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Results for “moderately solvating electrolyte”

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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Designing Moderately‐Solvating Electrolytes for High‐Performance Lithium–Sulfur Batteries

New electrolytes are critical for high‐energy lithium (Li)–sulfur (S) batteries (LSBs) to ensure their stability against Li metal anode and polysulfides (PSs) shuttling which hinder the large‐scale application of LSBs. In this study, the design principle of moderately solvating electrolytes (MSEs) for LSBs is demonstrated by using a multiple‐solvent system comprising of a highly solvating solvent, a weakly solvating solvent, and a non‐solvating solvent to create a well‐balanced electrolyte system. This resulting electrolyte significantly improves the cycle life of LSBs, achieving 300 cycles, which is twice as long as that of similar cells with the conventional electrolyte and it also ensures stable calendar life for at least seven months. The optimal MSE forms robust passivation layers enhancing the structural integrity of both S and Li metal electrodes after cycling. These virtues effectively hinder parasitic side reactions and self‐discharge behavior of LSBs. This electrolyte design principle is versatile and can be applied to other battery chemistries, providing a potential path toward the development of a more efficient and stable battery system. By addressing key challenges such as the instability of electrodes and shuttling of polysulfides, this electrolyte approach offers promising solutions for advancing LSB technology.

25 ENERGY STORAGE↗
DOE OSTI2026

Modulating Li + and Polysulfide Solvation with Low-Density Moderately Solvating Electrolytes for Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries show great promise as the next-generation rechargeable batteries, yet they still suffer from polysulfide shuttling and interphasial instability. Electrolyte, as the medium for ion transport and sulfur conversion, plays a crucial role in overcoming these challenges. Here, we introduce a moderately solvating electrolyte (MSE) based on low-density, low-viscosity, and nonfluorinated ether co-solvents that balances polysulfide suppression, Li metal stabilization, and redox kinetics. Through multiple solvent–solvent and solvent-ion interactions, the optimized MSE weakens Li + -solvent pairing while strengthening cation–anion interactions, thereby lowering the desolvation barrier and promoting the formation of a favorable solid–electrolyte interphase (SEI). Meanwhile, MSE limits the polysulfide dissolution but improves the accessibility of active material through better wettability and tailored solvation environment, leading to an altered sulfur deposition mechanism with β – α conversion. This approach enables a stable cycling of high-mass loading Li–S cells (> 3.5 mg cm -2 ) at both room temperature and 45 °C (where shuttling and side reactions are severer), and demonstrates a pouch cell with lean electrolyte content (4.5 µL mg s -1 ). This work highlights a practical route to develop high-performance electrolyte for Li–S cells and provides mechanistic insights into their operation.

25 ENERGY STORAGE↗
DOE OSTI2025

Tailoring Electrolytes by Decoupling the Roles of Li + and Lithium Polysulfides in Li–S Batteries

Understanding the distinct roles of lithium ions (Li + ) and lithium polysulfide intermediates, Li 2 S x (LiPS) is critical for designing electrolytes that can extend the practical cycle life of lithium–sulfur (Li–S) batteries. Here, in this work, we decouple the solvation and solubility effects of Li + and LiPS and correlate them with electrochemical performance through a cosolvent strategy. Li + solubility and solvation primarily dictate the electrolyte’s ionic conductivity and the reversibility of lithium anode stripping/plating. In contrast, LiPS solvation governs the thermodynamics of sulfur (S 8 ), LiPS, and lithium sulfide (Li 2 S) interconversion, while the LiPS solubility determines their redox kinetics. By employing a fluorinated–glyme (F-glyme) cosolvent, specifically 1,2-bis­(2,2-difluoroethoxy)­ethane (F4DEE), that exhibits low LiPS solubility yet moderate Li + solvation, we designed an electrolyte that enhances lithium anode stability while maintaining sufficient sulfur cathode kinetics, thereby prolonging Li–S cell cycle life. This study provides mechanistic insights into the interplay between Li+ and LiPS in Li–S electrochemistry and offers design principles for next-generation electrolytes for Li–S batteries.

Yang, Jingtian [Argonne National Laboratory (ANL),↗
DOE OSTI2025

Solvent Dynamics in Gel Polymer Electrolytes for Lithium–Sulfur Batteries

Li−sulfur (Li−S) batteries are promising as the next-generation energy storage technology but face challenges due to sluggish sulfur redox reaction (SRR) kinetics and a sulfur shuttling effect. While many studies have explored polycaprolactone (PCL)-based gel polymer electrolytes (GPEs) to address these issues, the influence of solvent properties, including dielectric constant (ϵ) and donor and acceptor numbers (DN and AN), remain unexplored despite their critical impact on performance and full-scale implementation. This study systematically compares three distinct electrolytes, dimethoxyethane (DME), dimethyl sulfoxide (DMSO), and tetraethylene glycol dimethyl ether (TEGDME)-paired with PCL, to correlate the varied solvent properties and their effects on the physical properties of the GPE, in terms of Li + transport and solvation, and polysulfide’s confinement. Among them, the DME-based GPE, with an intermediate DN, exhibited the lowest crystallinity (2.31%), highest ionic conductivity (7.49 mS/cm), and high Li + transference number (0.77). As a result, it achieved a specific capacity of 795 mAh/g sulfur and an average Coulombic efficiency of 97.5% after 120 cycles at C/5, outperforming its competitors. Operando Raman and UV−vis spectroscopy confirmed that PCL effectively confines long-chain polysulfides within its network, mitigating the shuttle effect and facilitating reversible polysulfide conversion. These findings demonstrate that GPEs with moderate DN values and balanced ϵ significantly enhance stability, extend cycle life, and improve rate performance for Li−S batteries. This work provides valuable insights into the design of advanced electrolyte systems for practical energy storage applications.

25 ENERGY STORAGE↗
DOE OSTI2026

Solvent–Diluent Engineering of Normal-Concentration Organosulfur Electrolytes for High-Voltage Lithium-Ion Batteries

Enabling high‑voltage batteries depends critically on rational electrolyte design. Conventional carbonate electrolytes with LiPF 6 suffer from insufficient oxidative stability, motivating the use of lithium bis(fluorosulfonyl)imide (LiFSI) for its superior high‑temperature and high‑voltage performance. However, LiFSI is relatively costly, and its electrolytes often require high concentrations to suppress aluminum current collector corrosion in cathode architectures and to adequately passivate electrode interfaces. Here, a low‑concentration LiFSI electrolyte is realized by combining a high‑voltage organosulfur solvent, ethyl methyl sulfone (EMS), with a non‑solvating fluorinated diluent, fluorobenzene (FB). Extended cycling of LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) full cells to 4.5 V reveals substantial long‑term performance advantages over conventional carbonate electrolytes. Comparison with a popular cyclic sulfone, tetramethylene sulfone (TMS), shows that ring‑containing structures such as TMS strongly influence passivation behavior, ultimately limiting performance and narrowing the viable operating window. Overall, EMS is identified as a uniquely stable solvent for LiFSI‑based electrolytes operating at moderately high voltages.

Dato, Michael A. [Argonne National Laboratory (ANL↗