the greenhouse gas CO2 into higher alcohols (HAs) is of great significance due to their potential applications as fuel additive and fine chemical intermediates. However, owing to the chemical inertness of CO2 molecules and uncontrollability of C-C coupling, this reaction still suffers from low CO2 conversion, poor HA selectivity and product rate. In this presentation, we show a CO2/H2O co-transport membrane reactor in the presence of multifunctional catalysts to capture CO2 and store H2 in HAs in one step. The results explicitly show that the captured CO2 from flue gas at retentate side can directly react with a sweeping H2 at the permeate side to form liquid chemicals such as HAs with specific catalysts. Due to transportability of H2O, a product of the CHR, from permeate side to retentate side of membrane reactor, the CHR conversion is expected to be shifted towards desirable HAs production. Besides, through gradual addition of CO2 into H2 stream along the membrane length, the tubular CO2/H2O co-transport membrane reactor can create CHR-favorable, high local H2/CO2 ratio for improved CO2 reduction into the reactive C1-species, which is highly desirable to facilitate subsequent C-C coupling and OH insertion to form the wanted HAs.
Teflon-Based Gas Diffusion Electrode with a Novel Current Collector Concept for Scalable Highly Efficient CO2 Reduction Electrolyzers
Authors: Filippi Michael , Möller Tim , Strasser Peter
Published: September 2023

In this work we developed a novel type of GDE that combines a PTFE membrane as GDL with an on top sprayed copper catalyst layer and a polymer coated metallic current collector. It is well known that PTFE based GDE`s are a good solution to circumvent flooding phenomena, however the scalability was so far not addressed in the CO2 reduction field. To use PTFE based GDE`s industrially we developed a metallic current collector with polymer coating and show different methods of implementing those. We will show the basic concept of the idea and the validation in lab scaled electrolyzes (5 cm2 and 100 cm2) and will give a future outlook on further development and use-case scenarios.
Utilizing Bayesian Optimization to Facilitate Differential Voltage Analysis of Lithium Ion Batteries
Authors: Zhao Ziqing , Kubal Joseph , Abraham Daniel P. , Ryan Emily
Published: September 2023

Differential voltage analysis (DVA) is a non-destructive, in situ method for analyzing degradation in lithium ion (Li-ion) batteries, and can be used to identify major modes of performance degradation, such as loss of lithium inventory (LLI) and loss of active material (LAM). Using the cycling voltage derivative with respect to capacity of half cells and full cells, DVA can be used to estimate which mode is the main contributor to degradation. Analysis of the signature peaks in the half cell to the full cell can reveal the degradation mode of full cell. Shifts in the peak can indicate LLI, while intensification and narrowing of peaks can indicate LAM. Analyzing the peak changes after cycling allows quantitative determination of how much cell aging has occurred, and what mode is involved in the cell aging process. However, the process of analyzing peak changes manually is inefficient and time consuming. In this work, we utilize a Bayesian optimization approach to facilitate the process of fitting full cell DVA data with pristine half-cell data. The Bayesian optimization algorithm finds the best deformation of pristine half-cell data to fit full-cell data automatically and efficiently for multiple chemistries. The only manual procedures for each fitting are reading data files into the program and determining a coarse bound. The rest is automated and takes less than ten minutes for each fitting. The fitting accuracy is comparable to manual fitting and significantly less time consuming. This method facilitates battery aging analysis and can be generalized to different kinds of data sets as well.
(Invited) Understanding the Role of Dopants (Al, Zn, Zr) in Altering Charge-Storage Capacity and Cycling Profiles of VFe2Ox
Authors: Johannes Michelle D. , Swift Michael W , Bernstein Noam , DeBlock Ryan H. , Ford Hunter O. , Chervin Christopher N. , Rolison Debra R. , Long Jeffrey W.
Published: September 2023

Vanadium ferrite (VFe2Ox) is a defective spinel system that can incorporate substantial Li+ and exhibits a high charge–discharge rate, particularly when structured as a nanoscale aerogel.1 Cations such as Zr, Zn and Al,2 can readily enter the structure substitutionally and have strong, but differing effects on the charge-storage capacity of the material. These earth abundant, cost- effective constituent elements give this class of materials strong potential as future Li-ion battery cathodes but optimizing the stoichiometry for maximum capacity and stability will require understanding the redox sequence of the host cations (Fe, V) and role of intentional dopants.

We use density functional theory calculations in concert with in situ and operando X-ray absorption near-edge spectroscopy (XANES) spectra obtained using an in-lab X-ray absorption spectrometer to uncover the quantum mechanical-level effects that underpin relevant energy- storage behaviors of doped and undoped VFe2Ox. Our experimental V K-edge and Fe K-edge spectra indicate reduction of both species during discharge but cannot distinguish between tetrahedral and octahedral Fe redox sites or fully resolve the valency of each element as a function of state of charge. Using a hybrid form of density functional theory that accounts for the strong correlation present in 3d elements, we show that both V and Fe are indeed reduced, but that only tetrahedral Fe is redox active until fully converted to Fe2+. Furthermore, both octahedral and tetrahedral Fe3+ are high spin configuration, but the 5μB moments in the fully filled majority spin channel at each symmetry site are anti-aligned. This arrangement allows for easy exchange of electrons and facilitates conduction. We also calculate XANES spectra based on first principles calculations to be compared directly to those measured in the lab. This cross- check allows us to understand the effect of Al, Zr, and Zn dopants on the redox sequence and relate these results to site preference and capacity. Our combined experimental and calculational investigation sheds light on how these complex materials store Li ions and points toward future alterations that may further improve their properties.
Localized Tortuosity Determination of Li-Ion Battery Electrode Using SECM and SICM
Authors: Raju Anjana Raj , Danis Andrew , Schougaard Steen Brian
Published: September 2023

Li-ion batteries’ limited power represents a barrier to their application in the domain of renewable energy. To examine the origin of this limitation, the effect of microstructural parameters such as porosity and tortuosity on ionic transport, especially through the electrolyte within the electrode pores needs to be studied. In this work, we tried to determine the local tortuosity in Li4Ti5O12 (LTO) electrodes with various porosities using two scanning probe microscopic techniques: Scanning Ion Conductance Microscopy (SICM) and Scanning Electrochemical Microscopy (SECM). SICM measures the effective ionic conductivity of Li+ ions whereas SECM probes the diffusion of electroactive species like anthracene.1,2 We observed that in both cases, the normalized current increases with porosity as more ions reach the tip through the pores of the electrode. The MacMullin number calculated from SICM and SECM measurements for the LTO electrodes having porosities from 50% to 63% shows that these techniques are complementary. Improved transport through these porous electrodes is indicated by the lower tortuosity values obtained compared to those anticipated by the mass transport models like the Bruggeman relationship. Hence, the tortuosity values determined from these microscopic techniques can be used as a strong tool to improve the modeling of electrolyte transport within electrodes. In turn, this should be highly valuable in the design of batteries with high power density.

References:

N. A. Payne, J. I. G. Dawkins, S. B. Schougaard and J. Mauzeroll, Anal. Chem., 2019, 91, 15718–15725.

Md. S. Hossain, L. I. Stephens, M. Hatami, M. Ghavidel, D. Chhin, J. I. G. Dawkins, L. Savignac, J. Mauzeroll and S. B. Schougaard, ACS Appl. Energy Mater., 2020, 3, 440–446.
(Invited) Development and Application of Titration Gas Chromatography in Elucidating the Behavior of Anode in Lithium Batteries
Authors: Bao Wurigumula , Meng Ying Shirley
Published: September 2023

The accelerated transition to renewable energy systems worldwide has triggered increasing interest in energy storage technologies, especially in lithium batteries. Accurate diagnosis and understanding of the batteries degradation mechanism are essential. Titration Gas Chromatography (TGC) has been developed to quantitively understand the anode. The inactive Li in the cycled anode can be categorized into two kinds: 1) trapped Li0 (such as trapped lithiated graphite (LixC6), Li0, and lithium silicon alloy (LixSi)) and 2) solid electrolyte interphase (SEI) Li+. Noted that only trapped Li0 can react with the protic solvent to generate the hydrogen (H2), while SEI (Li+) does not1. Therefore, the H2 gas quantification can be correlated to the trapped Li0 as the foundation mechanism of TGC. With the optimal solvent selection, we successfully applied TGC to investigated: 1) the degradation behavior of Si-based anode materials2, 3; 2) corrosion effects on electrochemically deposited Li metal anode4; 3) the cycling behavior of Gr anode; 4) Li inventory quantification in practical Li metal battery5. We demonstrate the various application of TGC techniques in quantitatively examining the Li inventory changes of the anode. Beyond that, the results can provide unique insights into identifying the critical bottlenecks that facilitate battery performance development.

References:

Fang, C.; Li, J.; Zhang, M.; Zhang, Y.; Yang, F.; Lee, J. Z.; Lee, M. H.; Alvarado, J.; Schroeder, M. A.; Yang, Y.; Lu, B.; Williams, N.; Ceja, M.; Yang, L.; Cai, M.; Gu, J.; Xu, K.; Wang, X.; Meng, Y. S., Quantifying inactive lithium in lithium metal batteries. Nature
2019,
572 (7770), 511-515.

Bao, W.; Fang, C.; Cheng, D.; Zhang, Y.; Lu, B.; Tan, D. H.; Shimizu, R.; Sreenarayanan, B.; Bai, S.; Li, W., Quantifying lithium loss in amorphous silicon thin-film anodes via titration-gas chromatography. Cell Reports Physical Science
2021,
2 (10), 100597.

Sreenarayanan, B.; Tan, D. H.; Bai, S.; Li, W.; Bao, W.; Meng, Y. S., Quantification of lithium inventory loss in micro silicon anode via titration-gas chromatography. Journal of Power Sources
2022,
531, 231327.

Lu, B.; Li, W.; Cheng, D.; Bhamwala, B.; Ceja, M.; Bao, W.; Fang, C.; Meng, Y. S., Suppressing chemical corrosions of lithium metal anodes. Advanced Energy Materials
2022, 2202012.

Deng, W.; Yin, X.; Bao, W.; Zhou, X.; Hu, Z.; He, B.; Qiu, B.; Meng, Y. S.; Liu, Z., Quantification of reversible and irreversible lithium in practical lithium-metal batteries. Nature Energy
2022,
7 (11), 1031-1041.
Interfaces Studies on LiNi0.82Mn0.07Co0.11O2 (NMC811) with Vinylene Carbonate Additive Using in-Situ Raman and X-Ray Absorption Spectroscopy at Ultra-High Operation Voltage
Authors: Dai Huidong , Mukerjee Sanjeev
Published: September 2023

Interfaces evolutions in lithium-ion battery determines the rate-limiting step for lithiation of most electrode materials by influencing Li+ insertion occurred in the solid phase boundary. To our best knowledge, we will be the first to employ the in-situ characterization techniques including Raman spectroscopy and X-ray absorption spectroscopy (XAS) to probe the cathode electrolyte interface (CEI) formation and its protective effect on NMC cathode with the presence a high concentration of vinylene carbonate (VC). The Raman data showed a brand new peak around 1000 cm-1 appeared after the initial cycle due to the VC polymerization indicating the maturity of CEI layer with a modified electrolyte system, the in-situ XAS data revealed that the surface reconstruction of NMC cathode was significantly suppressed with the VC additive by delta-R analysis from extended X-ray absorption fine structure (EXAFS) and the oxidation state of nickel was relatively stable compared to a baseline electrolyte environment when the operation voltage window was pushed to 4.8V. This work shed light on characterizing materials property across spatio-temporal scales relevant for various additives electrolyte system under in-situ/operando conditions including specific form factors, providing design principles for materials and composites, functional aspects of interfacial operation and degradation pathways.

Figure 1
(Invited) Improving Calendar Life of Si-Based Lithium-Ion Batteries By FEC/VC-Free Electrolytes
Authors: Kim Ju-Myung , Cao Xia , Yi Ran , Zhang Ji-Guang
Published: September 2023

Silicon (Si) has been regarded as one of the most promising anode materials for the next generation lithium-ion batteries (LIBs) with high energy density because it has 10 times higher theoretical specific capacity (4200 mAh/g) than that of graphite. However, severe volume change (~300%) of Si during lithiation and delithiation hinders the practical application of Si anode. In the last decade, significant progresses have been made on the specific energy and cycle life of Si based LIBs. However, calendar-life of these batteries is still far less than 10-year target required by DOE’s electrical vehicle (EV) project.

In the current work, the role of FEC/VC in conventional carbonate electrolytes has been investigated. It has been found that FEC/VC causes large impedance growth on both Si and graphite anodes at 55 oC. The cut-off voltage of NMC622 has been found to significantly affect its impedance. NMC622 at 4.2V shows no impedance growth at 55 °C for 8 days, while severe impedance growth is observed at 4.4V. To address the instability of both SEI and CEI at elevated temperature, a new Localized High Concentration Electrolyte (LHCE) has been developed to improve the calendar life of Si based LIBs by effectively limiting impedance growth of Si/NMC622 full cells. In addition, the cycle life of the full cell is improved. The mechanism of Si full cells with improved calendar life will also be discussed.
Solid-Electrolyte Interphase of Molecular Crowding Electrolytes
Authors: Xie Jing , Lu Yi-Chun
Published: September 2023

Molecular crowding electrolyte was proposed to improve the stability of water at a low concentration of Li salt (2 m LiTFSI )1. Low-cost and safe poly (ethylene glycol) (PEG, Mn=400) is adopted as a crowding agent to confine water molecules through hydrogen bonding and strengthen the covalent bond of H-O (H2O), leading to effective suppression of water decomposition (especially HER). However, the mechanism behind the improved cathodic stability of molecular crowding electrolyte is not yet fully understood. Specifically, the composition of the SEI and the impact of salt on the electrochemical stability of PEG-based electrolyte are still unknown. To gain a deeper insight into the stability mechanism in molecular crowding electrolytes, we investigated the cathodic stability of PEG-based molecular crowding electrolytes with LiTFSI and LiClO4 as the electrolyte salt. We characterized the composition and structure of SEI on Li4Ti5O12 electrode (LTO) derived from LiTFSI- and LiClO4-containing electrolytes, and correlated cathodic stability to the composition of the SEI. Comprehensive characterizations including linear sweep voltammetry (LSV), online electrochemical mass spectroscopy (OEMS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) are used to study the cathodic stability of water. The enhance mechanism will be discussed.

[1] Xie, J., Liang, Z. & Lu, Y. C. Molecular crowding electrolytes for high-voltage aqueous batteries. Nat. Mater. 2020, 19, 9, 1006-1011

[2] Xie, J., Guan, Y., Huang, Y., & Lu, Y. C. Solid–electrolyte interphase of molecular crowding electrolytes. Chem. Mater. 2022, 34, 11, 5176–5183

Acknowledgement

This work is supported by a grant from the Research Grant Council of Hong Kong Special Administrative Region, China (Project No. RFS2223-4S03) and a grant from the Innovation and Technology Commission of the Hong Kong Special Administrative Region, China (Project No. ITS/219/21FP).
Multifunctional Additive Ethoxy(pentafluoro)Cyclotriphosphazene Enables Safe Carbonate Electrolyte for SiOx-Graphite/NMC811 Batteries
Authors: Liu Sufu , Becker Maximilian , Huang-Joos Yuanye , Lai Huagui , Homann Gerrit , Grissa Rabeb , Egorov Konstantin , Fu Fan , Battaglia Corsin , Kuehnel Ruben-Simon
Published: September 2023

The silicon or silicon monoxide (SiO
x
)-graphite/nickel-rich (≥80% Ni) LiNi
x
Mn
y
Co
z
O2 (x+y+z = 1, NMC) cell chemistry is widely regarded as one of the most promising chemistries for next-generation electric vehicle batteries for due to its higher energy density compared to state-of-the-art graphite/Ni-rich NMC batteries. However, the drastic volume change during lithiation and delithiation of silicon poses a significant challenge to realize its high capacity with a practical cycle life. Besides performance degradation, it is desirable to address safety risks stemming from, e.g., the high flammability of carbonate solvents and oxygen release from highly delithiated Ni-rich NMC materials.

To address these problems, one of the most effective methods is to develop advanced electrolytes that combine flame-retardant properties and excellent electrochemical performance. Generally, in consideration of the balanced trade-offs between cost, scalability, safety, and electrochemical compatibility, the use of flame retardants is a very promising approach to realize the next-generation nonflammable electrolytes.However, it is still a huge challenge to optimize the electrolyte composition to stabilize Si-based and Ni-rich lithium-ion batteries.

Here, the compatibility of the flame retardant ethoxy(pentafluoro)cyclotriphosphazene (PFPN) as additive for carbonate electrolytes is studied, for the first time, in the SiO
x
-graphite/NMC811 full cells. [1] A synergistic effect is found between PFPN and lithium hexafluorophosphate (LiPF6) for the flame retardancy, and a modified electrolyte (1.35M LiPF6 in ethylene carbonate (EC):ethyl methyl carbonate (EMC) (3:7 by vol.) with 10 wt.% fluoroethylene carbonate (FEC) and 5 wt.% PFPN) displays a very low self-extinguishing time of only 3 s/g while also maintaining a high ionic conductivity of 8.4 mS/cm at 25 °C. Furthermore, the morphology evolution and interphase composition of both anode and cathode are investigated, gaining important insights into the decomposition mechanism of PFPN to stabilize the electrode-electrolyte interfaces. Meanwhile, the wetting properties of the modified electrolyte are also improved due to the excellent wettability of PFPN. As a result, half and full coin cells with SiO
x
-graphite anode and NMC811 cathode display better capacity retention during long-term cycling with the modified electrolyte than with 1M LiPF6 in EC:EMC (3:7 by vol.) with 10 wt.% FEC. In addition, the enhanced cycling performance with the modified PFPN-contained electrolyte is also confirmed for 1 Ah SiO
x
-graphite/NMC811 pouch cells cycled under various pressures. These results open a promising avenue for the development of safe and high-performance electrolytes for silicon-based lithium-ion batteries.

References

[1] S. Liu et al., to be submitted.
A New Class of Lithium Conductive Polymers Based on Electrochemically Stable Carbon Rings
Authors: Wang Peng , Bucur Claudiu , Allred Gary , Andrei Petru
Published: September 2023

Among all the various secondary battery technologies, lithium ion batteries (LIBs) have received a significant amount of attention in the last decades and turned into the most successful commercial batteries. LIBs are currently extensively used in portable electronics, electric vehicles, and energy storage stations. In recent years, the elevated requirements for high energy density and increased safety have driven the research to develop the next generation battery technology, and solid state batteries are one of the most potential alternatives for the mainstream LIBs. Polymer based solid state electrolyte (SSE) have been widely studied due to their nature of softness and flexibility that relieve the interface problems between electrodes and separator, especially compared with inorganic solid electrolyte. However, most of the SSEs developed so far show either limited Li+ conductivity or narrow electrochemical windows (< 4 V), which limits the area of applications of these electrolytes significantly. In order to overcome the above limitations, Piersica Inc. developed a new type of polymer (PG17) that can be used as SSEs and applied to the mainstream organic electrolyte based LIBs. The optimized SSE exhibits impressive conductivity (0.1 mS/cm) at room temperature and extremely high oxidized stability (approx. 4.9 V). When assembled using NMC811 cathodes and commercial graphite anodes, both the coin cells and the pouch cells demonstrated excellent capacity and cycling stability. In the near future, the PG17 will be optimized for applications in all solid state batteries.
Studying the Role of Additives in Carbonate Electrolytes for Graphite||NMC811 Batteries with Interface-Sensitive X-Ray Spectroscopies
Authors: Didwal Pravin N. N. , Weatherup Robert S
Published: September 2023

Li-ion rechargeable batteries are increasingly used as power sources for portable consumer products and electric vehicles. The formation of stable electrode-electrolyte interphases is critical to long-term performance, however, these typically degrade during extended cycling due to ongoing side reactions and electrode cross-talk. Over the past few years, various electrolyte additives have been reported as being able to improve the properties of the interphases formed on electrode surfaces and suppress cell degradation. However, these are often tuned for a specific electrode (e.g. cathode), and may negatively impact on the other electrode (e.g. anode). A key experimental challenge is therefore to reveal how additives affect the interfacial layers formed at both anode and cathode in full cells, their resulting influence on the cross-talk, and on the long-term stability of each electrode. Soft X-ray absorption spectroscopy (soft-XAS) and X-ray photoelectron spectroscopy (XPS) are powerful techniques to investigate the evolution of the short-range local structure and chemical species in complex systems. These properties make soft-XAS and XPS a suitable technique to study phase evolution, chemical species, local structure and stability of the interface formed on the electrodes. Here, we have studied carbonate-based electrolytes with various additives (such as Vinylene Carbonate, Lithium difluorophosphate, and fluoroethylene carbonate) in Graphite||NMC811 full cell. Soft-XAS and XPS have been performed to understand how additives in the electrolyte alter the chemical nature of interface formed on both anode and cathode in early cycles and their influence on extended longer-term degradation related to cross-talk, such as transition metal cross-over. Further, we identified which additives are beneficial for which electrodes and which cross-talk reactions they help to mitigate, this informs the development of electrolyte formulations where different additives are combined to improve battery lifetime and performance. Comparing the chemical information obtained with electrochemical cycling data we determined the connection between the chemical degradation of the electrodes and the reduction in electrochemical performance.
Data-Driven Approach to Analyze Interdependencies between Electrode Manufacturing Parameters and Electrochemical Performance of the Lithium-Ion Battery Cell
Authors: Haghi Sajedeh , Daub Rüdiger
Published: September 2023

The lithium-ion battery cell production is a complex process chain with a high number of process steps and manifold interdependencies. The majority of the properties determining the electrochemical performance of the battery cell are established during electrode manufacturing. An in-depth understanding of electrode manufacturing and its influence on cell performance can pave the way toward high-quality, cost-efficient cell production. Considering the complexity of the process chain and the high share of material costs in battery production, the classic one-factor-at-a-time experimentation is deemed inadequate and expensive.

Machine learning (ML) approaches have been proven suitable for analyzing complex process chains. Design of experiment (DoE) methods can be used to generate a sufficient informative database for ML techniques. This study was based on the joint application of DoE and ML methods in electrode manufacturing. For this purpose, in the first step, the response surface methodology (RSM) was used to conduct experiments and analyze the effect of mass loading, drying temperature, and porosity on cell performance. The study was focused on graphite anodes produced at a pilot scale. The electrochemical performance of electrodes was assessed on coin cells at discharge C-rates from C/10 to 5C. Additionally, symmetric coin cells were used to analyze the electrochemical impedance spectra. Supervised machine learning models were adopted to predict the cell characteristics based on the electrode properties. Additionally, a factor analysis reflecting the contribution and importance of each factor on the final cell properties was conducted. The efficient experiment-based data generation using RSM combined with the applied ML techniques can support practitioners towards smart quality-oriented battery cell production.
Uncovering the Mysterious Transformations during Cycling in Li-Ni-Mn-O Cathode Materials
Authors: Hebert Alex , Ting Michelle , Chen Ning , Muir David , McCalla Eric
Published: September 2023

Layered transition metal oxides, specifically LiNixMnyCozO2, lead the market for Li-ion battery cathode materials. Cobalt is a problematic metal to include in such a high-volume product like Li-ion batteries, as it is expensive, and it is mined using unethical practices. Contemporary electrodes use metal compositions with < 0.33 Co. However, even as the least abundant element in the material, eliminating Co entirely remains an important objective, but is so far necessary as it increases material stability leading to improved cycle life. Thus, research has been active in the Li-Ni-Mn-O system, looking for potential replacements for Co-containing layered oxides. The Li-Ni-Mn-O pseudo ternary system has been investigated in the past decade, revealing some interesting materials. Several compositions (including Li0.568Ni0.073Mn0.359O2 studied here) have been uncovered that show anomalous increasing capacity while cycling over 100 cycles, with some materials reaching 300 % capacity compared to their first cycle.1 It has been hypothesized that this is due to a phase transition occurring in the material, but to date the precise mechanism remains elusive. Other materials (including Li0.586Ni0.071Mn0.343O2 studied here), though very near to these compositions, show relatively stable capacities but dramatic voltage fade.2 In both materials, structural transformations are clearly at play during extended cycling. This work leverages X-ray absorption spectroscopy (XANES/EXAFS) and X-ray photoemission spectroscopy (XPS) to uncover the subtleties in the local environments of Ni and Mn before, during, and after cycling. XANES/XPS reveal to what extent there is a contrast between the oxidation states of the Ni/Mn cations at the surface vs. the bulk of the particles, which has been shown to be important in Ni containing cathodes.3 Interestingly, in both materials, no important changes are seen in the X-ray diffraction patterns, while the pair distribution functions from EXAFS evolve dramatically as shown in the figure here for the Ni environment. Interestingly, the material that shows capacity growth shows a less reversible , while there is no significant difference in the Mn site between the materials before and after charging. Analysis of the final structures shows conversion towards spinel-like structures in both cases, despite the dramatic differences in progression of the capacities, hinting that the spinel-like phases can behave very differently depending on composition.

Figure 1