bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysing the Effects of High-Intensive Dry Mixing on the Calendering Process and Cell Performance of NMC622 Based Cathodes
Authors: Diener Alexander , Mayer Julian Kristoffer , Zhang Yue , Kwade Arno
Published: July 2022

A reliable design of production processes for the manufacturing of lithium-ion battery electrodes requires a deep understanding of the interdependency of processes, the resulting electrode microstructure and the influence on the cell performance indicators, like energy density, cycle life and aging. In the present study, the focus lays on the calendering process during which the electrode coating is compacted with the aim of adjusting uniform electrode properties such as mechanical, electrical and electrochemical behavior. Compaction of the electrode coating affects the pore structure and therefore has a crucial influence on the electrical and electrochemical behavior of the cell. Consequently, process and machine parameters have to be adapted in order to generate electrode structures optimized for a desired application. To meet this target, an in-depth understanding of how the calendering process affects the electrode structure beyond the simple reduction of porosity and further how the calendering process itself is affected by the preceding process steps like dry or wet mixing is mandatory.

Thus, the focus of the presented work is to investigate the interdependency between the dry mixing process step and the subsequent calendering process by correlating powder properties adjusted via the dry mixing with the machine behavior during the calendering as well as the resulting coating density. The impact of the calendering process on the electrode microstructure and its correlation with electrode properties by developing process-product-property functions, regarding the above mentioned criteria, is an additional focus of the presented study.

Therefore, powder mixtures of NMC622 with carbon black were created under varying the dry mixing intensity and thus adjusting the carbon black agglomerate size. The created powder mixtures were comprehensively characterized, e.g. particle size distribution and powder conductivity, and then used to build up electrodes which afterwards were compacted to different coating densities. The correlation between the powder properties and the calendering behavior shows a higher compaction resistance with decreasing carbon black agglomerate size. Whereas reducing the carbon black agglomerate size leads to lower electrical resistivity and therefore strongly impacts the C-rate capability.
(Digital Presentation) H-BN Enhanced Gel Polymer Electrolyte for Solid State Li-Ion Batteries
Authors: Ho Kane , Liu Yifan , Zarrin Hadis
Published: July 2022

In order to address safety concerns of conventional carbonate liquid electrolytes, porous gel polymer electrolytes (GPE) can effectively encapsulate the solution while providing good electrolyte-electrode contact. In this work, a GPE is incorporated with exfoliated 2D hexagonal boron nitride nanosheets (BNNS) as an effective and safe polymer electrolyte for Li-ion batteries. With a facile Dr. Blade approach combined with phase inversion, a high porosity and electrolyte uptake can be maintained while still acting as a stable film. Utilising a 15 wt.% binary polymer mixture of polyvinylidene fluoride (PVDF) and polyethylene oxide (PEO) doped with exfoliated BN flakes, the final GPE is not only more thermal stable but able to effectively suppress dendrite growth through multiple cycles with a high ionic conductivity of 3.03 x10-3 S/cm at ambient conditions. Cell performance with this GPE includes strong cycling performance while sustaining a high coulombic efficiency.

Figure 1
One-Pot Synthesis of LiAlO2-Coated LiNi0.6Mn0.2Co0.2O2 Cathode Material
Authors: Touag Ouardia , Coquil Gael , Charbonneau Mathieu , Mankovsky Denis , Dollé Mickaël
Published: July 2022

The chemistry of lithium-ion batteries (LIBs) is an active area of research, notably through the increasing demand for high energy and power density in LIBs, especially for application in electric vehicles (EVs) and hybrid electric vehicles (HEVs).

Among the various cathode materials, LiNixCoyMn1-x-yO2 (NMC) intercalation compounds are the best candidates for applications in high performance LIBs. However, Ni-rich NMC suffers mainly from parasitic side reactions at the interface with the electrolyte, which leads to a lower thermal and electrochemical stability. Surface modification via coating is an effective concept to counter the capacity degradation of NMC and to improve the particles’ structural stability for enhancing their cycle-life [1], [2]. Different processing techniques that usually requires several steps are presented in the literature. However, to facilitate the integration of a new product in the current battery market, it is preferable to reduce the number of steps during the synthesis process. In this work, we propose a one-pot synthesis of LiAlO2-coated LiNi0.6Mn0.2Co0.2O2 particles, by using a continuous stirred-tank reactor (CSTR).

Firstly, the composition and morphology of the coated and uncoated cathode materials are characterized by SEM, TEM, EDX and XPS. Then, the structural characterization of our materials is validated by XRD analysis. Consequently, we will compare the electrochemical performance and thermal stability of coated and uncoated NMC particles.

We will demonstrate that our approach provides an easy way to apply surface treatment onto Ni-rich NMC particles and simplifies the synthesis process at large scale production.

KEYWORDS: Lithium-ion battery, Ni-rich NMC cathode, LiAlO2 coating, surface protection.

Negi, R.S., et al., Enhancing the Electrochemical Performance of LiNi0.70Co0.15Mn0.15O2 Cathodes Using a Practical Solution-Based Al2O3 Coating. ACS Applied Materials & Interfaces, 2020. 12(28): p. 31392-31400.

Kim, H.-S., et al., Enhanced electrochemical properties of LiNi1/3Co1/3Mn1/3O2 cathode material by coating with LiAlO2 nanoparticles. Journal of Power Sources, 2006. 161(1): p. 623-627.
(Digital Presentation) Thermal Acceleration Model for the Capacity Fade of a Rechargeable Li Ion Battery and Its Validation with 10+ Years of Testing Data
Authors: Ye Hui , Fang Zhi , Tamirisa Prabhakar , Jain Gaurav , Scott Erik
Published: July 2022

Rechargeable Li ion batteries have become not only a major power source for consumer electronics, but also a critical power source for high demanding applications like electrical vehicles, portable military devices and medical devices. Medtronic, one of the leading medical device companies has developed a breakthrough rechargeable Li ion battery technology-OverdriveTM to power implantable neurostimulators such as Intellis and Interstim Micro. OverdriveTM batteries have exceptional stable performance and fast charging capability. Figure 1 shows design verification test of capacity stability under two different discharge rate, C/24 and C/168; charging rate are 2C for both groups. As shown in Figure 1, there is virtually no capacity fade under C/168 discharge rate cycling and only a few percent capacity loss under C/24 rate cycling for more than 10 years of testing at 37oC.

It is crucial to have a good acceleration testing model to design a rechargeable battery with reliable performance over 10 years of service and to ensure robust design with foreseeing battery material replacement over time. In the early development stage, we established a thermal acceleration capacity fade model for our OverdriveTM battery based on 2 years of testing as shown in Figure 2. Figure 2 shows capacity fade of Overdrive battery cycling at different temperatures up to 10 years. The trend of additional 8 years of data is consistent with model prediction.

This presentation will highlight the performance characteristics of the OverdriveTM battery technology and provide the technical details of thermal acceleration capacity fade model. In addition, we will present how the model has been applied to understand the degradation mechanism of OverdriveTM battery and to improve the battery chemistry.

Figure 1
Offsetting Initial Lithium Loss By Pre-Forming SEI Layer on Graphite Surface
Authors: Yu Yikang , Xie Jian
Published: July 2022

The irreversible lithium loss due to the formation of solid electrolyte interphase (SEI) in the initial cycle greatly reduced the overall cell energy density of lithium ion batteries. Cathode prelithiation methods have been widely explored to compensate this lithium loss. However, these cathode additives with high lithium contents inevitable lower the active cathode materials loading. Here we report a facile graphite prelithiation method by pre-forming SEI layers on graphite surface (Pre-SEI graphite) in a flow cell. The Li accommodation in graphite anode could be controlled by the operation of the time and current density in flow cell for the electrochemical SEI formation. As a result, we demonstrate a 10% initial Columbic efficiency increase of the LiFePO4 electrode in a full cell configuration with our Pre-SEI graphite. The electrochemical pre-formation of SEI on graphite offers a novel route to offset initial lithium loss without a sacrifice of active cathode loading.
(Digital Presentation) Ti3C2
Tx
MXene As an Anode in Li- and Na-Ion Batteries: Where Does Electrochemical Capacity Stem from?
Authors: Koriukina Tatiana , Nyholm Leif , Hahlin Maria , Edstrom Kristina
Published: July 2022

The unique properties of the Ti3C2
Tx
MXene continue to attract attention within the energy storage field. Many of the previous reports on the use of this material in Li- and Na-ion batteries mainly concentrate on modifying the surface of the MXene or the cycling protocol in attempts to achieve higher specific capacities. Very few studies have, on the other hand, addressed the nature of the electrochemical reactions taking place during the electrochemical cycling of the material.

This study aims at gaining a deeper understanding of the electrochemical behavior of freestanding Ti3C2
Tx
electrodes without any binder and conductive additive. The results obtained with these electrodes, which were manufactured by vacuum filtration of MXene suspension in deionized water, are used to identify the electrochemical reactions yielding the observed capacities obtained in Li-metal cells using 1 M LiPF6 in EC:DEC (50:50 vol%) as the electrolyte and in Na-metal cells containing 1 M NaFSI in TEG-DME. Constant current and cyclic voltammetry cycling as well as in-house ex-situ XPS and synchrotron-based ex-situ HAXPES and XAS were used to identify the redox processes taking place upon the charging and discharging of the MXene electrodes.

The results, obtained when cycling the freestanding Ti3C2
Tx
MXene electrodes in Li-metal cells, indicate that the reversible capacity can be explained by redox reactions involving Ti species present in the Ti3C2
Tx
surface layer. The charge storage mechanism is hence faradic. The results of XAS measurements carried out in the transmission mode likewise indicate that the redox reactions are surface confined and do not involve the inner C-Ti-C layer of the Ti3C2
Tx
MXene.

When cycling material between 0 and 3 V vs. Na+/Na in Na-metal cells, the specific capacity of the Ti3C2
Tx
electrodes increases progressively with the cycle number (from 5 mAh/g on the first cycles to 50 mAh/g on the 200th cycle using a cycling rate of 10 mA/g). This effect is suggested to be connected to the deposition of sodium at about 0 V vs. Na+/Na as this count yield an activation of the electrodes. Comparisons of the cycling behavior of freestanding Ti3C2
Tx
electrodes with those of monolithic TiO2 (amorphous) nanotube electrodes with nanotubes lengths of about 4 μm suggest that the behavior of the Ti3C2
Tx
electrodes cannot be explained by the expected spontaneous formation of TiO2 on the surface of Ti3C2
Tx
electrodes. The capacity for the TiO2 nanotube anode was relatively high, i.e., 160 mAh/g, on the first cycle but was seen to decrease to about 90 mAh/g after 100 cycles when cycling at a rate of 10 mA/g. The reasons for the differences seen between the Ti3C2
Tx
and TiO2 nanotube electrodes will be discussed based on the general electrochemical behavior of the Ti3C2
Tx
electrodes.
(Digital Presentation) Role of Phosphorus Doping on Silicon Anode Performance in Lithium-Ion Batteries Via Facile Solid-State Synthesis
Authors: Xu Wei , Gordon Isabelle P. , Jow T. Richard , Stadie Nicholas P.
Published: July 2022

Lithiated silicon (Li15Si4) has a theoretical specific capacity of 3579 mAh g-1 compared to 372 mAh g-1 for graphite at conventional conditions. However, the large volume fluctuations during (de)lithiation result in irreversible damage to the solid-electrolyte interphase (SEI) and then gradual capacity loss as the electrolyte is reduced to reform the surface passivation layer in each cycle. One approach to mitigate this issue is to develop an artificial SEI layer on the silicon surface to limit strain-induced fracture during cycling. The approach presented herein is unique in that both surface functionalization and homogenous doping of the silicon are simultaneously achieved by introducing a trace amount of phosphorus via facile solid-state synthesis. Increased thermodynamic stability of the Li-P-Si ternaries as evidenced in previous studies has been corroborated herein, showing that the P-doped lithium silicide exhibits a contracted crystal lattice which both reduces the Li+ mobility and suppresses the chemical reaction between lithium silicide and typical organic electrolytes. The effect of P-doping, specifically the doping amount and depth within the silicon particles, on the electrochemical performance in lithium-ion batteries was investigated. In conclusion, the solid-state reaction between red phosphorus and nanoparticulate silicon is a relatively simple and tunable method enabling versatile studies of the interfacial chemistry of silicon electrodes over hundreds of cycles.
(Digital Presentation) Protective Effects of Lithium Plating on High Temperature Degradation of Lithium-Ion Cells
Authors: Poudel Pragati , Du Zhijia , Liaw Boryann (Bor Yann) , Iriyama Takuto , Zhang Guangsheng
Published: July 2022

Lithium plating and solid electrolyte interphase (SEI) growth are two main degradation mechanisms of lithium-ion cells. While lithium plating can occur during low temperature charging and/or fast charging, SEI growth is accelerated during high temperature operation. Here we report an interesting observation that lithium plating shows protective effects on high temperature degradation of lithium-ion cells. As shown in Figure 1, two baseline commercially available lithium-ion cells were cycled only at 60 °C. They rapidly degraded which can be attributed to SEI growth. In comparison, the other two cells were pre-cycled at 5 °C and experienced rapid degradation due to lithium plating. But when these two cells with lithium plating were further cycled at 60 °C, they showed slower degradation than the baseline cells. Similar results were also observed for cells cycled at 45 °C as shown in Figure 2. These preliminary results suggest that lithium plating has protective effects for high temperature cycling of lithium-ion cells. Such effects were further observed in lab-made lithium-ion cells with low negative/positive (N/P) ratio. As shown in Figure 3, baseline cells (N/P ratio=1.25) degraded quickly during 60 °C cycling (21 mA constant current charging to 4.2 V and 21 mA constant current discharging to 2.8 V). In comparison, low N/P ratio cells (N/P ratio=0.8) that had lithium plating induced during formation showed very stable discharge capacity for more than 600 cycles before abrupt degradation. Further analysis of these results will be reported.

Figure 1
Modeling Study of Commercial NCA Cylindrical Battery Cells’ Impedance Behavior Under Different Operation Conditions
Authors: Xie Yuanyuan , Kim Jonghoon , Na Woonki , Feng Zhange , Son Seoung-Bum
Published: July 2022

The classic 18650 and 21700 format cylindrical Li-ion batteries have been widely used today to power electric vehicles (EVs). Their wound jelly-roll structure (in a form of an Archimedean spiral) can provide a relatively higher energy density in the limited EV given space comparing with the battery cells using stacked electrodes. As the rapid development and deployment of EV technology require high performance and reliable Li-ion batteries, it is critical to understand the mechanism and process behind battery cell behaviors under various driving conditions. In this study, a series of impedance experiments is designed to explore the impact of battery state of charge (SOC), temperature, C-rates and other operating conditions. Then, an impedance mathematical model is developed to explore the potential mechanisms behind experimental observations. Our obtained results show that the impedance response of cylindrical NCA battery cells varies with the state of charge in both charge and discharge operation, and the SOC dependent impedance existed in different operating temperatures and C-rates. Through modeling analysis, results indicate the operating temperature and charge-discharge rate could significantly influence the impedance response of the battery cell but could not directly cause the variation of the impedance response at different SOC conditions. Besides, modeling results also show that the contact resistance variation, resulted from the expansion and contraction of cell electrodes during charge and discharge, could lead to a SOC dependent impedance behavior of the commercial cell and influence battery output performance.
(Digital Presentation) Modeling Thermal Behavior and Safety of Large Format All-Solid-State Lithium Metal Cells Under Thermal Ramp and Short Circuit Conditions
Authors: Johnson Nathan B , Albertus Paul
Published: July 2022

We are submitting this abstract in the understanding that a virtual option is likely to be offered for the Spring, 2022 ECS meeting. We are only interested in the virtual option for this presentation.

It has often been posited that solid-state batteries are inherently safer than liquid electrolyte Li-ion batteries because there is no flammable organic solvent present in the battery. However, thermal safety is a multi-faceted issue with other considerations such as onset temperature, maximum temperature, total heat generation, maximum heating rate, etc. These considerations need to be looked at in greater detail, including their dependence on the volumetric and gravimetric energy densities. Safety concerns become even more important as stable graphite anodes are replaced with potentially highly reactive and energetic lithium metal anode. In this presentation, we will report on our work using differential scanning calorimetry (DSC) heat flow data to construct a transient, 2D model of heat generation and temperature distribution in a large format cell with a LixCoO2 cathode, Li7La3Zr2O12 solid electrolyte, and lithium metal anode. We will present on the thermal runaway behavior of this cell chemistry during a thermal ramp test in an oven and due to the formation of an internal short circuit. Our analysis will focus on the total amount of heat generated, onset temperature for self heating, maximum temperature, and maximum heating rate. We also analyze how the battery state of charge affects these properties. Related work in our group focuses on collecting DSC data for Li metal solid state cells and may also be highlighted.
(Digital Presentation) Production and Characterization of TiO2-Based Photocatalyst
Authors: Rasouli Milad , Karbalaei Saleh Golnaz
Published: July 2022

TiO2-based nanostructures have received great attention in the past few years owing to their promising applications in water purification systems, sterilization, self-cleaning surfaces, photoelectrochemical conversion, and hydrogen evolution. However, the low-cost and environment-friendly synthesis procedure is an important step for transferring it to commercialization and industry application. Anodizing, one of the newest and most promising procedures in nanomaterial synthesis, is an electrodeposition process for creating nanotubes by altering the surface of the titanium. A variety of parameters influence the thickness of the oxide layer and the size of the nanotube formed during this process, including time, current density, applied voltage, electrolyte solution PH, and temperature. In this work, different anodizing times of 5, 10, 15, 20, 25, and 30 min as well as various voltages are examined to achieve the best conditions for making a titanium oxide nanotube substrate. We showed that the best-synthesized titanium oxide nanotube substrate with appropriate crystal size and optoelectrical properties was produced in 30 minutes at 20 volts.
Using Data Science and Machine Learning to Predict the Failure Rate of Pin Diodes
Authors: Gallagher James C , Mastro Michael , Koehler Andrew , Ebrish Mona , Jacobs Alan G. , Hite Jennifer K. , Gunning Brendan P. , Kaplar Robert J. , Hobart Karl D. , Anderson Travis J.
Published: July 2022

GaN research is important to the development of next generation power conversion technology because its large Baliga figure of merit GaN gives it the potential to outperform SiC. Presently, commercialized GaN technology is based on lateral high electron mobility transistors (HEMTs); however, large areas would be required for high voltage applications thus there is motive to switch to vertical GaN. Current GaN substrate manufacturing technology is known to produce inconsistent quality with a varying concentration of defects. These defects are known to cause catastrophic device failure, thus there is motive to develop quick, non-destructive techniques to predict the quality of the wafer before undergoing the expensive fabrication process. This talk focuses on using data science and machine learning to predict the quality of the diodes.

This work demonstrated that Raman spectroscopy can be used to detect high crystal stress points, which strongly correlates with an increased leakage current. Optical profilometry images can be used to detect defects that cause catastrophic failures; however, the presence of benign defects makes it difficult to predict the device quality using a simple algorithm. Thus, a machine learning algorithm relate optical profilometry images to device performance of subsequently processed device. The results showed that this algorithm was 91% accurate at predicting the forward bias behavior of devices, and it is possible that the devices it could accurately predict failures due to device processing errors.

This work was supported by the Office of Naval Research.
(Invited, Digital Presentation) Doping Gallium Oxide and Competing Ultra-Wide Bandgap Oxides
Authors: Lyons JOHN L
Published: July 2022

Although Ga2O3 is widely believed to be the among most promising ultrawide-bandgap semiconductors, its inability to be p-type doped hampers future applications. Moreover, alloying with aluminum increases the Ga2O3 band gap, but it is unclear if electrical conductivity of AlGO alloys can be controlled. The properties of group-IV (C, Si, Ge, and Sn) and transition metal (Hf, Zr, and Ta) substitutional dopants in AlGO alloys are systematically explored here using first-principles hybrid functional calculations. In Ga2O3, all dopants act as shallow donors. However, in Al2O3 all are deep defects, characterized by DX behavior or the emergence of positive-U (+/0) levels. Combining our calculations of dopant charge-state transition levels with information of the AlGO alloy band structure, the critical Al composition at which each dopant transitions from being a shallow to a deep donor is estimated. Si is identified as being the most efficient dopant to achieve n-type conductivity in high Al-content AlGO alloys, acting as a shallow donor over the entire predicted stability range for AlGO solid solutions. Compensation by other unintentional impurities (such as H and C) is also assessed.

Other oxide materials have also emerged as potential competitors to Ga2O3, but their propensity for hole conductivity is less well known. Here the stability of hole polarons in a set of ultrawide-bandgap oxides (Ga2O3, Al2O3, ZnGa2O4, MgGa2O4, LiGaO2 and GeO2) is examined and compared, both in pristine material and in the presence of acceptor impurities. Holes spontaneously self-trap in all oxides investigated, with varying stabilities. Acceptor impurities further stabilize these trapped holes, leading to large acceptor ionization energies. Hole trapping also leads to characteristic distortions and distinct optical transitions, which may explain some experimentally-observed signals. These results indicate that achieving p-type conductivity in any of these oxides is unlikely, with the possible exception of GeO2.

This work was performed in collaboration with Darshana Wickramaratne (NRL), Joel Varley (LLNL), Sai Mu (UCSB), Mengen Wang (UCSB) and Chris Van de Walle (UCSB), and was supported by the ONR/NRL 6.1 Basic Research Program.
Catalyst Dissolution Analysis in PEM Water Electrolyzers during Intermittent Operation
Authors: Milosevic Maja , Knöppel Julius , Ehelebe Konrad , Abbas Dunia , Escalera López Daniel , Thiele Simon , Cherevko Serhiy
Published: July 2022

Sustainable development of the global energy sector requires a transition from fossil fuels to renewable energies. Considering the continuously increasing energy demand, effective utilization of intermittent output from the renewable sources will depend on the efficiency of energy storage and utilization processes. Low chemical complexity and high energy density and efficiency make hydrogen produced via proton exchange membrane water electrolysis (PEMWE) a prominent solution for the mentioned challenges.

Acidic conditions and high potentials at the anode side of PEM water electrolyzers, where the oxygen evolution reaction (OER) takes place, demand for materials with high catalytic activity and corrosion stability. The state-of-the-art platinum and iridium (oxide) catalysts in the cathode and anode catalyst layers (CLs), respectively, demonstrate relatively good activity and stability during steady operation at low and moderate electrical loads. Indeed, it is anticipated that a significant decrease in the noble metal amount may be achieved without sacrificing the cell performance [1]. An intermittent operation of PEMWE, however, represents a considerable risk factor as both CLs may degrade with time. The extent of such degradation, especially at low catalyst loadings and high current densities, alternated with numerous off cycles is still not well understood and hence, difficult to predict and mitigate.

Recent results from our group indicate a severe discrepancy between OER catalyst dissolution in aqueous model systems (AMS) and membrane electrode assemblies (MEA), with the main reasons being a suggested discrepancy between estimated and real pH in MEA and stabilization occurring over time [2]. In this work, CLs degradation during dynamic electrolyzer operation in a specially designed PEMWE test station was studied via ex-situ inductively coupled mass spectrometry analysis (ICP-MS) and its influence on the cell’s overall performance was analyzed. The S number, a new metric for OER catalyst lifetime estimation [3], was also used to compare catalyst stability properties within the two systems.

References:

Bernt, A. Siebel, H. Gasteiger, J. Electrochem. Soc. 165 (5), F305-F314 (2018)

Knöppel, M. Möckl, D. Escalera-Lopez, K. Stojanovski, M. Bierling, T. Böhm, S, Thiele, M. Rzepka, S. Cherevko, Nat. Commun. 12, 2231 (2021)

Geiger, O. Kasian, M. Ledendecker, E. Pizzutilo, A. M. Mingers, W. T. Fu, O. Diaz-Morales, Z. Li, T. Oellers, L. Fruchter, A. Ludwig, K. J. J. Mayrhofer, M. T. M. Koper, Serhiy Cherevko, Nat. Cat. 1, 508 (2018)

Figure 1. Longterm stability of IrOx in AMS and MEA environment. a) Loading-normalized total dissolved iridium amount at current densities of 0.2 A mgIr
-1 and 2 A mgIr
-1 in AMS and MEA respectively; b) S-numbers calculated from the amount of dissolved iridium.

Figure 1
(Digital Presentation) Facile and Efficient Synthesis of Hollow Leaf-Shaped Iron Doped Nickel Cobalt Layered Double Hydroxide Using 2-D Metal-Organic Frameworks for Oxygen Evolution Reaction
Authors: Quoc Hao Nguyen , Kim Jinsoo
Published: July 2022

The oxygen evolution reaction (OER) at the anode is of prime importance in electrochemical water splitting. Recently, layered double hydroxide (LDH) has been considered as one of the most effective materials for OER catalysts which are prone to hydrolysis and oxidation under OER conditions. Metal-organic frameworks (MOFs) are new class of porous materials with high crystallinity and high internal surface area. Based on their properties, the design of LDH based on morphology-controlled MOFs is gaining increasing attention. In this study, we report a novel approach to fabricate hollow leaf-shaped iron doped nickel cobalt LDH (Fe-NiCoLDH) based on 2D leaf-shaped ZIF (ZIF-L). Iron doping played an important role to enhance the specific surface area as well as the pore structure, resulting in improvement of the OER performance. Among the investigated Fe concentrations (from 40 to 80 mg) in this study, Fe60-NiCo LDH showed the highest electrocatalyst performance for OER of 10 mA cm-2 at 253 mV as well as high stability for 20 h. The design of nanostructures such as leaf-shaped LDH has great potential in enhancing OER efficiency.
Exploring the Effectiveness of Carbon Cloth Electrodes for All-Vanadium Redox Flow Batteries
Authors: Caiado Ashley A. , Aravamuthan Sundar Rajan , Goulart James , Gallaway Joshua W , Agar Ertan
Published: July 2022

Redox flow batteries (RFBs) have proven to be a promising technology for the integration of intermittent renewable energy sources into the existing electrical grid due to their ability to decouple energy and power ratings, and the associated cost-effectiveness in long-duration energy storage [1]. Among various flow battery chemistries, vanadium redox flow battery (VRFB) is one of the most prominently studied flow battery system [2]. In comparison to other chemistries, four soluble oxidation states of vanadium are available and accessible. This characteristic of VRFBs eliminates cross-contamination between the positive and negative half-cells that would otherwise deteriorate the life and durability of the battery [3]. In a flow battery cell, porous electrode is the key component that determines the performance of the system by delivering liquid electrolytes, facilitating ion/charge transfer, and providing sites for electrochemical reactions [4]. Recently, it has been found that significant performance improvements can be achieved with fabric (carbon cloth) electrodes when coupled with a wetting electrolyte [5].

In this talk, we will report our experimental approach to evaluate the short- and long-term effectiveness of various carbon cloth electrode samples for use in VRFBs. Results generated from symmetric flow cell cycling coupled with electrochemical impedance spectroscopy and polarization curve measurements will be discussed. The key physico-chemical properties and their evolution during cycling will be elucidated.

References:

[1] Z. Li, M. S. Pan, L. Su, P.-C. Tsai, A. F. Badel, J. M. Valle, S. L. Eiler, K. Xiang, F. R. Brushett, Y.-M. Chiang, Joule, 1, 306-327 (2017).

[2] M. Nourani, C. R. Dennison, X. Jin, F. Liu, E. Agar, J. Electrochem. Soc.,
166, A3844-A3851 (2019).

[3] M. Nourani, B. I. Zackin, D. C. Sabarirajan, R. Taspinar, K. Artyushkova, F. Liu, I. V. Zenyuk, E. Agar, J. Electrochem. Soc.,
166, A353-A363 (2019).

[4] A. Forner-Cuenca, F. R. Brushett, Curr. Opin. Electrochem., 18, 113-122 (2019)

[5] K. M. Tenny, A. Forner-Cuenca, Y.-M. Chiang, and F. R. Brushett, J. Electrochem. Energy Convers. Storage, 17, 041010 (2020).
Nonaqueous Redox Flow Batteries Incorporating Novel Pyridinium Anolytes
Authors: Hengesbach Charley , Scott Jessica , Samaroo Sharmila , Bruggeman Chase , Hickey David , Guarr Thomas F.
Published: July 2022

While the use of nonaqueous solvents in redox flow batteries (RFBs) offers the promise of higher cell voltages than can typically be obtained in aqueous electrolytes, suitable compounds that are sufficiently soluble and stable to permit extended operation has proven challenging. Viologen anolytes have been successfully employed in aqueous systems, but their first reduction occurs at very modest potentials, thus limiting their advantage in nonaqueous systems. We have previously reported flow battery chemistry employing a series of extended bis(pyridinium) species with reduction potentials ca. 300-400 mV more negative than viologens and very long-lived, durable reduced states. However, these materials were difficult to access via common synthetic routes and often exhibited limited solubility.

In this presentation, we describe an extension of those studies to new pyridinium compounds that provide still more negative reduction potentials (ca. -1.6 to -1.7 V vs Fc/Fc+). Moreover, these compounds are readily synthesized in good yield from inexpensive raw materials, are highly soluble, display excellent electrochemical kinetics, and are extremely persistent in the reduced state. The synthesis and electrochemical characterization of compounds incorporating these groups will be presented, along with preliminary RFB cycling results.
(Digital Presentation) Development of a Bio-Inspired Non-Aqueous Redox Flow Battery Utilizing Anionic Active Materials
Authors: Pahari Shyam Kumar , Visayas Benjoe Rey B. , Brown Ross S , Gokoglan Barut Tugba Ceren , Golen James A , Agar Ertan , Mayes Maricris L. , Cappillino Patrick J.
Published: July 2022

Energy storage is an indispensable part of future electrical grids as they increasingly shift toward renewable energy sources.1 Although many other energy storage technologies have shown potential, redox flow batteries are especially promising because of advantages arising from their decoupled power and energy capacity, wide range of possible electroactive materials, wider potential window (in non-aqueous solvents) and safety. 2 However, the nascent non-aqueous redox flow battery (NRFB) technology currently faces key challenges that need to be addressed to ensure their reliability and widespread implementation. Low stability of active material during deep cycling is one such challenge that needs to be addressed while low solubility of active material in organic solvent is another main hurdle that greatly limits energy density.

Herein, we present a cost-effective, experimental-theoretical approach 3
,
4 to improve the solubility of a vanadium-based, highly stable, anionic active material known as vanadium-bis-hydroxyiminodiacetate (VBH). This is accomplished by tuning the key thermodynamic quantities of free energy of solvation and free energy of the lattice. We also demonstrate that the lattice free energy, which has been largely ignored in theoretical solubility models, is vital to obtain a meaningful prediction of solubility, and cannot be overlooked. Finally, we report the full cell cycling of the highly soluble VBH, coupled with an anthraquinone, exhibiting excellent cyclability and a reliable spectroscopic method to characterize pre- and post-cycled electrolytes.

References

(1) IEA. Renewable Energy Market Update 2021
; Paris, 2021.

(2) Dunn, B.; Kamath, H.; Tarascon, J.-M. Electrical Energy Storage for the Grid: A Battery of Choices. Science
2011, 334 (6058), 928-935. DOI: 10.1126/science.1212741.

(3) Pahari, S. K.; Gokoglan, T. C.; Visayas, B. R. B.; Woehl, J.; Golen, J. A.; Howland, R.; Mayes, M. L.; Agar, E.; Cappillino, P. J. Designing high energy density flow batteries by tuning active-material thermodynamics. RSC Advances
2021, 11 (10), 5432-5443, 10.1039/D0RA10913D. DOI: 10.1039/D0RA10913D.

(4) Visayas, B. R. B.; Pahari, S. K.; Gokoglan, T. C.; Golen, J. A.; Agar, E.; Cappillino, P. J.; Mayes, M. L. Computational and experimental investigation of the effect of cation structure on the solubility of anionic flow battery active-materials. Chemical Science
2021, 12 (48), 15892-15907, 10.1039/D1SC04990A. DOI: 10.1039/D1SC04990A.
Ammonia Driven Reversible Solid Oxide Cell As Large-Scale Grid Energy Storage System
Authors: Nami Hossein , Nemati Arash , Frandsen Henrik Lund
Published: July 2022

The global agreement on the reduction of greenhouses entails increased use of intermittent renewable energy sources such as wind and solar. In this contest, there is a huge need for efficient and cost-effective energy storage systems. Currently, different types of grid energy storage systems are under operation worldwide. However, few of them have the capacity of storing several MWhs of electricity. Large-scale energy storage systems will play a vital role in grid stabilization by reducing imbalances between energy production and demand. Solid oxide cells (SOC) are promising and efficient technologies operating both on electrolyzer and fuel cell modes applicable for energy storage and production. The efficiency of SOC can be further increase by utilization of excess high temperature steam from other processes like ammonia synthesis when it is operating as electrolyzer. In this way, part of the energy needed for electrlozer is covered and less input energy is required, which leads to higher efficiency. This is the main reason behind combining solid oxide cells with the ammonia synthesis process. In the present work, we propose a large-scale electricity storage system operating with reversible solid oxide cells (RSOC) to store electricity as synthetic ammonia. Ammonia can be easily produced, when RSOC operates as an electrolyzer, and stored in the liquid form during off-peak demand. During the peak demand, stored ammonia can be fed into the RSOC, when RSOC operates as a fuel cell, to produce green electricity. Besides the RSOC, the proposed system mainly consists of an air separation unit (ASU) and a Haber-Bosch loop (HBL). Besides large-scale storing of grid electricity, such a system can create an efficient link between electricity and ammonia markets. The system performance is evaluated at a component level thermodynamic analysis showing that a round-trip storage efficiency higher than 50% is achievable.
Incorporating ALD Based Pt Alloy Catalysts into Gas Diffusion Electrodes for Proton Exchange Membrane Fuel Cells
Authors: Tan Shunquan , Xu Shicheng , Dull Samuel , Jaramillo Thomas F , Prinz Fritz
Published: July 2022

Atom layer deposition is a promising method to fabricate gas diffusion electrodes (GDE) with platinum catalysts for high-power-density Proton Exchange Membrane Fuel Cells (PEMFCs). Alloying Pt with transition metals can further improve the intrinsic activity for oxygen reduction reaction due to the ligand and strain effects. Nevertheless, incorporating alloy catalysts into GDE posts more challenges.

In this study, we systematically explore and optimize alloy-based catalysts via ALD deposition on gas diffusion layers (GDL). While GDE tolerates 200 oC annealing for alloys that can form under low temperature (e.g.PtxZny) and present high ORR performance, GDE for PtxTiy alloy presents inferior performance after high-temperature annealing.

To circumvent this temperature compatibility issue, we successfully developed a modified high-temperature ALD method for PtxTiy alloy by taking advantage of a porous metal felt. With this, ALD-based high temperature annealed PtxTiy series alloy can maintain its atomic structure, and the GDL can keep its high hydrophobicity. Further Membrane Electrode Assembly (MEA) testing results and insights into active site areas and activation energy for different alloys and fabrication methods provide the in-depth elucidation of the relationship between reaction kinetics and GDE structures.
Platinum-Based Nanoparticle Fuel Cell Catalysts Synthesized By Sputtering Onto Liquid Substrates
Authors: Lönn Björn , Brown Rosemary , Pfeiffer Robin , Frederiksen Henrik , Wickman Björn
Published: July 2022

The quest of finding cheaper and better fuel cell catalyst materials has been long ongoing and remains a crucial step in making fuel cells a commercially viable technology. Platinum (Pt) is still the conventional catalyst used in proton exchange membrane (PEM) fuel cells, however, with slow cathode kinetics and high material cost. Platinum-rare earth (RE) and lanthanide alloys have been found to greatly enhance the catalytic activity towards the oxygen reduction reaction (ORR).1 Increases in ORR activity of up to one order of magnitude compared to pure platinum has been observed for these alloys, but high oxygen affinity of the RE alloying agents considerably complicates their synthesis. Sputter deposition into low vapor pressure liquid substrates, such as ionic liquids and certain polymers enables fabrication of clean nanoparticles, without the presence of air and other contaminates, making it a potential technique for Pt-RE nanoparticle synthesis.

Here, we will present our recent work on magnetron sputtering of Pt 2 and Pt-alloys into different liquid substrates, including polyethylene glycol and three imidazolium-based ionic liquids. We have investigated the influence of substrate temperature on Pt nanoparticle growth during sputtering, and in post-sputtering heat treatment.2 We show that whilst substrate temperature influences the Pt nanoparticle size, the effect is not as great as for other materials. Better understanding the growth processes of Pt nanoparticles sputtered into liquids is an important step towards tunable sizes and catalytic activities of Pt-RE nanocatalysts.

Escudero-Escribano, María, et al. "Tuning the activity of Pt alloy electrocatalysts by means of the lanthanide contraction." Science 352.6281 (2016): 73-76.

Brown, Rosemary, et al. "Plasma-Induced Heating Effects on Platinum Nanoparticle Size During Sputter Deposition Synthesis in Polymer and Ionic Liquid Substrates." Langmuir 37.29 (2021): 8821-8828.
The Understanding of the Improved Catalytic Performance of Steam-Activated Fe-N-C Catalyst for Alkaline Hydrazine Fuel Cell
Authors: Bae Sooan , Park Jihyeon , Jeong Beomgyun , Lee Jaeyoung
Published: July 2022

Fe-N-C materials are currently the most promising non-noble-metal-based ORR electrocatalyst, but their low density of surface active sites compared with Pt/C necessitates improving their utilization via porous structures. Previously, we studied modified Fe-N-C catalyst for the oxygen reduction reaction (ORR) in the cathodes of alkaline hydrazine liquid fuel cells (AHFC). Fe-N-C with magnetite particles and hierarchical pore structure was prepared by steam activation. The steam activation process significantly improves the power performance of the AHFC as indicated by the lower IR and activation voltage losses. The steam activation transformed the Fe3C nanoparticles in Fe-N-C into larger Fe3O4 particles, which caused the electrode surface to become more hydrophilic. Here, elimination of the Fe3O4 nanoparticles by acid leaching was conducted to investigate the effect of Fe3O4 nanoparticles, resulting in enhancing power performance for alkaline hydrazine liquid fuel cells.
Bifunctional Platinum-Free Mixed Metal Oxygen Electrocatalysts Based on Naturally Abundant Peat
Authors: Teppor Patrick , Jäger Rutha , Härmas Meelis , Aruväli Jaan , Volobujeva Olga , Koppel Miriam , Lust Enn
Published: July 2022

A functioning hydrogen economy requires efficient ways of producing and utilizing hydrogen via electrolyzers and fuel cells. The commercialization of these devices is well underway but their considerable capital costs still inhibit faster adoption by society1,2. One pathway towards more inexpensive devices is by tackling their respective bottlenecks, the oxygen evolution and reduction reactions, which currently require catalyst materials comprised of scarce precious metals. Intensive research is being conducted to introduce and develop suitable replacements for these catalysts. In this field, non-platinum group metal (NPGM) type catalysts have gained significant attention2,3.

We present several NPGM-type oxygen electrocatalysts synthesized by modifying peat-derived carbon with nitrogen and different combinations of transition metals (Fe, Co, Ni). The obtained catalysts were characterized with various methods to elucidate their structure-reactivity relations. Namely, SEM-EDS was used to confirm that the modification of peat-derived carbon was successful. Additionally, the various metal alloy species found in the catalysts were identified via X-ray diffraction analysis. The excellent bifunctional electrocatalytic activity of the peat-based materials towards oxygen evolution and reduction was confirmed with rotating disc electrode measurements conducted in a 0.1 M KOH solution. Correlations between the physical and electrochemical properties of the catalysts were established and analyzed.

Acknowledgments

This work was supported by the EU through the European Regional Development Fund under projects TK141 “Advanced materials and high-technology devices for energy recuperation systems” (2014-2020.4.01.15-0011), NAMUR “Nanomaterials - research and applications” (3.2.0304.12-0397), PRG676 “Development of express analysis methods for micro-mesoporous materials for Estonian peat derived carbon supercapacitors” (01.01.2020–31.12.2024) and PUT1581 (1.01.2017–31.12.2020).

References

E4tech, 2021, The Fuel Cell Industry Review 2020.

C. Lei, S. Lyu, J. Si, B. Yang, Z. Li, L. Lei, Z. Wen, G. Wu, Y. Hou, ChemCatChem 2019, 11, 5855.

L. Osmieri, J. Park, D. Cullen, P. Zelenay, D. Myers, K. Neyerlin, Curr Opin Electrochem 2021, 25, 100627.

Figure 1
Investigation of Oxygen Reduction on Platinum Nanoparticles Deposited Onto Peat-Derived Carbon Carrier
Authors: Lobjakas Wiljar , Nerut Jaak , Kasuk Heili , Adamson Anu , Thomberg Thomas , Aruväli Jaan , Valk Peeter , Teppor Patrick , Koppel Miriam , Mikli Valdek , Volobujeva Olga , Lust Enn
Published: July 2022

Carbon supported platinum catalysts for proton exchange membrane fuel cell (PEMFC) applications have been studied intensively in the scientific community.1,2 The catalytic activity of the catalyst depends on the characteristics of the carbon support material3 and on the Pt depositing method4,5. The aim of the study was to investigate the oxygen reduction reaction (ORR) on Pt nanoparticles deposited on peat-derived carbon. The Pt nanoparticles were deposited on the carbon support material by three different methods using NaBH4 (NBH), ethylene glycol (EG) and isopropyl alcohol (IA) as a reducing agent.

The studied materials were characterized using N2 sorption, X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Structure of the platinum nanocatalyst on carbon support was also studied using scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX). For electrochemical characterization, the electrochemically active surface area (ECA) of the materials were measured in a three-electrode system (0,1 M HClO4) and in a completed PEMFC. The ORR kinetics of the materials were studied by the rotating disk electrode (RDE) method as well as in a PEMFC configuration.

As a result, it was found that the higher the ECA of the material, the higher the catalytic activity. The catalytic activity of the synthesized materials increases in order: IA < NBH < EG. ECA of the materials increases in the same order. Also, the special surface area of the materials increases in the same order. The catalytic activities of the synthesized materials were compared to a commercial catalyst material, 60% Pt on HSA Ketjenblack.

References

O. Z. Sharaf and M. F. Orhan, Renew. sust. energ. rev., 32, 810–853 (2014).

Y. Wang, K. S. Chen, J. Mishler, S. C. Cho, and X. C. Adroher, Appl. Energ., 88, 981–1007 (2011).

S. Sharma and B. G. Pollet, J. Power Sources, 208, 96–119 (2012).

S. Sepp et al., Electrochim. Acta, 203, 221–229 (2016).

P. Valk et al., J. Electrochem. Soc., 165, F315–F323 (2018).

Acknowledgements

The author thanks the European Union Regional Development Fund for the financial support of the project TK141 “Innovative materials and high-tech equipment for energy recovery systems” (2014-2020.4.01.15-0011); the Estonian Research Agency project (personal research support group grant project No. PRG676) and the Estonian Energy Technology Program: SLOKT10209T “. Nanomaterials – research and applications (NAMUR)” project 3.2.0304.12-0397. The author also thanks the private limited company AuVe Tech.