bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Degradation Aspects of Electrocatalysts and Materials in PEM Water Electrolyzers
Authors: Carmo Marcelo 
Published: February 2020

When coupled to renewable but nonetheless intermittent power sources such as wind or solar, polymer electrolyte membrane (PEM) electrolyzers are intended to be in operation for tens of thousands of hours [1]. Hence, the long-term behavior of catalyst coated membranes (CCMs) under some specific operating characteristics is of great importance. Previous durability studies have focused on electrolyzers operating at constant current input, showing little to no significant degradation (<4µVh) after 40.000 h at moderate conditions (25 cell stack, around 50°C and 1,3 A/cm²)[2]. In another study, constant and highly variable operation mode was compared for three used stacks after 7.500 h and indicated that variable operation might result in higher cell decay [3]. To the best of our knowledge, no durability data has been published yet, that fundamentally contrasts the effects of defined dynamic load profiles and constant operation on the cell decay in single cell tests. This is particularly crucial, since coupling PEM electrolysis to renewable power sources involves dealing with fluctuating power inputs, startup, and shutdown incidents that for PEM fuel cells are known to accelerate degradation.
In this study we demonstrate for the first time, the different effect of a constant and defined dynamic operation on the cell decay. For this purpose, durability tests were performed using state-of-the-art PEM electrolysis cells. The physicochemical characteristics were comprehensively addressed and the main process constraints (e.g., electrical, reaction, and transport) were analyzed. Exceptional improvements could be demonstrated using new membrane and catalyst materials enhancing performance, gas separation, and overall durability. Our results also show an effect of the operation mode on the degradation rate. Moderate conditions of 1 A/cm² show no significant degradation after 1000h. This is in line with the above mentioned results for commercial electrolyzer units. At higher current densities significant degradation rates were found. This study undeniably suggests coupling PEM electrolyzers to intermittent power sources under long term operation, contributing to transformative knowledge in the field of energy conversion and storage.
[1]. M. Carmo, D. Fritz, J. Mergel and D. Stolten, International Journal of Hydrogen Energy, 38, 4901-4934 (2013)
[2] Katherine Ayers, presented at the DOE Fuel Cell Technologies Program Webinar, May 23, 2011
[3] 2013 Annual Merit Review Proceedings, II.A.2, Renewable Electrolysis Integrated Systems Development and Testing
A 10kW Class Ti/Mn Redox Flow Battery
Authors: Kaku Hirokazu , Yamaguchi Hideyuki , Dong Yong-Rong , Tatsumi Ryouta , Miyatake Kenichiro , Moriuchi Kiyoaki , Tsutsui Yasumitsu , Shigematsu Toshio 
Published: February 2020

Large-scale energy storage systems play an important role in the effective use of renewable energy such as wind and solar power. Redox flow batteries (RFBs) have attracted a great deal of attention because of high-speed response, the independent design of power and energy, and advantages in safety. RFBs consist of tanks of electrolyte which store chemical energy and electrochemical cells which reversibly convert chemical energy to electricity. All-vanadium RFBs are widely used as the most mature technology while other various redox species can also be utilized as the electrolyte.
Among redox species applicable in aqueous solution, we have reported an electrolyte of titanium and manganese. The discharged state consists of Ti (IV) and Mn (II), both of which are widely available from abundant and low-cost resources. An energy density of 23.5 kWh/m3 is achievable due to the two-electron reaction of manganese on the positive side [1]. Main issues of the Ti/Mn RFB are the precipitation of MnO2 over time in the positive electrolyte and its low power density. As for the precipitation, a systematic research on the effect of mixing Ti (IV) into the positive electrolyte revealed that Ti (IV) ions change the morphology and the crystal structure of MnO2 as well as the electrochemical property of the positive electrolyte [2]. The other issue of low power density can be overcome by thermal treatment of carbon electrodes [3]. Moreover, the low permeability of ions in the Ti/Mn electrolyte contributes to the high coulombic efficiency even when a thin membrane is used. We have reported that the combination of a heat-treated carbon electrode and a thin membrane led to the highest energy efficiency, which was 84.3% with a current density of 200 mA/cm2 [4].
In this work, long-term cycle test was performed in a scaled-up system in order to further investigate the reliability of Ti/Mn RFBs. The evaluation system was designed to be approximately 10 kW×1h. In charge-discharge cycle tests, it was confirmed that the cell performance was stable over 100 cycles. A stable energy density over 14 kWh/m3 was successfully confirmed with a current density of 200 mA/cm2. The coulombic efficiency remained over 99%. The characteristics of this Ti/Mn RFB will be discussed in details in the presentation.

References

[1] Y.-R. Dong et. al., ECS Trans., 69 (18), 59 (2015).
[2] H. Kaku et. al., ECS Trans., 72 (10), 1 (2016).
[3] Y.-R. Dong et. al., ECS Trans., 75 (18), 27 (2017).
[4] H. Kaku et. al., ECS Trans., 77 (11), 173 (2017).
(Invited) Status and Future Perspectives of Redox Flow Batteries
Authors: Yang Z. Gary 
Published: February 2020

The trends of growing renewable penetration and demand of reliable, flexible, clean and affordable electricity have driven ever increasing interests of electrical energy storage (EES). Applications of EES as utility assets have seen significant growth around the globe in the past few years. Among varied EES technologies, batteries that convert chemical energy into electricity or vice versa offer quick response and unparalleled flexibility and have thus been one of the most developed and commercialized. Particularly, redox flow batteries (RFB’) have been among the leader in emerging battery technologies for utilities, independent power producer, microgrid, and commercial and industrial customers. Unlike other battery chemistries, such as lead-acid and Li-ion or generally classified as solid-state batteries, RFB’ were developed specifically for utility applications. With energy stored in liquid electrolytes and without ionic diffusion in the solid electrodes, these batteries work in a unique way that enables a set of unique advantages over the solid-state batteries. These may include separated design of energy (kWh) and power kW), a superior cyclability, a long life and full access to rate capacities over the life. More importantly, the RFB so far, including vanadium RFB’ or VRFB’, Zn-halide, etc., most use aqueous electrolytes and are inherent safe. The unique advantages, along with the performance flexibility demonstrated allow for stacking benefits for a safe EES solutions of a maximized value to customers.
As emerging technologies, however, RFB’ have found a limited share in the early market that has been dominated by Li-ion batteries lately. Though there have been many deployments in the fields, the RFB’ are still being optimized to achieve a full maturity and have not yet produced at scales. Pressure is also on to reduce costs and make competitive in the markets. This paper will review progress and challenges of the redox flow battery industry and technology development and share perspectives in future directions.
(Invited) Zinc Based Flow Battery for Stationary Energy Storage
Authors: Li Xianfeng 
Published: February 2020

Key words: flow battery, zinc based, energy storage, prospects and challenges
Zn2+/Zn redox couple attracts more and more attention in flow battery due to its characteristics of high solubility, low cost electrochemical reversibility and environmental friendly. Until now, many zinc based flow battery systems such as zinc-bromine1, zinc- nickle and zinc-iron2,3 etc. have been investigated, which have very promising prospect for stationary energy storage. Among them, zinc-bromine is one of the most successfully example of zinc based flow battery system, while zinc nickle and zinc iron systems have obtained tremendous developments recently. At the same time, many new zinc based systems such as zinc iodine have been proposed and demonstrated great advantages in some aspects such as energy density. However, secondary batteries that use zinc electrodes typically exhibit short lifetimes, because of problems with undesirable zinc morphology especially zinc dendrites, that form during charge. Hence, the challenge is to deposit a compact, uniform and free of dendrite layer that ensure a long cycle secondary negative electrode.
In recent years, DICP devoted to Zinc based batteries and implemented several demonstrations on zinc bromine flow batteries in different fields.
Therefore, in this presentation we will introduce the research and development status of zinc based flow batteries at DICP.
References:
1 Wang, C. et al. Cage-Like Porous Carbon with Superhigh Activity and Br2 - Complex-Entrapping Capability for Bromine-Based Flow Batteries. Adv. Mater. 29, 1605815, (2017).
2 Xie, C., Duan, Y., Xu, W., Zhang, H. & Li, X. A Low‐Cost Neutral Zinc–Iron Flow Batterywith High Energy Density for Stationary Energy Storage. Angew. Chem. Int. Ed., 47, 14953-14957, (2017).
3 Yuan, Z., Duan, Y., Liu, T., Zhang, H. & Li, X. Toward a low cost alkaline zinc-iron flow battery with a polybenzimidazole custom membrane for stationary energy storage. iScience, (2018). doi:10.1016/j.isci.2018.04.006
A Low-Cost and Robust Aqueous Organic Redox Flow Battery
Authors: Yang Bo , Murali Advaith , Nirmalchandar Archith , Jayathilake Buddhinie Srimali , Surya Prakash G. K. , Narayanan S. R. 
Published: February 2020

Aqueous Organic Redox Flow Batteries (ORBAT) are attractive for large-scale energy storage. Quinone based ORBATs have the advantages of being low cost and also environmentally-friendly. However, it has been a challenge to find electrolyte materials that are stable because of the reactivity of the organic molecules with water. For grid-scale energy storage systems to be commercially viable, it is desirable that the levelized cost of energy storage (LCOS) is <5 cents/kWh and the operational life of the system is >10 years.
The flow battery research at the University of Southern California (USC) has previously identified the causes for capacity fade ORBATs operating on quinones. We have demonstrated molecular design strategies to prevent chemical transformations by the Michael reaction with water [1] and acid-catalyzed proto-desulfonation [2]. We have also demonstrated operational approaches to mitigate capacity fade by crossover through the proton exchange membrane separator [2].
Recently, we have developed a highly efficient redox flow battery system based on low-cost water soluble redox materials, which can deliver electricity at the target levelized cost of storage (LCOS) of 5 cents/kWh-cycle. The highly durable molecules at the positive and negative electrode have shown the ability to be discharged at current densities as high as 840 mA/cm2 (Figure 1). We have performed stable charge/discharge cycling experiments for over 700 cycles at 200 mA/cm2 (Figure 2) without any measurable capacity fade.
The system is distinguished by the remarkably low cost of redox materials of $6.5/kWh, the lowest cost for any known type of redox flow battery. Based on our preliminary tests and understanding of the chemical stability of the water-based solutions of the active materials, we can expect the system to realize the targets for long operational life. The ultra-low cost of redox materials, the inherent stability of redox materials, and the high efficiency during charge and discharge, gives this organic flow battery system a competitive edge over other systems.

References

[1] L. Hoober-Burkhardt et al., “A New Michael-Reaction-Resistant Benzoquinone for Aqueous Organic Redox Flow Batteries,” J. Electrochem. Soc., vol. 164, no. 4, pp. A600–A607, 2017.
[2] A. Murali et al., “Understanding and Mitigating Capacity Fade in Aqueous Organic Redox Flow Batteries,” J. Electrochem. Soc., vol. 165, no. 7, pp. A1193–A1203, 2018.

Figure 1
Enhancing Cell Performances of High Ni-Content NCM cathode By Surface Modification with SiO2
Authors: Kim Hyun-Soo , Lee Seung-Hwan , Park Gumjae , Jin Bong-Soo 
Published: February 2020

Recently, there is a growing demand for high-energy lithium ion batteries in order to apply to electric vehicles, hybrid electric vehicle, uninterruptible power supplies and portable devices. The cathode active material of three component layered LiNixCoyMnzO2 (NCM, 0≤x, y, z <1) delivers superior electrochemical performances, which is highly dependent on the composition of Ni, Co and Mn in the NCM. The high Ni content contributes to a high capacity and reduction in cost while sacrificing the long-term stability.
In this paper, we prepared SiO2 coated LiNi0.8Mn0.1Co0.1O2 cathode and investigated the effect of SiO2 coating layer on the electrochemical performances and thermal behavior. The SiO2 coated LiNi0.8Mn0.1Co0.1O2 cathode delivers outstanding electrochemical performances. Therefore, we believe that SiO2 coated LiNi0.8Mn0.1Co0.1O2 cathode is beneficial approach for high performance and reliability lithium ion batteries.
SiO2 coated LiNi0.8Mn0.1Co0.1O2 delivers high initial capacity of 200.7 mAh g-1 as well as the excellent cycleability (capacity retention of 87.3 % after 100 cycles at 0.5 C) and rate capability (82.2% at 2C). Such improvements are attributed to the SiO2 coating, which can suppress the irreversible phase transformation and play a role in obstacle to protect the LiNi0.8Mn0.1Co0.1O2 from electrolyte.
Nanoparticle Surface Charge Alters Membrane Ionic Permeability
Authors: Zhang Yunzhu , Sankarasubramanian Shrihari , Li Xue , Xie Xiaofeng , Ramani Vijay 
Published: February 2020

Redox flow batteries (RFBs)are promising devices for medium- to large-scale energy storage owing to their decoupled power and energy, safety, reliability, and portability.[1] Active ion crossover through the (dense) separator membrane between the electrolyte solutions reduces RFB cell efficiency. Embedding highly charged metal oxide nanoparticles (NPs) into the separator membranecan electrostatically repel cations and inhibit the active ion crossover, thereby enabling high membrane selectivity during long-term RFB operation. To better understand how to modulate (lower) membranepermeability, we investigated the effect of NP surface charge on cation permeability through the separator membrane.
We selected quaternary ammonium functionalized cardo-polyether ketone (QPEK TMA+Cl-) as the model separator membrane due to its demonstrated performance in all vanadium redox flow batteries[2], and tested three NPs (TiO2, SiO2and Al2O3) based on their zeta potential (ζ), which is a function of their surface charge. Under the typical acidic conditions that prevail in an RFB, membranes containing NPs exhibiting high positive zeta potentials (ζ>40 mV) exhibited lower Fe3+/Cr3+permeability coefficients than pristine membranes, while membranes with weakly charged NPs (ζ:0~10 mV) exhibited higher Fe3+/Cr3+permeability coefficients than pristine membranes. This result indicated that the cation permeability through the separator membrane could be tuned by using metal oxide NPs with modulated surface charge. We note that the surface charge of NPs also affects their aggregation behavior during membrane casting. In a neutral pH environment typical of the casting process, highly charged NPs demonstrated less aggregation and distributed more uniformly through the membrane cross-section.
[1] G. L. Soloveichik, Chemical Reviews
2015, 115, 11533-11558.
[2] S. Yun, J. Parrondo, V. Ramani, J. Mater. Chem. A
2014, 2, 6605-6615.
The Effect of Channel Tapering on the Performance of Vanadium Redox Flow Batteries
Authors: García-Salaberri Pablo A. , Moreno-Carrero Carlos , Gokoglan Tugba Ceren , Vera Marcos , Agar Ertan 
Published: February 2020

The recent growth of intermittent renewable energy sources, such as wind and solar, requires a simultaneous growth of grid-scale energy storage facilities to provide energy resilience and reliability. Redox flow batteries (RFBs) are electrochemical devices that stand out as potential candidates for the storage of large amounts of energy in an economical and flexible way due to their ability to decouple power and energy capacity. However, one of the main drawbacks that hinders the widespread adoption of RFBs is their relatively low power density, which results in large stack size and high system cost. In recent years, the optimization of engineering aspects, such as electrode materials and cell architectures, has become a key element on the roadmap towards high-performance and cost-effective RFBs. For example, flow fields are critical components for the transport of active species to/from the electrochemically active area of the electrode (i.e., the surface area of the fibers) and, therefore, their design significantly affects the power output and efficiency of the system.
In this work, the effects of interdigitated channel tapering on the performance of aqueous vanadium RFBs are examined experimentally, theoretically and numerically. Critical performance metrics, such as peak power density, limiting current density, round-trip efficiencies and pressure drop are obtained experimentally using flow cells with the tapered flow fields and compared to the ones obtained with the conventional (i.e., non-tapered) flow fields. To establish a fundamental understanding, the experimental results are further examined by means of a macroscopic multiphysics model. The initial results show that the use of novel flow-field designs can be an effective way to develop RFBs with superior performance, while maintaining pumping losses in acceptable levels. A mechanistic understanding on the transport behaviors and their coupling to the electrochemical performance will be provided.
Sodium Thiophosphate Cathodes and Polymeric Membranes for High Energy Density Redox Flow Batteries
Authors: Self Ethan Craig , Delnick Frank M. , Yang Guang , Lehmann Michelle , Gilmer Dustin B. , Ruther Rose E. , Saito Tomonori , Nanda Jagjit 
Published: February 2020

Redox flow batteries (RFBs) are promising energy storage devices for grid-level applications due to their long cycle life and the ability to independently scale their energy and power densities. The energy density of conventional RFBs is dictated by their capacity (which is directly related to the solubility of the redox species in the electrolyte) and operating potential. Aqueous RFBs generally have low operating potentials ca. 1.5 V, resulting in poor energy densities (25 – 30 Wh/kg for an all vanadium RFB), whereas systems containing organic electrolytes with wider electrochemical windows have moderately higher energy densities.
Our team recently demonstrated proof-of-concept for a revolutionary approach which uses mediated electrochemical reactions in a RFB configuration to drive reversible Na storage in a red P anode. Extremely high capacities ~1,000 mAh/gP have been demonstrated using this method. In this configuration, the anion radical mediators are recycled several times throughout the cell stack during a single charge/discharge cycle, effectively decoupling the RFB’s energy density from the redox species’ solubility in the electrolyte. By pairing this mediated red P anode with a sulfide-based cathode, energy densities up to 200 Wh/kg (~10x that of conventional RFBs) can potentially be achieved.
This presentation will describe our recent progress developing polymer membranes and high energy density cathodes/catholytes for RFBs. The preparation and characterization of ionically conductive, mechanically robust poly(ethylene oxide) (PEO)-based membranes which are chemically resistant to and prevent crossover of the radical mediators will be discussed. The synthesis and electrochemical properties of a new class of high energy density sodium thiophosphate cathodes for RFBs will also be provided.

Acknowledgements

This research is supported by Dr. Imre Gyuk, Manager, Energy Storage Program, Office of Electricity Delivery and Reliability, U.S. Department of Energy and the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy.
Low Temperature Molten Sodium-Based Batteries for Large Scale Electrical Energy Storage
Authors: Spoerke Erik D. , Percival Stephen , Small Leo J. , Peretti Amanda , Lamb Joshua , Chalamala Babu R. 
Published: February 2020

Despite the tremendous advances in batteries for portable electronics and vehicle electrification, truly effective battery technologies for large scale energy storage remain relatively underdeveloped. These systems have distinct requirements as safe, low-cost, reliable systems, critical to robust and agile energy distribution, integration of renewable energy, effective emergency response, and even emerging national defense initiatives. Here, we describe a promising new class of molten sodium-halide batteries that show exciting potential as safe, cost-effective, long-lived batteries for large-scale applications. These Na-NaI batteries comprise a molten sodium anode and a molten NaI-based halide salt catholyte, separated by highly conductive solid-state sodium-ion conducting membrane. This NaI-based system offers a higher voltage (>3V) than traditional molten sodium batteries and enables the use of fully molten catholytes desired for long cycle life. By engineering the materials chemistry of these batteries, we have driven down operating temperature to near 100°C, utilizing chemistries that avoid potential problems with thermal runaway or flammable organic electrolytes that often plague other battery technologies. This dramatic reduction of operating temperature (compared to ~300°C typical of traditional molten sodium batteries) opens the door to valuable reduction in costs and extension of battery life. This presentation will discuss specific advances in molten catholyte composition and electrochemistry, the performance of the solid-state separators at these reduced temperatures, and the efficient cycling behavior of laboratory-scale prototypes. The encouraging performance of these innovative “low” temperature molten salt batteries promises new opportunities to address the widespread need for safe, reliable, and cost-effective large scale energy storage solutions.
Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.