bluuebunny/crossref_metadata_2025_split huggingface dataset:
Untapped Potential: The Need and Pathways to High-Voltage Aqueous Redox Flow Batteries
Authors: Perry Mike L. , Rodby Kara E. , Brushett Fikile R. 
Published: July 2021

With the increasing desire to decarbonize, decentralize, and fortify the power grid, we must develop cost-effective electrical-energy storage (EES) technologies that can support a diverse set of large-scale applications1. Redox flow batteries (RFBs) are a potential energy storage solution that is increasingly competitive, on a capital cost basis, for EES applications that require longer discharge durations due to their unique decoupling of energy and power2. Both non-aqueous RFBs (NAqRFBs) and aqueous RFBs (AqRFBs) are possible, but AqRFBs are currently the dominant class of RFB chemistries due to their significantly lower solvent cost, inherently higher electrolyte conductivity, and relative safety (i.e., reduced flammability). The major advantage of NAqRFBs is they are not limited by the electrochemical stability window (ESW) of water, allowing for higher cell voltages. Most techno-economic studies, to date, have considered the maximum OCV of AqRFBs to be ≤1.5 V due to the common misconception that the ESW of water is limited to ~1.5 V. However, through careful consideration of electrolyte composition, cell design, and operating practices, AqRFBs with potentials >1.5 V can exist with minimal and/or manageable water splitting. Development of such systems would increase the attractiveness of this class of chemistries and is a promising pathway to low-cost RFB systems, especially since most NAqRFBs have not been able to stably achieve >3 V (generally, the voltage needed to overcome other techno-economic barriers of NAqRFBs to make them competitive).
We have performed basic techno-economic analyses to demonstrate the impact of higher cell voltages (up to 2.5 V) for AqRFB capital cost , and also consider the secondary benefits that can arise from the flexibility provided by higher power and energy densities. A major benefit seen at cell voltages ≈ 2 V or higher is significantly lower projected capital costs. There are multiple challenges to realizing AqRFBs with such high potentials, and we will discuss some potential pathways to enabling realistic systems. This includes the mitigation and remediation of hydrogen and oxygen evolution, as well as stability issues with other RFB components. We will also point out the need for fundamental research on a variety of topics, and new experimental protocols, that can assist the community in developing AqRFBs with higher OCVs.
We hope this perspective will inspire the field to reexamine the perceived upper limits of AqRFB chemistries and to explore options for achieving high-voltage systems.

References

Intergovernmental Panel on Climate Change. Global Warming of 1.5 C. https://www.ipcc.ch/sr15/ (2018).

Darling, R. M., Gallagher, K. G., Kowalski, J. A., Seungbum, H. & Brushett, F. R. Pathways to low-cost electrochemical energy storage: a comparison of aqueous and nonaqueous flow batteries. Energy Environ. Sci.
7, 3459–3477 (2014).
The Influence of Current Density on Transport of Vanadium Cations through Three Exemplary Membranes
Authors: Darling Robert M. , Saraidaridis James D , Shovlin Christopher , Fortin Michael 
Published: July 2021

Transport of a redox active molecule through the separator in a flow battery is an important source of inefficiency and electrolyte imbalance. This transport occurs by diffusion, migration, and convection, with driving forces that change with state of charge. Typically, only diffusive permeability and conductivity are measured to characterize transport in membranes, because they are straightforward experiments. The Nernst-Planck-Einstein equation for transport in electrolyte solutions suggests that this may be sufficient because the transference number of an ion can be calculated from its diffusion coefficient and conductivity.
We measured transport of four vanadium cations through Nafion (cation exchange), Fumasep FAPQ-330 (anion exchange), and polybenzimidazole as a function of current density. The measurements were made using a cell with three membranes and four flow compartments designed to collect vanadium passing through sample separators and into receiver compartments. These experiments were augmented with independent sorption and conductivity measurements to assist interpretation in the context of Nernst-Planck-Einstein.
The figure shows the sum of the partial current densities of V2+ and V3+ versus current density for the three membranes. Partial currents at zero total current are proportional to diffusive permeability and slopes at currents greater than zero approximate transference numbers. Transport of vanadium cations is hindered by an anion exchange membrane more than a cation exchange membranes as expected. The gaps in transport observed at zero current widen as current increases. Further data, not shown here, taken with VO2+ and VO2
+ ions on the same membranes indicate that transport is strongly influenced by the nature of the cation. All experimental results are compared to predictions from Nernst-Planck-Einstein.
Acknowledgements
This work was supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.

Figure 1
(Invited) Electro-Optical Techniques to Measure Traps in Organic-Based Devices: Why the Methods Originally Developed for Silicon-Based Devices Must be Modified
Authors: Gomes Henrique L , Medeiros Maria Carmo Raposo 
Published: July 2021

Electrical techniques to detect traps are a crucial part of the development of a new electronic materials and devices. Since most of our electronic technology relies on silicon, the well-established methods to measure traps were originally developed for silicon-based devices. The intense work developed in the 60’s to map all electronic defects in silicon brough the technology to today’s standards. Among the techniques developed are the deep level transient spectroscopy, photo-induced current spectroscopy, and admittance spectroscopy. Blood and Orton wrote and excellent textbook on these methods [1]. The methodology behind these techniques is the following: Traps are first filled using a voltage pulse or a light pulse, then the kinetics of the charge carrier release is measured usually as function of temperature. This allow us to determine the trap signature (energetic depth and cross-capture section). In organic semiconductors this methodology often does not apply, this is because the traps are extremely deep. A trap with an energetic depth of 0.1 eV is considered a very deep trap in silicon, but in organic electronics, is just a shallow trap. Traps in an organic semiconductor may have an energetic depth higher than 0.5 eV they can be so deep that a charge carrier may take minutes, hours or even days to be released. This makes unpractically the use of the popular methods to study traps in silicon. To detect the presence of the traps and their effects on the device performance the standard methods developed for silicon must be modified.
In this contribution we present a methodology to detect the presence of deep traps in organic based devices. This methodology relies on the measuring the trap filing process and not the trap emptying process. To perform this analysis, the traps must be first emptied, so the device is first brough into a state called “trap emptied state”. This state is then frozen to a specific low temperature and the trap filling recorded at that temperature. To reach a “trap empty state” several methods can be used, namely high temperature while the device is kept under short circuited conditions and/or light exposure for certain types of traps. This methodology was used to detect the effect of traps in organic- based transistors. Transistor devices produced by spin coating and by ink-jet printing methods were studied and presented in this work. The use of this methodology revels the presence of metastable traps that only become active above certain temperatures (200 K, 240 K, and 310 K). This type of metastable traps is only observed organic thin film transistors.
[1] J. W. Orton and P. Blood “Electrical Characterization of Semiconductors: Measurement of Minority Carrier Properties (Techniques of Physics)”, Academic Press (November 11, 1990).
(Invited) Simulations of Ion Diffusion throughout Perovskite Based Solar Cells - Device Level Electrochemistry
Authors: Bitton Sapir , Tessler Nir 
Published: July 2021

Defect chemistry plays a major role in the operation of perovskites cells. On one hand they are behind the remarkable self-healing,[1] while on the other they dictate the level of traps, non-radiative recombination,[2] as well as promote ion migration.[3] Moreover, once ions reach the electrodes the device degradation is accelerated.[4, 5] Combining the various reports it seems that if the perovskite would not lose its constituents it would self-heal and if it do lose them it is game-over. We claim that ion migration into the blocking layer is the most important electrochemical process standing in the way of long-term stability. As we will show at the presentation, a significant part of the electrochemistry behind ion leakage and consequently electrode reactions, is captured by a semiconductor device model that accounts for mixed electronic-ionic conduction.[6] While the mere transport of ions introduces no device degradation, introducing oxidation/reduction reactions at the electrodes reproduces the effect of light & bias on device stability. Lastly, we’ll discuss if it is possible to design the device to mitigate this ion leakage out of the perovskite layer.
References
[1] D. R. Ceratti et al., "Self-Healing Inside APbBr3 Halide Perovskite Crystals," Advanced Materials, vol. 30, no. 10, p. 1706273, 2018, doi: 10.1002/adma.201706273.
[2] J. M. Azpiroz, E. Mosconi, J. Bisquert, and F. De Angelis, "Defect migration in methylammonium lead iodide and its role in perovskite solar cell operation," Energy Environ. Sci., 10.1039/C5EE01265A vol. 8, no. 7, pp. 2118-2127, 2015, doi: 10.1039/C5EE01265A.
[3] D. Meggiolaro, E. Mosconi, and F. De Angelis, "Formation of Surface Defects Dominates Ion Migration in Lead-Halide Perovskites," ACS Energy Letters, vol. 4, no. 3, pp. 779-785, 2019/03/08 2019, doi: 10.1021/acsenergylett.9b00247.
[4] F. Galatopoulos, I. T. Papadas, G. S. Armatas, and S. A. Choulis, "Long Thermal Stability of Inverted Perovskite Photovoltaics Incorporating Fullerene-Based Diffusion Blocking Layer," Advanced Materials Interfaces, vol. 5, no. 20, p. 1800280, 2018/10/01 2018, doi: 10.1002/admi.201800280.
[5] B. Rivkin, P. Fassl, Q. Sun, A. D. Taylor, Z. Chen, and Y. Vaynzof, "Effect of Ion Migration-Induced Electrode Degradation on the Operational Stability of Perovskite Solar Cells," ACS Omega, vol. 3, no. 8, pp. 10042-10047, 2018/08/31 2018, doi: 10.1021/acsomega.8b01626.
[6] S. Bitton and N. Tessler, "Electronic-ionic coupling in perovskite based solar cells: Implications for device stability," Applied Physics Letters, vol. 117, no. 13, p. 133904, 2020, doi: 10.1063/5.0023902.
(Invited) New Insights on Charge Transport in Organic and Polymer Thin-Film Transistors
Authors: Dodabalapur Ananth , Wang Xiao , Liang Kelly , Mcculley Calla 
Published: July 2021

There have been many reports of thin-film transistors based on semiconductors with mobilities in the range 1-20 cm2/Vs in the past few decades. The mobilities and mean free paths are simply too low for the application of conventional semiconductor transport theories based on solutions to the Boltzmann transport equation (BTE). We will present a very general solution based on the statistical nature of charge transport and introduction of a factor related to the probability of mean free path exceeding the minimum transport length. We are then able to apply the BTE with appropriate scattering mechanisms and obtain very good results that agree well with experiment. This approach is very well suited to thin-film transistors based on polymer and organic semiconductors with room temperature mobilities in the range 1-20 cm2/Vs. We compare theory with experimental results for DPP-based polymers and also oxides.
Charge transport depends on carrier densities and electric fields in complex ways. We describe these dependencies in detail. Scaling down channel dimensions of organic and polymer semiconductor based thin-film transistors to submicron and nanoscale dimensions, required for higher speed operation, presents several challenges. Successful scaling will enable vastly improved device performance and hence the prospects are certainly very enticing. One of the biggest challenges is in making relatively low-resistance contacts. A more thorough understanding of velocity saturation mechanisms and charge transport at high electric fields is also necessary. We describe charge transport in oxide and polymer TFTs with an emphasis on scaling. We show that for some TFTs, scaling of the channel width facilitates scaling down of channel length and a nanostripe or nanogroove array channel geometry has advantages. Finally, we describe hybrid TFTs – with multiple materials that are better suited to scaling down.
(Invited) Multi-Gate Contact-Controlled Transistors
Authors: Sporea Radu Alexandru 
Published: July 2021

Contact effects are a central focus in the development of high performance thin-film transistors (TFTs) and circuits, motivated by the increased speed and current density achievable by reducing contact energy barriers. Conversely, the rectifying properties of contacts have been utilised to create devices in which the current is, for the most part, controlled by the contact properties and bias conditions rather than the semiconductor channel [1]. These transistors operate at lower speeds but bring operational advantages such as geometrical and bias stress tolerance and have been extensively studied in their operation [2] and potential applications [3, 4] in varied material systems [5-7].
We have recently introduced the Multimodal Transistor (MMT), in which channel conductance and charge injection at the source are controlled independently by individual gates [8], offering important benefits to the functionality of analog and mixed signal circuits. These devices build on earlier innovations which modulate contact barriers [1, 5, 6, 7, 9-11] and take advantage of the recent acceptance into the mainstream of multi-gate TFTs [12, 13] to enable constant transconductance, high-speed switching, low output conductance, low-voltage saturation, and robustness against geometrical variability.
Here, the structure and operation of MMTs (Figure 1) is briefly reviewed and challenges and opportunities for this device are discussed, focusing on the specifics of solution-processed and organic implementations.
[1] J. M. Shannon et al., IEEE Trans. Electron Devices, 60, 2444–2449 (2013).
[2] A. Valletta et al., J. Appl. Phys. 114 064501 (2013).
[3] R. A. Sporea et al., Scientific Reports
4 4295 (2014).
[4] Bestelink, E. et al., IEEE Sens. J., 20 (24), 14903 (2020).
[5] Zhang, J., et al, PNAS
116, 4843 (2019).
[6] Lee, S. and A. Nathan, Science
354, 302 (2016).
[7] Jiang, C. et al, Science 363, 719 (2019).
[8] E. Bestelink et al., Advanced Intelligent Systems, 2000199 (2020).
[9] Torricelli, F. et al, Nat. Commun. 7, 1 (2016).
[10] Yoo H. et al., Sci. Rep.
7, 1 (2017).
[11] Uemura T. et al., Adv. Mater.
26, 2983 (2014).
[12] Myny, K. et al., IEEE JSSC
46 (5), 1223, (2011).
[13] Lee S. et al., JSID 27, 507, (2019).
Figure 1. A) Schematic cross-sections of the multimodal transistor (MMT) showing its principle of operation: conduction state is set by the channel gate CG2, while current magnitude is controlled by source gate CG1. B) output characteristics of a nanocrystalline silicon MMT indicating the early saturation and constant transconductance, gm
. C and D) are transfer characteristics obtained by varying CG1 and CG2 voltages, respectively.

Figure 1
A 1 mWh Advanced Iron-Chromium Redox Flow Battery and 200 Kw Li-Ion Battery Hybrid Unit
Authors: LI Liyu 
Published: July 2021

An aqueous-based true redox flow battery has many unique advantages, such as long lifetime, safe, non-capacity decay, minimal disposal requirement, and flexible power and energy design. All these make it a great candidate for the vast renewable energy storage market. The key issue with this technology is the cost and availability of the energy-storage media. Due to the limited vanadium resources, it is very difficult for the widely studied vanadium-based redox flow battery to be commercially used for fast-growing renewable energy storage market.
Iron-chromium redox flow battery was invented by Dr. Larry Thaller’s group in NASA more than 45 years ago. The unique advantages for this system are the abundance of Fe and Cr resources on earth and its low energy storage cost. Even for a mixed Fe/Cr system, the electrolyte cost is still less than 10$/kWh. The major issue with this system is the continuous capacity decay due to hydrogen generation, which makes this system impractical for long-term operations.
In the past two years, this limiting problem was successfully solved by researchers at Creek Channel, Inc.1,2 By using a special system design, the hydrogen generation level was largely reduced, down to less than 0.5% per full cycle. A capacity recovery system was also successfully developed, which can compensate the system capacity loss due to hydrogen generation. More than 1000 cycles of operation have been carried out using a system with a kW-scale stack and 100 L electrolyte over a few months. Stable system capacity and stable continuous operation were successfully achieved.
With these breakthrough results, a demonstration project of 30 MWh capacity using containerized product is being developed at Lion Creek Co. Ltd. For a 20’ ISO container-sized product, the deliverable energy is 250 kWh, and the max discharge capacity is 35 kW. For a Two 40’ ISO container-sized product, by using a hybrid design integrating with a 200 kW and 100 kWh Li-ion battery, the deliverable energy is 1100 kWh, and the long-duration discharge power can be as high as 330 kW. Larger projects can be readily built up using multiple 1.1 MWh units. The cost for such these products is lower than 100$/kWh, and the energy storage cost using this product is less than $0.02/kWh. With this energy storage cost, it is possible to achieve our ambitious 100% renewable energy goal in the near future.
In this poster, we will present our recent progress on the development of a 1 MWh advanced Fe-Cr redox flow battery and 200 kW Li-ion battery hybrid unit.

US 10777836 B1. Redox Flow Battery Systems Including a Balance Arrangement and Methods of Manufacture and Operation.

US 10826102 B1. Fe-Cr Redox Flow Battery Systems Including a Balance Arrangement and Methods of Manufacture and Operation.

Figure 1
Bipolar Diimide Based Molecule for Nonaqueous Symmetric Redox Flow Battery
Authors: Nambafu Gabriel , Shao Minhua 
Published: July 2021

Redox flow batteries (RFBs) allow decoupling of power and energy capacity, a unique feature that makes them a promising energy storage technology for large scale applications[1]. In recent years, there has been a massive development in aqueous organic RFBs. However, their commercialization has been hindered by low energy density owing to low solubility of redox active materials and narrow electrochemical stability window of water which limits the cell voltage[2] .
Nonaqueous redox flow batteries based on organic redox active material are a regarded as an alternative to aqueous organic RFBs[3] . Apart from enjoying the advantages of organic redox active materials such as low cost, diverse molecular structure and tailorability, nonaqueous RFBs also benefits from using organic supporting electrolytes which provide a wider voltage window (2-5V) facilitating a high energy capacity and low-cost storage system[4, 5] .
Herein, a diimide based molecule is designed, chemically modified, analysed and employed as bipolar redox active materials for a total organic symmetric redox flow battery. Cyclic voltammetry studies show three redox couples, two anodic one electron transfer and one cathodic two electrons transfer redox transitions which are electrochemically reversible. The potential difference between the cathodic peak and the inner and outer anodic peaks leads to a promising cell voltage of 1.51V and 2.22V respectively in redox flow battery application. This work suggests an alternative way to design a multielectron redox active materials for symmetric batteries.
Figure 1: Cyclic voltammogram of 0.002M diimide based molecule in 0.1M tetrabutylammonium hexafluorophosphate in dimethylformamide recorded on a glassy carbon working electrode with a scan rate of 50 mV/s.

Acknowledgement

The work described in this paper was fully supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. T23-601/17-R)

References

[1] P. Alotto, M. Guarnieri, F. Moro, Renewable and Sustainable Energy Reviews. 29 (2014) 325-335.
[2] J. Luo, B. Hu, M. Hu, Y. Zhao, T.L. Liu, ACS Energy Letters. 4 (2019) 2220-2240.
[3] S. Shin, S. Yun, S. Moon, Rsc Advances. 3 (2013) 9095-9116.
[4] W. Wang, V. Sprenkle, Nature Chemistry. 8 (2016) 204-206.
[5] M. Hayyan, F.S. Mjalli, M.A. Hashim, I.M. AlNashef, T.X. Mei, Journal of Industrial and Engineering Chemistry. 19 (2013) 106-112.

Figure 1
Flowing Electrolyte Metal Batteries
Authors: Parekh Mihir , Rahn Christopher D 
Published: July 2021

Flowing electrolyte metal batteries (FEMBs) are a new class of energy storage devices with metal anodes and flowing electrolytes. In this presentation, electrochemical models predict that flowing electrolyte can accelerate diffusion-limited transport, reducing impedance, increasing stability, and improving coulombic efficiency and cycle life. Electrolyte flow toward the metal electrode reduces and, for flow velocities above a critical speed, changes the sign of the electrolyte impedance, allowing faster charging without exceeding voltage limits. The critical flow rate is very slow (~μm/s) and directly proportional to the charging current density. Concentration of diffusion flux at dendrite tips is responsible for accelerated dendrite growth in metal batteries, so introduction of creeping electrolyte flow normal to electrodes levels ion concentration and eliminates dendrites above the critical speed. Creeping normal flow also significantly reduces solid electrolyte interphase (SEI) growth rate [1]. Creeping Poiseuille and Couette flows that are parallel to the electrodes have no impact on impedance or SEI layer growth, but do reduce dendrite growth, albeit much less effectively than normal flow [2]. Both creeping normal and parallel flows eliminate/reduce dendrite growth, so introducing electrolyte flow, in general, is a promising method to control dendrite growth. As dead Li formation is tied to dendrite growth, and as creeping normal flow eliminates dendrites and reduces SEI layer growth [3], creeping normal flows significantly improve coulombic efficiencies, and cycle life. The low flow rates indicate potential for practical applications.
[1] Parekh, Mihir N., Christopher D. Rahn, and Lynden A. Archer. "Controlling dendrite growth in lithium metal batteries through forced advection." Journal of Power Sources 452 (2020): 227760.
[2] Parekh, Mihir N., and Christopher D. Rahn. "Reducing Dendrite Growth in Lithium Metal Batteries by Creeping Poiseuille and Couette Flows." Journal of the Electrochemical Society (2020).
[3] Parekh, Mihir N., and Christopher D. Rahn. “Solid electrolyte interphase growth on lithium metal electrodes with normal electrolyte flow.’’ Journal of the Electrochemical Society (Submitted).

Figure 1