Quasi-solid Electrolyte Research Articles

INTERACTION OF IONIC LIQUIDS BASED ON BIS(TRIFLUOROMETHYLSULFONIL)IMIDE ANION WITH HALLOYSITE NANOTUBES ACCORDING TO FT-IR SPECTROSCOPY

In this work, FT-IR spectroscopy was used to study the interactions in ionogels of the composition х[X]+[TFSI]−/(100 - x)НNT, where [TFSI]– is the bis(trifluoromethylsulfonyl)imide anion, the cation [X]+ = [BMPip]+ (1-butyl-1-methylpiperidinium), [BMPyr]+ (1-butyl-1-methylpyrrolidinium), and [BMIm]+ (1-butyl-3-methylimidazolium), HNT are halloysite nanotubes, х = (55.2±0.5) wt.%. A comparison of the spectra of the starting compounds and the resulting ionogels showed that the characteristic frequency of the stretching vibrations of OH bonds of adsorbed water molecules, observed in the spectra of pure halloysite, practically vanishes in the spectra of ionogel sts. The stretching vibrations of the C-H bond atoms of the cation, ν(CH), and the stretching vibrations of the C-F bond atoms of the CF3 group of the anion, ν(CF3), in the spectra of limited ionic liquids are shifted to the high frequency region by 1-3 cm-1. The ratio of the intensities of the asymmetric bending vibrations of the S=O bond atoms of the SO2 group, I(δasopSO2)/I(δasipSO2), which correspond to two different conformational isomers of the anion, increases by (15-19)%. As a result, it was found that the H2O molecules of halloysite are replaced by molecules of the ionic liquid due to the electrostatic interaction of the cation with the negatively charged outer siloxane (–Si–O–Si–) surface of the nanotubes and hydrogen bonds (CH···OSi), and due to the electrostatic interaction of the anion with a positively charged internal aluminol (–Al–OH) surface and hydrogen bonds (CF···HO–Al, SO···HO–Al). The restriction of the ionic liquid in the internal cavity of the HNT causes a conformational rearrangement of the [TFSI]− anion. The results obtained are of fundamental importance, make a certain contribution to understanding the effects in ionogels based on ionic liquids and nanoporous natural minerals, and can be used to develop quasi-solid electrolytes in the production of various electrochemical devices. For citation: Ramenskaya L.M., Grishina E.P., Kudryakova N.O. Interaction of ionic liquids based on bis(trifluoromethylsulfonil)imide anion with halloysite nanotubes according to FT-IR spectroscopy. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 3. P. 36-44. DOI: 10.6060/ivkkt.20236603.6752.

Quasi-Solid Polymer Electrolyte with Multiple Lithium-Ion Transport Pathways by In Situ Thermal-Initiating Polymerization.

Solid polymer electrolytes (SPEs) are considered to be attractive candidates for rechargeable batteries on account of their high safety and flexible processability. However, the restricted polymer segmental dynamics limit the Li+ conduction of SPEs. Herein, a composite electrolyte membrane was prepared via in situ thermal-initiating polymerization of diethylene glycol diacrylate (DEGDA) in a poly(vinylidene fluoride) frameworks (PVDF FMs) electrospun in advance. As a quasi-solid polymer electrolyte (QSPE), it provides multiple transport highways for Li+ built by the C═O or C-O or C═O/C-O groups in poly(diethylene glycol) diacrylate (PDEGDA), respectively, proved by density functional theory calculations together with the high-resolution 7Li solid-state nuclear magnetic resonance spectra. Since the interaction between Li+ and C═O is weaker than that between Li+ and C-O, Li+ tends to move along C═O dominating paths in PDEGDA/PVDF FMs QSPEs, even skipping back to C═O nodes from the original C-O dominating way. Multiple transport patterns facilitate Li+ migration within PDEGDA/PVDF FMs QSPEs, contributing to the ionic conductivity of 1.41 × 10-4 S cm-1 at 25 °C and the Li+ transference number of 0.454. Ascribing to the wetting capability of the monomer to the electrodes in use, compatible electrolyte/electrode interfaces with low interface resistance and compact cells were acquired by the in situ polymerization. Protective lithiated oligomers (RCOOLi) and LiF are enriched at the Li anode surface, promoting a lasting stable Li plating/stripping over 2000 h. By applying the QSPEs in LiFePO4 cell, a capacity of 157.7 mAh g-1 with almost 100% coulombic efficiency during 200 cycles is achieved at 25 °C.

Fluorine-regulated cathode electrolyte interphase enables high-energy quasi-solid-state lithium metal batteries

Lithium metal batteries (LMBs) enabled by quasi-solid electrolytes are under consideration for their prospect of reliable safety and high energy density. The limited oxidative stabilization and inferior chemical compatibility of quasi-solid electrolytes toward high-voltage cathodes are a long-standing challenge. Herein, we report that an additive level (0.05 M) of LiPF6 is introduced to a polymeric concentrated quasi-solid electrolyte (10 M LiFSI in poly-1,3-dioxolane [poly-DOL], ethylene carbonate [EC], and ethyl methyl carbonate [EMC]) to build in situ a fluorine-regulated cathode electrolyte interphase (CEI) on a highly catalytic LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode. The CEI with a conformal thickness of ∼7 nm features a fluorine-rich outer layer and manipulative LiF/organofluorine species, which mitigates the detrimental side reactions between the quasi-solid electrolyte and NCM cathode and maintains the structure of cycled NCM, as demonstrated by the characterizations of SEM, TEM, XRD, Raman spectroscopy, AFM, EDS, and XPS. As a result, the LiPF6-contained polymeric concentrated quasi-solid electrolyte not only provides a superior ionic conductivity of 3.1 × 10−4 S cm−1 at 25 °C and a remarkable electrochemical stability window of 5.5 V vs Li/Li+, but also achieves an excellent capacity retention of 74% after 100 cycles for LiǁNCM811 quasi-solid-state LMB, bringing a quasi-solid electrolyte design strategy of engineered CEI chemistry for LMBs.

Electrical and optical properties of electro chemical luminescence device with quasi solid electrolyte and ZnO/TiO2 electrode

In this work, a quasi-solid electrolyte process that can be simply manufactured for an electrochemical luminescence (ECL) device with a ZnO/TiO2 electrode was proposed, and the electro-optical characteristics of the fabricated ECL cells were investigated. The electrolyte was prepared by adding poly (vinylidene fluoride-co-hexa-fluoropropylen) with the Ru(bpy)3(PF6)2 as a luminescence material in 1:4 weigh ratio in 1 g of Acetonitrile (ACN). The ZnO/TiO2 films as an electrode were prepared by RF sputtering system. The ZnO and TiO2 targets were set up in co-sputtered system and FTO glass size 2 × 2 cm2 was used as a substrate. Argon gas flow rating as the working gas was fixed at 30 sccm. First, the ZnO layer is deposited on the FTO substrate at 100 W of RF power and at 10 mTorr of Argon gas pressure. TiO2 layer is deposited on the ZnO layer while increasing the sputtering time by 10 min. The morphological and optical properties of the thin films as electrode were confirmed using scanning electron microscope (SEM, Hitachi Su70), X-ray diffraction (XRD, Rigaku D/max 2100H) and UV–vis spectrometer (DH-2000-BAL Ocean Optics). The performance of proposed ECL devices were evaluated by varying operation voltage of 0.5 V from 2 V to 5 V. As the result, we can achieve high performance of device having a wide operating voltage margin and improved luminance intensity.

The construction of quasi-solid state electrolyte with introduction of Li6.4La3Zr1.4Ta0.6O12 to suppress lithium polysulfides’ shuttle effect in Li-S batteries

Lithium polysulfides (LiPSs) as intermediate products of Li-S batteries (LSBs) are easily dissolved into liquid electrolyte, which will shorten the cycling lifespan, hinder the rate capability, and confront severe self-discharge. Herein, we report a quasi-solid state electrolyte based on introduction of Li6.4La3Zr1.4Ta0.6O12 (LLZTO) into poly(ethylene oxide) (PEO), which possesses ionic conductivity of 0.8 × 10−3 S cm−1 at ambient condition. The LSBs with this quasi-solid state electrolyte exhibit desirable electrochemical behaviors and mitigated self-discharge property.

All-Solid-State Interdigitated Micro-Supercapacitors Based on Porous Gold Electrodes.

Recent developments in embedded electronics require the development of micro sources of energy. In this paper, the fabrication of an on-chip interdigitated all-solid-state supercapacitor, using porous gold electrodes and a PVA/KOH quasisolid electrolyte, is demonstrated. The fabrication of the interdigitated porous gold electrode is performed using an original bottom-up approach. A templating method is used for porosity, using a wet chemistry process followed by microfabrication techniques. This paper reports the first example of an all-gold electrode micro-supercapacitor. The supercapacitor exhibits a specific capacitance equal to 0.28 mF·cm-2 and a specific energy of 0.14 mJ·cm-2. The capacitance value remains stable up to more than 8000 cycles.

A quasi-solid polymer electrolyte initiated by two-dimensional functional nanosheets for stable lithium metal batteries.

Lithium-metal batteries (LMBs) are expected to serve as next-generation energy storage systems due to their high theoretical energy density. However, their practical application is largely impeded due to the safety risks that arise from the uncontrollable Li dendrite growth and the high reactivity between high flammability liquid organic electrolytes and metallic lithium. Here, we report a highly safe quasi-solid gel polymer electrolyte (GPE) to achieve stable cycling of lithium metal with high coulombic efficiency, and it is prepared by in situ polymerization of 1,3-dioxolane (DOL) assisted by multi-functional H3Sb3P2O14 sheets. H3Sb3P2O14 acts as an initiator and a functional additive simultaneously that promotes the formation of a stable solid electrolyte interface (SEI) layer, thereby regulating the uniform deposition of Li and improving the Li plating/stripping efficiency. The obtained quasi-solid GPE exhibits high ionic conductivity and enhanced oxidative stability, favoring a stabilized electrode/electrolyte interface. Using the GPE, the electrochemical performance of the quasi-solid-state LMB with a LiFePO4 cathode and a lithium metal anode is significantly improved, delivering a discharge capacity of 125.7 mA h g-1 even after 1000 cycles. Therefore, the high reversibility and remarkable battery cyclability suggest that such a GPE is a promising choice of electrolyte for LMBs, while its facile preparation makes its large-scale application possible in the future.

Fiber-reinforced quasi-solid polymer electrolytes enabling stable Li-metal batteries

Glass-fiber-reinforced polymeric films for a stable Li-metal electrode: unraveling the key attributes of efficient protecting layers.

Self-healable, super Li-ion conductive, and flexible quasi-solid electrolyte for long-term safe lithium sulfur batteries

Flexible polymer electrolytes exhibit high self-healing abilityviahydrogen/disulfide bonds and simultaneously achieve both high ion conductivity and excellent thermal/mechanical stabilityviaself-assembly for long-term safe lithium sulfur battery.

Enhancement of interfacial sodium ion transport stability in quasi-solid-state sodium-ion batteries using polyethylene glycol

The dendrite growth and solvent volatilization of quasi-solid-state sodium-ion batteries were inhibited by PEG modification of quasi-solid electrolytes.

Flexible self-powered photoelectrochemical-type photodetectors based on Bi2O2S/GO composites

Flexible Bi2O2S/GO photodetector with KOH quasi-solid electrolyte demonstrates excellent photoresponse and mechanical flexibility. It also shows outstanding, stable self-powering capabilities without an external power supply.

Lithium salt-regulated dual-stabilized elastomeric quasi-solid electrolyte for high-voltage lithium metal batteries

An elastomeric quasi-solid electrolyte was fabricated by the incorporation of LiDFOB. LiDFOB facilitated uniform lithium deposition morphology and decomposed to form a LiF-rich CEI to enhance the high-voltage (4.7 V) battery performance.

Confined in-situ polymerization of poly(1,3-dioxolane) and poly(vinylene carbonate)-based quasi-solid polymer electrolyte with improved uniformity for lithium metal batteries

In-situ polymerization to prepare solid/quasi-solid electrolytes for lithium batteries has been extensively researched in recent years, owing to its unique superiority in achieving good physical contact with rigid electrodes. However, the uniformity of in-situ polymerized electrolytes at elevated temperatures remains a challenge, which may be influenced by the uneven heat distribution during polymerization. In this work, we demonstrate a novel confined in-situ polymerization method, which allows the fabricated electrolytes with dual polymer networks to enhance the electrolyte homogeneity. 1,3-Dioxolane (DOL) is firstly cationically polymerized at room temperature, and next vinylene carbonate (VC) is free-radically polymerized at an elevated temperature under the confinement effect of the poly (DOL) skeleton. Using this stepwise strategy, more uniform polymerization of VC under heating treatment can be achieved. The obtained quasi-solid polymer electrolyte possesses a high ionic conductivity at room temperature of 1.98 × 10−3 S/cm, relatively low activation energy of 0.13 V and an oxidation potential up to 4.3 V. Full cell employing LiFePO4 cathode, Li metal anode and the in-situ polymer electrolyte possesses an initial discharge capacity of 117 mAh/g at a charge/discharge rate of 2C, with a high capacity retention ratio of 92.1% after 1500 cycles, showing promising application prospects.

Optimization of polymer blend electrolytes with tuneable conductivity potentials

The potential of electrolytes' performance in electrochemical devices is among the leading research. There are several ways to improve the conductivity of electrolytes, including the employment of additive materials and polymer blends. This research aims to improve the conductivity of a polymer blend with quasi solid state electrolyte. Poly-methyl methacrylate (PMMA) and poly-vinylidene fluoride (PVdF) possed great electrochemical stability and thermal stability. Hence, these materials were chosen as the target polymer for the synthesis of the polymer blend. The electrical impedance spectroscopy (EIS) analysis showed an optimum conductivity value of 3.44 × 10−6 Scm−1 with the ratio of PMMA: PVdF (70:30) at ambient temperature. The dependent temperature of PBE was also analyzed to prove that the conductivity increases with the increment of temperature and low activation energy (Ea). The thermogravimetric analysis (TGA) shows the stability of PBE up to 651 °C. Through this research, there are several different concentrations of PBE to investigate the stability of PBE with great value in the conductivity performance.

Electrophoretically deposited LAGP-based electrolytes - Structure and ion transport in plasticized systems

The development of an efficient devices for energy storage, conversion, and transmission is one of the key priority areas today. At the center of these activities is the development of all-solid-state high-energy and high-power lithium-ion batteries.Our research is focused on the study of ion transport in a plasticized-by-ionic-liquid composite membrane formed by electrophoretic deposition (EPD). The EPD membrane comprises above 85% of high-ion-conductivity ceramic matrix Li1.5Al0.5Ge1.5(PO4)3 (LAGP) and less than 15% polyethyleneimine (PEI). The EPD rate and morphology of the membrane was characterized by ESEM, TOFSIMS and DSC methods. 0.3 M LiTFSI–PYR14TFSI (IL) was infused in the membrane to form a quasi-solid electrolyte. The complex, non-Debye dielectric response of the quasi-solid electrolyte, tested over the temperature and frequency ranges of (−140 °C) to (+100 °C) and 10−2 – 106 Hz, has been described in terms of several distributed relaxation processes separated by different frequency and temperature ranges. While at low temperatures, the main contribution is from LAGP, in the middle- and high-temperature regions, the superposition of a few non-Arrhenius processes is observed. Relaxation is perturbed by clear phase transition related to melting of the ionic liquid. Different scales of the ionic transport and corresponding relaxation of the apparent dipole moment in the materials are discussed.

In situ prepared all-fluorinated polymer electrolyte for energy-dense high-voltage lithium-metal batteries

Solid-state batteries are an emerging technology that delivers significantly higher safety than conventional lithium-ion batteries. However, the energy density of devices still needs to be improved. Herein, a quasi-solid all-fluorinated polymer electrolyte (AFPE) is developed for high-voltage, solid-state, lithium-metal batteries. The AFPE is obtained by polymerizing in situ trifluoroethyl methacrylate in fluorinated ethylene carbonate. The two salts present (LiTFSI and LiDFOB) form LiF- and B-rich solid electrolyte interphases that are highly stable against lithium metal and high-voltage LiCoO2. The corresponding Li|AFPE10|LiCoO2 battery was cycled 500 times at a cut-off voltage of 4.5 V with a 92% capacity retention and 99.82% average Coulombic efficiency. Lithium-metal batteries with high cathode mass loadings up to 25 mg cm−2 and energy densities as high as 546 Wh kg−1 were prepared. This work opens a new avenue of research by developing AFPEs that can be synthesized in situ.

Lithium-Rich Porous Aromatic Framework-Based Quasi-Solid Polymer Electrolyte for High-Performance Lithium Ion Batteries.

The development of solid polymer electrolytes (SPEs) with high ionic conductivity, wide electrochemical window, and high mechanical strength is the key factor to realize high-energy-density solid lithium ion batteries (SLIBs). Porous aromatic frameworks (PAFs) have the advantages of high porosity, easily functionalized molecular structure, and rigid stable framework, which fully meet the requirements of solid polymer electrolytes with high Li+ capacity, fast Li+ transport, and safety. Herein, a lithium-rich amidoxime (AO)-modified porous aromatic framework (PAF-170-AO) was obtained through the absorption of LiTFSI by amidoxime groups and abundant pores and then compounded with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) to prepare a PAF-based quasi-solid polymer electrolyte (PAF-QSPE) with only tiny amounts of plasticizer (∼12 μL). The amidoxime groups of PAF-170-AO restricted the movement of the anions of LiTFSI through hydrogen bonding, which effectively promoted the dissociation and migration number of Li+ (tLi+), reduced the concentration polarization, and inhibited the growth of lithium dendrites. The PAF-QSPE exhibited a high ionic conductivity of 1.75 × 10-4 S cm-1 and tLi+ of 0.55 at room temperature. The activation energy was as low as 0.136 eV. Furthermore, the assembled SLIBs with the PAF-QSPE presented a discharge capacity of 163 mAh g-1 at 0.2 C and a capacity retention rate of 96% after 350 cycles, illustrating a stable cycling performance. This work demonstrated the great application potential of lithium-rich PAFs in QSPEs.

Highly Stretchable, Self-Healing, and Low Temperature Resistant Double Network Hydrogel Ionic Conductor as Flexible Sensor and Quasi-Solid Electrolyte.

With the rapid development of flexible energy storage and wearable strain sensing, conductive hydrogels are attracting attention as electrolyte materials for flexible strain sensors and flexible supercapacitors due to their excellent flexibility and wetting properties. In this work, antifreezing hydrogels with high stretchability, adhesion, and conductivity are designed and prepared by introducing phosphoric acid solutions into polyacrylamide and chitosan systems. The multifunctional hydrogel samples prepared by this method can be used as both quasi-solid electrolytes and wearable strain sensors. The hydrogel-based supercapacitor shows a charge/discharge efficiency of 99.67% and a capacitance retention of 98.85% after 10000 cycles charge/discharge tests at -30°C. The tiny characteristic heartbeat wave forms are detected by the hydrogel as a flexible strain sensor. It is foreseeable that PCP multifunctional hydrogel can be a promising flexible material for a new generation of flexible sensors and flexible energy storage devices in a certain range of temperatures.

Electrospun derived polymer-garnet composite quasi solid state electrolyte with low interface resistance for lithium metal batteries

Polymer garnet composite electrolyte is a promising stable electrolyte to replace the hazardous/unstable liquid electrolytes in lithium-ion batteries due to their synergistic advantage of solid organic polymer electrolytes and inorganic ceramic electrolytes. Herein, we report polymer blend-based garnet composite quasi solid state electrospun electrolytes for lithium metal batteries. To be specific, Ta doped lithium lanthanum zirconium oxide, Li6·4La3Ta0·6Zr1·4O12 (LLZTO) incorporated with poly (vinyldine fluoride-hexafluro propylene) (PVdF-HFP)/poly butyl methacrylate (PBMA) electrospun membrane as the composite electrolyte, named as Ta-ESM and similarly, LLZTO free electrolyte named as ESM. The inclusion of LLZTO into the polymer matrix enhances the room temperature ionic conductivity from 9.924 × 10−4 (ESM) to 4.858 × 10−3 S cm−1 (Ta-ESM) along with lithium-ion transference number (0.61). Furthermore, polymer garnet composite electrolytes (Ta-ESM) restraint the growth of lithium dendrites, confirmed by the time-dependent impedance method and galvanostatic cycling technique. We have demonstrated the charge-discharge behaviour of lithium-metal battery using LiFePO4 cathode and lithium metal anode using Ta-ESM electrolyte, delivering 178 mA h g−1 at 0.1C and cyclability of 100 cycles. The high electrolyte uptake (582%) and porosity (64.1%) in Ta-ESM help achieve fast ionic migration and thus attain stable cycling.

In situ cross-linked plastic crystal electrolytes toward superior lithium metal batteries

The low ionic conductivity and unstable electrolyte/electrode interface of solid-state electrolytes are the key issues hindering the progress of solid-state lithium batteries. Herein, a cross-linked succinonitrile (SN)-based solid-state electrolyte was synthesized by in situ thermal polymerization using polyethylene glycol diacrylate, vinyl carbonate, and SN. Vinyl carbonate and polyethylene glycol diacrylate are cross-linked to form a polymer network structure, which can immobilize SN and lithium difluoro(oxalato)borate in the electrolyte, thereby preventing the side reactions of SN and lithium metal. The as-prepared quasi-solid gel electrolyte exhibits a wide electrochemical window (5.3 V vs. Li+/Li), a high ionic conductivity (0.3 mS/cm), a good lithium-ion transfer number (0.58) at room temperature, and good interfacial stability between the electrodes and electrolyte. Therefore, cross-linked SN-based polymer electrolyte not only enables reversible lithium anode stripping/plating and impedes side reactions on the anode side but also accommodates high voltage cathode materials. The LiCoO2/Li cell shows a high specific capacity of 140 mAh/g, with a capacity retention rate of 87.2% after 350 cycles and a stable coulombic efficiency of about 99.5% at an operating voltage of 2.75∼4.3 V. This work paves a new path for designing high-safety electrolytes and facilitating the practical application of high-voltage lithium metal batteries.