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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Understanding the Solid-State Electrode–Electrolyte Interface of a Model System Using First-Principles Statistical Mechanics and Thin-Film X-ray Characterization

Intermixing of atomic species at the electrode-electrolyte boundaries can impact the properties of the interfaces in solid-state batteries. Herein, this work uses first-principles statistical mechanics along with experimental characterization to understand intermixing at the electrode-electrolyte interface. For the model presented in this work, lithium manganese oxide (LiMn 2 O 4 , LMO) and lithium lanthanum titanate (Li 3x La 2/3-x TiO 3 , LLTO) are employed as the cathode and electrolyte, respectively. The results of the computational work show that Ti-Mn intermixing at the interface is significant at synthesis temperatures. The experimental results in this work find that, at some critical temperatures between 600 and 700 degrees C for material preparation, the interface of LLTO-LMO becomes blurred. Calculations predict that the interface is unstable with regard to Ti-Mn intermixing starting at 0 K, suggesting that the critical temperature found in the experiment is related to kinetics. The work overall suggests that, in designing a solid-state battery, the fundamental reactions such as intermixing need to be considered.

25 ENERGY STORAGE↗
DOE OSTI2026

Interfacial Chemistry Involved in Selective Separation of NMC/LMO and LCO/LMO Binary Cathode Materials by Froth Flotation Using Oleic Acid

The variability in cathode compositions within recycled lithium-ion battery (LIB) feedstocks poses a significant challenge to efficient downstream refining processes. This study demonstrates the feasibility of using froth flotation with oleic acid as a collector to selectively separate lithium nickel-manganese-cobalt oxide (NMC) and lithium cobalt oxide (LCO) from lithium manganese oxide (LMO) materials. Laboratory-scale flotation tests achieved an 80% separation efficiency in a single stage, producing a froth product with >90% purity of NMC/LCO at approximately 90% yield. Concurrently, the LMO materials were enriched in the sink product with ∼90% purity and ∼90% yield. This approach was further validated using recycled cathode materials, confirming its applicability to realistic feedstocks. The underlying mechanism governing the selective separation of NMC/LCO from LMO was investigated using ζ-potential measurements, contact angle measurements, bubble-particle attachment experiments, and X-ray photoelectron spectroscopy (XPS) analysis. Both contact angle and bubble-particle attachment results confirmed that oleic acid adsorption rendered NMC and LCO surfaces hydrophobic, thereby enhancing flotation recovery. At pH 5, oleic acid adsorbed preferentially onto NMC and LCO surfaces via electrostatic interactions, while exhibiting minimal adsorption on LMO surfaces. However, separation efficiency deteriorated at higher pH, which was attributed to the co-flotation of LMO materials caused by oleate chemisorption on MnOH + species. This work establishes froth flotation as a viable cathode/cathode separation strategy, providing a low-cost, scalable pathway to preconcentrate and enrich nickel-rich and cobalt-rich cathode active materials from incompatible cathode chemistries for direct recycling or hydrometallurgical processing. Furthermore, this study reveals, for the first time, the mechanism of oleate adsorption on the surface of different cathode materials.

PH↗
DOE OSTI2026

Toward Sustainable Lithium Recovery: A Universal Hydrothermal Approach for Lithium Extraction

The rapid growth of lithium-ion battery (LIB) deployment presents critical challenges in sustainable end-of-life management and raw material recovery. Conventional pyrometallurgical and hydrometallurgical methods suffer from high energy demand, lithium loss, and complex wastewater treatment. This study established a universal, highly efficient, and sustainable hydrothermal route for lithium extraction and material recovery from various spent lithium-ion battery cathodes using 1,2,4,5-benzenetetracarboxylic acid (BTCA). The optimized process achieved over 99% lithium leaching efficiency for lithium iron phosphate (LFP) and LiNi x Mn y Co 1–x–y O 2 (NMC), with transition metal coleaching below 1%. It was also broadly applicable to lithium manganese oxide, lithium cobalt oxide, and black mass, achieving 98.5%, 98.95%, and 94.06% leaching efficiencies, respectively. The extracted lithium was directly converted into battery-grade lithium sources, while transition metals were recovered as oxides. Unreacted BTCA was efficiently regenerated and reused without degradation. Electrochemical evaluation confirmed that cathode materials synthesized with recovered lithium exhibit comparable performance to commercial products. Compared to conventional hydrometallurgy, the BTCA-based process increased revenue by over 40% and reduced greenhouse gas emissions by up to 39%. This closed-loop, chemistry-agnostic strategy offered a scalable and economically viable solution for industrial LIB recycling, enabling resource circularity and reducing dependency on primary critical materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Advancing Mn-Based Li-Ion Battery Cathodes via a Partially Cation-Disordered Zigzag-Type Li–Nb–Mn–O Framework

Mn-based Li-ion battery cathodes encompass a great variety of materials structures. Decades of research effort have proven that developing a Mn-based structure featuring a high redox activity, stable cycling, and cost-effectiveness is a longstanding challenge. Motivated by such a need and inspired by the structural diversity of Mn-based cathodes, we develop a partially cation-disordered lithium niobium manganese oxide with a zigzag structure, filling the knowledge gap between zigzag-ordered and fully disordered Li-Mn-based oxides. Electrochemically, the partially disordered cathode greatly unlocks the redox activity of the zigzag lattice and maintains the cycling stability. Mechanism-wise, the partial disordering suppresses the disproportionation reaction of Mn(III) and facilitates a disordered λ-MnO 2 -tetragonal cation-disordered rock salt structural transformation. Furthermore, the work suggests the substantial opportunity of using partial disordering as the key strategy to revive locked-up redox activities and realize new energy storage mechanisms, for the pursuit of high-performance cost-effective battery materials.

25 ENERGY STORAGE↗
DOE OSTI2023

Inhibiting collective cation migration in Li-rich cathode materials as a strategy to mitigate voltage hysteresis

Lithium-rich cathodes are promising energy storage materials due to their high energy densities. However, voltage hysteresis, which is generally associated with transition metal migration, limits their energy efficiency and implementation in practical devices. Here we reveal that voltage hysteresis is related to the collective migration of metal ions, and that isolating the migration events from each other by creating partial disorder can create high-capacity reversible cathode materials, even when migrating transition metal ions are present. In this study, we demonstrate this on a layered Li-rich chromium manganese oxide that in its fully ordered state displays a substantial voltage hysteresis (>2.5 V) associated with collective transition metal migration into Li layers, but can be made to achieve high capacity (>360 mAh g –1 ) and energy density (>1,100 Wh kg –1 ) when the collective migration is perturbed by partial disorder. This study demonstrates that partially cation-disordered cathode materials can accommodate a high level of transition metal migration, which broadens our options for redox couples to those of mobile cations.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Future material demand for automotive lithium-based batteries

The world is shifting to electric vehicles to mitigate climate change. Here, we quantify the future demand for key battery materials, considering potential electric vehicle fleet and battery chemistry developments as well as second-use and recycling of electric vehicle batteries. We find that in a lithium nickel cobalt manganese oxide dominated battery scenario, demand is estimated to increase by factors of 18–20 for lithium, 17–19 for cobalt, 28–31 for nickel, and 15–20 for most other materials from 2020 to 2050, requiring a drastic expansion of lithium, cobalt, and nickel supply chains and likely additional resource discovery. However, uncertainties are large. Key factors are the development of the electric vehicles fleet and battery capacity requirements per vehicle. If other battery chemistries were used at large scale, e.g. lithium iron phosphate or novel lithium-sulphur or lithium-air batteries, the demand for cobalt and nickel would be substantially smaller. Closed-loop recycling plays a minor, but increasingly important role for reducing primary material demand until 2050, however, advances in recycling are necessary to economically recover battery-grade materials from end-of-life batteries. Second-use of electric vehicles batteries further delays recycling potentials.

25 ENERGY STORAGE↗
DOE OSTI2021

Mechanistic Investigation of Redox Processes in Zn-MnO2 battery in Mild Aqueous Electrolytes

Zinc-MnO2 based batteries have acquired attention for grid-level applications, due to impressive theoretical performance, cost effectiveness and intrinsic safety. However, there are still many challenges that remain elusive due to the complex and controversial mechanisms of operation that hinders commercialization. In this work, the detailed redox processes that occur at the cathode during Zn-MnO2 battery operation are elucidated. Using a blend of structural and electrochemical techniques, the redox pairs that occur during operation are mechanistically studied while also showcasing the true impact of the electrolyte additive (0.1 M MnSO4) in a 1 M ZnSO4 electrolyte. An electrochemical quartz-crystal microbalance (EQCM) has been leveraged to reveal the effect of zinc hydroxy sulfate salt (Zn4SO4(OH)6·nH2O) and zinc manganese oxide (ZnxMnyOz) dissolution/deposition, which are believed to be major components during discharge and charge conditions. . These results provide insight not currently available, allowing a holistic view of the electrochemical reaction mechanisms during battery operation.

Rodriguez Perez, Ismael A.↗
DOE OSTI2025

Atomic-Scale Tracking of Topological Defect Motion and Incommensurate Charge Order Melting

Charge order pervades the phase diagrams of quantum materials where it competes with superconducting and magnetic phases, hosts electronic phase transitions and topological defects, and couples to the lattice generating intricate structural distortions. Incommensurate charge order is readily stabilized in manganese oxides, where it is associated with anomalous electronic and magnetic properties, but its nanoscale structural inhomogeneity complicates precise characterization and understanding of its relationship with competing phases. Leveraging atomic-resolution variable-temperature cryogenic scanning transmission electron microscopy, we characterize the thermal evolution of charge order as it transforms from its ground state in a model manganite system. We find that mobile networks of discommensurations and dislocations generate phase inhomogeneity and induce global incommensurability in an otherwise lattice-locked modulation. Driving the order to melt at high temperatures, the discommensuration density grows, and regions of order locally decouple from the lattice periodicity. Published by the American Physical Society 2025

Schnitzer, Noah (ORCID:0000000210421146)↗
DOE OSTI2022

A Simplified Numerical Approach to Characterize the Thermal Response of a Moving Bed Solar Reactor

Abstract Concentrated solar thermochemical storage in the form of a zero-emission fuel is a promising option to produce long-duration energy storage. Solar fuel is produced using a cavity reactor that captures concentrated solar radiation from a solar field of heliostats. In this paper, heat transfer model of a tubular plug-flow reactor designed and manufactured for a solar fuel production is presented. Experimental data collected from a fixed bed tubular reactor testing are used for model comparison. The system consists of an externally heated tube with counter-current flowing gas and moving solid particles as the heated media. The proposed model simulates the dynamic behavior of temperature profiles of the tube wall, gas, and particles under various gas flowrates and residence times. The heat transfer between gas–wall, solid particle–wall, and gas–solid particle is numerically studied. The model results are compared with the results of experiments done using a 4 kW furnace with a 150 mm heating zone surrounding a horizontal alumina tube (reactor) with 50.8 mm outer diameter and thickness of 3.175 mm. Solid fixed particles of magnesium manganese oxide (MgMn2O4) with the size of 1 mm are packed within the length of 250 mm at the center of the tube length. Simulation results are assessed with respect to fixed bed experimental data for four different gas flowrates, namely, 5, 10, 15, and 20 standard liters per minute of air, and furnace temperatures in the range of 200–1200 °C. The simulation results showed good agreement with maximum steady state error that is less than 6% of those obtained from the experiments for all runs. The proposed model can be implemented as a low-order physical model for the control of temperature inside plug-flow reactors for thermochemical energy storage applications.

Engineering↗
DOE OSTI2023

Experimental Performance of a Nonlinear Control Strategy to Regulate Temperature of a High-Temperature Solar Reactor

Abstract Despite the significant potential of solar thermochemical process technology for storing solar energy as solid-state solar fuel, several challenges have made its industrial application difficult. It is important to note that solar energy has a transient nature that causes instability and reduces process efficiency. Therefore, it is crucial to implement a robust control system to regulate the process temperature and tackle the shortage of incoming solar energy during cloudy weather. In our previous works, different model-based control strategies were developed namely a proportional integral derivative controller (PID) with gain scheduling and adaptive model predictive control (MPC). These methods were tested numerically to regulate the temperature inside a high-temperature tubular solar reactor. In this work, the proposed control strategies were experimentally tested under various operation conditions. The controllers were challenged to track different setpoints (500 °C, 1000 °C, and 1450 °C) with different amounts of gas/particle flowrates. Additionally, the flow controller was tested to regulate the reactor temperature under a cloudy weather scenario. The ultimate goal was to produce 5 kg of reduced solar fuel magnesium manganese oxide (MgMn2O4) successfully, and the controllers were able to track the required process temperature and reject disturbances despite the system's strong nonlinearity. The experimental results showed a maximum error in the temperature setpoint of less than 0.5% (6 °C), and the MPC controller demonstrated superior performance in reducing the control effort and rejecting disturbances.

Energy & Fuels↗
DOE OSTI2026

A dual membrane-adsorption evaporator for solar-powered lithium extraction from complex brines

A reliable supply of lithium is required to meet the increased demand for batteries over the coming decades. In this work, we demonstrated the potential to effectively extract lithium from brines by coupling solar-powered evaporation, adsorption, and membrane technologies together. We first synthesized a three-dimensional adsorptive evaporator by coating a lithium manganese oxide material onto a cotton stick using an easily scalable, one-step method. An osmotic membrane was then installed at the root of the evaporator to enhance the lithium to magnesium selectivity, prevent scaling caused by divalent cations, and thus further increase the water evaporation flux. The operation of the dual membrane-adsorption evaporator is entirely driven by osmosis and capillary force, demanding no extra energy input. The integration of the osmotic membrane was found to increase the lithium to magnesium selectivity over 10-fold to higher than 40. The dual process also produced high lithium to calcium selectivity and proved to sustain long-term stability by self-managing its internal osmotic pressure. Last, a test was done in three simulated brine solutions with varied brine chemistry and the evaporation rate stayed high and consistent throughout the long-term test. This illustrates that this technology can be used in varied brine solutions throughout the world providing efficient lithium capture and separation from competing divalent cations.

Eskafi, Aydin F. [University of California, Berkel↗
DOE OSTI2021

Polysulfide-Permanganate Flow Battery Using Abundant Active Materials

A new flow battery is presented using the abundant and inexpensive active material pairs permanganate/manganate and disulfide/tetrasulfide. A wetted material set is identified for compatibility with the strongly oxidizing manganese couple at ambient and elevated temperatures. Both solutions allow high active material solubility, with cells tested at theoretical energy densities up to 43 Wh l −1 for the ∼1.2 V cell. Full cells built with nickel foam electrodes and sodium-exchanged Nafion 115 membranes deliver a baseline area-specific resistance of 2.7 Ω-cm 2 . Incorporation of high-surface-area cobalt-coated carbon paper and high-surface-area stainless steel mesh electrodes, and an expanded Nafion 115 membrane delivers cells with 44% lower resistance at 1.6 Ω-cm 2 . All cells show performance decay over the course of cycling. The Co-decorated carbon paper electrodes provide significant kinetic improvements, shifting electrode performance from non-linear with Ni-foam to linear with a volume-normalized exchange current density value of 3.2 A cm −3 . The expanded membrane provides increased conductivity over the 13 mS cm −1 conductivity observed in as-received, sodium-exchanged Nafion 115. Although boiled membranes provide improved conductivity, it is at the cost of decreased Coulombic efficiency and poorer manufacturability. Full cell models suggest that similar cell resistances (1.7 Ω-cm 2 ) should be feasible with as-received Nafion 115 and advanced electrodes.

25 ENERGY STORAGE↗
DOE OSTI2024

Rechargeable Manganese Dioxide||Hard Carbon Lithium Batteries in an Ether Electrolyte

Earth-abundant, cost-effective electrode materials are essential for sustainable rechargeable batteries and global decarbonization. Manganese dioxide (MnO 2 ) and hard carbon both exhibit high structural and chemical tunability, making them excellent electrode candidates for batteries. Herein, we elucidate the impact of electrolytes on the cycling performance of commercial electrolytic manganese dioxide in Li chemistry. We leverage synchrotron X-ray analysis to discern the chemical state and local structural characteristics of Mn during cycling, as well as to quantify the Mn deposition on the counter electrode. By using an ether-based electrolyte instead of conventional carbonate electrolytes, we circumvent the formation of a surface Mn(II)-layer and Mn dissolution from Li x MnO 2 . Consequently, we achieved an impressive ~100% capacity retention for MnO 2 after 300 cycles at C/3. To create a lithium metal-lean full cell, we introduce hard carbon as the anode which is compatible with ether-based electrolytes. Commercial hard carbon delivers a specific capacity of ~230 mAh g -1 at 0.1 A g -1 without plateau, indicating a surface-adsorption mechanism. The resulting manganese dioxide||hard carbon full cell exhibits stable cycling and high Coulombic efficiency. Our research provides a promising solution to develop cost-effective, scalable, and safe energy storage solutions using widely available manganese oxide and hard carbon materials.

25 ENERGY STORAGE↗
DOE OSTI2025

Direct Conversion of MnO2 into Atomic Mn Sites for Oxygen Reduction

Development of platinum group metal (PGM)-free catalysts has been investigated to replace the platinum group metal catalyst in future inexpensive polymer electrolyte membrane (PEM) fuel cells. Usually, synthetic methods for these PGM-free catalysts involve introducing transition-metal salts or molecules. Herein, we demonstrate a facile synthetic method to prepare PGM-free Mn-N-C catalysts by directly converting manganese oxides into highly active MnN4 sites. Typically, MnO2 is used as a Mn source. Ammonium chloride and benzimidazole are introduced during high-temperature treatment to enhance catalytic activity and stability further. Ammonia generated from the decomposition of ammonium chloride can improve the intrinsic ORR activity of MnNx moieties through chemical or electronic effects by introducing additional nitrogen groups. The Mn-N-C catalyst exhibits promising ORR activity, achieving a half-wave potential of 0.83 V in 0.5 M H2SO4, outperforming most PGM-free ORR catalysts. The robust carbon structure resulting from organic-molecule treatment is also verified by electrochemical and physical characterization, thereby improving the catalyst's durability.

Yang, Xiaoxuan↗
DOE OSTI2023

Surface Science Studies of Selective Fischer-Tropsch Chemistry on Cobalt Carbide Surfaces

Advances in catalysis science are critical to the progress of the United States. Catalysis is employed, in one way or another, in the production of almost every chemical and product manufactured. The catalysis research that we undertook here, regarding the role of specific facets of cobalt carbide in the Fischer-Tropsch production of low molecular weight olefins (FTO), is motivated by the work of many previous investigators. In particular two research groups from China had discovered FTO catalysts that work very selectively for low molecular weight olefins coupled with low production of methane. These are potentially very important findings that could find significant industrial utility if improvements can be discovered. With the research undertaken here we chose to focus on one of these studies and especially the Co 2 C surfaces that they implicate as being responsible for this exciting FTO catalysis with low production of methane. In this study, Zhong and co-workers investigated cobalt-manganese oxide catalysts for the Fischer-Tropsch to Olefins process. After reaching steady-state their catalyst showed a good selectivity to light olefins and low selectivity to methane with a carbon monoxide conversion of 31.8% at one atmosphere (with a H 2 /CO ratio of two and a temperature of 250°C). Lower H 2 /CO ratios and lower pressures increased the olefin production. Their catalyst characterization studies indicated that cobalt carbide quadrangular nanoprisms with preferentially exposed (101) and (020) facets were important in favoring lower olefin production and inhibiting methane formation. The authors stated that these cobalt carbide nanoprisms are a promising new catalyst system for directly converting synthesis gas to lower olefins. Motivated by the studies of Zhong and co-workers, our goal with the research here was to contribute to a better understanding of catalysis science through the study of surface chemical reactions related to the Fischer-Tropsch to Olefins reaction on specific facets of planar model cobalt carbide catalysts in ultrahigh vacuum.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Task 12 PV Sustainability - Environmental Life Cycle Assessment of Residential PV and Battery Storage Systems

Using a life cycle assessment (LCA), the environmental impacts from generating 1 kWh of electricity for self-consumption via a photovoltaic-battery system are determined. The system includes a 10 kWp multicrystalline-silicon photovoltaic (PV) system (solar irradiation about 1350 kWh/m2/year and annual yield 1000 kWh/kWp), an iron phosphate lithium-ion (LiFePO4) battery, and other components such as the control system, battery housing, and two inverters (one for the PV system and one for the battery system). Three options for the AC-coupled system with changing battery capacities (5, 10, or 20 kWh nominal capacity) are investigated. The environmental impacts are assessed using the indicators greenhouse gas emissions and cumulative energy demand (separated into total and non-renewable cumulative energy demand). In addition, the four most important impact categories for PV electricity - respiratory inorganics (particulate matter), acidification, energy carrier resource use, and minerals and metals resource use - are assessed according to the environmental footprint (EF) method. Data are drawn from the DETEC data DQRv2:2018, recent literature, and product details provided by manufacturers. The results show larger environmental impacts of PV-battery systems with increasing battery capacity; for capacities of 5, 10, and 20 kWh, the cumulative greenhouse gas emissions from 1 kWh of electricity generation for self-consumption via a PV-battery system are 80, 84, and 88 g CO 2- eq/kWh, respectively. The cumulative greenhouse gas emissions of PV electricity consumed directly or fed into the grid are 54 g CO 2 -eq/kWh. The corresponding total cumulative energy demands are 5.27, 5.40, and 5.50 MJ oil-eq/kWh, with non-renewable energy carriers contributing 1.16, 1.22, and 1.29 MJ oil-eq/kWh. In the investigated EF impact categories, we similarly observe a larger environmental burden with increasing battery capacity, except in the use of minerals and metals. Our sensitivity analyses show that using a nickel cobalt manganese oxide (NCM) lithium-ion battery, instead of an LiFePO 4 battery, leads to a comparable environmental impact in terms of greenhouse gas emissions and cumulative energy demand. However, the NCM battery increases the impact in the EF categories of acidification and respiratory inorganics by 7 and 10%, respectively, whereas energy carrier resource use decreases by 4% and minerals and metals resource use decrease by 1%. Using a copper indium selenium (CIS) PV panel instead of a multicrystalline-silicon decreases greenhouse gas emissions by 24%, non-renewable cumulative energy demand by 13%, and particulate matter emissions by 60% (the largest decrease). Furthermore, the calculated environmental impacts are sensitive to the assumed battery lifetime. A decrease from 5000 to 3000 charge cycles increases non-renewable cumulative energy demand by 24% and greenhouse gas emissions by 16%. Increasing from 5000 to 7000 charge cycles decreases the environmental impacts by 6% and 7% in terms of non-renewable cumulative energy demand and greenhouse gas emissions, respectively. A utility-scale battery system case study shows that using batteries to store PV electricity overproduction reduces greenhouse gas emissions compared to using natural gas backup electricity generation.

14 SOLAR ENERGY↗
DOE OSTI2024

Solid State Solar Thermochemical Fuel (SoFuel) for Long Duration Storage

Efficient thermal storage systems, when coupled with renewable energy, enable the decarbonization of numerous industrial processes requiring high temperature steam or air, and provide a path for seasonal building heating, especially for colder climates. Existing thermal storage systems face a significant challenge due to losses inherent to all high temperature systems. A viable route to long-term storage is to use thermochemical reactions to convert concentrated solar energy to a fuel that is shelf-stable and can be stored at room temperature, thus eliminating losses associated with high temperature storage. The Solid-State Solar Thermochemical Fuel (SoFuel) technology developed by Michigan State University, Oregon State University, and Mississippi State University provides reactors and processes with minimal sensible heat losses and allows storing solar energy as a solid-state fuel at room temperature for long duration. The production of SoFuel occurs within a cylindrical cavity reduction chemical reactor that captures concentrated solar radiation from a solar field. Reactive magnesium manganese oxide (Mg-Mn-O) resides within the cylindrical cavity chemical reactor and undergoes thermal reduction as the temperature exceeds 1350°C. The thermally reduced Mg-Mn-O pellets (the SoFuel) are cooled down through a recuperative process and stored within a bin until used. The SoFuel can directly supply up to 1100°C heat to an adjacent power plant for electricity generation or industrial heating. Oxidation of SoFuel pellets occurs in a counter flow reactor and supplies heat to the user for electricity generation or industrial processing, after which the fuel is returned to the concentrating solar field where it is regenerated for re-use. Both reactors can be controlled well using a variety of strategies. With the low cost of the material, its cyclability, and the possibility of using the pelletized with on-sun reactors, or with electricity that would be curtailed, this project offers a viable option of medium- and long-term thermal energy storage.

14 SOLAR ENERGY↗
DOE OSTI2025

Solid State Solar Thermochemical Fuel (SoFuel) for Long Duration Storage

Efficient thermal storage systems, when coupled with renewable energy, enable the decarbonization of numerous industrial processes requiring high temperature steam or air, and provide a path for seasonal building heating, especially for colder climates. Existing thermal storage systems face a significant challenge due to losses inherent to all high temperature systems. A viable route to long-term storage is to use thermochemical reactions to convert concentrated solar energy to a fuel that is shelf-stable and can be stored at room temperature, thus eliminating losses associated with high temperature storage. The Solid-State Solar Thermochemical Fuel (SoFuel) technology developed by Michigan State University, Oregon State University, and Mississippi State University provides reactors and processes with minimal sensible heat losses and allows storing solar energy as a solid-state fuel at room temperature for long duration. The production of SoFuel occurs within a cylindrical cavity reduction chemical reactor that captures concentrated solar radiation from a solar field. Reactive magnesium manganese oxide (Mg-Mn-O) resides within the cylindrical cavity chemical reactor and undergoes thermal reduction as the temperature exceeds 1350°C. The thermally reduced Mg-Mn-O pellets (the SoFuel) are cooled down through a recuperative process and stored within a bin until used. The SoFuel can directly supply up to 1100C heat to an adjacent power plant for electricity generation or industrial heating. Oxidation of SoFuel pellets occurs in a counter flow reactor and supplies heat to the user for electricity generation or industrial processing, after which the fuel is returned to the concentrating solar field where it is regenerated for re-use. Both reactors can be controlled well using a variety of strategies. With the low cost of the material, its cyclability, and the possibility of using the pelletized with on-sun reactors, or with electricity that would be curtailed, this project offers a viable option of medium- and long-term thermal energy storage.

25 ENERGY STORAGE↗