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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

R&D Insights for Extreme Fast Charging of Medium- and Heavy-Duty Vehicles: Insights from the NREL Commercial Vehicles and Extreme Fast Charging Research Needs Workshop, August 27-28, 2019

As battery costs have declined and battery performance has improved, the applicability of vehicle electrification has expanded beyond passenger cars to the commercial vehicle sector. However, due to the larger batteries that would be needed for the medium- and heavy-duty (MDHD) sector, the electric charging capabilities to serve these larger commercial vehicles will need to be substantially more powerful than light-duty chargers. More specifically, such 'extreme fast charging' (XFC) will likely need to reach the megawatt scale to provide a full charge in less than 30 minutes in some applications. In addition, the combined cost of electrified vehicles and charging must be competitive with the costs of petroleum-based technologies and other alternatives to encourage widespread adoption of battery electric vehicles (BEVs) among MDHD fleets. Most of these fleets have a commercial mission and demand low total cost of ownership (TCO) (which motivates minimal refueling times) and high performance from their vehicles.

25 ENERGY STORAGE↗
DOE OSTI2021

Sensitivity and reliability of key electrochemical markers for detecting lithium plating during extreme fast charging

Lithium plating is one of the key challenges for enabling extreme fast charging (XFC, ≤10 to 15 min charging at ≥6C) in graphite-based lithium-ion batteries. Significant R&D effort has been focused on how to mitigate Li plating. Parallel effort is also being devoted to developing methods to detect Li plating when and if it happens during fast charging. In that regard, electrochemical (EC) signature-based detection techniques are less resource intensive, more convenient, and more practical from an end-user application perspective. However, a comprehensive understanding of key plating related EC signatures for extreme fast charging is presently unavailable. In particular, there exist distinct issues of unreliability with key plating-related EC signatures—e.g., incremental capacity (dQ.dV -1 ), differential OCV (dOCV.dt -1 ), end of lithiation (EOL) rest voltage—at XFC conditions, and the underlying reasons have not been explored and identified methodically. Using a comprehensive test matrix and XFC conditions with Li/graphite half cells, this article highlights the unreliability issues associated with the EC Li plating diagnostics and explains the underlying root cause. This study finds distinct sensitivity and unreliability issues with plating related dQ.dV -1 , dOCV.dt -1 , and EOL rest voltage signatures with charging rates. Furthermore, the complex interaction between graphite and plated Li that happens through multiple competing mechanisms —Li stripping and chemical intercalation— at different charging rates is at the core of the sensitivity and unreliability issue.

25 ENERGY STORAGE↗
DOE OSTI2022

Experimental Investigation of a Phase Change Material Charged Finned-Tube Heat Exchanger

Understanding different thermal performance aspects of phase change material heat exchangers (PCM-HX) is critical for designing future energy-efficient thermal energy storage systems. This paper presents an experimental performance analysis of a vertically oriented annular finned-tube PCM-HX in a cylindrical container tested under six different melting and solidification test conditions, varied by heat transfer fluid’s (HTF) inlet temperatures and flow directions. The PCM-HX structure with 20 evenly spaced fins was 3D printed in aluminum, and the PCM-HX container was 285 mm in height. The PCM-HX average porosity was 89.7%, where the PCM mass was 246.4 g. Water served as the HTF, and a PCM with a nominal phase change temperature of 35 °C was selected. Instead of opaque conventional insulation sheets, a combination of air-and-argon-filled see-through insulation cylinders was assembled with the PCM-HX to visualize the phase-change phenomena, while minimizing the uncertainties due to heat loss. In total, there were 78 T-type thermocouples installed in the test section which allows a more precise assessment of thermal mass and heat loss, which are often neglected in similar studies found in the literature. We validated the reliability of the test facility as the repeated test results had negligible deviations under the same test conditions. The energy balances between the estimated theoretical and experimentally calculated PCM storage, considering heat loss and thermal mass, were within ±9% deviation for all test conditions. From the experimental investigations, we made several following observations. It was found that the melting pattern of the finned-tube PCM-HX with small gaps between the container wall and the fins was largely affected by the HTF flow directions, unlike the typical straight annular tube PCM-HX. For effective charging and discharging processes, a combination of upward melting and downward solidification is recommended to shorten the test duration. However, an upward solidification should be considered to minimize the cavity formation between the fins caused by the PCM volume contraction during the solidification process.

25 ENERGY STORAGE↗
DOE OSTI2024

Technoeconomic Analysis of Discrete and Unitized Reversible Fuel Cells for Energy Storage Applications

Reversible Fuel Cell (RFC) systems offer promising characteristics for stationary long duration energy storage applications. Two main configurations of RFC systems exist: discrete RFC systems and unitized RFC systems. While discrete RFC systems combine independent fuel cell and electrolyzer systems for energy storage, unitized RFC systems utilize a single electrochemical stack and might share balance of plant (BOP) components for both charging and discharging processes. While this configuration reduces upfront capital costs, challenges of unitized RFC designs include potential performance trade-offs due to dual-mode stack design and operational complexities across varying loads and operating conditions. Furthermore, these tradeoffs might be different for low-temperature PEM RFCs than for high-temperature reversible solid oxide cell systems. The goal of this project is to assess unitized RFC system potential in the context of long duration grid energy storage and HFTO's technical targets for different discrete fuel cell and electrolyzer technologies. This presentation presents preliminary review of state-of-the-art unitized RFC cells and assesses how they perform relative to HFTO's technical targets. It also presents literature-derived system configurations worth investigating. This review indicates that lab-scale unitized RFCs are making good progress towards meeting HFTO's technical targets.

HYDROGEN↗
DOE OSTI2020

Comparison of Model Predictions and Performance Test Data for a Prototype Thermal Energy Storage Module

Although model predictions of thermal energy storage (TES) performance have been explored in previous investigations, relevant test data that enable experimental validation of performance models have been limited. This is particularly true for high-performance TES designs that facilitate fast input and extraction of energy. In this paper, we present a summary of experimental tests of a high-performance TES unit using lithium nitrate trihydrate phase change material as a storage medium. Performance data are presented for complete dual-mode cycles consisting of extraction (melting) followed by charging (freezing). These tests simulate the cyclic operation of a TES unit for asynchronous cooling in a variety of applications. Finally, the model analysis is found to agree reasonably well, within 10%, with the experimental data except for conditions very near the initiation of freezing, a consequence of subcooling that is required to initiate solidification.

25 ENERGY STORAGE↗
DOE OSTI2021

Dynamics of a single polyampholyte chain

Polymers that feature both positive and negative charges along chains, known as polyampholytes, represent a class of materials that hold promise for a new generation of energy storage devices, the design of which will require knowledge of the underlying structure and dynamics. Here, we develop a theory based on the Rouse model for the dynamic structure factor of a single polyampholyte chain in the weak coupling regime (negligible intramolecular electrostatics) or subjected to weak external electric fields (governed by linear response). Neglecting effects of small ions, we find deviations in scaling from the classic Rouse theory and make predictions for scattering experiments performed on polyampholytes. We find that, under weak coupling with arbitrarily strong fields, the dynamics are highly dependent on the charge distribution and consequently look at two representative examples—random charge densities and periodic charge densities—with different scaling properties. Additionally, under weak fields, the dynamics are largely independent of charge distribution. Finally, we investigate the influence of hydrodynamic effects and the implications of including inertial effects in the model.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Mechanistic insights into structural parameters maximizing energy storage density in Si mesoporous electrodes for Li-ion batteries

Mesoporous Si electrodes have an interesting set of structural parameters, which, when carefully optimized, can lead to ultrahigh energy density Si electrodes for Li-ion batteries. We present here in this paper details of a systematic research leading to the discovery of an “ideal” structure of mesoporous Si electrode, which results in exceptional cracking/damage resistance, while simultaneously having very high specific (>2000 mAh g-1) and total (>1.5 mAh cm-2) capacities for large number of cycles. The electrodes near the “ideal” value of the characteristic structural parameter (the ratio of Si wall thickness to pore diameter) are free from first-cycle capacity degradation, and are efficient in accommodating the volume changes during lithiation by uniformly filling up the porous space between Si walls. Interestingly, these electrodes are also found to be structurally damage-resistant, surviving through many lithiation-delithiation cycles. Using charge-discharge cycling and electron microscopy we show that ideal structure is the key for achieving ultrahigh energy storage density in Si mesoporous electrodes for Li-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2025

THERMS Technology Commercialization Fund Final Report

The technology commercialization fund assisted with the design and development of an intermediate scale packed be thermal energy storage system. Presented in this final report is the design, testing, and modeling of a 100 kWh th radial packed-bed. Air is used as a heat transfer fluid and 3/8” pea gravel is used as the storage medium. Testing has demonstrated the formation of a thermocline within the packed-bed. An air charging temperature of 450 °C was achieved resulting in a charging power of 26.5 kWh th . The radial packed-bed was charged for 5 hours and discharged for 5 hours. Minimal temperature variation was observed at the bottom, middle, and top axial locations of the radial packed-bed which suggests that buoyancy and hydrodynamics in the injection well had a minimal effect on the uniformity of air flow through the bed during charging and discharging. This indicates that the forced convection in a radial direction is dominating the flow regime compared to the buoyancy. The findings of this study suggest an increased air duct diameter through the air heater will increase the charging temperature and increase air mass flow through the system. Increased mass flow through the packed-bed is hypothesized to shorten the thermocline length. Modeled and measured results are compared, and it is here determined that a more comprehensive CFD model will aid in the understanding of air flow and thermocline evolution within the packed-bed.

25 ENERGY STORAGE↗
DOE OSTI2026

Jumpstart Opportunities to Unleash Leadership in Energy Storage (JOULES)

Current-generation Li-ion batteries with cobalt- and nickel-containing cathodes and graphite anodes are approaching performance and cost limits. In this program, 24M Technologies, Inc. (24M) is teaming with the Massachusetts Institute of Technology (MIT) and University of Michigan (UM) to develop low cost and fast charging sodium metal batteries with good low-temperature performance and high energy density, building upon previous work performed under ARPA-E programs. Key achievements include optimization of solid electrolyte and anode current collector, optimized cathode active materials, development of high-performance electrolyte formulations, and integration of these components into full cells. The cell design incorporates (1) an ultra-thick cathode (>9 mAh/cm 2 ) comprising advanced cobalt-free, sodium cathode active material, (2) advanced fast-charging electrolyte (up to 12 mS/cm) developed using machine learning and automated high-throughput screening technology by UM, and (3) ceramic modified separator that enable smooth Na transport and deposition, developed at MIT, enabling a high-energy density anode-free configuration and maximizing the energy density of sodium batteries. The team has successfully combined these approaches to sodium chemistry and paved the way to meeting the fast-charging, high-energy density, and low-cost requirements of next-generation drone, electric vertical take-off and -landing, and electric vehicle batteries. Performance for anode-free sodium cells developed under this program is more powerful than the commercial Li-ion batteries. The final deliverable cell design has achieved over 300 Wh/kg and volumetric energy density above 800 Wh/L (Table 1). Additionally, the team has achieved over (1) a lifetime of 340 cycles, (2) 80% capacity retention at -20 °C (compared 25 °C), and (3) the ability to fast charge to 80% SOC in 20 minutes.

25 ENERGY STORAGE↗
DOE OSTI2024

Electric Vehicles Charging Time Constrained Deliverable Provision of Secondary Frequency Regulation

Aggregation of electric vehicles (EVs) is a promising technique for providing secondary frequency regulation (SFR) in highly renewable energy-penetrated power systems. Equipped with energy storage devices, EV aggregation can provide reliable SFR. However, the main challenge is to guarantee reliable intra-interval SFR capacities and inter-interval delivery following the automatic generation control (AGC) signal. Furthermore, aggregated EV SFR provision will be further complicated by the EV charging time anxiety because SFR provision might extend EV's charging time. This paper proposes a deliverable EV SFR provision with a charging-time-constrained control strategy. First, a charging-time-constrained EV aggregation is proposed to address the uncertainty of EV capacity based on the state-space model considering the charging-time restriction of EV owners. Second, a real-time economic dispatch and time domain simulation (RTED-TDS) cosimulation framework is proposed to verify financial results and the dynamic performance of the EV SFR provision. Last, the proposed charging time-constrained EV aggregation is validated on the IEEE 39-bus system. In conclusion, the results demonstrate that with charging time-constrained EV aggregation, the dynamic performance of the system can be improved with a marginal increase in total cost. More importantly, the charging time constraint can be respected in the proposed SFR provision of the EV aggregation.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2022

Measuring the maximum capacity and thermal resistances in phase-change thermal storage devices

Thermal energy storage can increase the efficiency of the electric grid by adding flexibility to thermal systems. The value of thermal storage is a function of its energy and power density, which are driven by the capacity and thermal resistances in the storage device. Measuring these properties in-situ at the device level is an important step to understanding the performance and improving the design of thermal storage systems. Here, we present methods to measure the total capacity and thermal resistances in heat exchangers with integrated phase change materials. These methods are demonstrated on two thermal storage devices - a 570-kWh ice-based storage tank and a 0.35-kWh graphite-tetradecane composite device. The results show how thermal resistances evolve with the state of charge and discharge rate in these devices and quantify the impact of applied pressure on the contact resistance in composite phase change material heat exchangers. The proposed method allows for easy comparison between different systems and provides information on the thermal bottlenecks limiting performance. Ultimately, these measurements will allow designers to make robust, high-performance thermal storage devices for next-generation thermal systems.

25 ENERGY STORAGE↗
DOE OSTI2023

Optimal Strategies for Hybrid Battery‐Storage Systems Design

As stationary hybrid energy‐storage systems (HESS) for power systems applications have recently drawn interest due to their enhanced performance and decreasing cost, developing systematic approaches for HESS design while considering controls is gaining traction. Herein, a method is presented to optimally design hybrid battery storage by proposing a mathematical modeling framework, formulated as a mixed integer linear programming model. The optimization is capable of handling multiple subsystems of batteries, considering their economic and technological performance. Decisions involve sizing of the batteries, optimal temporal and strategic dispatch to end uses, and energy sources for charging each battery. The applicability of the model is tested on four case studies for three battery chemistries representing distinct objectives: high‐power, high‐energy, and second life. Compared to traditionally designed battery storage with a homogeneous battery, optimally designed hybrid systems can save 12%–26% of system costs, depending on the nature of the dispatch profile. Findings point to design preference toward the second life battery supplemented with some high‐power or high‐energy battery capacity, or both. With the utilized electricity price structure, customers can experience approximately 10%–35% reduction in their bills.

Koleva, Mariya↗
DOE OSTI2026

A Comprehensive Comparison of Methods for Evaluating Dispatch of Long-Duration Energy Storage in Power Systems Models

Long-duration energy storage (LDES) could play a pivotal role in the transformation of electricity grids with high shares of variable renewable energy (VRE) such as solar and wind. However, the weather-dependent nature of VRE introduces challenges for grid balancing and stability, which LDES - along with short-duration energy storage (SDES) - can help address. However, modeling LDES in production cost models (PCMs) is particularly challenging due to the need for high temporal resolution over extended optimization windows while preserving chronology, which ensures the alignment of energy storage operations with VRE generation over multi-day periods. This report compares traditional dispatch methods with advanced LDES dispatch strategies, such as the extended horizon approach, across different PCM platforms and examines tradeoffs and scalability. The comparison reveals that the traditional 1-day optimization horizon within the PCM leads to inefficient utilization of LDES. In contrast, extending the optimization horizon as much as possible significantly reduces curtailment and improves storage dispatch, especially in renewable-dense systems. There is also promise in using state-of-charge or end volume targets set by an external model, however this requires an additional modeling set and generally increases computational burden. This paper presents a comparison of these various methods in a number of power systems, showing algorithms initially in small test systems and scaling up to large, country-wide simulations. Overall, the research presents the trade-offs of various computational methods and illustrates how LDES may play an essential role in power systems of the future.

14 SOLAR ENERGY↗
DOE OSTI2020

Balancing Ionic and Electronic Conduction for High‐Performance Organic Electrochemical Transistors

Abstract Conjugated polymers that support mixed (electronic and ionic) conduction are in demand for applications spanning from bioelectronics to energy harvesting and storage. To design polymer mixed conductors for high‐performance electrochemical devices, relationships between the chemical structure, charge transport, and morphology must be established. A polymer series bearing the same p‐type conjugated backbone with increasing percentage of hydrophilic, ethylene glycol side chains is synthesized, and their performance in aqueous electrolyte gated organic electrochemical transistors (OECTs) is studied. By using device physics principles and electrochemical analyses, a direct relationship is found between the OECT performance and the balanced mixed conduction. While hydrophilic side chains are required to facilitate ion transport—thus enabling OECT operation—swelling of the polymer is not de facto beneficial for balancing mixed conduction. It is shown that heterogeneous water uptake disrupts the electronic conductivity of the film, leading to OECTs with lower transconductance and slower response times. The combination of in situ electrochemical and structural techniques shown here contributes to the establishment of the structure–property relations necessary to improve the performance of polymer mixed conductors and subsequently of OECTs.

Savva, Achilleas↗
DOE OSTI2024

Oxadiazole derivatives as stable anolytes for >3 V non-aqueous redox flow battery

Effective utilization of energy from renewable sources such as wind and solar requires the development of long duration energy storage (LDES) systems that can accommodate intermittent energy accrual. One option under investigation is the use of a redox flow battery (RFB). A significant amount of work has explored aqueous RFB systems with a variety of inorganic and organic carriers. However, moving to a nonaqueous solvent such as acetonitrile (MeCN) for RFB provides a much larger electrochemical window, which could lead to increased energy density if properly utilized. Here, in this work, we investigate a series of 2,5-diphenyl-1,3,4-oxadiazole (DiPhenOx) derivatives as anolytes for a redox flow battery. DiPhenOx has a low voltage redox event that, while reversible by cyclic voltammetry, was determined to be irreversible during bulk electrolysis. To improve cycling performance, we introduced various ester and cyano groups to the phenyl rings of DiPhenOx using molecular engineering. We characterized these derivatives spectroscopically and electrochemically to assess their feasibility for flow battery applications. The ester derivatives with the best cycling performance were tested in a flow cell vs. ferrocene, 2,5-di-tert-butyl-1,4-bis(2-methoxyethoxy)benzene (DBBB) and thianthrene, which resulted in ~2 V, ~3 V and ~3 V redox flow batteries, respectively.

25 ENERGY STORAGE↗
DOE OSTI2022

Mechanistic Insights into the Interplay between Ion Intercalation and Water Electrolysis in Aqueous Batteries

Improving electrolyte stability to suppress water electrolysis represents a basic principle for designing aqueous batteries. Herein, we investigate counterintuitive roles that water electrolysis plays in regulating intercalation chemistry. Using the Na x Fe[Fe(CN) 6 ]∥NaTi 2 (PO 4 ) 3 (x < 1) aqueous battery as a platform, we report that high-voltage overcharging can serve as an electrochemical activation approach to achieving concurrent Na-ion intercalation and an electrolytic oxygen evolution reaction. When the cell capacity is intrinsically limited by deficient cyclable Na ions, the electrolytic water oxidation on the cathode allows for extra Na-ion intercalation from the electrolyte to the NaTi 2 (PO 4 ) 3 anode, leading to a major increase in cyclable Na ions and specific capacity. Furthermore, the parasitic oxygen generation and potential transition-metal dissolution, as proved by our synchrotron and imaging tools, can be significantly mitigated with a simple reassembling approach, which enables stable electrochemical performance and sheds light on manipulating ion intercalation and water electrolysis for battery fast charging and recycling.

25 ENERGY STORAGE↗
DOE OSTI2024

Accumulation of Large Ion Populations with High Ion Densities and Effects Due to Space Charge in Traveling Wave-Based Structures for Lossless Ion Manipulations (SLIM) IMS-MS

The accumulation of very large ion populations in traveling wave (TW)-based Structures for Lossless ion Manipulations (SLIM) has been studied to better understand aspects of ‘in-SLIM’ ion accumulation, and particularly its use in conjunction with ion mobility spectrometry (IMS). A linear SLIM ion path was implemented that had a ‘gate’ for blocking and accumulating ions for arbitrary time periods. Removing the gate potential caused ions to exit and the spatial distributions of accumulated ions were examined. The ion populations for a set of peptides were observed to increase with increased accumulation times until space change effects became significant, after which the peptide precursor ion populations decreased due to growing space charge-related ion activation, reactions, and losses. Ions closest to the gate were preferentially activated, and increasingly so with added storage times, TW amplitude, and the size of the total ion population. For analytical applications, we found that relatively weak TWs in the accumulation/storage region should be utilized to prevent or minimize ion losses and/or ion heating effects that can also lead to fragmentation. Our results further indicate that an accumulation region close to the SLIM entrance is advantageous for both speeding accumulation, minimizing ion heating, and avoiding ion population profiles that result in IMS peak tailing. Importantly, space charge-driven separations were observed for large populations of accumulated species and attributed to the opposing effects of space charge and the TW. In these separations, ion species form distributions or peaks, sometimes moving against the TW, and ordered in the SLIM based on their mobilities. Such separations may offer utility for ion pre-fractionation of ions and increasing the dynamic range measurements, increasing the resolving power of IMS separations by decreasing peak widths for accumulated ion populations, and other purposes benefitting from separations of extremely large ion populations.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Current rectification by nanoparticles in bipolar nanopores

Bipolar nanochannels comprising two domains of positively and negatively charged walls along the pore axis are known to rectify current when exposed to an electric potential bias. We find that addition of charged nanoparticles can increase rectification considerably, by approximately one order of magnitude. Two bipolar channel geometries are considered here; their behavior is examined at rest and under the influence of a negative bias and a positive bias, respectively. We do so by relying on a molecular-level model of the electrolyte solution in the channels. The large increase in current rectification can be explained by the inherent electric field that charged nanoparticles generate within the channel. This effect is found to be largely dependent on the pore's geometry, its charge distribution, and the sign of the nanoparticles' charge, thereby offering new opportunities for design of engineered nanopore membrane-nanoparticle systems for energy storage.

77 NANOSCIENCE AND NANOTECHNOLOGY↗