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Li+ ion conduction in two aligned liquid crystalline electrolytes consisting of 10 mol% Li+ salt of a pro-mesogenic anion derived from [closo-1-CB11H12]− in non-ionic hosts was investigated. Using electrochemical impedance spectroscopy (EIS), the ionic conductivity in the parallel (σ‖) and perpendicular (σ⊥) directions of the electrolyte samples was determined using two types of cells: an interdigitated gold electrode and a nylon 6-coated ITO cell. The ratio of ionic conductivities σ⊥/σ‖ in the electrolyte with a nona(ethylene oxide) spacer was about 3 in the entire SmA phase, while in the shorter homologue, the ratio monotonically increases from about 0.4 to 2.9. The liquid crystalline behavior of the hosts and the electrolytes was investigated by optical, thermal, and powder XRD methods. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DES) exhibit comparable thermal and chemical stability to ionic liquids, coupled with excellent ionic conductivity. Moreover, they boast a higher degree of safety owing to lower toxicity and increased accessibility. Hence, the utilization of DES in gel preparation emerges as an effective solution to address the challenges associated with the inadequate stability of traditional hydrogels and the heightened toxicity of gels composed of ionic liquids. In this paper, eutectogels with excellent low-temperature sensing properties were prepared by using methacrylic acid (MAA) and pyrrole (Py) as monomers and DES as solvent. The eutectogel exhibits excellent sensing capability, with a gauge factor reaching 5.21. Additionally, DES prepared using choline chloride and urea endows the eutectogel with good freeze resistance, enabling sensing at −20 °C while maintaining stability. Moreover, the eutectogel accurately monitors changes in environmental temperature, providing a promising material for temperature-measuring flexible wearable sensor applications. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries (ZIBs) offer numerous advantages, such as high energy density, enhanced safety, and low cost, making them an ideal choice for energy storage and conversion applications in the “postlithium” era. Hydrogel electrolytes, as the key component of flexible ZIBs, combine the ionic conductivity of traditional water electrolytes with the dimensional stability of solid polymer electrolytes. However, it remains a challenge to design comprehensive and appropriate hydrogel electrolytes to provide flexible ZIBs with good reversibility and versatility. This review discusses the engineering design of hydrogel electrolytes required for flexible ZIBs from the viewpoint of an electrolyte designer. The basic properties of the hydrogel electrolytes, zinc anodes, cathodes and electrolyte stabilization effects are described in detail. Furthermore, we explore the various challenges faced by hydrogel electrolytes and propose corresponding strategies. Finally, the review offers insights into the future development of hydrogel-stabilized ZIBs. [ABSTRACT FROM AUTHOR]

The current study focuses on the development of an antibacterial, conducting and biocompatible nanocomposite for wound healing applications comprising of polyvinyl alcohol (PVA), chitosan (CS), graphene oxide (GO), and zinc oxide–silver oxide composite (ZnO–Ag2O) through the solution casting method. The XRD, FTIR, Raman as well as the FESEM–EDAX results confirmed the presence of the ternary nanocomposite at different concentrations (5–15 wt%) in the polymer system. Additionally, variations in the surface roughness of the polymer composites were documented through the AFM images. The highest ionic conductivity value of 0.345 × 10−4 S cm−1 was reported for PVA–CS–GO–ZnO–Ag2O (5 wt%). The nanoparticles as well as polymeric nanocomposites showcased superior antibacterial activity against both E. coli and S. aureus. Furthermore, the prepared polymeric composites exhibited excellent cytocompatibility towards RBCs as well as RAW 264.7 cells. Hence, the developed polymeric composite exhibiting outstanding antibacterial efficacy, improved ionic conductivity, and excellent biocompatibility holds promise as an innovative candidate for the formulation of advanced wound dressings. [ABSTRACT FROM AUTHOR]

The slow Li+ transport rate in the thick sulfur cathode of the Li--S battery affects its capacity and cycling performance. Herein, Fe-doped highly ordered mesoporous silica material (Fe--HSBA-15) as a sulfur carrier of the Li--S battery shows high ion conductivity (1.10 mS cm-1) and Li+ transference number (0.77). The Fe--HSBA-15/S cell has an initial capacity of up to 1216.7 mA h g-1 at 0.2C and good stability. Impressively, at a high sulfur load of 4.34 mg cm-2, the Fe--HSBA-15/S cell still maintains an area specific capacity of 4.47 mA h cm-2 after 100 cycles. This is because Fe--HSBA-15 improves the Li+ diffusion behavior through the ordered mesoporous structure. Theoretical calculations also confirmed that the doping of iron enhances the adsorption of polysulfides, reduces the band gap and makes the catalytic activity stronger. [ABSTRACT FROM AUTHOR]

Due to the inherent limitations of commercial liquid electrolytes, such as flammability, volatility, leakage, and their inability to effectively inhibit the growth of lithium dendrites, the lithium battery research community has shifted its attention towards advancing solid-state electrolytes. Notably, polyethylene oxide (PEO) has emerged as a respected solid-state electrolyte, but its ionic conductivity still exhibits a relatively modest level. In this study, we fabricated the Li-IL@Fe-BDC composite by integrating lithium salt-loaded ionic liquids (Li-ILs) into cost-effective and environmentally friendly Fe-based MOF frameworks (Fe-BDC). The resulting composite filler was then incorporated into a PEO matrix, yielding flexible composite polymer electrolytes (CPEs) with a "brick and mortar" hybrid structure. This unique arrangement enhances the mechanical strength of CPEs, providing dispersed sites and multi-ion transport channels. Consequently, it achieves a high conductivity of approximately 4.9 × 10-4 S cm-1, an extended electrochemical window of about 4.8 V, and a notable Li+ transference number of ~0.6. Moreover, the composite demonstrates excellent interfacial compatibility with the Li metal and remarkable resistance against dendrite growth during plating/stripping cycles, sustaining over 800 hours at a current density of 0.2 mA cm-2. Furthermore, LiFePO4/CPEs/Li cells exhibit outstanding capacity retention, reaching as high as 95.8% after 700 cycles at 1 C. These exceptional electrochemical performances can be attributed to the distinctive characteristics of the Li-IL@Fe-BDC composite filler, which provides multiple pathways for lithium ion migration and enhances interfacial stability. Consequently, this study unveils a promising approach for achieving high Li-ion conductivity and interfacial stability in CPEs, offering valuable insights for future breakthroughs in this burgeoning field with a focus on green chemistry principles. [ABSTRACT FROM AUTHOR]

Flexible supercapacitors (SCs) using gel polymer electrolytes (GPEs) have attracted increasing attention given the popularity of portable and wearable electronics. However, the facile preparation of GPEs with not only outstanding mechanical and electrochemical properties but also recyclability, flame-resistance and sustainability is still a challenge. Herein, a dual cross-linking strategy was developed using levulinic acid (LA) and sodium borate to engineer chitosan into flame-resistant and recyclable GPEs with satisfactory mechanical properties and high ionic conductivity for application in flexible SCs. In this strategy, LA functioned as a protonation reagent to make chitosan soluble in water and a crosslinker via imine formation between its ketone groups and the amino groups of chitosan to form a crosslinked polymer network. Sodium borate functioned as not only a cross linker but also an ionic conductor and flame retardant in the GPEs. The engineered GPEs exhibited high flame-resistant ability (self-extinguishing time <1 s), desirable mechanical performance (0.87 MPa), and high ionic conductivity (24.02 mS cm−1). The assembled flexible SC exhibited a high energy density of 14.58 W h kg−1 and cycling stability over 35 000 cycles. Furthermore, benefiting from the pH sensitivity of the formed imine bonds, the GPEs could be easily degraded in acidic conditions, and then recycled for the fabrication of other GPEs. Overall, it is believed that the as-prepared eco-friendly and safe electrolyte shows great promise for applications in consumable electronics. [ABSTRACT FROM AUTHOR]

Understanding how microscopic mechanisms govern macroscopic transport properties is important for development of improved electrolytes for Li-ion batteries. The archetypal polymer electrolyte PEO–LiTFSI has been investigated for more than three decades, but the fundamental ion transport mechanisms are still elusive. Molecular Dynamics (MD) simulations enable us to determine transport properties by directly probing particle movements. Both transport properties and microscopic interactions that govern them can be studied simultaneously. In this work, ionic conductivity and transport numbers of PEO–LiTFSI electrolytes are computed as a function of salt concentration and PEO chain length. The values are obtained using the Nernst–Einstein approximation for dilute or ideal systems, in addition we determine the Onsager coefficients that take into account ionic correlations. We observe significant differences between the two methods, indicating non-ideality. The motion of Li and TFSI is anticorrelated, causing super-ionicity. We discuss the relevance of the frame of reference. The static and dynamic properties of Li-ion coordination environments are analyzed. The distributions of cation-solvent and cation–anion residence times are investigated and indicate that the TFSI facilitate Li transport and Li jumps in the polymer network. Finally, the thermodynamic factors are computed and used to quantify the non-ideality of the systems. [ABSTRACT FROM AUTHOR]

Alkaline anion exchange membranes (AAEMs) have drawn more attention in recent days due to the ample advantages that the membranes possess for potential applications in electrochemical systems. In an attempt to make a highly conducting and stable anion exchange membrane, this work is devoted to the development of a morphologically tailored, partially fluorinated anion exchange polymer with quaternary ammonium functionalities. Herein, the quaternized partially fluorinated anion exchange polymers are prepared via an easy and facile synthetic route, which is a unique and new approach in the research domain of anion exchange membranes. Structural confirmation of the synthesized partially fluorinated aromatic copolymers was accomplished by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopic analyses. The morphological features of the anion exchange membrane with an interconnected network structure as revealed by microscopic techniques are rather interesting. Thermal analysis revealed the high thermal stability of these copolymers and their corresponding anion exchange membranes. The optimized anion exchange membrane with a proper ratio of anion exchange polymer and poly(vinylidene fluoride) (PVDF) showed an ionic conductivity as high as 1.0 × 10−2 S cm−1 and an ion-exchange capacity of 1.7 mmol g−1; a membrane electrode assembly comprising the developed membrane and Ni@Ni-foam electrodes demonstrated stable performance for ∼200 h in a water electrolyser cell. [ABSTRACT FROM AUTHOR]

A gel polymer electrolyte (GPE) supported by a polyimide (PI) nanofiber membrane with Li6.5La3Zr1.5Ta0.5O12 (LLZTO) nanoparticles (PI/LLZTO/GPE) shows excellent flexibility and electrochemical properties, the ionic conductivity is 1.87 mS cm−1 and the Li+ transfer number is 0.64 at room temperature. The assembled Li metal battery with a LiFePO4 (LFP) cathode retains a 56.4 mA h g−1 discharge capacity at 10C. [ABSTRACT FROM AUTHOR]

Germanium nanowire (GeNW) electrodes have shown great promise as high-power, fast-charging alternatives to silicon-based electrodes, owing to their vastly improved Li ion diffusion, electron mobility and ionic conductivity. Formation of the solid electrolyte interphase (SEI) on the anode surface is critical to electrode performance and stability but is not completely understood for NW anodes. Here, a systematic study characterizing pristine and cycled GeNWs in charged and discharged states with SEI layer present and removed is performed using Kelvin probe force microscopy in air. Correlating changes in the morphology of the GeNW anodes with contact potential difference mapping at different cycles provides insight into SEI layer formation and growth, and the effect of the SEI on battery performance. [ABSTRACT FROM AUTHOR]

Traditional metal–organic-frameworks (MOFs) have been extensively studied and applied in various fields across chemistry, biology and engineering in the past decades. Recently, a family of emerging MOF liquids and glasses have gained ever-growing research interests owing to their fascinating phase transitions and unique functions. To date, a growing number of MOF crystals have been found to be capable of transforming into liquid and glassy states under external stimuli, which overcomes the limitations of MOF crystals by introducing functional disorder in a controlled manner and offering some desirable properties. This review is dedicated to compiling recent advances in the fundamental understanding of the phase and structure evolution during crystal melting and glass formation in order to give insights into the underlying conversion mechanism. Benefiting from the disordered metal–ligand arrangement and free grain boundaries, various functional properties of liquid and glassy MOFs including porosity, ionic conductivity, and optical/mechanical properties are summarized and evaluated in detail, accompanied by the structure–property correlation. At the same time, their potential applications are further assessed from a developmental perspective according to their unique functions. Finally, we summarize the current progress in the development of liquid/glassy MOFs and point out the serious challenges as well as the potential solutions. This work provides perspectives on the functional applications of liquid/glassy MOFs and highlights the future research directions for the advancement of MOF liquids and glasses. [ABSTRACT FROM AUTHOR]

Ionic liquid (IL)-based gels (ionogels) have received considerable attention due to their unique advantages in ionic conductivity and their biphasic liquid–solid phase property. In ionogels, the negligibly volatile ionic liquid is retained in the interconnected 3D pore structure. On the basis of these physical features as well as the chemical properties of well-chosen ILs, there is emerging interest in the anti-bacterial and biocompatibility aspects. In this review, the recent achievements of ionogels for biomedical applications are summarized and discussed. Following a brief introduction of the various types of ILs and their key physicochemical and biological properties, the design strategies and fabrication methods of ionogels are presented by means of different confining networks. These sophisticated ionogels with diverse functions, aimed at biomedical applications, are further classified into several active domains, including wearable strain sensors, therapeutic delivery systems, wound healing and biochemical detections. Finally, the challenges and possible strategies for the design of future ionogels by integrating materials science with a biological interface are proposed. [ABSTRACT FROM AUTHOR]

A Li6PS5Cl-rich composite is prepared using a PEG-borate ester solid-state polymer electrolyte (BSPE). BSPE is a highly accessible compound with high ionic conductivity and excellent electrochemical stability against Li metal. Thereby, the stability of the Li6PS5Cl-rich composite with BSPE improved significantly. [ABSTRACT FROM AUTHOR]

In order to overcome the tradeoff between the mechanical and electrochemical properties of polymer electrolytes, a novel semi-interpenetrating network structure is proposed. It can effectively solve the problems of low conductivity, poor interface stability, and weak mechanical strength of polymer electrolytes. Specifically, we use a plastic crystal composite polyacrylate polymer electrolyte doped with PVDF-HFP and after in situ UV curing, the polymer matrix with a semi-interpenetrating structure is formed by linear PVDF-HFP and cross-linked polyacrylate network structure (S-PCCE). A significant feature of the semi-interpenetrating network structure is the fine integration of the cross-linked polymer network and the linear polymer, resulting in synergistic effects that can improve the flexibility, mechanical strength, and ionic conductivity of the plastic-crystal composite polymer electrolyte. The ionic conductivity can reach 1.45 × 10−3 S cm−1 at room temperature and 4.8 × 10−3 S cm−1 at 60 °C, which is conducive to high battery performance. The LiFePO4/S-PCCE/Li battery has an initial discharge specific capacity of 156 mA h g−1 and a maximum discharge specific capacity of 163 mA h g−1 at 0.2C. After 50 cycles, the battery can still maintain a high discharge specific capacity of 155 mA h g−1 and a Coulomb efficiency of 99.4%. At the same time, the thermogravimetric curve shows that the electrolyte has good adaptability to high temperatures. Therefore, polymer electrolytes with a semi-interpenetrating network structure have good application prospects. [ABSTRACT FROM AUTHOR]

The thrust towards a higher energy density and safer alternative to traditional-liquid-electrolyte-based batteries has driven academic and industrial efforts in developing solid-state batteries and particularly solid-state Li/Na–metal batteries (SSLMBs/SSNMBs). Despite research on solid electrolytes seemingly being on a perpetual trajectory, there have been considerable critical issues to be overcome for solid electrolytes, including the insufficient ionic conductivity, low ion-transference number, and poor compatibility with lithium–metal anodes and intercalation cathodes. This feature article sets out efforts to regulate the cubic structure of garnet-type electrolytes, along with a discussion of the solid-solution synthetic approach to produce garnet-type and NASICON (sodium super ion conductor)-type electrolytes, followed by the synthetic strategy for sintering dense nano-grained NASICON-type electrolytes. Next, the mechanochemical synthetic approach and hybrid electrolyte design strategy to mitigate the issues associated with PEO-based composite electrolytes are presented. Finally, the advancement of promising polymeric electrolytes is discussed. We end the perspective with an opinion on the future research in this area. [ABSTRACT FROM AUTHOR]

A ternary-salt solid polymer electrolyte (TS-SPE) consisting of LiPF6-LiTFSI-LiFSI salts and poly(1,3-dioxolane) is created by in situ polymerization. The TS-SPE possesses high ionic conductivity, high Li+ ion transference number, and stable SEI with low interfacial impedance, thereby realizing excellent rate performance and long-life stability in Li metal batteries. [ABSTRACT FROM AUTHOR]

We report, for the first time, the preparation and ionic conductivity of a Mg2+-containing metal–organic framework (MOF) having type A features, i.e., an anionic framework containing Mg2+ as the counter cation. We prepared Mg3[(MnMo6O18)2L] (L12− = C{C6H4CH＝NC(CH2O)3}412−) (MOF-688-Mg) through a simple ion exchange reaction, and it showed high ionic conductivity above 10−5 S cm−1 at 25 °C under MeCN vapor. [ABSTRACT FROM AUTHOR]

Li–O2 batteries are actively being investigated due to their high theoretical energy density (∼11 000 Wh kg−1), which would compete with gasoline energy per Kg in electric vehicles. Linear glymes are the most appealing electrolytes for Li–O2 batteries due to their large electrochemical window, stability against radicals and solubility of Li+ metal ions. However, all these superior properties are tarnished by their high toxicity. Herein, a greener glyme derived from bio-sourced glycerol (1,2,3-trimethoxypropane (TMP)), is proposed for the first time as a solvent in an electrolyte for Li–O2 batteries. TMP performance has been compared to its toxic linear isomer, diglyme, and most popular tetraglyme as a liquid electrolyte and gel polymer electrolyte (GPE) membranes. GPEs were based on a mix of mono-, di- and tri- functional acrylates, cured simultaneously within a liquid electrolyte mix (1 M LiTFSI in the plasticizers) by UV-photopolymerisation. GPE-TMP based membranes showed a high ionic conductivity (2.33 × 10−3 S cm−1 at 25 °C), directly comparable to the other glymes. Moreover, this remarkable conductivity was very close to the liquid TMP-based electrolyte (3.59 × 10−3 S cm−1 at 25 °C). When used as electrolytes in lithium symmetrical cells, the GPE-TMP electrolyte enhanced the polarisation when compared to the liquid TMP-based cells, especially at higher rates (<0.6 V observed at ±1 mA cm−2). Performance in Li–O2 cells showed that GPE-TMP electrolytes achieved a discharge capacity as high as 2.75 mA h cm−2 (3819 mA h g−1), ahead of GPE-diglyme or GPE-tetraglyme electrolytes (2.34 and 2.09 mA h cm−2, respectively). When cycled, cells using TMP-based electrolyte had a similar capacity retention than the ones with tetraglyme, confirming the potential use of TMP as solvent/plasticizer in electrolytes for Li–O2 cells. [ABSTRACT FROM AUTHOR]

Polyethylene oxide (PEO) based polymer electrolytes have been widely used in solid-state lithium batteries (SSBs) owing to the high solubility of lithium salt, favourable ionic conductivity, flexibility for improved interfacial contact and scalable processing. In this work, we summarize the main limitations remaining to be solved before the large-scale commercialization of PEO-based SSBs, including (1) improving ionic conductivity toward high-rate performance and lower operating temperature, (2) enhancing mechanical strength for improved lithium dendrite resistance and large-scale processing, (3) strengthening electrochemical stability to match high energy density electrodes with high voltage, and (4) achieving high thermal stability toward safe operation. Meanwhile, the characterization methods to investigate the ion transportation mechanism, lithium dendrite growth and decomposition reaction are also discussed. [ABSTRACT FROM AUTHOR]

A thin free-standing composite solid electrolyte film (CSE, ∼15 μm) is prepared by a tape casting and solution infusion method, which owns a high ionic conductivity (2.76 × 10−4 S cm−1 at 25 °C) and a wide electrochemical stability window (4.8 V vs. Li+/Li). The CSE-based solid-state lithium metal batteries with the LiCoO2 cathode present good cycling stability and capacity retention with a 4.5 V cut-off voltage. [ABSTRACT FROM AUTHOR]

Solid polymer electrolytes (SPEs) for lithium metal batteries (LMBs) exhibit predominant safety over traditional carbonate-based organic liquid electrolytes. However, the low ionic conductivity of SPEs related to crystallinity at room temperature still hinders their practical application. The incorporation of nonflammable and ion-conductive ionic liquids (ILs) as plasticizer agents plays an active role in suppressing crystallinity. Herein, the relationship between the cations for ILs and the cycling performance of Li/LiFePO4 batteries were investigated. EMIM+ demonstrates the best ability for reversible Li+ intercalation/deintercalation behavior over other cations due to its superior cationic solvation, highest ion conductivity and lowest viscosity. The Li/LiFePO4 batteries based on the optimized EMIM+-encapsuled ionogel electrolyte could operate steadily over 120 cycles at 0.5C and room temperature. The results illustrate that the IL-plasticized hybrid electrolyte is a promising electrolyte candidate for room temperature solid state LMBs with high energy densities. [ABSTRACT FROM AUTHOR]

All-solid-state lithium batteries (ASSLBs) have attracted increasing attention recently because they are more safe and have higher energy densities than conventional lithium-ion batteries. In particular, ASSLBs composed of Ni-rich cathodes, sulphide-based solid-state electrolytes (SSEs) and lithium metal anodes have been regarded as the most competitive candidates. Ni-rich cathodes possess high operating potential, high specific energy and low cost, and sulphide-based SSEs have excellent ionic conductivity comparable to that of liquid electrolytes. However, severe parasitic reactions and chemo-mechanical issues hinder their practical application. Herein, the structure, ionic conductivity, chemical or electrochemical stability and mechanical property of sulphide-based SSEs are introduced. Critical interfacial problems between Ni-rich cathodes and sulphide-based SSEs, including chemical or electrochemical parasitic reactions, space charge layer effect, mechanical stress and contact loss, are summarised. The corresponding solutions including coating layer construction and structure design are expounded. Finally, the remaining challenges are discussed, and perspectives are outlined to provide guidelines for the future development of ASSLBs. [ABSTRACT FROM AUTHOR]

A high-performance gel polymer electrolyte (GPE) based on polyvinylidene fluoride (PVDF) and natural lignocellulose (LC) was successfully prepared via a simple coating method. The mechanical strength of the composite membrane is greatly enhanced and the dissociation of lithium salt is significantly promoted. Additionally, when the content of PVDF is 30 wt%, the prepared composite membrane presents high liquid electrolyte (LE) uptake (205 wt%) and excellent thermal stability. The corresponding GPE exhibits high ionic conductivity of 1.44 mS cm-1 and good compatibility with the lithium anode. Moreover, the corresponding Li8GPE8LiFePO4 battery maintains a relatively high capacity after being tested for 300 cycles at a rate of 1.0C, showing excellent cycle performance. [ABSTRACT FROM AUTHOR]

The addition of a small amount of plant biomass-based lignin causes a large improvement in the ionic conductivity of composite polymer electrolytes at room temperature, which can be fabricated easily in a low carbon way for use in future all-solid-state battery applications. [ABSTRACT FROM AUTHOR]

The presence of hydroxyl groups that can act as active sites to interact with cations has led to the potential usage of disaccharides as plasticisers. In this research, density functional theory (DFT) was used to understand theoretically the effect of disaccharides such as sucrose and lactose on chitosan chains. Theoretical studies showed that the chitosan–disaccharide combination weakens the hydrogen bond in the chitosan molecular chain itself. The effect of disaccharides on the electrochemical properties of chitosan-based solid polymer electrolytes (SPEs) was further confirmed experimentally. Chitosan-based SPEs incorporated with lithium nitrate (LiNO3) and disaccharides were produced via a solution casting technique. Electrochemical impedance spectroscopy (EIS) analysis showed that the highest ionic conductivity for both types of disaccharides was at 15 weight percent (wt%) and the incorporation of disaccharides in chitosan increased the lithium transference number (TLi+) in the chitosan-based SPEs to ∼0.26. This study proved the potential of disaccharides as plasticisers for polymer electrolyte system-based chitosan as they can increase the flexibility of chitosan molecular chains, thus enhancing the conductivity and dissociation of ions. [ABSTRACT FROM AUTHOR]

1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI–TFSI) is one type of ionic liquid (IL) that has attracted much attention for its application as a lithium-ion battery electrolyte due to its large diffusion coefficient, wide temperature range of the liquid form, and high thermal stability. To gain insight into the performance of EMI–TFSI, the intermolecular interactions and temperature-concentration dependence of ion transport in EMI–TFSI/LiTFSI electrolytes were investigated using density functional theory (DFT) and molecular dynamics (MD). The DFT calculation results showed that a strong donor–acceptor interactions between the lone pair (LP) electrons of TFSI− and the lone vacant (LV) orbital of Li+ lead to a higher stabilization energy of the EMI–TFSI/LiTFSI system (88.47 kcal mol−1) compared to that of pure EMI–TFSI (48.52 kcal mol−1). The intermolecular interactions that occur among the ions consist of non-covalent and weak electrostatic interactions which are stabilized by a strong non-bonded attraction and steric interactions. The ionic transport properties calculated by MD simulations showed that the increase of Li+ ion concentration could decrease the diffusion coefficients and ionic conductivities of the system. Further analysis of the temperature–concentration dependence of EMI–TFSI/LiTFSI electrolyte transport showed that an optimum value of lithium-ion conductivity (σLi+) can be achieved using a moderate Li+ ion concentration (xLi) between 0.1 to 0.2, dependent on the temperature. In addition, we found that the highest lithium-ion conductivity (σLi+) at 298 K was 6.82 × 10−5 S cm−1 at xLi = 0.15, which increased to 5.15 × 10−4 S cm−1 at 338 K. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) metal–organic framework containing Li-oxygen clusters, namely {[Li2(IPA)]·DMF}n (1) (H2IPA = isophthalic acid), has been constructed under solvothermal conditions. The Li-based MOF can be applied to lithium energy storage. For example, it shows good compatibility with a PEO (LiTFSI) solid-state polymer electrolyte (SSPE). The PEO (LiTFSI) with the MOF additive shows an ionic conductivity of 1.1 × 10−5 S cm−1 at room temperature. The 1D rhombic channels should facilitate lithium ion transportation and provide fast lithium ion pathway. Having assembled the PEO-MOF SSPE in a Li/Li symmetric cell and cycled at a current density of 0.1 mA cm−2, the polarization voltage was below 0.1 V during a 100 h test. The PEO-MOF SSPE was also used in a LiFePO4-Li full cell and a high specific capacity of 144 mA h g−1 was achieved. [ABSTRACT FROM AUTHOR]

In the state-of-the-art lithium-ion battery, sustainability and safety have often been 'sacrificed' in favor of 'performance' and 'cost'. Regarding the electrolyte, volatile and flammable solvents and highly toxic fluorinated lithium salts need replacements. Thus, the first fluorine-free ternary polyethylene oxide-based polymer electrolyte plasticized with ionic liquid (IL) is hereby presented using the non-fluorinated 4,5-dicyano-1,2,3-triazolate (DCTA) as the anion for both conducting lithium salt and the IL plasticizer, respectively. Due to its low molecular weight, membranes with a high molar percentage of IL can be achieved, up to a PEO : LiDCTA : Pyr14DCTA ratio of 20 : 2 : 4, without crosslinking the polymer part. DCTA membranes feature glass transition temperatures (Tgs) and ionic conductivities in the same range as their bis(trifluoromethanesulfonyl)imide (TFSI) analogs and much higher transference numbers. The 20 : 2 : 4 membrane has a Tg of −55.4 °C and an ionic conductivity of 5.2 × 10 4 S cm−1 at 40 °C. LFP‖‖Li metal cells devoid of any critical raw materials and including this non-fluorinated TSPE were successfully cycled 300 times. [ABSTRACT FROM AUTHOR]

Nickel–iron based layered double hydroxide (NILDH) was used for the first time as an inorganic filler to prepare poly(ethylene-oxide)/nickel–iron based layered double hydroxide (PEO/NILDH) composites to improve the properties of PEO-based solid electrolytes. The SEM micrographs and EDS images confirmed the homogeneous dispersion of NILDH particles in the PEO matrix. The XRD and DSC results indicated that the PEO crystallinity tended to decrease with the increase in the amount of NILDH. Meanwhile, the addition of NILDH promoted the improvement of ionic conductivity for PEO/NILDH composites and the maximum value (1.644 × 10−4 S cm−1) appeared at the NILDH concentration of 10 wt%. NILDH with a positive charge surface could increase the lithium-ion transference number by attracting and anchoring the anion of LiTFSI. Meanwhile, the formation of amorphous regions around NILDH was beneficial for the Li+ ion conduction. Furthermore, the electrochemical stability windows of the composite electrolyte were increased to 5.2 V after the addition of NILDH, and the all-solid-state lithium battery using this composite electrolyte showed a specific capacity of 148 mA h g−1 and better cycling performance. The tensile strength of PEO/NILDH composites was enhanced when NILDH was introduced into the PEO matrix with a filler loading of not more than 10 wt%. The remarkable properties of the PEO/NILDH composite make it a potential solid electrolyte material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

A polymer electrolyte with high elasticity and high performance is prepared by IN SITU polymerization. The polymer electrolyte is amorphous and has a high ionic conductivity of 7.9 × 10−4 S cm−1 and good elasticity. The discharge capacity of Li/LiFePO4 in the 100th cycle is 133.90 mA h g−1 (0.5C, 25 °C). [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) emerging as a type of functional material have been widely used in electrochemical energy storage and conversion in recent years. Hollow MOFs with a large pore volume and surface area can increase the contact area between active materials and electrolytes, thus improving the ionic conductivity of the materials. Herein, we obtained a kind of hollow MOF (ZIF-8) using carboxylate-terminated polystyrene microspheres as exterior templates. Transmission electron microscopy and N2 adsorption/desorption analysis revealed that the average cavity diameter of hollow ZIF-8 is 1 μm. Moreover, hollow ZIF-8 exhibits excellent electrochemical quality with an ionic conductivity of 7.36 × 10−4 S cm−1, a lithium ion transference number of 0.83 and an activation energy of 0.15 eV in a wide stable electrochemical window of 2.0–6.5 V at room temperature. Compared with the traditional non-hollow ZIF-8, the electrochemical performance has been improved obviously. Consequently, our strategy of fabrication of large pore volume hollow MOFs provides a new perspective for the development of solid electrolytes with excellent lithium ionic conductivity. [ABSTRACT FROM AUTHOR]

We report a rare-earth triflate catalyst Sc(OTf)3 for the ring-opening polymerization of 1,3-dioxolane and the in situ production of a quasi-solid-state poly(1,3-dioxolane) electrolyte, which not only demonstrates a superior ionic conductivity of 1.07 mS cm−1 at room temperature, but achieves dendrite-free lithium deposition and a high Coulombic efficiency of 92.3% over 200 Li plating/striping cycles. [ABSTRACT FROM AUTHOR]

The role of diketopyrrolopyrrole (DPP-H) as an additive on the ionic conductivity of poly(ethylene oxide) (PEO)-based gel polymer electrolytes (GPE) was studied for DSSC applications. The pure PEO/PC/KI/TPAI/I2 GPE was prepared with a mixture of propylene carbonate (PC) as a non-volatile plasticizer and iodide salts, such as potassium iodide (KI), tetrapropylammonium iodide (TPAI) and iodine (I2), together with PEO. The modified GPEs were prepared with different weight percentage (wt%) ratios (0.5%, 0.75%, 1% and 1.25%) of DPP-H using acetonitrile as a solvent. The polymer gel electrolytes were characterized by X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR), and the electrochemical properties were analyzed to relate the nature of the polymer and iodine ion conducting properties. The pure PEO/PC/TPAI/KI/I2 electrolyte exhibited an ionic conductivity value of 0.084 mS·cm−1 at room temperature. Upon the optimized addition of DPP-H (0.75 wt%), the ionic conductivity was found to be improved to a maximum value of 0.393 mS·cm−1, and the highest diffusion coefficient of 1.02 × 10−6 cm2 s−1 was observed. The optimized GPEs photovoltaic characterization studies showed higher power conversion efficiency (PCE) of 6.69% for DSSC under light illumination intensity of 100 mW cm−2. The same was compared with pure electrolyte, which delivered PCE of 4.39%. To gain an in-depth understanding of the interfacial resistance of the fabricated devices, the electron lifetime and transient photo response was analyzed. These above studies showed that prepared GPE could be an efficient alternative for traditional DSSCs with liquid electrolyte. [ABSTRACT FROM AUTHOR]

Poly(vinyl alcohol)–phosphoric acid–phosphomolybdic acid hydrate (PVA–H3PO4–PMo12, PPP) and poly(vinyl alcohol)–phosphoric acid–sodium molybdate (PVA–H3PO4–Na2MoO4, PPM) are synthesized to form an asymmetric gel polymer electrolyte (GPE) system PPP‖PPM. PPM and PPP GPEs worked on the sides of the positive and negative electrodes respectively to fabricate a carbon paper (CP) supercapacitor. The influence of PMo12-to-PVA and Na2MoO4-to-PVA mass ratios on the ionic conductivity of GPEs is discussed. The maximum ionic conductivity of PPP‖PPM can reach 36.43 mS cm−1 which is 5 times that of PVA-H3PO4. Both the Na2MoO4 electrolyte and the PMo12 electrolyte exhibit reversible redox activity and provide excellent pseudo-capacitance to improve the capacitance performance. Accordingly, the asymmetric PPP‖PPM GPE has the highest specific capacitance of 170.03 mF cm−2 and an energy density of 236.15 mW h m−2 at 0.5 mA cm−1 when compared with 23.80 mF cm−2 and 32.06 mW h m−2 for the PP GPE. In addition, it shows outstanding cycling stability with an 80% capacitance retention ratio at 0.5 mA cm−2 after 1000 charge per discharge cycles. Density functional theory calculations are used to investigate the interaction between electrolytes and electrodes. The enhancement of the electrochemical performance of the GPE is assigned to the reversible faradaic reaction associated with the redox PMo12 (Mo(V)/Mo(VI)) and Na2MoO4 (Mo(VI)/Mo(V)) in the asymmetric GPE system. [ABSTRACT FROM AUTHOR]

By introducing multiple molecule/intermolecular dynamic reversible hydrogen bonds into the polydimethylsiloxane elastomer system, a solid polymeric electrolyte with high ion conductivity (2.5 × 10−4 S cm−1) and a stable electrochemical window (>5 V) shows a fast self-healing speed. [ABSTRACT FROM AUTHOR]

We report the synthesis and structure/property correlations of a series of eight poly(ionic liquid)s (PILs) obtained from sequential AA + BB polyaddition by copper(I)-catalyzed azide–alkyne cycloaddition and the subsequent N-alkylation reaction. The different repeat units contain one to four ion pairs, with one to four bis(trifluorosulfonyl)imide (TFSI) anions and one or two types of ammonium, imidazolium or 1,2,3-triazolium counter-cations. Their physical, ion conducting and electrochemical properties are discussed based on the repeat unit charge density and structure of the cationic moieties. The comparison of several pairs of polyelectrolytes revealed that ionic conductivity is dependent on (1) the ratio between the number of charge carriers per monomer unit and the number of surrounding atoms/groups that can solvate the ions and (2) the nature of the cation. The highest conductivity (1.8 × 10−5 S cm−1 at 25 °C) was reached when PILs contain two 1,2,3-triazolium cations that are separated by an oxyethylene spacer. The incorporation of an additional type of cation (either imidazolium or ammonium with 1,2,3-triazolium) in one PIL allows its cathodic limit to be increased up to −0.4 V vs. Li+/Li (70 °C) and the oxidation instability of 1,2,3-triazolium cations to be overcome. [ABSTRACT FROM AUTHOR]

The enhancement in specific energy (SE) of supercapacitors (SCs) by increasing the operating voltage and/or specific capacitance is the focus of this study, particularly for the quasi-solid-state supercapacitors. Herein, a redox-active "water-in-salt" (WIS) hydrogel polymer electrolyte (HPE) possessing a wide operating voltage and exhibiting pseudocapacitance was synthesized by the stepwise dissolution of polyvinyl alcohol (PVA) and redox additive KBr in a 5 m (mol kgwater−1) lithium bis(trifluoromethylsulphonyl)imide (LiTFSI) WIS solution. The dependence of the ionic conductivity of PVA–LiTFSI–KBr HPE on the KBr mass was investigated and the optimized PVA–LiTFSI–KBr HPE with a maximum ionic conductivity of 43.3 mS cm−1 was acquired. The optimized PVA–LiTFSI–KBr HPE was covered by two identical activated carbon (AC) electrodes to form a sandwich-configuration SC. This device can deliver a large SE of 34.5 W h kg−1, mainly attributed to the observation that the as-prepared HPE inherits the character of the WIS electrolyte, in which the reduced water activity leads to suppressed water decomposition, resulting in the wide operating voltage of 2.0 V. The Br−/Br3− redox reaction at the HPE/AC electrode interface exhibits additional pseudocapacitance. In addition, a remarkable cyclic stability and excellent self-discharge performance are demonstrated in this device. [ABSTRACT FROM AUTHOR]

An alternating copolymer-based poly(ionic liquid) (PIL) was synthesized and blended with PVDF-HFP to obtain solid-state polymer electrolytes with both high mechanical strength and high ionic conductivity. Structural analysis reveals that the high performance is attributed to the nanophase separation of PVDF-HFP with a PIL in the nanometric scale, which benefits from an alternating polymer architecture of the PIL. [ABSTRACT FROM AUTHOR]

To increase the energy density of quasi-solid-state supercapacitors, a redox-active gel polymer electrolyte (GPE) was prepared by evaporating the excess water in a neutral gel that consists of polyvinyl alcohol (PVA), Na2SO4 and the ionic liquid (IL) N-butyl-N-methylpyrrolidinium bromide (Pyr14Br). The influence of IL Pyr14Br on the ionic conductivity of GPE was investigated. The maximum ionic conductivity of PVA–Na2SO4–Pyr14Br GPE can reach 27.1 mS cm−1. The optimized GPE was assembled with two activated carbon electrodes into a quasi-solid-state supercapacitor. The electrochemical performances of this supercapacitor were evaluated by cyclic voltammetry, galvanostatic charge/discharge, electrochemical impedance spectroscopy and self-discharge measurements. The assembled supercapacitor exhibits a high energy density of 33.0 W h kg−1, which is due to the wide working voltage (2.0 V) as a result of the strong solvation of Na+ cations and SO42− anions and the production of an additional pseudocapacitive contribution from the Br−/Br3− redox reaction at the electrolyte/electrode interface. This supercapacitor exhibits outstanding cyclic stability with an 81.0% capacitance retention ratio after 8000 charge/discharge cycles. Moreover, this supercapacitor presents good self-discharge behavior. [ABSTRACT FROM AUTHOR]

This communication reports a novel hyperbranched polymer with poly(ethylene glycol)9 segments and carboxylate groups. The combined advantages of single-ion conduction and a hyperbranched structure make the as-prepared polymers very promising as a solid-state polymer electrolyte for lithium ion batteries, by showing high ionic conductivity up to 1.2 × 10−4 S cm−1 at 85 °C, a high lithium transference number (tLi+) of 0.86, and simultaneously, a stable potential window up to 4.8 V versus Li+/Li. [ABSTRACT FROM AUTHOR]

We report a new synthetic strategy for single Li-ion conducting solid polymer electrolytes based on the fully aromatic polymer poly(ether ether ketone) (PEEK) grafted with differently substituted bis(sulfonyl)imide groups for use in lithium metal and lithium-ion batteries. The preferred polymer contains no fluorine and is particularly advisable from an environmental point of view. Its ionic conductivity reaches 0.03 mS cm−1 at 65 °C. [ABSTRACT FROM AUTHOR]

Solid polymer electrolyte (SPE)-based lithium sulfur battery offers high energy and safety for new energy vehicles and storage. However, the low room temperature ionic conductivity of the existing SPE limits the battery performance. Herein, a novel SPE film using food grade starch as a host was fabricated. This electrolyte provides exceptional lithium ion transportability with an ionic conductivity of 3.39 × 10−4 S cm−1 and lithium ion transference number of 0.80 at 25 °C. The application potential of this starch hosted electrolyte was demonstrated by all-solid-state lithium sulfur battery systems presenting the initial discharge capacity of 1442 mA h g−1, an average discharge capacity of 864 ± 16 mA h g−1 at 0.1 C for 100 cycles, 562 ± 118 mA h g−1 at 0.5 C for 1000 cycles at room temperature, and 388 ± 138 mA h g−1 for 2000 cycles at 2 C and 45 °C. This opens a bright route towards realizing energy power and safety with low cost and high sustainability. [ABSTRACT FROM AUTHOR]

A hybrid gel–solid-state polymer electrolyte has been used as the separator and an electrolyte for lithium oxygen batteries. It can not only avoid electrolyte evaporation but also protect the lithium metal anode during reactions over long-term cycling. Due to its high ionic conductivity and low activation energy, excellent cycling performance is demonstrated, in which the terminal voltage is higher than 2.2 V after 140 cycles at 0.4 mA cm−2, with a capacity of 1000 mA h g(composite)−1. [ABSTRACT FROM AUTHOR]