Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “electrolyte formulation”

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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Electrolytes for Use in High Energy Lithium-ion Batteries with Wide Operating Temperature Range

Met programmatic milestones for program. Demonstrated improved performance with wide operating temperature electrolytes containing ester co-solvents (i.e., methyl butyrate) containing electrolyte additives in A123 prototype cells: Previously demonstrated excellent low temperature performance, including 11C rates at -30 C and the ability to perform well down to -60 C. Excellent cycle life at room temperature has been displayed, with over 5,000 cycles being demonstrated. Good high temperature cycle life performance has also been achieved. Demonstrated improved performance with methyl propionate-containing electrolytes in large capacity prototype cells: Demonstrated the wide operating temperature range capability in large cells (12 Ah), successfully scaling up technology from 0.25 Ah size cells. Demonstrated improved performance at low temperature and good cycle life at 40 C with methyl propionate-based electrolyte containing increasing FEC content and the use of LiBOB as an additive. Utilized three-electrode cells to investigate the electrochemical characteristics of high voltage systems coupled with wide operating temperature range electrolytes: From Tafel polarization measurements on each electrode, it is evident the NMC-based cathode displays poor lithium kinetics (being the limiting electrode). The MB-based formulations containing LiBOB delivered the best rate capability at low temperature, which is attributed to improved cathode kinetics. Whereas, the use of lithium oxalate as an additive lead to the highest reversible capacity and lower irreversible losses.

low temperature batteries↗
DOE OSTI2024

Improving tubular protonic ceramic fuel cell performance by compensating Ba evaporation via a Ba-excess optimized proton conducting electrolyte synthesis strategy

Protonic ceramic fuel cells (PCFCs) are emerging as a promising technology for reduced temperature ceramic energy conversion devices. The BaCe 0.4 Zr 0.4 Y 0.1 Yb 0.1 O 3–δ (BCZYYb4411) electrolyte is notable for its high proton conductivity. However, the tendency of barium to volatilize in BCZYYb4411 during high-temperature sintering compromises its chemical stability and performance. This study investigates the effects of intentionally incorporating excess barium into BCZYYb4411, formulated as Ba 1+x Ce 0.4 Zr 0.4 Y0.1Yb 0.1 O 3–δ (where x = 0, 0.1, 0.2, and 0.3), with the aim of compensating barium evaporation and enhancing the physical and chemical properties. We find that excess barium results in a greater shrinkage rate, facilitating a denser electrolyte structure. This barium-enriched electrolyte demonstrates improved electrochemical performance by effectively counteracting the deleterious effects of barium evaporation. Applying this strategy to tubular PCFCs, we achieved a peak power density of 480 mW•cm –2 at 600 °C. This unique approach provides a simple, tunable, and easy-to-implement processing modification to achieve high-performance tubular PCFC.

25 ENERGY STORAGE↗
NASA NTRS1976

Electrochemical performance investigations on the hydrogen depolarized CO2 concentrator

An extensive investigation of anode and cathode polarization in complete cells and half cells was conducted to determine the factors affecting HDC electrode polarization and the nature of this polarization. Matrix-electrolyte-electrode interactions and cell electrolyte composition were also investigated. The electrodes were found to have normal performance capabilities. The HDC anode polarization characteristics were correlated with a theoretical kinetic analysis; and, except for some quantitative details, a rather complete understanding of the causes for HDC electrode polarization was formulated. One of the important finding resulting from the kinetic analysis was that platinum appears to catalyze the decomposition of carbonic acid to carbon dioxide and water. It was concluded that the abnormal voltage performance of the One Man ARS HDC cells was caused by insufficient cell electrolyte volume under normal operating conditions due to deficiencies in the reservoir to cell interfacing.

Aylward, J. R.↗
DOE OSTI2024

Optimizing high energy density sulfur cathodes: A multivariate approach to electrode formulation and processing

Lithium-sulfur (Li-S) batteries involve complex solid-liquid-solid phase transformations during both discharging and charging processes, where cathode materials, formulation, and structure play a crucial role. Here, a design of experiments (DoE) methodology and an empirical model are developed to systematically explore the interactions and trade-offs among cathode factors and process variables, and to obtain generalizable effects estimates for the multivariate system. Compared to the conventional one-factor-at-a-time (OFAT) approach, this work demonstrates advantages in both efficiency and accuracy by allowing the data to guide future research and decisions. Further, an optimized cathode formulation and processing parameters are predicted and validated experimentally, achieving over 1000 mAh g -1 in discharge capacity and improved cycling under practical lean electrolyte (4 µL mg -1 S) and high S-loading cathodes (>4 mg cm -2 ) conditions. The optimized cathode was scaled up and assembled into Li-S pouch cells, achieving 316 Wh kg -1 in cell-level energy, proving that the comprehensive and rigorous framework for optimizing complex systems with DoE leads to improved performance in a practical pouch cell system.

25 ENERGY STORAGE↗
DOE OSTI2026

Enhanced cycling stability of Ni-rich Li-metal cells enabled by dual vinylene carbonate and tris(trimethylsilyl)borate electrolyte additives

NMC811 (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) and other high-Ni chemistries are promising cathode candidates for high-performance electric vehicles, owing to their high energy density and reduced cobalt content. However, their long-term cycling stability is hindered by surface degradation, particularly when paired with conventional electrolytes and a lithium metal anode. Electrolyte additives represent a practical approach to enhance interfacial stability and improve overall battery performance by promoting the formation of a robust electrolyte–electrode interphase (EEI). In this study, we revisit the effects of vinylene carbonate (VC) and tris(trimethylsilyl)borate (TMSB) additives on single-crystal SC-NMC811||Li cells. While TMSB only increases the open-circuit voltage and initial overpotential, it delivers superior capacity retention at C/3 compared to cells containing only VC or a dual additive system (VC and TMSB). Notably, under fast-charging conditions (1C, 2C, and 5C), the dual-additive system significantly outperforms other formulations, achieving markedly enhanced long-term capacity retention. Comprehensive electrochemical and spectroscopic analyses reveal that the VC/TMSB dual-additive system suppresses surface transition in NMC811, mitigates structural degradation by forming a thin, LiF-deficient cathode-electrolyte interface (CEI) layer. Moreover, they promote smooth and dense Li deposition and generate a LiF-deficient solid-electrolyte interphase (SEI). Consequently, the synergistic stabilization of both the CEI and SEI effectively limits the overall cell impedance growth during extended cycling. These findings provide key insights into co-additive strategies for engineering stable interfaces in high-energy Ni-rich Li-metal batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Nanostructured ligament and fiber Al–doped Li 7 La 3 Zr 2 O 12 scaffolds to mediate cathode-electrolyte interface chemistry

In this study, scaffold structures of electrospun aluminum–substituted lithium lanthanum zirconate Li 7 La 3 Zr 2 O 12 (Al-LLZO) were synthesized and used as an additive in a LiNi 0.6 Mn 0.2 Co 0.2 O 2 composite cathode. The scaffolds were crystalized in the cubic phase after calcination at 700 °C. The Al-LLZO scaffold morphology was dependent on the precursor formulation (aqueous and dimethylformamide. The aqueous precursors resulted in scaffolds of densely coalesced ligaments, whereas the dimethylformamide precursors resulted in high–aspect ratio nanofiber scaffolds. The long-term cycling stability and rate performance of the cells were found to depend on the Al-LLZO scaffold morphology. The uniformly dispersed Al-LLZO fibers resulted in a more stable cathode electrolyte interface formation through the reduced decomposition of the LiPF 6 salt during cycling, resulting in a better high-rate and long-term cycling performance.

25 ENERGY STORAGE↗
DOE OSTI2024

Formulation of Conductive Inks for DIW Printed Battery Electrodes

Ink formulations for DIW printing of Li ion battery electrodes were optimized for high conductivity, surface area and printability. Our focus is particularly on optimizing Li-ion battery electrodes for low temperature applications by 3-D printing the cathodes into high surface area shapes. The sluggish kinetics of ion transport at the solid-electrolyte phase boundary can be a major problem in batteries at low temperatures, so optimizing for ion transport can help combat these issues. Two families of DIW ink were investigated; aqueous conductive polymer suspension with graphene nano platelets (GNP) ink, and “oil in water” graphene oxide (GO) micro emulsion ink which carbonizes to an open cell graphene aerogel. By iterative formulation changes, the conductivity of PEDOT:PSS based ink was increased over tenfold, and stiffness of GO emulsion ink was increased to provide better printability without sacrificing porosity.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Concealed Cathode Degradation in Lithium-Ion Cells with a Ni-Rich Oxide

Difficulties with sourcing cobalt and the interest in increasing cell energy have motivated the development of Ni-rich oxide materials for lithium-ion battery cathodes. Despite the intense research on the topic, there is limited information available on the long-term performance of novel cathode formulations. Here, we evaluate the stability of LiNi 0.9 Mn 0.05 Co 0.05 O 2 in full-cells tested for over five months, assessing how cycling, voltage and electrolyte additives impact cathode aging. We use differential voltage analysis to extract insights about the cathode from the full-cell data and identify the isolation of cathode particles in the delithiated (charged) state as a relevant mode of aging. Importantly, this particular mechanism of cathode aging does not cause immediate cell capacity fade, causing the simple analysis of cell capacity retention to overestimate the cathode stability under the investigated conditions. So, our observations serve as cautionary tale indicating that careful analysis of data from extended testing may be required for assessing the performance of Ni-rich cathodes and for evaluating how these materials are affected by electrolyte additives.

25 ENERGY STORAGE↗
DOE OSTI2026

Networks of electrochemical oxidation of common lithium-ion Battery solvents revealed by NMR spectroscopy

Raising the upper cutoff voltage of lithium-ion batteries (LIBs) to increase energy density often exceeds the electrolyte’s anodic stability limit, accelerating degradation and creating a major durability tradeoff. Designing electrolytes that can sustain long-term high-voltage cycling requires a clearer understanding of the fundamental mechanisms occurring when commercial carbonate solvents oxidize. Here, to this end, simplified single-salt, single-solvent formulations of LiClO 4 and LiPF 6 in dimethyl carbonate (DMC), ethylene carbonate (EC), or ethyl methyl carbonate (EMC) were anodically electrolyzed on inert electrodes and monitored for extended periods of time using 1 H, 13 C, 19 F, and 35 Cl nuclear magnetic resonance (NMR) spectroscopy. The controlled environment of the experiments, coupled to the unique sensitivity of NMR, unveiled novel metastable intermediates and the formation of branching networks of products with temporal evolution. Oxidation of the pristine solvent primarily proceeds through a radical pathway that also produces highly reactive protons but faces competition from a second pathway involving a radical carbocation intermediate. In all cases, the intermediates follow a variety of downstream pathways that can intersect with each other. The concomitant network of reactions represents a significant increase in complexity compared to common descriptions in the literature, yet, critically, it helps explain the wide range of products typically identified in electrolyte oxidation in complete cells. The results highlight the need for refocusing fundamental research on anodic stability to analysis of the hierarchy of reaction networks to better inform efforts to mitigate the detrimental effects on battery performance, including prevention and harvesting of proton and radical products.

Electrolytes↗
DOE OSTI2024

Electrochemical CO 2 Conversion Commercialization Pathways: A Concise Review on Experimental Frontiers and Technoeconomic Analysis

Technoeconomic analysis (TEA) studies are vital for formulating guidelines that drive the commercialization of electrochemical CO 2 reduction (eCO 2 R) technologies. In this review, we first discuss the progress in the field of eCO 2 R processes by providing current state-of-the-art metrices (e.g., faradic efficiency, current density) based on the recent heterogeneous catalysts’ discovery, electrolytes, electrolyzers configuration, and electrolysis process designs. Next, we assessed the TEA studies for a wide range of eCO 2 R final products, different modes of eCO 2 R systems/processes, and discussed their relative competitiveness with relevant commercial products. Finally, we discuss challenges and future directions essential for eCO 2 R commercialization by linking suggestions from TEA studies. We believe that this review will catalyze innovation in formulating advanced eCO 2 R strategies to meet the TEA benchmarks for the conversion of CO 2 into valuable chemicals at the industrial scale.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Reprocessable and Recyclable Polymer Network Electrolytes via Incorporation of Dynamic Covalent Bonds

Mechanically durable polymer network electrolytes are desirable for batteries; however, covalent cross-linking adversely affects their large-scale manufacturing, and they are difficult to recycle post-lifespan. In this work, we address the electrolyte reprocessability and recyclability challenges through the use of dynamic covalent bonds for polymer network solid electrolytes. Specifically, the associative dynamic vinylogous urethane motif is incorporated into a poly(ethylene oxide) network electrolyte containing lithium bis(fluorosulfonyl)imide (LiFSI) salt. The resulting dynamic covalent network electrolyte possesses a modest ion conductivity (~10–5 S/cm at room temperature) and good reprocessability. Stress–relaxation studies indicate that the LiFSI salt can catalyze the bond exchange and enhance the network dynamics. Furthermore, the reprocessability associated with bond exchange can be tuned by simply adjusting the formulation of reagent compositions, in which increasing the amount of excess amine or using a shorter chain of PEO prepolymer can further enhance the network dynamics and corresponding reprocessability.

25 ENERGY STORAGE↗
NASA NTRS2007

Ion-Conducting Organic/Inorganic Polymers

Ion-conducting polymers that are hybrids of organic and inorganic moieties and that are suitable for forming into solid-electrolyte membranes have been invented in an effort to improve upon the polymeric materials that have been used previously for such membranes. Examples of the prior materials include perfluorosulfonic acid-based formulations, polybenzimidazoles, sulfonated polyetherketone, sulfonated naphthalenic polyimides, and polyethylene oxide (PEO)-based formulations. Relative to the prior materials, the polymers of the present invention offer greater dimensional stability, greater ease of formation into mechanically resilient films, and acceptably high ionic conductivities over wider temperature ranges. Devices in which films made of these ion-conducting organic/inorganic polymers could be used include fuel cells, lithium batteries, chemical sensors, electrochemical capacitors, electrochromic windows and display devices, and analog memory devices. The synthesis of a polymer of this type (see Figure 1) starts with a reaction between an epoxide-functionalized alkoxysilane and a diamine. The product of this reaction is polymerized by hydrolysis and condensation of the alkoxysilane group, producing a molecular network that contains both organic and inorganic (silica) links. The silica in the network contributes to the ionic conductivity and to the desired thermal and mechanical properties. Examples of other diamines that have been used in the reaction sequence of Figure 1 are shown in Figure 2. One can use any of these diamines or any combination of them in proportions chosen to impart desired properties to the finished product. Alternatively or in addition, one could similarly vary the functionality of the alkoxysilane to obtain desired properties. The variety of available alkoxysilanes and diamines thus affords flexibility to optimize the organic/inorganic polymer for a given application.

Kinder, James D.↗
DOE OSTI2020

Concentration dependent properties and plastic deformation facilitate instability of the solid-electrolyte interphase in Li-ion batteries

Lithium-ion batteries (LIBs) often suffer from capacity fading and poor cyclic performance due to mechanical degradation of the solid-electrolyte interphase (SEI). Here we perform numerical simulations and theoretical analysis to elucidate the role of plasticity in wrinkling and ratcheting behaviors of an SEI/electrode system. A coupled diffusion and finite deformation framework is formulated and numerically implemented as a user-element subroutine (UEL) to describe transient lithium diffusion and accompanying elastic–viscoplastic deformation of the electrode. It is found that concentration dependent properties and plastic deformation facilitate wrinkling in such a system. A wrinkled morphology may further lead to ratcheting and related failure under cycling. A phase diagram of four types of cyclic behaviorsis identified in terms of the charging rate and time. Our analysis suggests several potential strategies to avoid wrinkling and ratcheting instabilities, such as charging/discharging the electrode at a sufficiently slow rate, and/or introducing a thick artificial SEI with a pre-tension.

25 ENERGY STORAGE↗
NASA NTRS1973

Oxidation of organic molecules by photoproduced holes of ZnO.

Two experimental techniques were developed. In the first, an electrochemical method was used with a single crystal ZnO electrode and with the material of interest dissolved in the electrolyte. In the other an electron spin resonance method was used so that measurements related to thermal control coatings could be made with the ZnO in the form of powder, either alone or in formulation of a binder. A simplified model regarding the relationship between the electron density and time is considered.

Sancier, K. M.↗
NASA NTRS1987

Theoretical performance of hydrogen-bromine rechargeable SPE fuel cell

A mathematical model was formulated to describe the performance of a hydrogen-bromine fuel cell. Porous electrode theory was applied to the carbon felt flow-by electrode and was coupled to theory describing the solid polymer electrolyte (SPE) system. Parametric studies using the numerical solution to this model were performed to determine the effect of kinetic, mass transfer, and design parameters on the performance of the fuel cell. The results indicate that the cell performance is most sensitive to the transport properties of the SPE membrane. The model was also shown to be a useful tool for scale-up studies.

Savinell, Robert F.↗
NASA NTRS1988

Theoretical performance of hydrogen-bromine rechargeable SPE fuel cell

A mathematical model was formulated to describe the performance of a hydrogen-bromine fuel cell. Porous electrode theory was applied to the carbon felt flow-by electrode and was coupled to theory describing the solid polymer electrolyte (SPE) system. Parametric studies using the numerical solution to this model were performed to determine the effect of kinetic, mass transfer, and design parameters on the performance of the fuel cell. The results indicate that the cell performance is most sensitive to the transport properties of the SPE membrane. The model was also shown to be a useful tool for scale-up studies.

Savinell, R. F.↗
DOE OSTI2025

Machine learning-enabled discovery of ionic liquid–solvent electrolytes exhibiting high ionic conductivity

Ionic liquids (ILs), which are a class of materials with versatile nature and growing popularity, are facing impediments toward widespread usage as electrolytes due to various factors such as low ionic conductivity, high viscosity, high market price etc. One of the ways these limitations can be addressed is by mixing ILs with a molecular solvent. In a combinatorial sense, there exists an immense number of specific IL–solvent combinations. An exhaustive experimental or even simulation-based investigation of the chemical space spanned by such combinations can be extremely time-consuming, expensive, and nearly impossible. An alternative approach is to employ machine learning-based models developed from available databases. Although there exists prior literature that integrates machine learning to investigate mixtures of specific solvents with ILs, these models lack generalization necessitating development of a large number of ML models to handle various solvents. To remedy this shortcoming, as a part of designing green electrolytes with high ionic conductivity that can have potential applications in next-generation batteries and solar cells, this work aims to develop a unified machine learning model to predict ionic conductivity of any IL–solvent mixture system. In this regard, three models, namely, Random Forest, extreme gradient boosting (XGBoost), and artificial neural network (ANN) were formulated using the NIST ILThermo database. The dataset contained 549 unique ionic liquids from 16 cation families and 81 unique solvents, representing a total of 23 712 datapoints. SHAPLEY additive explanation (SHAP) method was used to assess the impact of various features on model prediction and their significance was compared with literature to gain physical insight about the model behavior. Finally, using the developed models, approximately 2.5 million IL–solvent mixtures at five different compositions were screened at room temperature. The high-throughput screening yielded nearly 19 000 IL–solvent mixtures for which ionic conductivity was found to exceed the ionic conductivity of conventional Li-ion battery electrolyte.

25 ENERGY STORAGE↗