Electrolytes For Lithium Batteries Research Articles

Recent Advances in Poly(ethylene oxide)-Based Solid-State Electrolytes for Lithium-Ion Batteries

Recent Advances in Poly(ethylene oxide)-Based Solid-State Electrolytes for Lithium-Ion Batteries

Ethyl Isopropyl Sulfone Modulating to Achieve Stable High-Voltage Electrolyte for Lithium-Ion Batteries.

The demand for efficient large-scale energy storage necessitates high-energy-density batteries, making research on high-voltage electrolytes particularly important. In this article, ethyl isopropyl sulfone (ES), which has a high dielectric constant, is added to traditional carbonate-based electrolyte solvents and analyzed. Based on calculated and analyzed results, different proportions of ES are added to the conventional carbonate-based electrolyte. The high-voltage performance, the influence on the surface of the electrode, the active material structure after cycling, the electrochemical behavior, and the impedance of the electrode were studied systematically. As a result, ES addition is applied in high-voltage lithium-ion batteries and exhibits excellent electrochemical properties. These results will provide support for the research and application of sulfone additives in increasing the decomposition voltage of lithium-ion battery electrolytes and improving battery cycle stability.

Confined Polyethylene Glycol Anchored in Kaolinite as High Ionic Conductivity Solid-State Electrolyte for Lithium Batteries.

Solid-state electrolytes (SSEs) have garnered significant attention as critical materials for enabling safer, energy-dense, and reversible electrochemical energy storage in batteries. Among the various types of solid electrolytes developed, composite polymer electrolytes (CPEs) have stood out as some of the most promising candidates due to their well-rounded performance. In this study, we choose polyethylene glycol (PEG) as the covalent grafting intercalant and lithium perchlorate as carrier source to prepare a fast lithium ion conductor, K-PEG-Li doped with clay-based active filler as a CPE. The CPE exhibits excellent lithium conduction (4.36 × 10-3 S cm-1 at 25 °C and 3.32 × 10-2 S cm-1 at 115 °C), great mechanical performance with good tensile strength (6.07 MPa) and toughness (strain 313%), and convincing flame-retardancy. These outstanding conducting and mechanical functionalities indicate that such a clay-based active filler doped composite polymer electrolyte will find promising application in solid-state lithium batteries.

Understanding Li6.24La3Zr2Al0.24O11.98 effect on poly(ionic liquid)-based electrolytes for high voltage solid-state lithium batteries working at room temperature

Hybrid electrolytes composed of poly(ionic liquid), ionic liquids (ILs), and fillers are very promising candidates for solid-state lithium metal batteries (SSLMBs). However, a significant knowledge gap in the field of hybrid electrolytes lies in the understanding of filler effect on properties and performance. Herein, we have investigated hybrid electrolytes based on poly(diallyldimethylammonium) bis(fluorosulfonyl)imide (PDDA-FSI), N-Propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (PYR13FSI), Lithium bis(fluorosulfonyl)imide (LiFSI) and different loadings (from 0 to 19.2 vol%) of Li6.24La3Zr2Al0.24O11.98 particles. All the electrolytes present a homogeneous morphology and excellent thermal stability. Moreover, our results demonstrate that Al-LLZO particles do not contribute to the ionic conductivity of the hybrid electrolytes. A 2.6 vol% of Al-LLZO led to the excellent performance in full cells at RT. Surprisingly, the battery performance was not correlated with the transport properties. Instead, this study found out a mechanical-performance relationship, which follows a master equation: t = A (−12.48 (1-e(1.53x10-4σy))) / P that enables to correlate the effect Al-LLZO particles on the cell performance, and predict, for the first time, the lifetime of the battery through the mechanical properties.

A rapid pressureless sintering strategy for LLZTO ceramic solid electrolyte sheets prepared by tape casting

Garnet-type electrolytes are regarded as one of the most promising solid-state electrolytes (SSEs) for lithium-ion batteries due to their potential advantages in terms of energy density, electrochemical stability and safety. To achieve the maximum energy density, it is necessary to ensure that the electrolyte layer is as thin as possible. Nevertheless, thin sheet SSE is more challenging to sinter than pellet due to the greater lithium volatilization from the high surface/volume ratio. Garnet-type SSE (Li6.5La3Zr1.5Ta0.5O12, LLZTO) green tape was prepared by the tape-casting technique. The effects of supporter, sintering temperature and dwell time on the relative density, microstructure and ionic conductivity of thin sheet were investigated. A ceramic SSE sheet with a thickness of 173 μm, a relative density of 97.2 %, an ionic conductivity of 2.02 × 10−4 S/cm at 25 °C and an activation energy of 0.25 eV, was achieved using a rapid pressureless sintering at 1250 °C for 25 min with a MgO supporter. This work offers insights into the practical production of LLZTO sheets.

FFF/FDM 3D-Printed Solid Polymer Electrolytes Based on Acrylonitrile Copolymers for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are essential in modern electronics, particularly in portable devices and electric vehicles. However, the limited design flexibility of current battery shapes constrains the development of custom-sized power sources for advanced applications like wearable electronics and medical devices. Additive manufacturing (AM), specifically Fused Filament Fabrication (FFF), presents a promising solution by enabling the creation of batteries with customized shapes. This study explores the use of novel poly(acrylonitrile-co-polyethylene glycol methyl ether acrylate) (poly(AN-co-PEGMEA)) copolymers as solid polymer electrolytes for lithium-ion batteries, optimized for 3D printing using FFF. The copolymers were synthesized with varying AN:PEGMEA ratios, and their physical, thermal, and electrochemical properties were systematically characterized. The study found that a poly(AN-co-PEGMEA) 6:1 copolymer ratio offers an optimal balance between printability and ionic conductivity. The successful extrusion of filaments and subsequent 3D printing of complex shapes demonstrate the potential of these materials for next-generation battery designs. The addition of succinonitrile (SCN) as a plasticizer significantly improved ionic conductivity and lithium cation transference numbers, making these copolymers viable for practical applications. This work highlights the potential of combining polymer chemistry with additive manufacturing to provide new opportunities in lithium-ion battery design and function.

Electrolytes for High-Safety Lithium-Ion Batteries at Low Temperature: A Review.

As the core of modern energy technology, lithium-ion batteries (LIBs) have been widely integrated into many key areas, especially in the automotive industry, particularly represented by electric vehicles (EVs). The spread of LIBs has contributed to the sustainable development of societies, especially in the promotion of green transportation. However, the high demand for battery performance and safety in these fields has made the high viscosity, volatility, and potential leakage inherent in traditional organic liquid electrolytes a constraint on their further expansion. Especially at low temperature, the increased viscosity of the electrolyte, reduced solubility of lithium salts, crystallization or solidification of the electrolyte, increased resistance to charge transfer due to interfacial by-products, and short-circuiting due to the growth of anode lithium dendrites all affect the performance and safety of LIBs. Therefore, improving the safety performance of LIBs under low-temperature environments has become a focus of current research. This paper primarily reviews the progress made in utilizing different types of electrolytes in LIBs to enhance safety and optimize low temperature performance and discusses the current research progress as well as the future development direction of the field.

Electrolytes from Alkoxyalkyl-substituted Imidazolium ionic liquids. Synthesis, characterization, properties and cell performance in LiFePO4 half-cells

Electrolytes based on lithium bis(trifluoromethane)sulfonimide (LiTFSI) salt and alkoxyalkyl-substituted imidazolium ionic liquids (ILs) have been studied. We have synthesized three different 1-alkoxyalkyl-3-methylimidazolium TFSI salts with different chain lengths (from 4 to 10 atoms) and with one to three oxygen atoms at position 1- of the imidazole ring. Both the neat ILs as well as the cognate lithium doped electrolytes have been structurally and physicochemically characterized and electrochemically evaluated.Thermal analyses indicate that the glass transition temperature of the electrolytes is displaced to higher temperatures than those of the corresponding neat ILs, being also higher (more positive) upon increasing the number of oxyethylene units. On the other hand, all 1 M LiTFSI doped synthesized electrolytes are thermally stable up to 300 °C.Raman spectroscopy results indicate that the fraction of TFSI anions coordinated to lithium ion decreases on increasing the number of alkoxy units. This finding implies that there is more “free” lithium ion available to link to the ethereal oxygen of the side chain of the imidazolium ring system. This fact influences the ionic conductivity of the neat ILs and their cognate electrolytes.The electrochemical properties —namely high room temperature conductivities as well as wide electrochemical stability windows— indicate that these materials are promising electrolytes for lithium-ion batteries (LIBs). Lithium half-cells using LiFePO4 (LFP) olivine have been assembled in order to assess the electrochemical performance by means of both cyclic voltammetry and galvanostatic charge/discharge tests. Overall, we have found that the electrochemical performance of these cells is better than that reported 1 M LiTFSI [Pyr14][TFSI], a common electrolyte in LIBs. The generated half-cell from the 1-alkoxyalkyl-3-methylimidazolium TFSI salts possess a high capacity up to 145 mAh∙g−1 at a current of 2C.The results reported herein show a striking relationship between structure and properties.

In Situ Fabrication of Solvent-Free Solid Polymer Electrolytes for Wide-Temperature All-Solid-State Lithium Metal Batteries.

All-solid-state lithium metal batteries (ASSLMBs) have been regarded as promising candidates to settle the safety issues of liquid electrolytes for rechargeable lithium batteries. However, the currently reported gel polymer electrolytes still have flammable liquid solvents, thus leading to the potential safety hazard. Here, solvent-free deep eutectic solid polymer electrolytes (SPEs) are designed and fabricated via an in situ polymerization, which are composed of a poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) electrospun membrane, succinonitrile (SN), poly(ethylene glycol) diacrylate (PEGDA200, Mn = 200 g mol-1), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium difluoro(oxalato)borate (LiDFOB). The deep eutectic solvent (DES) with SN/LiTFSI provides a superior room-temperature ionic conductivity, while the PEGDA200 precursor acts as cross-linking network to form SPEs under thermal initiation for free radical polymerization, and LiDFOB can form a stable solid electrolyte interface (SEI) layer. The PVDF-HFP electrospun membrane with a three-dimensional nanofibrous network structure for SN/PEGDA200/LiTFSI/LiDFOB SPEs exhibits a wide electrochemical stability window, high lithium-ion transference number, and good compatibility with the lithium metal anode. Furthermore, the obtained SPEs assembled with Li//LiMn0.6Fe0.4PO4, Li//LiFePO4, and Li//LiNi0.8Co0.1Mn0.1O2 asymmetric cells show excellent cycling performance and rate capability at a wide temperature. This strategy provides a promising path in designing high-energy-density ASSLMBs for practical application.

High Throughput Electrochemical Screening of Phosphate-Rich Nonflammable Electrolytes in Lithium-Ion Batteries

Abstract Frequent fires and explosions in lithium-ion batteries (LIBs) used in grid energy storage systems (ESS) highlight the necessity of revisiting nonflammable phosphate electrolytes as alternatives to the currently used flammable carbonates. However, previous studies have shown the difficulty of integrating phosphate solvents into LIB electrolytes due to compatibility issues with graphite. In this work, we developed a high-throughput (HTP) electrochemical characterization method, akin to pH test paper, to rapidly screen potential phosphate electrolytes and graphite materials. Through HTP screening, we identified 101 promising combinations out of 1,740. This number was reduced to 26 after testing in Li/Graphite half cells. The optimized phosphate-rich electrolyte (60 v% phosphate) with cosolvents demonstrated 300 stable cycles at 0.1 C in Graphite/LiFePO4 (LFP) full cells with thick electrodes (~3.0 mAh/cm²), surpassing prior research findings. This unique HTP method provides a powerful tool to expedite the development of safe LIBs for ESS applications.

Rational design of the temperature-responsive nonflammable electrolyte for safe lithium-ion batteries

The development of nonflammable electrolytes is critical for breaking the trade-off between the safety and energy density in Li-ion batteries (LIBs). Here, a rational design strategy of temperature-responsive nonflammable electrolytes (TRNEs) is proposed which are capable to prevent the heat accumulation and extinguish the fire efficiently during thermal runaway. Compared to the conventional phosphate- or halogen-based flame retardants, the TRNE based on low-cost and multifunctional methylurea (MU) was demonstrated with the lowest volatility (11.6 % weight loss) below 250 °C, and the highest efficacy to extinguish the fire at >210.4 °C through heat absorption, inert gases generation and char layer formation. In addition, the developed MU-based TRNEs enable higher stability and rate capability of LIBs compared to various nonflammable electrolytes. A Li||LiFePO4 (LFP) cell employing MU-based TRNE achieved higher stability (94.9 % capacity retention for 1500 cycles) than commercial electrolyte. A Ni-rich Li||LiNi0.8Mn0.1Co0.1O2 (NMC811) system was demonstrated with superior rate capability and high stability for 700 cycles (2.72 months) with the capacity retention of 89.9 %. Combining low cost and volatility, as well as high stability, rate capability and fire extinguishing efficacy, we demonstrate a promising design strategy to improve the battery safety for high-energy-density LIBs.

Ethylene Carbonate-Free Electrolytes for High Voltage Lithium-Ion Batteries: Progress and Perspectives

Ethylene Carbonate-Free Electrolytes for High Voltage Lithium-Ion Batteries: Progress and Perspectives

The research progress on COF solid-state electrolytes for lithium batteries.

Lithium metal batteries have garnered significant attention due to their high energy density and broad application prospects. However, the practical use of traditional liquid electrolytes is constrained by safety and stability challenges. In the exploration of novel electrolytes, solid-state electrolyte materials have emerged as a focal point. Covalent organic frameworks (COFs), with their large conjugated structures and unique electronic properties, are gradually gaining attention as an emerging class of solid-state electrolyte materials. In recent years, outstanding electrochemical performance has been achieved through the design and synthesis of various types of COF-based solid-state electrolytes, along with successful integration with other functional materials. This review will provide an overview of the research progress on COFs as solid-state electrolyte materials for lithium metal batteries and offer insights into their future potential in battery technology.

Pyrrolidinium-Based Ionic Liquids as Advanced Non-Aqueous Electrolytes for Safer Next Generation Lithium Batteries

In the current context of increasing energy demand, ionic liquids (ILs) are presented as possible candidates to replace conventional electrolytes and to develop more efficient energy storage devices. The IL 1-Methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide has been selected for this work, due to the good thermal and chemical stabilities and good electrochemical performance of the pyrrolidinium cation based ILs. Binary mixtures of this IL and lithium salt with the same anion, [TFSI], have been prepared with the aim of assessing them, as possible electrolytes for lithium batteries. These mixtures were thermally and electrochemically characterised through DSC and dielectric spectroscopy studies. The ionic conductivity decreases as the salt concentration increases, finding values ranging between 0.4 S/m and 0.1 S/m at room temperature. Additionally, a wide liquid range was found for the mixtures, which would reduce or even eliminate some of the most common problems of current electrolytes, such as their crystallisation at low temperatures and flammability. Finally, the toxicity of pure IL and the intermediate salt concentration was also evaluated in terms of the bioluminescence inhibition of the Alivibrio Fischeri bacteria, observing that, although the toxicity increases with the salt addition, both samples can be classified as practically harmless.

Concentration Controlling of Carboxylic Ester-Based Electrolyte for Low Temperature Lithium-Ion Batteries.

Low temperature has been a major challenge for lithium-ion batteries (LIBs) to maintain satisfied electrochemical performance, and the main reason is the deactivation of electrolyte with the decreasing temperature. To address this point, in present work, we develop a low-temperature resistant electrolyte which includes ethyl acetate (EA) and fluoroethylene carbonate (FEC) as solvent and lithium difluoro(oxalato)borate (LiDFOB) as the primary lithium salt. Due to the preferential decomposition of LiDFOB and FEC, a solid electrolyte interface rich in LiF is formed on the lithium metal anodes (LMAs) and lithium cobalt oxide (LCO) cathodes, contributing to higher stability and rapid desolvation of Li+ ions. The batteries with the optimized electrolyte can undergo cycling tests at -40 °C, with a capacity retention of 83.9 % after 200 cycles. Furthermore, the optimized electrolyte exhibits excellent compatibility with both LCO cathodes and graphite (Gr) anodes, enabling a Gr/LCO battery to maintain a capacity retention of 90.3 % after multiple cycles at -25 °C. This work proposes a cost-effective electrolyte that can activate potential LIBs in practical scenarios, especially in low-temperature environments.

Fluorinated Linkers Enable High-Voltage Pyrrolidinium-based Dicationic Ionic Liquid Electrolytes.

Novel fluorinated, pyrrolidinium-based dicationic ionic liquids (FDILs) as high-performance electrolytes in energy storage devices have been prepared, displaying unprecedented electrochemical stabilities (up to 7 V); thermal stability (up to 370 °C) and ion transport (up to 1.45 mS cm-1). FDILs were designed with a fluorinated ether linker and paired with TFSI/FSI counterions. To comprehensively assess the impact of the fluorinated spacer on their electrochemical, thermal, and physico-chemical properties, a comparison with their non-fluorinated counterparts was conducted. With a specific focus on their application as electrolytes in next-generation high-voltage lithium-ion batteries, the impact of the Li-salt on the characteristics of dicationic ILs was systematically evaluated. The incorporation of a fluorinated linker demonstrates significantly superior properties compared to their non-fluorinated counterparts, presenting a promising alternative towards next-generation high-voltage energy storage systems.

Advancements in Polyethylene Oxide (PEO)-Active Filler Composite Polymer Electrolytes for Lithium-Ion Batteries: A Comprehensive Review and Prospects.

Polyethylene oxide (PEO) has become a highly sought-after polymer electrolyte for lithium-ion batteries (LIBs) due to its high ionic conductivity, strong mechanical properties, and broad electrochemical stability range. However, its usefulness is hindered by its limited ionic conductivity at typical temperatures (<60 °C). Many researchers have delved into the integration of active fillers into the PEO matrix to improve the ionic conductivity and overall efficiency of composite polymer electrolytes (CPEs) for LIBs. This review delves deeply into the latest developments and insights in CPEs for LIBs, focusing on the role of PEO-active filler composites. It explores the impact of different types and morphologies of active fillers on the electrochemical behavior of CPEs. Additionally, it explores the mechanisms that contribute to the improved ionic conductivity and Li-ion transport in PEO-based CPEs. This paper also emphasizes the present obstacles and prospects in the advancement of CPEs containing PEO-active filler composites for LIBs. It serves as a valuable reference for scientists and engineers engaged in the domain of advanced energy storage systems, offering insights for the forthcoming development and enhancement of CPEs to achieve superior performance in LIBs.

Glass fiber-based metal organic gel composite electrolytes for solid-state lithium batteries

Abstract Quasi-solid-state electrolytes encounter great obstacles in structural stability due to their inherent heterogeneity. Here, we introduce a new composite structure of glass-fiber-based metal-organic gel as a solid-state electrolyte and explore its electrochemical properties in lithium-metal batteries. We use a straightforward in-situ sol-gel method to synthesize this composite electrolyte, where glass fiber acts as matrices, ferric nitrate reacts with trimeric acid to form interconnected channels with abundant unsaturated metal sites, while ionic liquid electrolyte is in-situ confined into interconnected channels. The as-prepared composite electrolyte membrane has a uniform structure and composition, exhibiting a high room-temperature ionic conductivity of 1.79×10−3 S cm−1 and a high electrochemical oxidation potential of 4.76 V vs Li/Li+. This composite has excellent cycling performance in LiFePO4//Li (99.5% after 100 cycles) and NCM811//Li (86.6% after 200 cycles) batteries.

Rapid treatment of LLZTO solid electrolyte surface impurities by lactic acid solution

Abstract LLZO solid-state electrolytes of the garnet type exhibit exceptional electrochemical stability towards lithium metal and possess a remarkable level of ionic conductivity, and thus are considered to be one of the most promising solid-state electrolytes for solid-state lithium-ion batteries. However, LLZO is unstable in humid air and reacts with H2O and CO2 in the air to form Li2CO3, which reduces the wettability with lithium metal and decreases the overall ionic conductivity of LLZO. In this paper, a novel, fast, and simple method, lactic acid treatment, is proposed. The results show that Li2CO3 on the LLZO surface can be completely removed by acid treatment for 30 seconds, resulting in a pure LLZTO surface and improved wettability with lithium metal. Meanwhile, the assembled lithium symmetric battery can be cycled stably for 240 hours at 0.2 mA/cm2.

Developmental Toxicity and Apoptosis in Zebrafish: The Impact of Lithium Hexafluorophosphate (LiPF6) from Lithium-Ion Battery Electrolytes.

With the growing dependence on lithium-ion batteries, there is an urgent need to understand the potential developmental toxicity of LiPF6, a key component of these batteries. Although lithium's toxicity is well-established, the biological toxicity of LiPF6 has been minimally explored. This study leverages the zebrafish model to investigate the developmental impact of LiPF6 exposure. We observed morphological abnormalities, reduced spontaneous movement, and decreased hatching and swim bladder inflation rates in zebrafish embryos, effects that intensified with higher LiPF6 concentrations. Whole-mount in situ hybridization demonstrated that the specific expression of the swim bladder outer mesothelium marker anxa5b was suppressed in the swim bladder region under LiPF6 exposure. Transcriptomic analysis disclosed an upregulation of apoptosis-related gene sets. Acridine orange staining further supported significant induction of apoptosis. These findings underscore the environmental and health risks of LiPF6 exposure and highlight the necessity for improved waste management strategies for lithium-ion batteries.