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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Electrolytes Containing Triethyl Phosphate Solubilized Lithium Nitrate for Improved Silicon Anode Performance

An electrolyte consisting of lithium nitrate (LiNO3) and lithium difluoro(oxalato)borate (LiDFOB) in ethylene carbonate (EC), ethylmethyl carbonate (EMC), and triethyl phosphate (TEP) is used to improve the long-term cycling stability of silicon anodes. TEP was selected for its ability to dissolve LiNO 3 in carbonates to a concentration of ~0.2 M. The large amount of LiNO 3 combined with the LiDFOB salt leads to a capacity retention of 87.1% after one hundred cycles due to the formation of a relatively stable solid electrolyte interphase (SEI). Ex-situ surface analysis reveals that the SEI consists of oxalates, lithium alkyl carbonates, borates, and nitrate reduction products. By selecting two components which are preferentially reduced (LiNO 3 and LiDFOB), the SEI is able to inhibit continuous solvent decomposition and allows for improved electrochemical cycling for pure silicon anodes.

25 ENERGY STORAGE↗
DOE OSTI2022

Performance Improvement of Lithium Metal Batteries Enabled By LiBF 3 CN as a New Electrolyte Additive

A newly synthesized electrolyte additive, lithium trifluoro(cyano) borate (LiBF 3 CN), has been investigated for electrochemical performance improvement of lithium metal batteries. The LiBF 3 CN has a structure where one fluorine atom of BF 4 – is substituted with a cyano group (–CN) prepared by the reaction of boron trifluoride etherate with lithium cyanide. The electrochemical performance in symmetric Li/Li cells and NCM523/Li cells is significantly improved upon the incorporation of LiBF 3 CN as an electrolyte additive into a carbonate-based electrolyte. Extensive characterization of the deposited lithium metal reveals that a thin (≈20 nm) and robust SEI composed of LiN x O y , Li 3 N and Li 2 O is formed by the reductive decomposition of the LiBF 3 CN additive, which plays an important role in decreasing the resistance and stabilizing lithium deposition/stripping. The insight into the substitution effect of a functional group obtained from this work provides guidance for the design of new electrolyte additives.

25 ENERGY STORAGE↗
DOE OSTI2024

Mitigating Calendar Aging in Si-NMC Batteries with Advanced Dual-Salt Glyme Electrolytes

In addressing the critical challenge of calendar aging in silicon (Si)-based lithium-ion batteries, this study introduces a groundbreaking strategy utilizing glyme-type dual-salt electrolytes (lithium bis(trifluoromethanesulfonyl)imide [LiTFSI] and lithium difluoro(oxalato)borate [LiDFOB]). These electrolytes are demonstrated to significantly mitigate parasitic reactions and capacity loss in Si-NMC (lithium nickel manganese cobalt oxide) full cells, especially when compared with traditional carbonate-based electrolytes. Further, our exhaustive mechanistic analysis reveals that such electrolytes not only preserve the integrity of the Si anode but also improve the cathode/electrolyte interphases (CEI) through the formation of a conformal coating on the high-voltage cathode surface. This dual-salt approach, enhanced by the addition of a phosphate additive, effectively decelerates calendar aging, marking a substantial advance in the quest for durable and reliable Si-based energy storage technologies. The findings underscore the vital role of electrolyte composition in extending the calendar life of Si batteries, offering an alternative avenue toward maximizing the performance and longevity of next-generation Li-Si batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Seamless aperture and length enlargement of single crystalline materials for high-energy laser applications

An optically seamless method for increasing the aperture or length of nonlinear materials has been developed, which is suitable for optics in high energy laser systems and other applications. Differences between aperture and length scaling are analyzed. Bonding of component pairs of a nonlinear crystal, lithium tri-borate, is experimentally demonstrated by GAMDAN Optics Inc. and tested at the Laboratory of Laser Energetics at the University of Rochester. Here, a bonded crystal is shown to deliver beam quality and second harmonic conversion efficiency that is equivalent to that of a monolithic crystal of similar dimensions.

aperture scaling↗
DOE OSTI2024

Succinonitrile-Lithium Salt Complexes as Solid Catholytes for LLZO-Based Solid-State Batteries

The thermal and electrochemical properties of several succinonitrile (SN)-based organic ionic plastic crystals (OIPCs) containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalate) borate (LiBOB) or mixtures of the two salts, were investigated with the goal of determining which is most promising for use as a catholyte in solid-state lithium batteries. The best combination of properties for this use was found for the mixture containing 3 mol% LiTFSI and 2 mol% LiBOB in SN. Based on these observations, several solid-state cells containing Al-substituted Li 7 La 3 Zr 2 O 12 separators with composite cathodes consisting of LiNi 0.33 Mn 0.33 Co 0.33 O 2 (NMC111), carbon black, and the succinonitrile-salt mixtures were assembled and cycled at room temperature, without exogenous pressure, using a simple design.

25 ENERGY STORAGE↗
DOE OSTI2023

Improved Performance of Silicon-Containing Anodes with Organic Solvent-Solubilized Lithium Nitrate

Three different organic solvents (dimethylacetamide (DMAc), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO)) were used to improve the solubility of LiNO 3 in a standard carbonate-based electrolyte with lithium difluoro(oxalato)borate (LiDFOB) as the salt. Together, the LiDFOB and organic-solvent solubilized LiNO 3 preferentially reduce on the surface of silicon-containing anodes to create an SEI rich in oxalates, nitrate decomposition species, and B-F species. The improved stability of the SEI throughout the first 100 cycles results in silicon and silicon/graphite composite anodes with better capacity retention than observed with standard electrolytes or fluoroethylene carbonate (FEC) containing electrolytes. This study demonstrates the feasibility of the use of non-traditional electrolyte solvents in the improvement and optimization of lithium ion-battery electrolytes.

25 ENERGY STORAGE↗
DOE OSTI2025

Modulating physicochemical interfaces enables li-rich oxides based ceramic solid-state li batteries under ambient conditions

Li-rich layered oxides exhibit promising potential applications in high-energy-density solid-state lithium metal batteries. Nevertheless, the strong oxidative oxygen species generate at high voltage, which poses great challenges to positive electrode-side interface stability. Herein, a robust in-situ polymerization gel polymer electrolyte with bifunctional additives is designed for interface modification. These additives, include lithium difluoro(oxalate) borate and LiPO 2 F 2 , regulate the Li + chemical environment in gel polymer electrolyte to enhance crosslink density without residual oligomer, which reduce gas generation and suppress contact loss, thus avoiding interfacial impedance divergence. Concurrently, the designed gel polymer electrolyte enables a wide electrochemical stability window (up to 4.7 V) and a high Li + transference number (0.82). Additionally, the additives induced F- and B-rich inorganic cathode-electrolyte interphase inhibits side reactions and oxygen/transition metal loss effectively, stabilizing the chemical interface. The as-constructed Li-rich layered oxides-based ceramic solid-state lithium metal batteries with gel polymer electrolyte interface modification exert a high discharge capacity of 276.5 mAh g -1 at 30 °C without external pressure, delivering a retention of 81.7% after 100 cycles at 25 mA g -1 during 2.0-4.7 V. This work provides a guideline for developing high-voltage solid-state lithium metal batteries via interfacial design.

Hu, Xinchao [Xiamen University (China)]↗
DOE OSTI2021

Novel Low-Temperature Electrolyte Using Isoxazole as the Main Solvent for Lithium-Ion Batteries

A novel electrolyte system with an excellent low temperature performance for lithium-ion batteries (LIBs) has been developed and studied. It was discovered for the first time, in this work, that when isoxazole (IZ) was used as the main solvent, the ionic conductivity of the electrolyte for LIBs is more than doubled in a temperature range between -20 and 20 °C compared to the baseline electrolyte using ethylene carbonate–ethyl methyl carbonate as solvents. To solve the problem of solvent cointercalation into the graphite anode and/or electrolyte decomposition, the lithium difluoro(oxalato)borate (LiDFOB) salt and fluoroethylene carbonate (FEC) additive were used to form a stable solid electrolyte interphase on the surface of the graphite anode. Benefitting from the high ionic conductivity at low temperature, cells using a new electrolyte with 1 M LiDFOB in FEC/IZ (1:10, vol %) solvents demonstrated a very high reversible capacity of 187.5 mAh g -1 at -20 °C, while the baseline electrolyte only delivered a reversible capacity of 23.1 mAh g -1 .

25 ENERGY STORAGE↗
DOE OSTI2025

Influence of Electrolyte Additives on Interfacial Stability of Manganese-Rich Lithium-Ion Battery Cathodes

Affordable, long-lasting energy storage has become critical to support increased electricity demand in recent years. Cobalt-free, lithium- and manganese-rich lithium nickel manganese oxide (LMR-NM) cathodes stand to reduce cost and supply-chain concerns associated with traditional cobalt-containing cathodes for lithium-ion batteries by leveraging more earth-abundant materials; however, they have shown issues with long-term cycling stability. Here, we investigate lithium difluoro(oxalate)borate (LiDFOB), tris(trimethylsilyl) phosphite (TMSPi), and vinylene carbonate (VC) electrolyte additives for their ability to improve cycling performance of LMR-NM (0.3 Li 2 MnO 3 + 0.7 LiMn 0.5 Ni 0.5 0 2 ) cells. Cryogenic scanning transmission electron microscopy (cryo-STEM) with electron energy loss spectroscopy enables the construction of a structure–function relationship between cathode electrolyte interphase (CEI) characteristics and the electrochemical performance of cells aged with these additives. We find the combination of 2 wt % TMSPi + 1 wt % LiDFOB performs better than any single additive, achieving a 28% improvement in specific capacity over the baseline electrolyte after long-term cycling. We attribute this to LiDFOB mitigating Mn ion dissolution, with cryo-STEM showing Mn stabilized up to the CEI surface, coupled with improved CEI structure and chemistry enabled by TMSPi, evidenced by a moderately thick (∼7–15 nm) CEI that appears to protect against further electrolyte reactions with the particle. These results, achieved through site-specific nanoscale characterization, directly reveal mechanisms through which electrolyte engineering can improve the performance of earth-abundant cathodes, enabling informed development of more affordable and reliable batteries to meet future energy storage needs.

25 ENERGY STORAGE↗
DOE OSTI2025

Fast-Charging Li-Ion Battery Enabled by an Acetonitrile-Based Electrolyte

Fast charging remains a critical challenge for current-generation lithium-ion batteries (LIBs), particularly in electric vehicle applications. Here, in this study, we present a highly conductive electrolyte formulation based on a ternary solvent system consisting of acetonitrile (AN), fluoroethylene carbonate (FEC), and ethylene carbonate (EC), combined with a tailored additive, lithium difluoro­(oxalato)­borate (LiDFOB). This electrolyte demonstrates significantly enhanced ionic conductivity and a higher Li + transference number, enabling accelerated Li + transport kinetics. The synergistic effect of the solvents and the additive promotes the formation of a robust, low-resistance, inorganic-rich solid-electrolyte-interphase (SEI) that effectively passivates the graphite surface and suppresses AN decomposition. As a result, the electrolyte substantially reduces internal cell resistance and overpotential, both of which are critical for reliable fast charging. These findings highlight the essential role of rational electrolyte design in addressing the limitations of fast-charging LIBs.

Wu, Dezhen [Argonne National Laboratory (ANL), Arg↗
DOE OSTI2021

Improved Low Temperature Performance of Graphite/Li Cells Using Isoxazole as a Novel Cosolvent in Electrolytes

An investigation of novel electrolyte formulations to improve low temperature performance of Li/graphite half cells has been conducted. A novel electrolyte co-solvent, isoxazole (IZ), has been investigated in electrolyte systems composed of lithium difluoro(oxalato)borate (LiDFOB) in fluoroethylene carbonate (FEC) and LiDFOB in ethylene carbonate (EC). Cells containing 1 M LiDFOB FEC: IZ electrolyte have a significant improvement in capacity retention and reversible capacity at −10 °C. Ex-situ surface analysis of the cycled electrodes suggests that reduction of LiDFOB results in an oxalate rich solid electrolyte interphase (SEI). Addition of FEC, results in improved stability of the anode SEI preventing further decomposition of isoxazole solvent and improving cycling performance.

25 ENERGY STORAGE↗
DOE OSTI2022

Performance of a Novel In-Situ Converted Additive for High Voltage Li-ion Pouch Cells

In search for new classes of additives for high voltage NMC/graphite lithium-ion cells, the precursor additive bis(trimethylsilyl) malonate (bTMSM) is shown to be activated via a spontaneous reaction with LiPF 6 and LiBF 4 salts in carbonate-based electrolyte to form lithium tetrafluoro(malonato)phosphate (LiTFMP), and lithium difluoro(malonato)borate (LiDFMB), respectively. The reaction schemes and rates were studied via NMR spectroscopy and GCMS. The effects of LiTFMP and LiDFMB on high voltage electrochemical performance were then examined up to 4.5 V in Li[Ni 0.4 Mn 0.4 Co 0.16 ]O 2 (NMC442)/graphite and Li[Ni 0.6 Mn 0.4 Co 0.0 ]O 2 (NMC/640)/graphite pouch cells using aggressive voltage-hold cycling, long-term charge/discharge cycling, storage experiments, electrochemical impedance spectroscopy, and gas evolution measurements. While in situ converted additives suffer from gassing issues due to the presence of trimethylfluorosilane (TMSF) gas, a side product of the in situ reaction of bTMSM with LiPF 6 , the cycling and storage capability for the activated additives under study shows competitive performance and controlled impedance when compared to other well-known high voltage additives. Micro X-ray fluorescence spectroscopy (μXRF) confirmed that LiTFMP successfully minimizes the rate of transition metal deposition on the surface of graphite apparently by forming a protective agent at the cathode surface, hence allowing for improved cycling performance at high voltages.

25 ENERGY STORAGE↗
DOE OSTI2026

Quantifying SEI Reaction Rate in the Presence and Absence of Mn 2+

In this work, a methodology utilizing potentiostatic holds is developed for measuring side-reaction rates at graphite (Gr) electrodes. The influence of Mn 2+ on parasitic reactions is evaluated in the presence of various preformed solid-electrolyte interphases (SEI). Gr SEI preformation was carried out using vinylene carbonate (VC) or lithium difluoro(oxalato)borate (LiDFOB) as an additive. In addition, a highly fluorinated electrolyte, free of traditional non-fluorinated organic carbonates, was used. Parasitic current increases were observed for all preformed Gr SEIs when Mn 2+ was present. Of the preforming electrolytes, the VC-derived SEI showed the lowest parasitic currents both with and without Mn 2+ .

Tornheim, Adam [Argonne National Laboratory (ANL),↗
DOE OSTI2020

A Single‐Ion Conducting Borate Network Polymer as a Viable Quasi‐Solid Electrolyte for Lithium Metal Batteries

Abstract Lithium‐ion batteries have remained a state‐of‐the‐art electrochemical energy storage technology for decades now, but their energy densities are limited by electrode materials and conventional liquid electrolytes can pose significant safety concerns. Lithium metal batteries featuring Li metal anodes, solid polymer electrolytes, and high‐voltage cathodes represent promising candidates for next‐generation devices exhibiting improved power and safety, but such solid polymer electrolytes generally do not exhibit the required excellent electrochemical properties and thermal stability in tandem. Here, an interpenetrating network polymer with weakly coordinating anion nodes that functions as a high‐performing single‐ion conducting electrolyte in the presence of minimal plasticizer, with a wide electrochemical stability window, a high room‐temperature conductivity of 1.5 × 10 −4 S cm −1 , and exceptional selectivity for Li‐ion conduction ( t Li+ = 0.95) is reported. Importantly, this material is also flame retardant and highly stable in contact with lithium metal. Significantly, a lithium metal battery prototype containing this quasi‐solid electrolyte is shown to outperform a conventional battery featuring a polymer electrolyte.

Shin, Dong‐Myeong↗
DOE OSTI2023

Borate salts, polymers and composites

Described herein are borate salts useful as additives, binders, and electrolyte salts for solid state lithium ion batteries. In particular, the borate salts of Formula (I), Formula (II) and Formula (III) as described herein: can be polymerized, or can be bound to an existing polymer, to provide polymeric binders for ceramic solid state electrolytes that are themselves capable of ion transport independent of the ceramic.

Liao, Chen↗
DOE OSTI2022

Closo ‐Borate Gel Polymer Electrolyte with Remarkable Electrochemical Stability and a Wide Operating Temperature Window

Abstract A major challenge in the pursuit of higher‐energy‐density lithium batteries for carbon‐neutral‐mobility is electrolyte compatibility with a lithium metal electrode. This study demonstrates the robust and stable nature of a closo ‐borate based gel polymer electrolyte (GPE), which enables outstanding electrochemical stability and capacity retention upon extensive cycling. The GPE developed herein has an ionic conductivity of 7.3 × 10 −4 S cm −2 at room temperature and stability over a wide temperature range from −35 to 80 °C with a high lithium transference number ( = 0.51). Multinuclear nuclear magnetic resonance and Fourier transform infrared are used to understand the solvation environment and interaction between the GPE components. Density functional theory calculations are leveraged to gain additional insight into the coordination environment and support spectroscopic interpretations. The GPE is also established to be a suitable electrolyte for extended cycling with four different active electrode materials when paired with a lithium metal electrode. The GPE can also be incorporated into a flexible battery that is capable of being cut and still functional. The incorporation of a closo ‐borate into a gel polymer matrix represents a new direction for enhancing the electrochemical and physical properties of this class of materials.

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

Electrolytes for lithium batteries with carbon and/or silicon anodes

Electrolytes for lithium ion batteries with carbon-based, silicon-based, or carbon- and silicon-based anodes include a lithium salt; a nonaqueous solvent comprising at least one of the following components: (i) an ester, (ii) a sulfur-containing solvent, (iii) a phosphorus-containing solvent, (iv) an ether, (v) a nitrile, or any combination thereof, wherein the lithium salt is soluble in the solvent; a diluent comprising a fluoroalkyl ether, a fluorinated orthoformate, a fluorinated carbonate, a fluorinated borate, or a combination thereof, wherein the lithium salt has a solubility in the diluent at least 10 times less than a solubility of the lithium salt in the solvent; and an additive having a different composition than the lithium salt, a different composition than the solvent, and a different composition than the diluent.

Xu, Wu↗