Electrolytes For Lithium Batteries Research Articles

Computational Screening Guiding the Development of a Covalent-Organic Framework-Based Gas Sensor for Early Detection of Lithium-Ion Battery Electrolyte Leakage.

This study presents a computationally guided approach for selecting covalent organic frameworks (COFs) for the selective detection of the trace ethylene carbonate (EC) vapor, a key indicator of electrolyte leakage from lithium-ion batteries (LIBs). High-throughput screening, employing grand canonical Monte Carlo (GCMC) simulation complemented by density functional theory (DFT) calculations, was used to identify potential COF candidates from the CURATED COF database. Among the screened materials, an imine COF functionalized with quaternary ammonium (QA) groups, named COF-QA-4, exhibited a high adsorption capacity (5.88 mmol/g) and selectivity of EC vapor. DFT analysis revealed strong molecular interactions driven by a partial charge transfer mechanism between EC and the COF-QA-4 framework, underpinning its superior adsorption properties. Experimental validation through chemiresistive gas sensors fabricated with COF-QA-4 demonstrated excellent sensitivity and reversibility to 1.15 ppmv of EC vapor, maintaining consistent performance over three response-recovery cycles. This work highlights the potential of computationally guided material discovery for advancing sensor technologies in LIB safety monitoring.

Enhancing Prediction of Electron Affinity and Ionization Energy in Liquid Organic Electrolytes for Lithium-Ion Batteries Using Machine Learning

The electron affinity (EA) and ionization energy (IE) of battery electrolyte molecules are pivotal in determining the electrochemical properties of electrode materials, significantly impacting the performance and safety of batteries. In this study, we employed a suite of machine learning algorithms, including linear regression, gradient boosting, CatBoost, XGBoost, and random forest regression, to predict these properties. Our analysis leveraged a comprehensive dataset of 24432 electrolyte molecules extracted from the Joint Center for Energy Storage Research (JCESR) Molecules database, and used RDKit and Mordred tools to generate a series of molecular descriptors. Through meticulous feature engineering and selection using the maximum relevance minimum redundancy (mRMR) algorithm, we identified the most influential molecular features for predicting EA and IE. The CatBoost model emerged as the most accurate, outperforming other models with its ability to handle complex nonlinear relationships and provide robust predictions with lower errors. The model's predictions were further validated through 10-fold cross-validation, demonstrating its generalization capability and resistance to overfitting. The CatBoost model achieved a root mean squared error (RMSE) of 0.239 eV for IE and 0.427 eV for EA, with R-squared (R2) values of 0.944 and 0.879, respectively. SHapley Additive exPlanations (SHAP) value analysis elucidated the contribution of each feature to the model's predictions, highlighting the molecular characteristics that significantly influence EA and IE. Our findings offer valuable insights for the design of novel electrolyte materials with tailored electronic properties, advancing the development of high-performance battery technologies.

Three-Dimensionally Printed Ionogel-Coated Ceramic Electrolytes for Solid-State Lithium Batteries.

Stereolithography three-dimensional (3D) printing technology enables the customization of ceramic-based solid electrolyte structures with desired electrochemical properties; however, formulating slurries that both are highly ceramic-loaded and have low viscosity for printing poses a challenge. Here, we propose an ionogel-coated ceramic approach to prepare a shear-thinning fast-ion conductor ceramic (Li6.5La3Zr1.5Ta0.5O12) slurry, which possesses both a high ceramic content of 50 wt % and a low viscosity of 1.53 Pa·s. Utilizing this slurry, 3D symmetric honeycomb briquette-like electrolyte films are printed, and solid-state lithium batteries are easily fabricated by filling the cathode and anode slurries into the respective symmetric honeycombs. The atomic-level interaction between ceramic/ionogel interfaces and the integrated electrode/electrolyte interface facilitates rapid Li+ transport across multiscale interphases in batteries. Additionally, the interactions of ceramic nanoparticles and ionic liquids with Li salt substantially increase the concentration of free Li+, both of which enhance the ionic conductivity and ensure stable Li+ transport efficiency. Solid-state lithium batteries can cycle stably 500 times without obvious degradation at 0.5 C and 50 °C. The strategy offers a feasible solution for printing customized solid-state ceramic-based electrolytes.

Saccharinate‐based ionic liquids and lithium battery electrolytes

Fluorine‐free ionic liquids (ILs) and electrolytes based on ether‐functionalized pyrrolidinium or imidazolinium cations coupled with a “greener”, non‐basic, and hydrolytically stable saccharinate (Sac) anion, are herein presented with their thermal, transport and electrochemical properties. The thermal stability, glass transition temperature, and electrochemical stability of the imidazolinium based ILs surpasses the pyrrolidinium IL, while the latter offer better (ion) transport properties. Ether‐functionalization of the IL cation improves the transport properties with negligible effects on the thermal and electrochemical stabilities. The Li+ conducting electrolytes – created by adding 10 mol % of lithium saccharinate (LiSac) to the neat (BMMIm)(Sac) and (C201MMIm)(Sac) ILs show an as low initial overpotential as ±0.05 V and outstanding Li stripping/plating performance over 100 hours at 60 °C for the latter, but a very large polarization interfacial resistance, 4730 Ω cm2, impeding the kinetics of stripping/plating, even at these elevated temperatures for the former. Hence the rather modest modification has an enormous impact in practice.

Development of PFAS-Free Locally Concentrated Ionic Liquid Electrolytes for High-Energy Lithium and Aluminum Metal Batteries.

ConspectusLithium-ion batteries (LIBs) based on graphite anodes are a widely used state-of-the-art battery technology, but their energy density is approaching theoretical limits, prompting interest in lithium-metal batteries (LMBs) that can achieve higher energy density. In addition, the limited availability of lithium reserves raises supply concerns; therefore, research on postlithium metal batteries is underway. A major issue with these metal anodes, including lithium, is dendritic formation and insufficient reversibility, which leads to safety risks due to short circuits and the use of flammable electrolytes.Ionic liquid electrolytes (ILEs), composed of metal salts and ionic liquids, offer a safer alternative due to their nonflammable nature and high thermal stability. Moreover, they can enable high Coulombic efficiency (CE) for lithium metal anodes (LMAs) and allow reversible stripping/plating of various post-lithium metals for battery application, e.g., aluminum metal batteries (AMBs). Despite these advantages, ILEs suffer from high viscosity, which impairs ion transport and wettability. To resolve these challenges, researchers have developed locally concentrated ionic liquid electrolytes (LCILEs) by adding low-viscosity nonsolvating cosolvents, e.g., hydrofluoroether, to ILEs. These cosolvents do not coordinate with cationic charge carriers, thereby reducing viscosity and improving ion transport without compromising the compatibility of electrolytes with metal anodes. However, due to the inherent difference of molecular organic solvents and ionic liquids full of charged species, the most used nonsolvating cosolvents, i.e., hydrofluoroether, are less effective for ILEs with respect to concentrated electrolytes based on conventional organic solvents. Moreover, hydrofluoroether contains environmentally problematic -CF3 and/or -CF2- groups, i.e., per- and polyfluoroalkyl substances (PFAS), with their use subject to restrictions.In this Account, we provide an overview of the endeavors of our research group on the development of PFAS-free LCILEs for high-energy LMBs and AMBs. First, aromatic organic cations and aromatic less/nonfluorinated cosolvents are proposed to weaken the organic cation-anion interaction and strengthen the organic cation-cosolvent interaction, respectively. This is with consideration of the uncovered phase nanosegregation structure of LCILEs that effectively reduces the viscosity and promotes the Li+ transport ability with respect to the conventional nonaromatic organic cations and highly fluorinated PFAS cosolvents. Then, the effect of electrolyte components that do not coordinate to Li+, including organic cations and nonsolvating cosolvents, on the SEI composition and LMA reversibility is presented, which confirms the feasibility of reaching a high lithium stripping/plating CE up to 99.7% in the developed PFAS-free LCILEs. In the subsequent discussion on cathode compatibility, we present that in addition to LiFePO4 with high cyclability but inferior energy density, nickel-rich layered oxide and sulfurized polyacrylonitrile (SPAN) can be employed to construct high-energy LMBs for PFAS-free LCILEs with different anodic stability. Additionally, the feasible application of the LCILE strategy to promote the kinetics of AMBs relying on a different anode chemistry is demonstrated. Lastly, future research directions with an emphasis on nonsolvating component optimization, electrolyte dynamics, and electrode/electrolyte interphase formation are provided.

Disorder-induced enhancement of lithium-ion transport in solid-state electrolytes

Enhancing the ion conduction in solid electrolytes is critically important for the development of high-performance all-solid-state lithium-ion batteries (LIBs). Lithium thiophosphates are among the most promising solid electrolytes, as they exhibit superionic conductivity at room temperature. However, the lack of comprehensive understanding of their ion conduction mechanism, especially the effect of structural disorder on ionic conductivity, is a long-standing problem that limits further innovations in all-solid-state LIBs. Here, we address this challenge by establishing and employing a deep learning potential to simulate Li3PS4 electrolyte systems with varying levels of disorder. The results show that disorder-driven diffusion dynamics significantly enhances the room-temperature conductivity. We further establish bridges between dynamical characteristics, local structural features, and atomic rearrangements by applying a machine learning-based structure fingerprint termed “softness”. This metric allows the classification of the disorder-induced “soft” hopping lithium ions. Our findings offer insights into ion conduction mechanisms in complex disordered structures, thereby contributing to the development of superior solid-state electrolytes for LIBs.

Exploring the Physicochemical Properties and Electrochemical Behavior of Phosphonium-Based Ionic Liquids as Additives in Carbonate Electrolytes for Lithium-Ion Batteries

Exploring the Physicochemical Properties and Electrochemical Behavior of Phosphonium-Based Ionic Liquids as Additives in Carbonate Electrolytes for Lithium-Ion Batteries

Ion Networks in Water-based Li-ion Battery Electrolytes.

ConspectusWater-in-salt electrolytes (WiSEs) are promising electrolytes for next-generation lithium-ion batteries (LIBs), offering critical advantages like nonflammability and improved safety. These electrolytes have extremely high salt concentrations and exhibit unique solvation structures and transport mechanisms dominated by the formation of ion networks and aggregates. These ion networks are central to the performance of WiSEs, govern the transport properties and stability of the electrolyte, deviating from conventional dilute aqueous or organic electrolytes.The availability of free water molecules is significantly reduced in WiSEs, leading to a shift in the solvation environment. Lithium ions (Li+) typically travel with their solvation shells in dilute solutions and form stronger interactions with anions, resulting in the formation of complex ion aggregates. Despite the high viscosity of WiSEs, they exhibit surprisingly high ionic conductivity attributed to the decoupling of viscosity and ionic mobility. Instead of moving through free water, Li+ ions are transported along the pathways formed by the ion networks, minimizing direct solvent interaction and enhancing mobility.Advanced spectroscopic techniques, such as infrared IR pump-probe (IR-PP) and two-dimensional IR (2D-IR) spectroscopy, and molecular dynamics (MD) simulations have illuminated the critical role of these ion networks in facilitating transport. These studies have shown that even at extreme salt concentrations, some water molecules retain properties similar to bulk water, essential for fast ion movement. In WiSEs, bulk-like water molecules form transient hydrogen-bond networks that serve as conduits for Li+ ions, while anion-bound water molecules play a less active role in transport due to their slower dynamics.As the salt concentration increases, the structure of WiSEs becomes more dominated by 3D ion networks. MD simulations reveal that these networks, stabilized by chaotropic anions such as bis(trifluoromethanesulfonyl)imide (TFSI-), disrupt the hydrogen-bonding network of water and provide a stable, interconnected structure that supports the movement of Li+ ions. The formation of these extensive ion networks is critical for maintaining ionic mobility and the electrochemical stability of the electrolyte.The shift from traditional vehicular transport mechanisms to structural diffusion is a hallmark of WiSEs. Li+ ions no longer move with their solvation shells but hop between coordination sites within the ion network. This structural diffusion mechanism enables high ionic mobility despite the reduced presence of water and the increased viscosity of the solution. In conclusion, the formation of ion networks and aggregates in WiSEs not only stabilizes the electrolyte but also drives an unconventional ion transport mechanism. By understanding and controlling these aggregates, WiSEs offer a pathway toward safer, high-performance electrolytes for LIBs and other aqueous energy storage technologies.

Enhanced Ion Solvation and Conductivity in Lithium-Ion Electrolytes via Tailored EMC-TMS Solvent Mixtures: A Molecular Dynamics Study.

The development of stable, high-performance electrolytes is essential to addressing the safety concerns and limited lifespan caused by the thermal and chemical instability of traditional organic carbonate-based electrolytes in lithium-ion batteries (LIBs). This study examined the potential of mixed solvent systems, specifically ethyl methyl carbonate (EMC) and tetramethylene sulfone (TMS), to modify ion solvation and improve ionic conductivity in LIB electrolytes. Through molecular dynamics simulations, we investigated the solvation structure and transport properties of lithium ions (Li+) in these solvent environments. The inclusion of TMS altered the solvation structure, with TMS molecules preferentially coordinating with Li+ ions, displacing PF6 - anions and reducing their electrostatic interference. Our results demonstrated a synergistic interaction between EMC and TMS, where an EMC/TMS ratio of 1:2 led to a significant improvement in ionic conductivity, reaching 0.91 mS/cm, with a corresponding Li+ transference number of 0.40. These findings provide key insights into the molecular-level interaction governing electrolyte behavior, offering guidance for the design of future solvent mixtures to improve the safety and efficiency of LIBs.

Composite solid-state electrolytes for all solid-state lithium batteries: progress, challenges and outlook

Composite solid-state electrolytes (CSEs) with multiple phases offer greater flexibility to customize and combine the advantages of single-phase electrolytes, making them promising candidates for commercial all-solid-state batteries (ASSBs).

Research Progress of Solid Electrolytes in Solid-State Lithium Batteries

Research Progress of Solid Electrolytes in Solid-State Lithium Batteries

Ionic liquid–metal–organic framework-modified composite electrolyte for high-performing lithium-ion batteries

Solid polymer electrolyte membranes for Li-ion batteries with improved ionic conductivity for practical performance.

Interfacially-localized high-concentration electrolytes for high-performance rechargeable aqueous lithium-ion batteries

Interfacially-localized high-concentration electrolytes were developed using an anionic surfactant and a magnesium(ii) salt to achieve selective Li ion transport, high electrochemical stability and superior SEI formation in aqueous electrolytes.

Development of Lithium Ion Conducting Liquid: Methylurea-Based Eutectic Electrolytes for Lithium Batteries

Development of Lithium Ion Conducting Liquid: Methylurea-Based Eutectic Electrolytes for Lithium Batteries

Highly Conductive Boron-Containing Electrolytes by Integrating Modeling and Experiments.

A highly conducting polymer electrolyte was developed, where the structure included molecular elements guided by computational modeling results. The electrolyte comprises acidic boron and basic oxygen atoms within the molecular structure. Because of the presence of the boron and oxygen atoms within the structure, it interacts with the anion and cation of the dissolved salt and functions as an ion separator by increasing the bond length between the anion and cation. Increasing the bond length weakens the electrostatic interaction between the anion and cation, resulting in a decreased level of aggregation within the electrolyte matrix and higher ionic conductance. The new electrolytes show ionic conductivity values of 10-3 S cm-1 at 25 °C, which are suitable for lithium-ion polymer batteries. The approach demonstrates the importance of integrating computational modeling with experimental studies to design and develop promising electrolytes for lithium-ion polymer batteries.

Spray-Flame Synthesis (SFS) and Characterization of Li1.3Al0.3-xYxTi1.7(PO4)3 [LA(Y)TP] Solid Electrolytes.

Solid-state electrolytes for lithium-ion batteries, which enable a significant increase in storage capacity, are at the forefront of alternative energy storage systems due to their attractive properties such as wide electrochemical stability window, relatively superior contact stability against Li metal, inherently dendrite inhibition, and a wide range of temperature functionality. NASICON-type solid electrolytes are an exciting candidate within ceramic electrolytes due to their high ionic conductivity and low moisture sensitivity, making them a prime candidate for pure oxidic and hybrid ceramic-in-polymer composite electrolytes. Here, we report on producing pure and Y-doped Lithium Aluminum Titanium Phosphate (LATP) nanoparticles by spray-flame synthesis. The as-synthesized samples consist of an amorphous component and anatase-TiO2 crystalline particles. Brief annealing at 750-1000 °C for one hour was sufficient to achieve the desired phase while maintaining the material's sub-micrometer scale. Rietveld analysis of X-Ray diffraction data demonstrated that the crystal volume increases with Y doping. At the same time, with high Y incorporation, a segregation of the YPO4 phase was observed in addition to the desired LATP phase. Another impurity phase, LiTiOPO4, was observed besides YPO4 and, with higher calcination temperature (1000 °C), the phase fraction for both impurities also increased. The ionic conductivity increased with Y incorporation from 0.1 mS/cm at room temperature in the undoped sample to 0.84 mS/cm in the case of LAY0.1TP, which makes these materials-especially considering the comparatively low sintering temperature-highly interesting for applications in the field of solid-state batteries.

Boosting cation mobility in sol-gel derived organic-inorganic hybrid solid electrolytes through physical conditioning.

Organic-inorganic hybrid materials are explored for application as solid electrolytes for lithium-ion batteries. The material consists of a porous silica network, of which the pores are infiltrated by poly(ethylene oxide) and lithium perchlorate. The synthesis involves two steps: First, the inorganic backbone is created by the acid-catalyzed sol-gel synthesis of tetraethyl orthosilicate to ensure continuity of the backbone in three dimensions. In the second step, the polymer and salt are imbued into the porous backbone via solvent exchange. During drying, the cylindrical disk-shaped specimens shrink mainly in the radial direction, which results in spatially non-uniform structural developments. While this inhomogeneity is not discernible in the material's chemical compositional or thermal properties, it is manifest in its ionic conductivity and adiabatic elastic modulus. The ionic conductivity in the center of the specimens is projected to be between one and two orders of magnitude higher than the measured average across the sample diameter. The process that yields a structure with enhanced ionic mobility during post-synthesis physical conditioning is inferred from careful analysis and numerical interpretation of measurable quantities, and the implications for the design of nanostructured hybrid electrolytes with high ionic conductivity are discussed.

Machine Learning Prediction of Physicochemical Properties in Lithium-Ion Battery Electrolytes With ActiveLearning Applied to Graph Neural Networks.

Accurate prediction of physicochemical properties, such as electronic energy, enthalpy, free energy, and average vibrationalfrequencies, is critical for optimizing lithium-ion battery (LIB) performance. Traditional methods like density functional theory(DFT) are computationally expensive and inefficient for large-scale screening. In this study, we apply active learningontop of graph neural networks (GNNs) to efficiently predict these properties. By focusing on uncertain data points, active learning reduces training data size while maintaining high accuracy. Applied to the LIBE and MPcules datasets, the model achieved an R-squared (R2) values of 0.9977 with a mean absolute error (MAE) of 9.66 Ha for electronic energy and an R2 values of 0.957 with an MAE of 13.94 cm-1 for average vibrational frequencies. SHapley Additive exPlanations (SHAP) provided insights into key features influencing predictions, such as atomic number and spin multiplicity. This approach enhances both predictive accuracy and model interpretability, offering a scalable solution for LIB electrolyte discovery.

Effect of Additives With Phenyl and Acid Anhydride Functional Groups on the Wide Temperature Operation Performance of LiNi0.8Co0.1Mn0.1O2||SiO/Graphite Pouch Cells

ABSTRACTHigh‐nickel LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode paired with silicon‐based graphite (SiO/Gr) is pivotal for enhancing the energy density of lithium‐ion batteries (LIBs). However, the high reactivity of NCM811 with the electrolyte and the volumetric expansion issues associated with SiO/Gr pose significant challenges to their practical application. To settle these issues, we explore the impact of additives with phenyl and acid anhydride moieties on the performance of NCM811‖SiO/Gr pouch cells across a wide temperature range of −20°C~60°C. Acid anhydride additives are capable of diminishing the internal resistance in NCM811‖SiO/Gr pouch cells, as well as curbing gas evolution and thickness increase during the operational phase. Notably, the batteries enriched with citraconic anhydride (CAn) and succinic anhydride (SAn) additives after 120 cycles at 45°C demonstrated enhanced capacity retention from 83.2% to 88.1% and 85.5%, respectively. Intriguingly, the inclusion of phenyl‐containing additives in the electrolyte was found to be advantageous for NCM811‖SiO/Gr pouch cells' low‐temperature performance. Furthermore, neither type of functional group significantly enhanced performance at room conditions. Consequently, the combination of additives is necessary to fulfill the stringent requirements of LIBs for extreme environment applications. This work guides designing composite electrolytes for high energy density wide temperature operation LIBs.

Revealing Lithium Ion Transport Mechanisms and Solvation Structures in Carbonate Electrolytes.

Optimizing lithium-ion battery (LIB) electrolytes is essential for high-current applications such as electric vehicles, yet experimental techniques to characterize the complex structural dynamics responsible for the lithium transport within these electrolytes are limited. In this study, we used ultrafast infrared spectroscopy to measure chemical exchange, spectral diffusion, and solvation structures across a wide range of lithium concentrations in propylene carbonate-based LiTFSI (lithium bis(trifluoromethanesulfonimide) electrolytes, with the CN stretch of phenyl selenocyanate as the long-lived vibrational probe. Phenyl selenocyanate is shown to be an excellent dynamical surrogate for propylene carbonate in Li+ solvation clusters. A strong correlation between exchange times and ionic conductivity was observed. This correlation and other observations suggest structural diffusion as the primary transport mechanism rather than vehicular diffusion. Additionally, spectral diffusion observables measured by the probe were directly linked to the desolvation dynamics of the Li+ clusters, as supported by density functional theory and molecular dynamics simulations. These findings provide detailed molecular-level insights into LIB electrolytes' transport dynamics and solvation structures, offering rational design pathways to advanced electrolytes for next-generation LIBs.