Properties Of Electrolytes Research Articles

Carbon Dots Enabling High-Performances Sodium-Ion Batteries.

Carbon dots (CDs), known for their quantum size, abundant surface functional groups, excellent biocompatibility, and non-toxicity, have emerged as promising candidates for enhancing various advanced rechargeable batteries. Recent research indicates that electrodes based on or modified with CDs in sodium-ion batteries (SIBs) have shown significant improvements in key performance metrics such as Coulombic efficiency, cycle life, and capacity compared to traditional electrodes. Several key impacts of CDs contribute to these enhancements, including increased conductivity due to their conductive graphitized core, rich absorption sites, and excellent dispersity facilitated by abundant surface functional groups. These features accelerate ion transport through interface edges and ion diffusion paths, inhibit electrode material dissolution, buffer electrode material volume expansion, ensure electrode uniformity and stability, and promote the electrochemical reaction process between the electrode and electrolyte. This review summarizes recent developments, challenges, and opportunities in leveraging CDs as additives in SIBs, focusing on their impact on electrolyte properties, electrode materials, and overall battery performance. It provides a comprehensive understanding of the potential of CDs to significantly advance SIB technology.

Halogen-Bonding Nanoarchitectonics in Supramolecular Plasticizers for Breaking the Trade-Off between Ion Transport and Mechanical Strength of Polymer Electrolytes for High-Voltage Li-Metal Batteries.

The low ionic conductivity of poly(ethylene oxide) (PEO)-based polymer electrolytes at room temperature impedes their practical applications. The addition of a plasticizer into polymer electrolytes could significantly promote ion transport while inevitably decreasing their mechanical strength. Herein, we report a supramolecular plasticizer (SMP) to break the trade-off effect between ionic conductivity and mechanical properties in PEO-based polymer electrolytes. Accordingly, the SMP is constructed by tetraethylene glycol dimethyl ether (G4) and SbF3 through halogen bonds. The SMP-plasticized PEO electrolyte (PEO/SMP) presents a simultaneously enhanced ionic conductivity of 2.4 × 10-4 S cm-1 (25 °C) and a high mechanical strength of 8.1 MPa, compared to those of pristine PEO-based electrolytes. Benefiting from the halogen bonds between G4 and SbF3, the Li-O coordination in PEO/SMP is evidently weakened, and thus rapid Li+ transport is achieved. Furthermore, the PEO/SMP electrolyte possesses a wide electrochemical stability window of 4.5 V and, importantly, derives an inorganic-rich SEI with a low interfacial resistance on a lithium metal surface. By using PEO/SMP, the lithium-metal battery with the LiNi0.5Co0.2Mn0.3O2 cathode exhibits a good rate and long-term cycling performance with a capacity retention of 75.3% (500 cycles). This work offers a rational guideline for the design of polymer electrolytes suitable for high-performance lithium-metal batteries.

Dynamic Processes at the Electrode‐Electrolyte Interface: Implications for Lithium Deposition Stability

AbstractLithium (Li) metal is a promising negative electrode material for high‐energy‐density rechargeable batteries, owing to its exceptional specific capacity, low electrochemical potential, and low density. However, challenges such as dendritic Li deposits, leading to internal short‐circuits, and low Coulombic efficiency hinder the widespread adoption of lithium‐metal batteries (LMBs). These issues stem from the morphological instability of Li deposition, influenced by dynamic processes at the electrolyte|Li interface. Understanding the interplay between electrolyte properties, interfacial kinetics, and Li deposition stability is crucial yet challenging due to their simultaneous occurrence and the complexity of the solid electrolyte interphase (SEI) layer. This review discusses three key dynamic processes influencing Li deposition: desolvation of Li+ ions, transport through the SEI, and electrochemical reduction. The effects of electrolyte properties on these processes and their interplay with electroplating stability are discussed, highlighting contradictions in the literature and proposing explanations for the discrepancies. Despite numerous reviews on SEI structure and composition effects, this article emphasizes the kinetic aspects at interfaces, aiming to provide clarity and direction for future research in achieving stable Li deposition in LMBs.

Electrochemical properties of plasticized PVA-based electrolyte inserted with alumina nanoparticles for EDLC application with enhanced dielectric constant

In the current study, the role of alumina nanoparticles was examined in the electrochemical and device performance of PVA-based electrolytes. The NaSCN was used as a cation provider for the host electrolyte, and the glycerol plasticizers were used to enhance conductivity and flexibility. The ratio of salt and plasticizer was fixed, while nanoparticles were varied. The results of impedance AC conductivity confirm that 3 wt% of alumina insertion results in high DC conductivity, which is sufficient for electrochemical device application. Electrode polarization region and plateau area are clearly distinguished in AC spectra. The study of the Dielectric constant reveals that charge storage is maximum at 3 wt% of alumina. The dielectric constant values are about twice the dielectric loss value, which is the topic of immense scientific discussion. The contribution of ion fraction was found to be 0.94, which is excellent compared to the negligible contribution of electrons, which is about 0.05. Electrochemical stability is an additional crucial factor and was found to be 2.47 V. To identify any Redox or non-Redox phenomena occurring in the electrical double-layer capacitor (EDLC) cyclic voltammetry (CV) as the simplest analysis method has been carried out on the sample having the highest DC value. A leaf-like form of the CV plot was noticed at high scan rates, while a rectangular shape was identified at low scan rates. The charge-discharge shape is almost close to the ideal triangular pattern. The discharge part was used to calculate critical EDLC device parameters such as ESR, efficiency, specific capacitance power density, and energy density over 2000 cycles. Low ESR (below 60 Ω) and stable efficiency (almost 100 %) of the device results in high capacitance (≈87 F/g), power density (2978 Wh/kg), and energy density (12.86 W kg−1). The results established that nan-fillers alongside plasticizer is crucial to deliver EDLC devices with improved performances.

Ultralow Concentration Nonflammable Electrolytes Mediated by Intermolecular Interactions for Safer Potassium‐Ion Sulfur Batteries

AbstractDesigning electrolytes that are compatible with graphite anodes and possess flame‐retardant features is strongly demanded in potassium‐ion batteries (PIBs) to inhibit solvent co‐insertion and graphite exfoliation, and also stabilize the highly active potassium‐based species (e.g., KC8). Herein, a nonflammable electrolyte is designed by introducing the fluoroethers to stabilize graphite anodes, particularly at an ultralow concentration (<0.43 m) that is rarely reported before. It is discovered that intermolecular interactions can form between the 1,1,2,2‐tetrafluoroethyl‐2,2,3,3‐tetrafluoropropyl ether (i.e., HFE) diluent and trimethyl phosphate (TMP) flame‐retardant by electronegative fluorine (δ−F) and electropositive hydrogen (δ+H). The intermolecular interactions can change the potassium ion (K+) solvation structure (e.g., weakening the K+‐TMP interaction), and then determine the properties of the K+‐solvent‐anion complex at the electrode interface. a molecular interfacial model is presented with a new coordination mechanism involving the diluent to elucidate the relationship between the intermolecular interactions and electrode performance (i.e., K+‐solvent co‐insertion, or reversible K+ (de)intercalation) at the molecular scale, facilitating the design of high safety and high energy density potassium‐ion sulfur batteries. This study sheds light on the importance of intermolecular interactions to tune electrolyte properties and also opens new avenues for designing electrolytes for safe and practical PIBs.

Key Issues of Salt Cavern Flow Battery

Salt cavern flow batteries (SCFBs) are an energy storage technology that utilize salt caverns to store electrolytes of flow batteries with a saturated NaCl solution as the supporting electrolyte. However, the geological characteristics of salt caverns differ significantly from above-ground storage tanks, leading to complex issues in storing electrolytes within salt caverns. Therefore, investigating and summarizing these issues is crucial for the advancement of SCFB technology. This paper’s innovation lies in its comprehensive review of the current state and development trends in SCFBs both domestically and internationally. First, the current development status of SCFB energy storage technology both domestically and internationally is summarized. Then, eight main issues are proposed from the perspectives of salt cavern geological characteristics (tightness, conductivity, ions, and temperature) and electrolyte properties (selection, permeability, corrosion, and concentration). Finally, a novel SCFB system is proposed to address the most critical issue, which is the low concentration and uneven distribution of active materials in the current SCFB system. The review in this paper not only comprehensively summarizes the development status of SCFBs both domestically and internationally, but also points out the direction for the future research focussing on SCFBs.

Deep Neutral Network Enhanced Mesoscopic Thermodynamic Model for Unlocking the Electrode/Electrolyte Interface

Structure and properties of the electrode/electrolyte interface significantly influence the electrochemical processes of energy storage and conversion, yet the challenge lies in accurate description of both molecular characteristics and external field effects. Here, we develop a mesoscopic thermodynamic model that calculates the thermodynamic properties of electrolytes based on chemical potential, and its efficiency is enhanced by a deep neutral network. The deep neutral network enhanced mesoscopic thermodynamic (DeepMT) model effectively bridges the gap between micro‐level characteristics of ions and macro‐level effects of external field, enabling precise presentation of ion density distributions over complex conditions. Our result indicates that the DeepMT model not only demonstrates a computational efficiency improvement of approximately four orders of magnitude over direct theoretical calculations, but also accurately predicts interface properties including ion adsorption, surface charge, and differential capacitance through the statistical analysis of density distributions.

Deep Neutral Network Enhanced Mesoscopic Thermodynamic Model for Unlocking the Electrode/Electrolyte Interface.

Structure and properties of the electrode/electrolyte interface significantly influence the electrochemical processes of energy storage and conversion, yet the challenge lies in accurate description of both molecular characteristics and external field effects. Here, we develop a mesoscopic thermodynamic model that calculates the thermodynamic properties of electrolytes based on chemical potential, and its efficiency is enhanced by a deep neutral network. The deep neutral network enhanced mesoscopic thermodynamic (DeepMT) model effectively bridges the gap between micro-level characteristics of ions and macro-level effects of external field, enabling precise presentation of ion density distributions over complex conditions. Our result indicates that the DeepMT model not only demonstrates a computational efficiency improvement of approximately four orders of magnitude over direct theoretical calculations, but also accurately predicts interface properties including ion adsorption, surface charge, and differential capacitance through the statistical analysis of density distributions.

Stabilizing the Bilateral Interfaces by a PVDF-Based Double-Layer Solid Composite Electrolyte with a Relieved Dehydrofluorination Effect for Solid-State Lithium Metal Batteries.

The dehydrofluorination effect of poly(vinylidene fluoride) (PVDF) induced by ceramic fillers with an alkaline surface compromises the comprehensive properties of the solid composite electrolyte (SCE) and leads to the deficient performance of the solid-state lithium metal batteries (SLMBs). In this work, a unique PVDF-based double-layer solid electrolyte was fabricated, which consisted of a Li6.4La3Zr1.4Ta0.6O12 (LLZTO)-filled SCE with poly(acrylic acid) (PAA) as an alkalinity-scavenging agent in contact with the Li anode, and another SCE with lithium difluoro(oxalato)borate (LiDFOB) as a film-formation additive facing the cathode. It is found that a moderate amount of PAA relieves the dehydrofluorination degree of the PVDF matrix and improves the Li plating/stripping reversibility, and the addition of LiDFOB is involved in the formation of a stable passivation film on the cathode. Consequently, the resultant double-layer SCE holds favorable overall properties, especially being well-compatible with both electrodes, endowing the SLMBs with superior cycle and rate performance at room temperature.

Synergistic effect of ceramic filler in polymer salt complex for improved ion dissociation and migration mechanism

Abstract Use of Ceramic filler is one of the most common approaches to improve the conductivity and stability properties of a solid polymer electrolyte (SPE) cum separator. Among them, active fillers like Garnet have been extensively used to enhance the stability and conductivity of SPE. However, SPE suffers from limited ion migration at room temperature acting as a bottleneck for their application in all solid-state batteries. An extensive study on these fillers' role in ion dissociation and migration can be a stepping stone for advanced SPE. In the present work, an FTIR analysis has primarily been used to identify and evaluate cation coordinate site-cation, and ion pair interactions in a Li6.5La3Zr1.75Te0.25O12 loaded polyethylene oxide-LiCF3SO3 matrix with varying ceramic concentrations. Further, the Trukhan model has been used to calculate diffusion coefficient, mobility, and charge carrier density to interpret relaxation parameters, conductivity, and FTIR results in the SPE samples. Finally, an ion migration model has been proposed based on the results obtained in experimental studies.

Scaling the ionic conductivity and electrochemical properties of bio-based gel polymer electrolytes reinforced with Al2O3 nanofibers for energy storage applications

Scaling the ionic conductivity and electrochemical properties of bio-based gel polymer electrolytes reinforced with Al2O3 nanofibers for energy storage applications

A Novel Super-Toughness and Self-Healing Solid Polymer Electrolyte for Solid Sodium Metal Batteries.

Solid sodium metal batteries (SSMBs) offer an alternative promising power source for electrochemical energy storage due to their high energy density and high safety. However, the inherent sodium dendrite growth and poor mechanical properties of electrolytes seriously limit their application. Herein, a network structure composed of polyethylene oxide-based composite polymer electrolyte (CPE) is designed with liquid metal nanoparticles (LM) for SSMBs, in which LM can move in the solid electrolyte with the electric field driven. This effect can facilitate the inactivated sodium return to the metal sodium anode, and alloy with dendrites at the same time, which is beneficial for inhibiting the growth of dendrites. The symmetric cell with the CPE containing LM achieves good cyclic stability of more than 1800 and 800h at 0.1 and 0.2mAcm-2, respectively. The energy density of the pouch battery can reach 230Whkg-1. In sum, LM presents great potential to be employed as a performance reinforcement filler for CPEs, which paves the way for achieving high-performance SSMBs.

Self-forming Na3P/Na2O interphase on a novel biphasic Na3Zr2Si2PO12/Na3PO4 solid electrolyte for long-cycling solid-state Na-metal batteries

A novel biphasic Na3Zr2Si2PO12/Na3PO4 solid electrolyte is proposed to effectively address critical anode interface challenges for solid-state Na-metal batteries (SSSMBs). The Na3PO4 phase, at an optimal composition of ∼20 mol%, transforms the interface chemistry throughout the NZSP electrolyte, which results in dense electrolytes with high Young's modulus, rapid ion transport (6.2 × 10−4 S cm-1) at low activation barrier (0.19 eV), negligible electronic conductivity, and excellent sodiophilicity. The AIMD/DFT calculations and XPS analysis reveal a self-formed, (electro)chemically stable mixed Na+/electron-conducting interphase, comprising Na3P and Na2O, at the Na anode interface. The interphase not only homogenizes the Na+ flux distribution and accelerates the interfacial charge transport, but prevents continuous interfacial reactions, thereby stabilizing the anode interface against dendrite formation. Benefiting from the low-impedance, dendrite-free anode interface, Na symmetric cells demonstrate a low interface resistance of 12.7 Ω cm2 and exceptional cyclability of 3000 h. Additionally, full cells with Na3V2(PO4)3 cathodes achieve 93 % capacity retention after 550 cycles at 0.5 C. This research comprehensively elucidates and leverages the critical advantages of Na3PO4 in enhancing the bulk and interface properties of Na3Zr2Si2PO12 solid electrolytes. The design strategy of biphasic solid electrolytes presented here offers new insights into the developing high-performance solid electrolytes for advanced SSSMBs.

A Knowledge–Data Dual‐Driven Framework for Predicting the Molecular Properties of Rechargeable Battery Electrolytes

Developing rechargeable batteries that operate within a wide temperature range and possess high safety has become necessary with increasing demands. Rapid and accurate assessment of the melting points (MPs), boiling points (BPs), and flash points (FPs) of electrolyte molecules is essential for expediting battery development. Herein, we introduce Knowledge‐based electrolyte Property prediction Integration (KPI), a knowledge–data dual‐driven framework for molecular property prediction of electrolytes. Initially, the KPI collects molecular structures and properties, and then automatically organizes them into structured datasets. Subsequently, interpretable machine learning further explores the structure–property relationships of molecules from a microscopic perspective. Finally, by embedding the discovered knowledge into property prediction models, the KPI achieved very low mean absolute errors of 10.4, 4.6, and 4.8 K for MP, BP, and FP predictions, respectively. The KPI reached state‐of‐the‐art results in 18 out of 20 datasets. Utilizing molecular neighbor search and high‐throughput screening, 15 and 14 promising molecules, with and without Chemical Abstracts Service Registry Number, respectively, were predicted for wide‐temperature‐range and high‐safety batteries. The KPI not only accurately predicts molecular properties and deepens the understanding of structure–property relationships but also serves as an efficient framework for integrating artificial intelligence and domain knowledge.

A Knowledge-Data Dual-Driven Framework for Predicting the Molecular Properties of Rechargeable Battery Electrolytes.

Developing rechargeable batteries that operate within a wide temperature range and possess high safety has become necessary with increasing demands. Rapid and accurate assessment of the melting points (MPs), boiling points (BPs), and flash points (FPs) of electrolyte molecules is essential for expediting battery development. Herein, we introduce Knowledge-based electrolyte Property prediction Integration (KPI), a knowledge-data dual-driven framework for molecular property prediction of electrolytes. Initially, the KPI collects molecular structures and properties, and then automatically organizes them into structured datasets. Subsequently, interpretable machine learning further explores the structure-property relationships of molecules from a microscopic perspective. Finally, by embedding the discovered knowledge into property prediction models, the KPI achieved very low mean absolute errors of 10.4, 4.6, and 4.8 K for MP, BP, and FP predictions, respectively. The KPI reached state-of-the-art results in 18 out of 20 datasets. Utilizing molecular neighbor search and high-throughput screening, 15 and 14 promising molecules, with and without Chemical Abstracts Service Registry Number, respectively, were predicted for wide-temperature-range and high-safety batteries. The KPI not only accurately predicts molecular properties and deepens the understanding of structure-property relationships but also serves as an efficient framework for integrating artificial intelligence and domain knowledge.

On the Fabrication Processes of Structural Supercapacitors by Resin Transfer Molding and Vacuum-Assisted Resin Transfer Molding

This study investigated the manufacturing processes for structural supercapacitors (SSCs) using smear molding (RS), resin transfer molding (RTM), and vacuum-assisted resin transfer molding (VARTM). Woven carbon fibers were used as the electrode, woven glass fibers as an insulating layer, and an alkaline/epoxy compound as the electrolyte. In the RTM process, due to the vacuum and the high-pressure injection of the electrolyte, the electrochemical and mechanical properties of the SSC can be greatly improved, and the void contents in the SSC can be reduced. The balanced electrochemical performance and mechanical properties of SSCs were observed in the range of epoxy content from 15 wt% to 30 wt%. This study contributes to the development of SSCs through the establishment of the fabrication process for improvements in part quality. The fabrication method demonstrated here can be directly applied by industries to produce even larger-scale SSCs, opening up new possibilities for practical implementation and scalability.

Structure and transport properties of LiTFSI-based deep eutectic electrolytes from machine-learned interatomic potential simulations.

Deep eutectic solvents have recently gained significant attention as versatile and inexpensive materials with many desirable properties and a wide range of applications. In particular, their characteristics, similar to those of ionic liquids, make them a promising class of liquid electrolytes for electrochemical applications. In this study, we utilized a local equivariant neural network interatomic potential model to study a series of deep eutectic electrolytes based on lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) using molecular dynamics (MD) simulations. The use of equivariant features combined with strict locality results in highly accurate, data-efficient, and scalable interatomic potentials, enabling large-scale MD simulations of these liquids with first-principles accuracy. Comparing the structure of the liquids to the reported results from classical force field (FF) simulations indicates that ion-ion interactions are not accurately characterized by FFs. Furthermore, close contacts between lithium ions, bridged by oxygen atoms of two amide molecules, are observed. The computed cationic transport numbers (t+) and the estimated ratios of Li+-amide lifetime (τLi-amide) to the amide's rotational relaxation time (τR), combined with the ionic conductivity trend, suggest a more structural Li+ transport mechanism in the LiTFSI:urea mixture through the exchange of amide molecules. However, a vehicular mechanism could have a larger contribution to Li+ ion transport in the LiTFSI:N-methylacetamide electrolyte. Moreover, comparable diffusivities of Li+ cation and TFSI- anion and a τLi-amide/τR close to unity indicate that vehicular and solvent-exchange mechanisms have rather equal contributions to Li+ ion transport in the LiTFSI:acetamide system.

Multifaceted Analysis of Electrolyte Properties for Batteries

Multifaceted Analysis of Electrolyte Properties for Batteries

Characterization and properties of solid-state nanocomposite Acacia gum electrolytes with emphasis on diverse applications

A novel, natural, eco-friendly, solid-state Acacia gum nanocomposite electrolyte has been prepared with different weight ratios of nanoparticle ZrO2 introduced to the standard composition of 70% Acacia gum and 30% ZnSO4·7H2O. Sequential examinations, encompassing XRD, and FTIR, were conducted to evaluate the amorphous characteristics, complexation nature, and interaction of dopant nanoparticles within the acacia-salt electrolyte matrix network. The optimum ionic conductivity of nanocomposite electrolytes was found using electrochemical impedance analysis. The remarkable ionic conductivity was achieved for the electrolyte sample consisting of 10% nanoparticle ZrO2 introduced to the standard composition of 70% of Acacia gum and 30% of ZnSO4·7H2O(AZR4) at 100 °C, 6.1×10−3S/cm, at room temperature (RT) the electrolyte sample exhibited conductivity value of 1.13×10−3 S/cm. Additionally, an examination of the dielectric characteristics dependent on frequency demonstrated the existence of space charge polarization in the electrolyte and a notable tail in the low-frequency area. Through the parameters of the dielectric modulus, the research also investigated the hopping mechanism and relaxation time. Furthermore, nano-composite electrolytes were employed in the construction of solar cell devices. The outstanding results were obtained for electrolyte upon (10 wt%) nanoparticle-introduced, overall power conversion efficiency (ƞ) reached 5.38%, short-circuit photocurrent density (Jsc) 10.92 mA/cm2, open-circuit voltage (Voc) at 735 mV, and fill factor (FF) at 0.63.

Nonflammable Ether and Phosphate-Based Liquid Electrolytes for Sodium-Ion Batteries.

This study investigates a group of electrolytes containing NaPF6 or NaBF4 salts in phosphate- and ether-based solvents for high-mass loading sodium-ion batteries. It explores physicochemical properties such as ionic conductivity, dynamic viscosities, and nonflammability. The combination of experimental with computational studies reveals detailed insights into the physicochemical properties of the nonflammable liquid electrolytes. Diglyme-based electrolytes become nonflammable with 50 vol % phosphate solvents, while tetraglyme-based electrolytes require 70 vol %. The solvation structure has been investigated using NMR and is combined with computational studies to provide information about properties such as solvation structure, ionic conductivity, and viscosity. The molecular dynamic simulations confirm the enhanced solvation in diglyme-based liquid electrolytes observed experimentally by 23Na-NMR. Despite lacking sufficient electrochemical stability, this work provides a fundamental understanding of the solvation structure and physicochemical properties of a novel electrolyte system. This is an important contribution to be applied in future electrolyte design rationale.