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Abstract The future U.S. electric grid is being transformed with deep decarbonization of generation (i.e., removing or reducing reliance on fossil fuels and replacing them with renewable and clean energy resources), which in practice is not achievable without a dramatic increase in the reliance on long-duration energy storage (LDES) technologies. Regulators at both the state and federal level are well advised to take steps to address current policy gaps, build frameworks that will enable a greater role for LDES to contribute to grid reliability and be fairly compensated for its grid services.. Decarbonization by definition is dependent on an increasing reliance on variable renewable energy, primarily wind and solar resources, that needs to be stored for longer durations to maintain electric grid reliability and provide operational flexibility to grid operators. However, despite the growing realization of the need for long-duration energy storage (LDES) technologies, a persistent gap of policy levers at the federal and state level creates a vacuum in terms of defining how and where LDES technologies can be utilized to support the electric grid, along with an inadequate regulatory framework wherein these resources will need to be valued and compensated for the services they can provide. This paper—which is primarily intended for US decision makers, but should be of value for all energy professionals and the general public—addresses policy gaps, needs, and opportunities for LDES that require urgent attention from US-based policymakers at the federal and state level. This paper also provides background information on how the US E&U industry is structured and regulated, along with perspectives on LDES technologies and applications, all of which have direct relevance to the paper’s primary focus on the need for LDES policymaking. Discussion Despite a generally accepted future need for long-duration energy storage (LDES) technologies that is directly tied to the rapid of renewable resources on the U.S. electric grid, there is a lack of policymaking, market designs, and compensation mechanisms for LDES technologies. Decarbonization (i.e., the goal of removing or reducing reliance on fossil fuels) cannot be achieved at the aggressive levels envisioned without utilizing LDES. Policymakers must take steps now to build frameworks that recognize the unique ways in which LDES will increasingly contribute to grid reliability and resilience, and receive appropriate compensation for the services it provides. Graphical abstract

Changes in the Demand Profile and a growing role for renewable and distributed generation are leading to rapid evolution in the electric grid. These changes are beginning to considerably strain the transmission and distribution infrastructure. Utilities are increasingly recognizing that the integration of energy storage in the grid infrastructure will help manage intermittency and improve grid reliability. This recognition, coupled with the proliferation of state-level renewable portfolio standards and rapidly declining lithium-ion (Li-ion) battery costs, has led to a surge in the deployment of battery energy storage systems (BESSs). Although BESSs represented less than 1% of grid-scale energy storage in the United States in 2019, they are the preferred technology to meet growing demand because they are modular, scalable, and easy to deploy across diverse use cases and geographic locations.

Energy storage systems (ESSs) are being deployed widely due to numerous benefits including operational flexibility, high ramping capability, and decreasing costs. This study investigates the economic benefits provided by battery ESSs when they are deployed for market-related applications, considering the battery degradation cost. A comprehensive investment planning framework is presented, which estimates the maximum revenue that the ESS can generate over its lifetime and provides the necessary tools to investors for aiding the decision making process regarding an ESS project. The applications chosen for this study are energy arbitrage and frequency regulation. Lithium-ion batteries are considered due to their wide popularity arising from high efficiency, high energy density, and declining costs. A new degradation cost model based on energy throughput and cycle count is developed for Lithium-ion batteries participating in electricity markets. The lifetime revenue of ESS is calculated considering battery degradation and a cost–benefit analysis is performed to provide investors with an estimate of the net present value, return on investment and payback period. The effect of considering the degradation cost on the estimated revenue is also studied. The proposed approach is demonstrated on the IEEE Reliability Test System and historical data from PJM Interconnection.

A generic constant-efficiency energy flow model is commonly used in techno-economic analyses of grid energy storage systems. In practice, charge and discharge efficiencies of energy storage systems depend on state of charge, temperature, and charge/discharge powers. Furthermore, the operating characteristics of energy storage devices are technology specific. Therefore, generic constant-efficiency energy flow models do not accurately capture the system performance. In this work, we propose to use technology-specific nonlinear energy flow models based on nonlinear operating characteristics of the storage devices. These models are incorporated into an optimization problem to find the optimal market participation of energy storage systems. We develop a dynamic programming method to solve the optimization problem and perform two case studies for maximizing the revenue of a vanadium redox flow battery (VRFB) and a Li-ion battery system in Pennsylvania New Jersey Maryland (PJM) interconnection's energy and frequency regulation markets.

The Battery Lifecycle (BLC) Framework is an open-source platform that provides tools to visualize, analyze, and share battery data through the technology development cycle, including data from material characterization, cell testing, manufacturing, and field testing. The BLC framework provides users with a unified view of their data that they can use to optimize materials and cell configurations, validate cell performance under application conditions, and mitigate manufacturing variations and field failures. BLC has four components: data importers, one or more databases, a front-end for querying the data and creating visualizations, and an application programming interface to process the data. Instead of building the system from the ground up, we developed BLC around Redash, a robust open-source extract-transform-load engine. BLC has been deployed for two applications: (i) tracking the development of a single battery technology from the lab to a manufacturing line and systems installed in the field, and (ii) comparing studies of multiple cells of the same battery chemistry and configuration. The latter implementation is publicly available at www.BatteryArchive.org. The open-source software package is available at: https://github.com/battery-lcf/battery-archive-sandbox.

Reliable engineering quality, safety, and performance are essential for a successful energy-storage project. The commercial energy-storage industry is entering its most formative period, which will impact the arc of the industry's development for years to come. Project announcements are increasing in both frequency and scale. Energy-storage systems (ESSs) are establishing themselves as a viable option for deployment across the entire electricity infrastructure as grid-connected energy-storage assets or in combination with other grid assets, such as hybrid generators. How the industry will evolve-in direction and degree-will depend largely on building a firm foundation of sound engineering requirements into project expectations.

More utilities, energy providers, and governments are considering the transition to 100% renewable or carbon-free generation to satisfy electricity demand. This transition requires consideration of numerous factors including cost, resource adequacy, and geographical location, among others. Therefore, models that can explore the optimality of tradeoffs between multiple factors are crucial for planning this transition. An optimization problem formulation is proposed to analyze the amount of renewable generation and energy storage required to balance 100% of a utility's electricity demand on an hourly timescale over multiple years, while minimizing a desired cost. This formulation accounts for geographical location and accommodates regional energy trading, and it enables analysis of important metrics for planning, such as firm capacity, capacity factors, land area requirements, and amount of curtailed generation. This optimization-based approach is used to explore case studies in New Mexico, which is an area with significant potential for solar and wind generation in the United States. Considering multiple years of historical meteorological data and electricity demand data, results show that the amount of renewable generation required is an order of magnitude larger than the average demand, and that most of the generation is curtailed, which motivates a regional energy trading approach.

Mathematical models of Redox Flow Batteries (RFBs) can be used to analyze cell performance, optimize battery operation, and control the energy storage system efficiently. Among many other models, physics-based electrochemical models are capable of predicting internal states of the battery, such as temperature, state-of-charge, and state-of-health. In the models, estimating parameters is an important step that can study, analyze, and validate the models using experimental data. A common practice is to determine these parameters either through conducting experiments or based on the information available in the literature. However, it is not easy to investigate all proper parameters for the models through this way, and there are occasions when important information, such as diffusion coefficients and rate constants of ions, has not been studied. Also, the parameters needed for modeling charge-discharge are not always available. In this paper, an efficient way to estimate parameters of physics-based redox battery models will be proposed. This paper also demonstrates that the proposed approach can study and analyze aspects of capacity loss/fade, kinetics, and transport phenomena of the RFB system.

For nearly a century, global power systems have focused on three key functions: generating, transmitting, and distributing electricity as a real-time commodity. Physics requires that electricity generation always be in real-time balance with load-despite variability in load on time scales ranging from subsecond disturbances to multiyear trends. With the increasing role of variable generation from wind and solar, the retirement of fossil-fuel-based generation, and a changing consumer demand profile, grid operators are using new methods to maintain this balance.

In this paper, we study, analyze, and validate some important zero-dimensional physics-based models for vanadium redox batch cell (VRBC) systems and formulate an adequate physics-based model that can predict the battery performance accurately. In the model formulation process, a systems approach to multiple parameters estimation has been conducted using VRBC systems at low C-rates (∼C/30). In this batch cell system, the effect of ions' crossover through the membrane is dominant, and therefore, the capacity loss phenomena can be explicitly observed. Paradoxically, this means that using the batch system might be a better approach for identifying a more suitable model describing the effect of ions transport. Next, we propose an efficient systems approach, which enables to help understand the battery performance quickly by estimating all parameters of the battery system. Finally, open source codes, executable files, and experimental data are provided to enable people's access to robust and accurate models and optimizers. In battery simulations, different models and optimizers describing the same systems produce different values of the estimated parameters. Providing an open access platform can accelerate the process to arrive at robust models and optimizers by continuous modification from the users' side.

This paper proposes a spatiotemporal optimization strategy for an energy storage system (ESS) connected to the power grid, with an objective of maximizing its economic benefits. This optimization framework includes both spatial and temporal aspects by optimizing the location of the ESS in the network and the annual dispatch strategy, respectively. Energy arbitrage and frequency regulation are chosen to be the revenue streams as they have proved to be the most profitable applications for grid-connected storage systems. A lithium-ion battery is used for this study due to its widespread popularity, which arises from its high energy density, high efficiency, and decreasing costs. The degradation cost of the battery is taken into account while calculating the revenue to generate a more realistic estimate. Mixed-integer nonlinear programming is utilized in solving the spatiotemporal optimization problem. Results for the proposed method are validated using the IEEE Reliability Test System along with PJM Interconnection historical data.

Understanding systematic trends in degradation of Li-ion batteries through a broad range of operating conditions is critical to improving their performance. Over the course of the last few years, researchers at Sandia National Labs have been conducting a systematic study of battery cycling behavior. In this study, dozens of commercial NCA (LiNixCoyAl1-x-yO2) and NMC (LiNixMnyCo1-x-yO2) cells were cycled to 80% capacity across a range of temperatures, discharge rates, and depth of discharge windows. Analysis of both in situ electrochemical data and postmortem materials degradation was done and correlated to determine root causes of rapid capacity fade. During cycling, Electrochemical Impedance Spectroscopy (EIS) and Incremental Capacity Analysis (ICA) experiments were conducted periodically. The data from these experiments were used to understand the state of health (SoH) of cycling cells, including SEI formation and Li plating, as well as general mass transport and kinetic properties. X-ray Computed Tomography (XCT) scans completed before cell disassembly showed large scale deformation in the cells’ jelly rolls. For the postmortem analysis, cells in pristine condition and 80% capacity were disassembled, and their electrodes were analyzed with X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Differential Scanning Calorimetry (DSC). These techniques analyzed different aspects of the electrodes’ physical and chemical properties, including Li plating, micro-cracking, SEI layer formation, and phase changes in cathode materials. DSC measurements also provided insight into changes in the degree to which aged electrodes undergo thermal runaway events. Correlation of the postmortem materials analysis with the in situ electrochemical analysis showed that cells with the most rapid rate of capacity fade had multiple degradation mechanisms active during cycling. The scale of this electrochemical and materials evaluation fills in gaps in the literature about commercial Li-ion battery performance. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & 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.

Rechargeable alkaline Zn–MnO2 (RAM) batteries are a promising candidate for grid-scale energy storage owing to their high theoretical energy density rivaling lithium-ion systems (∼400 Wh/L), relatively safe aqueous electrolyte, established supply chain, and projected costs below $100/kWh at scale. In practice, however, many fundamental chemical and physical processes at both electrodes make it difficult to achieve commercially competitive energy density and cycle life. This review presents a detailed and timely analysis of the constituent materials, current commercial status, electrode processes, and performance-limiting factors of RAM batteries. We also examine recently reported strategies in RAM and related systems to address these issues through additives and modifications to the electrode materials and electrolyte, special ion-selective separators and/or coatings, and unconventional cycling protocols. We conclude with a critical summary of these developments and discussion of how future studies should be focused toward the goal of energy-dense, scalable, and cost-effective RAM systems.

In order to improve the operation of Li-ion batteries the long-term performance is the subject of much research. Of particular importance is understanding systematic trends in degradation through a broad range of operating conditions. Over the course of the last few years, researchers at Sandia National Labs have conducted a systematic study of battery cycling behavior. In this study, dozens of commercial NCA (LiNixCoyAl1-x-yO2) and NMC (LiNixMnyCo1-x-yO2) cells were cycled to 80% capacity and end of life across a range of temperatures, discharge rates, and depth of discharge windows. Analysis of both in situ electrochemical data and postmortem materials degradation was done. During cycling, cell resistance (IR), Electrochemical Impedance Spectroscopy (EIS), and differential capacity (dQ/dV) experiments were conducted periodically. The data from these experiments were used to understand the state of health (SoH) of cycling cells, including SEI formation and Li plating, as well as general mass transport and kinetic properties. X-ray Computed Tomography (X-ray CT) scans completed before cell disassembly showed large scale deformation in the cells’ jelly rolls. For the postmortem analysis cells in pristine condition, 80% capacity, and end of life were disassembled, and their electrodes were analyzed with X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), and Brunauer-Emmett-Teller Isotherms (BET). These techniques analyzed different aspects of the electrodes’ physical and chemical properties, including Li plating, micro-cracking, SEI layer formation, and phase changes in cathode materials. BET and DSC measurements also provided insight into changes in the degree to which aged electrodes undergo thermal runaway events. Correlation of the postmortem materials analysis with the in situ electrochemical analysis gave an in-depth understanding of the origins of performance fade during cycling. The scale of this electrochemical and materials evaluation fills in gaps in the literature about battery performance and degradation beyond 80% capacity. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & 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.

High voltage and energy density have increased the use of lithium-ion batteries (LiBs) in many applications, including consumer electronics, electric vehicles, and grid-tied energy storage systems (ESS). However, with increasing energy density and installation size come heightened concerns about safety, including the risk of thermal runaway and serious fires. To understand the risks and outcomes of LiB failure, numerous studies have examined the response of fresh cells to mechanical, electrical, and thermal abuse. However, given the expected lifetime of LiBs, it is critical to consider the abuse response of aged cells. In this presentation, we review previous results on the abuse of aged cells to facilitate understanding of how aging conditions (such as temperature and cycle rate) and abuse methodology (including calorimetry, short circuit, and overcharge) impact key metrics of safety relative to fresh cells. In general, the conditions used to produce aged cells in these studies have involved extreme temperatures. Thus, we also share more recent calorimetry of cells aged to 80% capacity by relatively mild protocols to understand the abuse response of cells from more typical device operating conditions. These results facilitate a more data-informed risk assessment of aged energy storage systems and the development and adoption of appropriate failure mitigation strategies. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & 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.

Batteries are increasingly becoming a more viable form of grid-level energy storage as time progresses. Among the different types of batteries present, Li-ion batteries have particularly gained widespread popularity due to their high energy density, high efficiency and decreasing costs. This paper presents a detailed study on maximizing the monetary benefits from a Li-ion Battery Energy Storage System (BESS) for a number of applications, considering the BESS degradation process. The BESS is assumed to be participating in the energy market and is also being applied to supply critical loads when outage events occur to improve the resilience and reliability of the power system. Different operating strategies are tested and the results can be summarized into several suggestions on how to optimally operate the battery while performing energy arbitrage, enhancing system resilience and reliability, and also inhibiting the degradation of the battery.

Techno-economic analyses of energy storage currently use constant-efficiency energy flow models. In practice, charge/discharge efficiency of energy storage varies as a function of state-of-charge, temperature, charge/discharge power. Therefore, using the constant-efficiency energy flow models will cause suboptimal results. This work focuses on incorporating nonlinear energy flow models based on nonlinear efficiency models in the revenue maximization problem of energy storage. Dynamic programming is used to solve the optimization problem. A case studies is conducted to maximize the revenue of a Vanadium Redox Flow Battery (VRFB) system in PJM's energy and frequency regulation market.

Energy storage is a unique grid asset in that it is capable of providing a number of grid services. In market areas, these grid services are only as valuable as the market prices for the services provided. This paper formulates the optimization problem for maximizing energy storage revenue from arbitrage (day-ahead and real-time markets) in the California Independent System Operator (CAISO) market. The optimization algorithm was then applied to three years of historical market data (2014–2016) at 2200 nodes to quantify the locational and time-varying nature of potential revenue. The optimization assumed perfect foresight, so it provides an upper bound on the maximum expected revenue. Since California is starting to experience negative locational marginal prices (LMPs) because of increased renewable generation, the optimization includes a duty cycle constraint to handle negative LMPs. Two additional trading algorithms were tested that do not require perfect foresight. The first sets a buy price threshold and a sell price threshold (e.g., limit orders) for participation in the real time market, subject to the constraints of the energy storage system. The second uses the day-ahead prices as an estimate for the real time prices and performs an optimization on a rolling time horizon. The simple threshold algorithm performed the best, but both fell well short of the potential revenue identified by the optimization with perfect foresight.

Li-ion batteries currently dominate electrochemical energy storage for grid-scale applications, but there are promising aqueous battery technologies on the path to commercial adoption. Though aqueous batteries are considered lower risk, they can still undergo problematic degradation processes. This perspective details the degradation that aqueous batteries can experience during normal and abusive operation, and how these processes can even lead to cascading failure. We outline methods for studying these phenomena at the material and single-cell level. Considering reliability and safety studies early in technology development will facilitate translation of emerging aqueous batteries from the lab to the field.

Redox flow batteries are well suited to provide modular and scalable energy storage systems for a wide range of energy storage applications. In this paper, we review the development of redox-flow-battery technology including recent advances in new redox active materials, cell designs, and systems, all from the perspective of engineers interested in applying this technology. We discuss cost, performance, and reliability metrics that are critical for deployment of large flow-battery systems. The technology, while relatively young, has the potential for significant improvement through reduced materials costs, improved energy efficiency, and significant reduction in the overall system costs.

The single largest barrier to adoption of electrochemical storage in the grid is often stated to be the value of a battery over the life of the system. To ensure long-term system safety and reliability, batteries must be selected based on application specific requirements and performance characteristics. Our approach to addressing the uncertainty in the performance and cycle life of commercially viable lithium ion batteries for grid storage has been to design studies with multiple chemistries, and conduct long term life cycle evaluations with systematically varied cycling conditions. Namely, we initiated a large-scale, multi-year cycling study of commercial LiFePO4/LFP, LiNixCoyAl1-x-y­O2/NCA, and LiNixMnyCo1-x-yO2/NMC cells. This study looks at chemistry specific influences on efficiency and cycle life under variables that include discharge rate, depth of discharge (DoD) and temperature, and is complemented by a calendar aging study. The source of differences in aging behavior was investigated through electrochemical impedance spectroscopy and differential capacity analysis. We compare results to literature to identify the degree to which variations may be expected with manufacturer and version, as products can see manufacturing changes year to year. Understanding variations is critical for lifetime assessment and economic evaluation that is meaningful for installed systems. We further look at how these best-case scenario results from single cell studies may be used as a baseline in moving toward understanding aging in module and system configurations. The overarching goal is to begin to effectively understand laboratory cell studies in a context applicable to grid storage systems. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & 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.

To defray the upfront cost of lithium-ion electric vehicle (EV) batteries and to minimize waste, there is substantial interest in repurposing them after their EV end-of-life for grid-related applications (battery second life). The reliability of any economic or technical feasibility analysis for second life batteries strongly depends on the battery degradation behavior, but insight into this degradation in the region of interest remains limited. Most cycling studies in the open literature only age batteries to about 80% capacity (the typical cutoff for marking end-of-life). A few studies that have cycled batteries beyond 80% capacity have suggested the existence of a ‘tipping point’ upon which rapid degradation is initiated, but a limited set of cycling conditions and chemistries were explored. We have previously reported on our large-scale, multi-year aging study of commercial LiFePO4/LFP, LiNixCoyAl1-x-y­O2/NCA, and LiNixMnyCo1-x-yO2/NMC cells, varying the discharge rate, depth of discharge (DoD), and environment temperature. Now that many of those cells have reached 80% capacity, we have initiated a second life aging study. The advantage of studying these cells compared to those from second-hand EV battery suppliers is that the cycling history is known. Thus, it is more feasible to determine the extent to which prior cycling conditions influence later degradation and the early markers that could foreshadow the possibility of rapid degradation beyond 80% capacity. Diverse cycling conditions were studied to determine what protocols, if any, can mitigate rapid degradation. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & 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. SAND2019-4631 A

The safety of lithium-ion batteries is mainly quantified by thermal runaway characteristics such as onset temperature, peak heating rate (HR), and maximum pressure release. This talk evaluates the materials aspects of thermal runaway of commercial lithium-ion batteries by correlating the contributions from individual cell components to thermal runaway trends. An accelerating rate calorimeter was used to define the thermal runaway behavior of three commercial 18650 lithium-ion batteries (LiCoO2, LiFePO4, and LiNixCoyAl1-x-y­O2) at various states of charge (SOC). Cells were also disassembled and the thermal properties of their component materials was evaluated by thermogravimetric analysis, differential scanning calorimetry, and temperature-resolved X-ray diffraction. Broadly, lithium-ion battery thermal runaway process begins with solid-electrolyte interface and negative active material decomposition followed by the positive active material breakdown. The experimental results show that the onset temperature is generally independent of SOC and peak HR increases with SOC as a result of cathode destabilization. Overall, LiNixCoyAl1-x-yO2 decomposes readily, and charged LiCoO2 is also metastable, although it decomposes more gradually than LiNixCoyAl1-x-y. Contrary to the layered transition metal oxides, LiFePO4 is stable to > 500oC, even when charged. The results are aimed at informing future engineering and fire protection of commercial lithium-ion batteries. Sandia National Laboratories is a multimission 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. SAND2018-3360 A

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.

The articles in this special issue focuses on energy storage technologies, with particular emphasis on batteries and energy conversion technologies and applications.

The safety of lithium-ion batteries is mainly quantified by thermal runaway characteristics such as onset temperature, peak heating rate (HR), and maximum pressure release. This talk evaluates the materials aspects of thermal runaway of commercial lithium-ion batteries by correlating the contributions from individual cell components to thermal runaway trends. An accelerating rate calorimeter was used to define the thermal runaway behavior of three commercial 18650 lithium-ion batteries (LiCoO2, LiFePO4, and LiNixCoyAl1-x-y­O2) at various states of charge (SOC). Cells were also disassembled and the thermal properties of their component materials was evaluated by thermogravimetric analysis, differential scanning calorimetry, and temperature-resolved X-ray diffraction. Broadly, lithium-ion battery thermal runaway process begins with solid-electrolyte interface and negative active material decomposition followed by the positive active material breakdown. The experimental results show that the onset temperature is generally independent of SOC and peak HR increases with SOC as a result of cathode destabilization. Overall, LiNixCoyAl1-x-yO2 decomposes readily, and charged LiCoO2 is also metastable, although it decomposes more gradually than LiNixCoyAl1-x-y. Contrary to the layered transition metal oxides, LiFePO4 is stable to > 500oC, even when charged. The results are aimed at informing future engineering and fire protection of commercial lithium-ion batteries. Sandia National Laboratories is a multimission 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. SAND2018-3360 A

Redox Flow Batteries (RFBs) are receiving significant attention as a promising technology for grid storage applications.1 While there has been great progress in experimental aspects of flow battery technology, there is a lack of modeling approaches to rapidly evaluate system performance. For example, a common practice has been to determine parameters in mathematical RFB models either through conducting experiments or based on the information available in the literature.2,3,5 However, it is not easy to investigate all parameters for models through this way, and there are occasions when important information, such as diffusion coefficients and rate constants of ions, is not studied. In addition, the parameters needed for modeling charge-discharge are not always available. In this presentation, we demonstrate that an optimization-based robust modeling framework, which is based on a physics-based electrochemical engineering model and parameter estimation techniques,2-5 is useful in studying and analyzing RFB systems. We have studied aspects of capacity loss/fade, kinetics, and transport phenomena of the system and further optimized our model using a laboratory-scale all-vanadium redox static cell setup. The practical impact of this work will be reviewed by providing executable files that enable to identify the performance of redox batteries without the need for software installation and a priori programming knowledge. Acknowledgements This work was supported by the Clean Energy Institute located in University of Washington, Seattle and Washington Research Foundation. The battery experimental work has been supported by program manager Dr. Imre Gyuk through the U.S. Department of Energy, Office of Electricity Delivery and Energy Reliability. 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. References K. T. Cho, P. Ridgway, A. Z. Weber, S. Haussener, V. Battaglia, and V. Srinivasan, Journal of The Electrochemical Society, 159 (11), A1806-A1815 (2012).. K. Knehr, E. Agar, C. Dennison, A. Kalidindi, and E. Kumbur, Journal of The Electrochemical Society, 159 (9), A1446-A1459 (2012). A. Shah, R. Tangirala, R. Singh, R. Wills, and F. Walsh, Journal of the Electrochemical society, 158 (6), A671-A677 (2011). A. Tang, J. Bao, and M. Skyllas-Kazacos, Journal of Power Sources, 196 (24), 10737-10747 (2011). P. A. Boettcher, E. Agar, C. Dennison, and E. C. Kumbur, Journal of The Electrochemical Society, 163 (1), A5244-A5252 (2016).

This paper discusses the possibility of cheap and fast fabrication of high-quality, even custom, plastic-based flexible integrated circuits with the aid of the low-cost technologies of inkjet printing. An important advantage of the inkjet print process over conventional techniques is that the jet process puts the circuit material only where it is needed, whereas the conventional process puts the material down over the whole substrate and then etches most of it away. By eliminating the high-temperature, high-vacuum steps used in conventional circuit manufacture, the jet process has the potential to substantially cut the manufacturing cost.

Flexible, large area electronics - macroelectronics - using amorphous silicon, low-temperature polysilicon, or various organic and inorganic nanocrystalline semiconductor materials is beginning to show great promise. While much of the activity in macroelectronics has been display-centric, a number of applications where macroelectronics is needed to enable solutions that are otherwise not feasible are beginning to attract technical and/or commercial interest. In this paper, we discuss the application drivers and the technology needs and device performance requirements to enable high performance applications to include RF systems.

The focus of this issue of MRS Bulletin is to explore the impact of materials science and technology on microelectronics packaging and integration. Progress in microelectronics packaging has been intimately tied to the continuous advances made in the associated materials, process technologies, and design tools. This is especially true now, as packaging moves into an era driven by the need for complex system-level solutions. This issue is our attempt to present the current status of microelectronics packaging technology and integration and to highlight various perspectives on the future evolution of the field.

An important issue in field emission vacuum microelectronics is the stability of the field emitters with the residual ambient gas. Particularly important is that the field emitter tips made of refractory metals like molybdenum, niobium and tungsten are susceptible to oxidation. The corresponding metal oxides are insulating and adversely affect the emission current characteristic by increasing the width of the effective tunneling barrier. With this perspective, we studied iridium oxide field emitters to evaluate the characteristics of conductive oxide tips. We studied the field emission characteristics of iridium and thermally prepared iridium oxide field emitters using field emission microscopy and current–voltage measurements. We found that, upon oxidation, the voltage required to achieve the desired emission current desire dropped significantly. In addition, oxidation led to a decrease of emission current fluctuations. The development of stable conductive oxide field emitters should improve the performa...

Recent technical and market advances have created a resurgence of interest in miniature vacuum devices based on field-emission vacuum microelectronics. For several operational conditions, these new devices have inherent advantages over their solid-state counterparts. Vacuum microelectronic devices are less sensitive to temperature variations, provide high-speed switching capabilities, and are less susceptible to radiation damage. In addition, electron beams can be steered with external electric and magnetic fields, and electron devices are capable of operation with high current densities. In this article, we describe the development of this new generation of vacuum microelectronic devices and showcase some exciting applications arising from this technology, ranging from flat-panel displays to electron beam devices.

A simple method for the evaluation of materials suitable for the fabrication of field emission displays is presented. The technique is based on the sensitivity of a large field emitter array to the outgassing or desorption of gas species from thin films under electron beam excitation. We demonstrate the usefulness of the technique for the evaluation of thin film materials suitable for use with Mo field emitter arrays.

A simple instrument to determine field emission tip work functions and shape functions from simultaneous current–voltage (I–V) characteristics and field emission energy distributions of field emitter tips and tip arrays is described. This instrument uses a cylindrical energy analyzer with a few correcting elements to simulate a hemispherical analyzer and provides a low cost and more compact alternative to a commercial hemispherical spectrometer. I–V curves and energy distributions may be automatically obtained as a function of time to study field emission tip degradation with usage and/or exposure to gases of interest.

We report field emission microscopy images from single walled carbon nanotubes showing resolvable fine structure with five- and six-fold symmetry. We present evidence indicating that these images have atomic resolution and that they depict the electronic structure of individual nanotube caps under high-field conditions. Fine structure is observed only after removal of surface adsorbates. Prior to adsorbate removal, these images show symmetrical lobed patterns and several other behaviors characteristic of chemisorbed resonant tunneling states.

Discusses the prospects for India as it seeks to invest and develop high technology products and services.