Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Organic cathode”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Impact of electrolyte solutions on carbon dioxide fixation in single chamber Al–CO 2 battery

Governments and research & development (R&D) organizations are actively initiating various programs and research strategies for CO 2 capture, its utilization, and integration with long duration energy storage from renewable sources worldwide. In line with the carbon capture goals, here we report a novel electrochemical Al-CO 2 battery cell, that can simultaneously capture CO 2 and convert it into value-added products, in addition to long-duration energy generation and storage. Here, this innovative approach employs cost-effective Al metal as an anode and an in-house synthesized Ni–Fe based bimetallic double hydroxide catalyst as the cathode, with meticulously optimized compositions and morphologies. We explore the impact of different aqueous electrolyte solutions compositions on the cell performance, demonstrating up to 10 h of stable long duration energy storage with a stable voltage profile. The cell exhibits low polarization even at high current densities of up to 12 mA cm -2 and maintains stable cycling over 500 h. Through Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray Diffraction and X-ray photoelectron spectroscopy (XPS) analysis, we determined that the discharge product is either NaAlCO 3 (OH) 2 or KAlCO 3 (OH) 2 , distinct from the Al 2 (CO 3 ) 3 typically reported in conventional Al–CO 2 batteries.

25 ENERGY STORAGE↗
DOE OSTI2022

A Fiber-Based 3D Lithium Host for Lean Electrolyte Lithium Metal Batteries

3D hosts are promising to extend the cycle life of lithium metal anodes but have rarely been implemented with lean electrolytes thus impacting the practical cell energy density. To overcome this challenge, a 3D host that is lightweight and easy to fabricate with optimum pore size that enables full utilization of its pore volume, essential for lean electrolyte operations, is reported. The host is fabricated by casting a VGCF (vapor-grown carbon fiber)-based slurry loaded with a sparingly soluble rubidium nitrate salt as an additive. The network of fibers generates uniform pores of ≈3 µm in diameter with a porosity of 80%, while the nitrate additive enhances lithiophilicity. This 3D host delivers an average coulombic efficiency of 99.36% at 1 mA cm -2 and 1 mAh cm -2 for over 860 cycles in half-cell tests. Full cells containing an anode with 1.35-fold excess lithium paired with LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cathodes exhibit capacity retention of 80% over 176 cycles at C/2 under a lean electrolyte condition of 3 g Ah -1 . This work provides a facile and scalable method to advance 3D lithium hosts closer to practical lithium-metal batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Electrodeposition of Complex High Entropy Oxides via Water Droplet Formation and Conversion to Crystalline Alloy Nanoparticles

We report that a combination of electrodeposition and thermal reduction methods have been utilized for the synthesis of ligand-free FeNiCo alloy nanoparticles through a high-entropy oxide intermediate. These phases are of great interest to the electrocatalysis community, especially when formed by a sustainable chemistry method. This is successfully achieved by first forming a complex five element amorphous FeNiCoCrMn high-entropy oxide (HEO) phase via electrodeposition from a nanodroplet emulsion solution of the metal salt reactants. The amorphous oxide phase is then thermally treated and reduced at 570–600 °C to form the crystalline FeNiCo alloy with a separate CrMnO x cophase. The FeNiCo alloy is fully characterized by scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy elemental analysis and is identified as a face-centered cubic crystal with the lattice constant a = 3.52 Å. The unoptimized, ligand-free FeNiCo NPs activity toward the oxygen evolution reaction is evaluated in alkaline solution and found to have an ~185 mV more cathodic onset potential than the Pt metal. Beyond being able to synthesize highly crystalline, ligand-free FeNiCo nanoparticles, the demonstrated and relatively simple two-step process is ideal for the synthesis of tailor-made nanoparticles where the desired composition is not easily achieved with classical solution-based chemistries.

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

Communication—On the Lack of Correlation between the Voltammetric Redox Couple and ORR Activity of Fe-N-C Catalysts

Platinum group metal-free catalysts for polymer electrolyte fuel cells are analyzed in different electrolytes (H 2 SO 4 and HClO 4 ) and at different pH values to gain insight into the oxygen reduction reaction (ORR) mechanism. Two Fe-N-C type catalysts showing a reversible voltammetric redox couple around 0.77 V vs RHE in HClO 4 electrolyte are investigated. A notable cathodic shift of the redox couple to 0.62 V is observed in H 2 SO 4 and is assigned to bisulfate adsorption. Concurrently, the ORR activity of the catalysts is unaffected, suggesting an independent nature of the reductive mechanism with the redox peak species.

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

A molecular mediator for reductive concerted proton-electron transfers via electrocatalysis

Electrocatalytic approaches to the activation of unsaturated substrates via reductive concerted proton-electron transfer (CPET) must overcome competing, often kinetically dominant hydrogen evolution. We introduce the design of a molecular mediator for electrochemically triggered reductive CPET through the synthetic integration of a Brønsted acid and a redox mediator. Cathodic reduction at the cobaltocenium redox mediator substantially weakens the homolytic nitrogen-hydrogen bond strength of a Brønsted acidic anilinium tethered to one of the cyclopentadienyl rings. The electrochemically generated molecular mediator is demonstrated to transform a model substrate, acetophenone, to its corresponding neutral α-radical via a rate-determining CPET.

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

3D‐Printed Structure Boosts the Kinetics and Intrinsic Capacitance of Pseudocapacitive Graphene Aerogels

Abstract The performance of pseudocapacitive electrodes at fast charging rates are typically limited by the slow kinetics of Faradaic reactions and sluggish ion diffusion in the bulk structure. This is particularly problematic for thick electrodes and electrodes highly loaded with active materials. Here, a surface‐functionalized 3D‐printed graphene aerogel (SF‐3D GA) is presented that achieves not only a benchmark areal capacitance of 2195 mF cm −2 at a high current density of 100 mA cm −2 but also an ultrahigh intrinsic capacitance of 309.1 µF cm −2 even at a high mass loading of 12.8 mg cm −2 . Importantly, the kinetic analysis reveals that the capacitance of SF‐3D GA electrode is primarily (93.3%) contributed from fast kinetic processes. This is because the 3D‐printed electrode has an open structure that ensures excellent coverage of functional groups on carbon surface and facilitates the ion accessibility of these surface functional groups even at high current densities and large mass loading/electrode thickness. An asymmetric device assembled with SF‐3D GA as anode and 3D‐printed GA decorated with MnO 2 as cathode achieves a remarkable energy density of 0.65 mWh cm −2 at an ultrahigh power density of 164.5 mW cm −2 , outperforming carbon‐based supercapacitors operated at the same power density.

asymmetric supercapacitors↗
DOE OSTI2020

Self-supported MoO 2 /MoS 2 nano-sheets embedded in a carbon cloth as a binder-free substrate for high-energy lithium–sulfur batteries

As one of the most prospective candidates for next-generation rechargeable batteries, lithium-sulfur (Li-S) batteries currently still encounter great challenges associated with the low conductivity, severe shuttle effects, and sluggish redox kinetics. Herein, a self-supported sulfur host is fabricated by an in-situ growth of MoO 2 /MoS 2 nano-sheets on a carbon cloth (CC). First, carbon cloth serves as a good template for the morphology-controlled synthesis of nanostructured materials, which not only alleviates the agglomeration of MoO2/MoS2, but also enhances the flexibility and mechanical strengthen of the hybrid architecture as a free-standing host. Second, the polysulfide-trapping ability can be greatly enhanced by both physical and chemical adsorption from the MoO 2 /MoS 2 -anchored carbon cloth. Moreover, the partially sulfurized MoO 2 /MoS 2 nano-sheets integrate the benefits of conductive MoO 2 and sulfiphilic MoS 2 , thus facilitating fast charge transfer and redox kinetics of polysulfide conversion. As a result, these attributes enable the host to hold a high sulfur loading (up to 7.6 mg cm -2 ), which exceeds most of the reported carbon cloth-related cathode work in the literature. Furthermore, the Li-S cells can achieve a high peak capacity of 1350 mA h g -1 , excellent rate capability (C/20 - 2C rate), impressive areal capacity (up to 6.3 mA h cm -2 ), and a high capacity retention of 85% after 100 cycles.

25 ENERGY STORAGE↗
DOE OSTI2021

Design of High-Voltage Stable Hybrid Electrolyte with an Ultrahigh Li Transference Number

Considering the high energy consumption during processing, and the low compliance and adhesion of ceramic electrolytes, the integration of polymer into ceramic electrolytes provides a way to mitigate the interfacial issues. However, the severe ion concentration gradient, low ionic conductivity, and instability toward Li metal and high-voltage cathodes become the major concerns in applying hybrid electrolytes. In this work, we report a single-ionconducting hybrid electrolyte (SIE-LLZO) with 64 wt % Li 7 La 3 Zr 2 O 12 (LLZO) particles embedded in a fluoroboron-centered Li-conductive polymer framework (LiBFSIE). The SIE-LLZO electrolyte exhibited a high Li transference number of 0.94 and electrochemical stability up to 5.6 V vs Li/Li + . Promising averaged Coulombic efficiencies of 99.97% and 99.91% were achieved in cells with LiNi 0.8 Co 0.15 Al 0.05 O 2 and LiNi 0.6 Mn 0.2 Co 0.2 O2 cathodes for 400 and 200 cycles, respectively. Finally, the Li-conducting pathway in the hybrid electrolyte was further investigated by a 6 Li-to- 7 Li isotope replacement method, indicating that Li transport mainly relies on the LLZO and interface between LiBFSIE and LLZO.

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

Lithium battery cathode

A novel lithium battery cathode, a lithium ion battery using the same and processes and preparation thereof are disclosed. The battery cathode is formed by force spinning. Fiber spinning allows for the formation of core-shell materials using material chemistries that would be incompatible with prior spinning techniques. A fiber spinning apparatus for forming a coated fiber and a method of forming a coated fiber are also disclosed.

25 ENERGY STORAGE↗
DOE OSTI2024

Performance Restoration of Iron Electrodes by Polarity Reversal after Long-Term Surface Fouling in Wastewater Electrocoagulation

Iron electrocoagulation (Fe-EC) performance often declines with time, producing lower contaminant removal efficiencies and higher energy requirements due to formation of a fouling layer on the electrodes. Here, we investigate the formation of the fouling layer and the effectiveness of polarity reversal to restore the Fe-EC performance. A thin, porous iron oxide layer initially forms on the anode, thickening into a dense, over 150-μm thick crystalline layer after extended operation. This fouling layer restricts dissolution and diffusion of Fe ions into the bulk solution, thus increasing the anode potential required to maintain a desired electrical current and decreasing Faradaic efficiency. Polarity reversal applied when performance decline is observed effectively removes the fouling layer, thereby restoring Faradaic and contaminant removal efficiencies and decreasing energy consumption. Our findings suggest that gas generation at the cathode surface after polarity reversal causes removal of the fouling layer. This study enhances the current understanding of fouling-layer formation in Fe-EC and offers a practical approach, involving polarity reversal, to maintain electrode reactivity and optimal Fe-EC performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Influence of diluent concentration in localized high concentration electrolytes: elucidation of hidden diluent-Li + interactions and Li + transport mechanism

Localized high concentration electrolytes (LHCE) offer a viable dilution strategy for high concentration electrolytes (HCE) as the dilution process barely impacts the enhanced reductive/oxidative behavior of the HCE formulation but significantly lowers the overall viscosity and, in most cases, increases the ionic conductivity. On the other hand, experimental studies indicate that fluorinated ether electrolytes such as 1,1,2,2-tetrafluoroethylene 2,2,3,3-tetrafluoropropyl ether (TTE) help grow enhanced passivation layers on Ni-rich NMC cathodes. In this work, we study LHCE formulations based on lithium bis(fluorosulfonyl)imide (LiFSI), dimethyl carbonate (DMC), and TTE as the diluent. Here we use molecular dynamics methodologies, and Raman spectra measurements, to address to what extent the diluent content impacts the coordination behavior of the aggregated structures in the electrolyte and to evaluate the Li + transport properties under the influence of an external electric field. In contrast to other fluorinated ethers, we find that TTE interacts with Li + via fluorine atoms, partially limiting the DMC–Li + interactions hence altering the Li + solvation coordination. This competitive interaction with Li+ between the organic solvent and the TTE diluent influences the electrolyte's reductive/oxidative behavior. Nevertheless, the bonding strength of the Li + –F TTE is much weaker than those of the Li + –O DMC and Li + –OFSI – . Therefore, the existence of Li + –F TTE is in a transient state rather than in a steady state. These results provide plausible guiding rules for future dilution strategies of HCE electrolytes. We also demonstrate that Li + ions drift under the electric field's influence via repeated ion dissociation/association processes following a hopping conduction mechanism. Li + ions jump between aggregated networks where Li–O interactions dominate via diluent-enriched phases, a process in which the solvation shells temporarily mutate to a Li–F dominated coordination structure. We expect our results to contribute an improved atomic-level understanding of the solvation structure and dynamics of LHCE electrolytes.

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

Compositions and Formation Mechanisms of Solid-Electrolyte Interphase on Microporous Carbon/Sulfur Cathodes

We report the formation mechanism and compositions of a solid-electrolyte interphase (SEI) on a microporous carbon/sulfur (MC/S) cathode in Li–S batteries using a carbonate-based electrolyte (1 M LiPF 6 in ethylene carbonate (EC)/dimethyl carbonate, v:v = 1:1). Through characterizations using 1D and 2D solution-phase nuclear magnetic resonance spectroscopy, coupled with model chemical reactions and DFT calculations, we have identified two critical roles of Li + in steering the SEI formation. First, the preferential solvation of Li + by EC in the mixed carbonate electrolyte renders EC as the dominant participant in the SEI formation, and second, Li + coordination to the EC carbonyl alters activation barriers and changes the reaction pathways relative to Na + . The main organic components in the SEI are identified as lithium ethylene monocarbonate and lithium methyl carbonate, which are virtually identical to those formed on Li and graphite anodes of lithium-ion batteries but via a different pathway.

25 ENERGY STORAGE↗
DOE OSTI2024

Physical and Electrochemical Characterization of Aluminum Electrodes during Electrocoagulation

Electrocoagulation (EC) of synthetic groundwater was conducted using a sacrificial aluminum electrode in a flow-through EC reactor with short retention times (<1 min) under varying hydrodynamic and electrochemical conditions. The treated water was allowed to settle for 24 h and achieved silicate removal of up to 50 ± 4%, and hardness removal of 11 ± 1%. Physical, chemical, and electrochemical characterization was performed to explore changes in electrode surface morphology and composition. Electrochemical impedance spectroscopy (EIS) showed that chemical reactions at the electrode/water interface are sensitive to changes in the immediate chemical environment. We demonstrate that the most energy-intensive step in EC is aluminum dissolution at the anode, which remained fairly constant due to the continuous renewal of the anode’s surface, a result of aluminum dissolution. At the cathode, a structural change in the oxide layer, from γ-Al 2 O 3 to gibbsite, was detected by grazing-incidence X-ray diffraction, which decreased the resistance to charge transfer at the cathode surface, resulting in decreased electrode resistance. The high flow rate in the system minimized the accumulation of aluminum hydroxide solids and aluminum ions at the electrode/water interface, which minimized the formation of thick scalants and amorphous Al(OH) 3 on the cathode and anode, respectively. In conclusion, it was further demonstrated by EIS that under these conditions the resistance to charge transfer was constant throughout the duration of the experiment.

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

Suppressing electrolyte-lithium metal reactivity via Li + -desolvation in uniform nano-porous separator

Lithium reactivity with electrolytes leads to their continuous consumption and dendrite growth, which constitute major obstacles to harnessing the tremendous energy of lithium-metal anode in a reversible manner. Considerable attention has been focused on inhibiting dendrite via interface and electrolyte engineering, while admitting electrolyte-lithium metal reactivity as a thermodynamic inevitability. Here, we report the effective suppression of such reactivity through a nano-porous separator. Calculation assisted by diversified characterizations reveals that the separator partially desolvates Li + in confinement created by its uniform nanopores, and deactivates solvents for electrochemical reduction before Li 0 -deposition occurs. The consequence of such deactivation is realizing dendrite-free lithium-metal electrode, which even retaining its metallic lustre after long-term cycling in both Li-symmetric cell and high-voltage Li-metal battery with LiNi 0.6 Mn 0.2 Co 0.2 O 2 as cathode. The discovery that a nano-structured separator alters both bulk and interfacial behaviors of electrolytes points us toward a new direction to harness lithium-metal as the most promising anode.

25 ENERGY STORAGE↗
DOE OSTI2022

Low-Pressure Electrolytic Ammonia (LPEA) Production

The project goal was to advance and demonstrate the techno-economic viability of a low-pressure electrolytic ammonia (LPEA) process for producing ammonia from electricity, hydrogen, and nitrogen. The critical enabling technology of the LPEA process is a proton-conducting electrolyte (PCE) developed by EERC and North Dakota State University (NDSU) capable of high proton conductivity (at least 1×10 -2 [0.01] siemens/centimeter [S/cm]) at 200°–300°C. An affordable PCE that works at 200°–300°C has been a major goal of the global electrochemistry industry for over 25 years, because it would enable operation at temperatures high enough to prevent catalyst poisoning and simplify water management and low enough to avoid temperature-driven degradation of fuel cell components comprising materials with differing coefficients of thermal expansion. Also critical to LPEA performance is a cathode catalyst capable of ammonia synthesis at a rate of ≥1×10 -10 moles/second-cm 2 catalyst surface area (mol-s -1 cm -2 ) in screening tests conducted at room temperature, and 1×10 -7 mol-s -1 cm -2 at 200°–300°C for commercial viability.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Catalytic cathode for a lithium-oxygen battery

A metal-air battery includes an anode; a low-dimensional catalyst cathode; and an electrolyte; wherein: the low-dimensional catalyst cathode comprises a functional metal layer on a carbon support overcoated with a catalyst layer; the electrolyte comprises an aprotic solvent that is an ether-based solvent, a fluorinated ether-based solvent, an oligo (ethylene oxide) solvent, or a mixture of any two or more thereof; and the electrolyte is free of carbonate solvents.

25 ENERGY STORAGE↗
DOE OSTI2025

Ambient Rare Earth Metal Electrodeposition in Nitrogen-Coordinated Silylamide Electrolyte

The transition to a sustainable, low-carbon economy demands energy-efficient and environmentally benign methods for rare earth metal (REM) production. Furthermore, while high-temperature molten salt electrolysis remains energy-intensive, corrosive, and environmentally unfriendly, emerging room-temperature processes based on conventional ionic liquids are also hindered by high viscosity and chemical instability. In this study, a nitrogen-coordinated, water-, oxygen-, and fluorine-free silylamide-based electrolyte is presented as a promising system for room-temperature REM electrodeposition. Derived from commercially available lithium silylamide precursors, the system enables facile synthesis, broad electrochemical stability, and tunable metal–ligand interactions. Electrochemical analysis reveals high voltammetric stripping reversibility, stable cathodic and anodic potentials, and selective neodymium (Nd) deposition at appreciable current densities (>1 mA/cm 2 ), with minimal parasitic reactions. Bulk experiments produced high-purity Nd with reproducible performance across multiple batches. Scaled deposition yielded over 1 g of Nd with near-theoretical mass efficiency (0.40 mg/C) and >90% purity. Using sacrificial dysprosium (Dy) and Nd metal anodes, the system maintained constant Nd loading during extended deposition and enabled cathodic codeposition of stripped anode material, demonstrating the electrolyte’s dual functionality for REM electrorefining. Collectively, this silylamide platform offers a compelling combination of electrochemical robustness, chemical resilience, and process scalability for sustainable ambient REM recovery.

36 - MATERIALS SCIENCE↗
DOE OSTI2023

Novel Modular Electrocatalytic Processing for Simultaneous Conversion of Carbon Dioxide and Wet Shale Gas into Valuable Products

This report examines solid oxide electrolyzer cell (SOEC) technology as an alternative process for the manufacture of carbon monoxide (CO) and the separation of ethane (C 2 H 6 ) from wet natural gas (WNG). SOEC cathodes for the electrochemical reduction of carbon dioxide (CO 2 ) to CO and SOEC anodes for the selective electrochemical oxidation of C 2 H 6 to ethylene (C 2 H 4 ) are described and presented. Lifecycle and techno-economic analyses (LCA and TEA) utilizing SOEC technology for the production of CO are also reported.

03 NATURAL GAS↗