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Showing papers on "Ionic conductivity published in 2020"


Journal ArticleDOI
TL;DR: Ceramic and polymer are closely combined by strong chemical bonds, thus the problem of interface compatibility is resolved and the ions can transport rapidly by an expressway.
Abstract: Ceramic/polymer hybrid solid electrolytes (HSEs) have attracted worldwide attentions because they can overcome defects by combining the advantages of ceramic electrolytes (CEs) and solid polymer electrolytes (SPEs). However, the interface compatibility of CEs and SPEs in HSE limits their full function to a great extent. Herein, a flexible ceramic/polymer HSE is prepared via in situ coupling reaction. Ceramic and polymer are closely combined by strong chemical bonds, thus the problem of interface compatibility is resolved and the ions can transport rapidly by an expressway. The as-prepared membrane demonstrates an ionic conductivity of 9.83 × 10-4 S cm-1 at room temperature and a high Li+ transference numbers of 0.68. This in situ coupling reaction method provides an effective way to resolve the problem of interface compatibility.

251 citations


Journal ArticleDOI
TL;DR: In this article, the authors reviewed the latest achievements in the application of PVA-based gel polymer electrolytes for flexible supercapacitors and new findings on the improvement of their ionic conductivity, mechanical properties, and overall electrochemical performance.
Abstract: Flexible solid-state supercapacitors with high power density and rate performance, long cycle life, high safety and ease of fabrication are highly desirable. They can be used in an emerging market of flexible and wearable electronic gadgets. Gel polymer electrolytes are being considered as one of the best candidates. They typically have higher ionic conductivity than solid electrolytes without safety concerns of liquid electrolytes. This article reviews the latest achievements in the application of PVA-based gel polymer electrolytes for flexible supercapacitors and new findings on the improvement of their ionic conductivity, mechanical properties, and overall electrochemical performance. Several current kinds of research attempt to overcome these challenges with the main goal of improving ionic conductivity and electrochemical properties. There is no limitation for ionic conductivity of gel electrolyte because high ionic conductivity can lead to higher specific capacitance and also sufficient electrochemical performance. A recent study of gel electrolytes has shown the highest ionic conductivity of 82 mS.cm−1 for PVA/H2SO4/Glutaraldehyde/H2O which results in a large areal capacitance of 488 mF.cm−2 (100 reference).

248 citations


Journal ArticleDOI
TL;DR: In this paper, a flexible all-solid-state composite electrolyte is synthesized based on oxygen-vacancy-rich Ca-doped CeO2 (Ca-CeO2) nanotube, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and poly(ethylene oxide) (PEO), namely Ca −Ce O2/Li TFSI/PEO.
Abstract: Stable and seamless interfaces among solid components in all-solid-state batteries (ASSBs) are crucial for high ionic conductivity and high rate performance. This can be achieved by the combination of functional inorganic material and flexible polymer solid electrolyte. In this work, a flexible all-solid-state composite electrolyte is synthesized based on oxygen-vacancy-rich Ca-doped CeO2 (Ca–CeO2) nanotube, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and poly(ethylene oxide) (PEO), namely Ca–CeO2/LiTFSI/PEO. Ca–CeO2 nanotubes play a key role in enhancing the ionic conductivity and mechanical strength while the PEO offers flexibility and assures the stable seamless contact between the solid electrolyte and the electrodes in ASSBs. The as-prepared electrolyte exhibits high ionic conductivity of 1.3 × 10−4 S cm−1 at 60 °C, a high lithium ion transference number of 0.453, and high-voltage stability. More importantly, various electrochemical characterizations and density functional theory (DFT) calculations reveal that Ca–CeO2 helps dissociate LiTFSI, produce free Li ions, and therefore enhance ionic conductivity. The ASSBs based on the as-prepared Ca–CeO2/LiTFSI/PEO composite electrolyte deliver high-rate capability and high-voltage stability.

203 citations


Journal ArticleDOI
TL;DR: Reducing the thickness of oxide ceramic electrolytes is crucial to reduce the resistance of electrolytes and improve the energy density of Li-metal batteries.
Abstract: Ceramic oxide electrolytes are outstanding due to their excellent thermostability, wide electrochemical stable windows, superior Li-ion conductivity, and high elastic modulus compared to other electrolytes. To achieve high energy density, all-solid-state batteries require thin solid-state electrolytes that are dozens of micrometers thick due to the high density of ceramic electrolytes. Perovskite-type Li0.34 La0.56 TiO3 (LLTO) freestanding ceramic electrolyte film with a thickness of 25 µm is prepared by tape-casting. Compared to a thick electrolyte (>200 µm) obtained by cold-pressing, the total Li ionic conductivity of this LLTO film improves from 9.6 × 10-6 to 2.0 × 10-5 S cm-1 . In addition, the LLTO film with a thickness of 25 µm exhibits a flexural strength of 264 MPa. An all-solid-state Li-metal battery assembled with a 41 µm thick LLTO exhibits an initial discharge capacity of 145 mAh g-1 and a high capacity retention ratio of 86.2% after 50 cycles. Reducing the thickness of oxide ceramic electrolytes is crucial to reduce the resistance of electrolytes and improve the energy density of Li-metal batteries.

185 citations


Journal ArticleDOI
TL;DR: The observed changes in the ionic conductivity and tuning of the site occupations provide an additional approach towards the design of better SSEs.
Abstract: The enabling of high energy density of all-solid-state lithium batteries (ASSLBs) requires the development of highly Li+-conductive solid-state electrolytes (SSEs) with good chemical and electrochemical stability. Recently, halide SSEs based on different material design principles have opened new opportunities for ASSLBs. Here, we discovered a series of LixScCl3+x SSEs (x = 2.5, 3, 3.5, and 4) based on the cubic close-packed anion sublattice with room-temperature ionic conductivities up to 3 × 10-3 S cm-1. Owing to the low eutectic temperature between LiCl and ScCl3, LixScCl3+x SSEs can be synthesized by a simple co-melting strategy. Preferred orientation is observed for all the samples. The influence of the value of x in LixScCl3+x on the structure and Li+ diffusivity were systematically explored. With increasing x value, higher Li+, lower vacancy concentration, and less blocking effects from Sc ions are achieved, enabling the ability to tune the Li+ migration. The electrochemical performance shows that Li3ScCl6 possesses a wide electrochemical window of 0.9-4.3 V vs Li+/Li, stable electrochemical plating/stripping of Li for over 2500 h, as well as good compatibility with LiCoO2. LiCoO2/Li3ScCl6/In ASSLB exhibits a reversible capacity of 104.5 mAh g-1 with good cycle life retention for 160 cycles. The observed changes in the ionic conductivity and tuning of the site occupations provide an additional approach toward the design of better SSEs.

182 citations


Journal ArticleDOI
05 Feb 2020
TL;DR: In this paper, the authors used a hydrogen-bond topological network as the design principle to construct an ionic gel material based on cellulose, ionic liquid, and H2O.
Abstract: Summary Design of polymeric networks with unique structural motifs can permit dynamic features, yet most existing material systems exhibit limited operational states or irreversible responsiveness. Here, we use a hydrogen-bond topological network as the design principle to construct an ionic gel material based on cellulose, ionic liquid, and H2O (designated as Cel-IL dynamic gel). The prepared Cel-IL dynamic gels exhibit tunable properties of mechanical strength, ionic conductivity, viscoelasticity, and self-healing. With limited H2O, the Cel-IL dynamic gel exhibits a bramble-like Turing-pattern microstructure with excellent adhesion, rapid self-healing, and moderate ionic conductivity features. By increasing the H2O content to 32 wt %, the microstructure switched to a dense and compact Turing pattern network, giving the gel good stretchability, robust toughness, and a high ionic conductivity. With this material, we demonstrate a flexible, transparent, designable, and biocompatible ion sensor device, which exhibits great potential for use in electronic skins and intelligent devices.

175 citations


Journal ArticleDOI
TL;DR: Values of ion dissociation for ILs and IL solutions (aqueous and nonaqueous) determined by both the traditional molar conductivity/PFG-NMR method and the ρ, η, λ method are presented.
Abstract: The extent to which cations and anions in ionic liquids (ILs) and ionic liquid solutions are dissociated is of both fundamental scientific interest and practical importance because ion dissociation has been shown to impact viscosity, density, surface tension, volatility, solubility, chemical reactivity, and many other important chemical and physical properties. When mixed with solvents, ionic liquids provide the unique opportunity to investigate ion dissociation from infinite dilution in the solvent to a completely solvent-free state, even at ambient conditions. The most common way to estimate ion dissociation in ILs and IL solutions is by comparing the molar conductivity determined from ionic conductivity measurements such as electrochemical impedance spectroscopy (EIS) (which measure the movement of only the charged, i.e., dissociated, ions) with the molar conductivity calculated from ion diffusivities measured by pulse field gradient nuclear magnetic resonance spectroscopy (PFG-NMR, which gives movement of all of the ions). Because the NMR measurements are time-consuming, the number of ILs and IL solutions investigated by this method is relatively limited. We have shown that use of the Stokes-Einstein equation with estimates of the effective ion Stokes radii allows ion dissociation to be calculated from easily measured density, viscosity, and ionic conductivity data (ρ, η, λ), which is readily available in the literature for a much larger number of pure ILs and IL solutions. Therefore, in this review, we present values of ion dissociation for ILs and IL solutions (aqueous and nonaqueous) determined by both the traditional molar conductivity/PFG-NMR method and the ρ, η, λ method. We explore the effect of cation and anion alkyl chain length, structure, and interaction motifs of the cation and anion, temperature, and the strength of the solvent in IL solutions.

161 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated salt-concentrated electrolytes based on relatively inexpensive acetate salts and showed that an electrochemical window of 3.4 V was achieved in 1.6 m Zn(OAc)2+31 m KOAc electrolyte, self-supported α-MnO2-TiN/TiO2 cathode and Zn foil anode.

124 citations


Journal ArticleDOI
TL;DR: In this article, the current status of SIC-GPEs in terms of designs, preparation methods, electrochemical performances and applications is described in a review, and the development directions and future prospects of single-ion conducting gel polymer electrolytes are also discussed.
Abstract: Electrolytes as pivotal components of lithium-ion batteries (LIBs) and lithium metal batteries (LMBs) influence the capacity, cycle stability, safety and operating conditions of the batteries. An ideal electrolyte should possess high ionic conductivity, enhanced safety, unity lithium ion transference number (LITN) and good electrochemical stability. Single-ion conducting solid polymer electrolytes (SIC-SPEs) have garnered considerable attention due to their unique unity LITNs. In SIC-SPEs, immobilization of anions gives rise to unity LITNs, the absences of anionic concentration polarization, low internal impedances, higher discharge voltages and suppressions of lithium dendrite growth. Single-ion conducting gel polymer electrolytes (SIC-GPEs) can be fabricated by adding plasticizers to SIC-SPEs to enhance the ionic conductivities. Meanwhile, the original feature of unity LITNs (∼0.98) remains. Therefore, SIC-GPEs have been widely applied in LFP cells, LTO cells, LMO cells and Li/S cells, which showed excellent cycle stabilities, good rate capabilities and high capacities at ambient temperature. Good compatibility with lithium metal anodes and suppression of lithium dendrites that benefited from immobilization of anions are also inherited for SIC-GPEs. The current status of SIC-GPEs in terms of designs, preparation methods, electrochemical performances and applications is described in this review. The development directions and future prospects of SIC-GPEs are also discussed.

123 citations


Journal ArticleDOI
TL;DR: A thiol-branched solid polymer electrolyte (SPE) is introduced featuring high Li+ conductivity and good mechanical strength, thus unblocking the tradeoff between ionic Conductivity and mechanical robustness in polymer electrolytes.
Abstract: Lithium-metal batteries (LMBs) with high energy densities are highly desirable for energy storage, but generally suffer from dendrite growth and side reactions in liquid electrolytes; thus the need for solid electrolytes with high mechanical strength, ionic conductivity, and compatible interface arises. Herein, a thiol-branched solid polymer electrolyte (SPE) is introduced featuring high Li+ conductivity (2.26 × 10-4 S cm-1 at room temperature) and good mechanical strength (9.4 MPa)/toughness (≈500%), thus unblocking the tradeoff between ionic conductivity and mechanical robustness in polymer electrolytes. The SPE (denoted as M-S-PEGDA) is fabricated by covalently cross-linking metal-organic frameworks (MOFs), tetrakis (3-mercaptopropionic acid) pentaerythritol (PETMP), and poly(ethylene glycol) diacrylate (PEGDA) via multiple CSC bonds. The SPE also exhibits a high electrochemical window (>5.4 V), low interfacial impedance ( 1300 h cycling test. Moreover, a Li|M-S-PEGDA|LiFePO4 full cell demonstrates discharge capacity of 143.7 mAh g-1 and maintains 85.6% after 500 cycles at 0.5 C, displaying one of the most outstanding performances for SPEs to date.

122 citations


Journal ArticleDOI
TL;DR: In this article, a norbornene-based tetrablock copolymer with an ion exchange capacity of 3.88 meq/g was synthesized for fuel cells.
Abstract: High ionic conductivity membranes can be used to minimize ohmic losses in electrochemical devices such as fuel cells, flow batteries, and electrolyzers. Very high hydroxide conductivity was achieved through the synthesis of a norbornene-based tetrablock copolymer with an ion-exchange capacity of 3.88 meq/g. The membranes were cast with a thin polymer reinforcement layer and lightly cross-linked with N,N,N',N'-tetramethyl-1,6-hexanediamine. The norbornene polymer had a hydroxide conductivity of 212 mS/cm at 80°C. Light cross-linking helped to control the water uptake and provide mechanical stability while balancing the bound (i.e. waters of hydration) vs. free water in the films. The films showed excellent chemical stability with <1.5% conductivity loss after soaking in 1 M NaOH for 1000 h at 80°C. The aged films were analyzed by FT-IR before and after aging to confirm their chemical stability. A H2/O2 alkaline polymer electrolyte fuel cell was fabricated and was able to achieve a peak power density of 3.5 W/cm2 with a maximum current density of 9.7 A/cm2 at 0.15 V at 80°C. The exceptionally high current and power densities were achieved by balancing and optimizing water removal and transport from the hydrogen negative electrode to the oxygen positive electrode. High water transport and thinness are critical aspects of the membrane in extending the power and current density of the cells to new record values.

Journal ArticleDOI
TL;DR: The insufficient ionic conductivity of oxide-based solid electrolytes and the large interfacial resistance between the cathode material and the solid electrolyte severely limit the performance of r... as mentioned in this paper.
Abstract: The insufficient ionic conductivity of oxide-based solid electrolytes and the large interfacial resistance between the cathode material and the solid electrolyte severely limit the performance of r...

Journal ArticleDOI
TL;DR: The key problems and challenges of NASICON-type solid electrolyte are described from the aspects of ionic conductivity, electrode interface, and electrochemical stability and the solutions to improve the conductivity of electrolytes and deal with electrode/electrolyte interface problems are described.
Abstract: NASICON-type (lithium super ionic conductor) solid electrolyte is of great interest because of its high ionic conductivity, wide potential window, and good chemical stability. In this paper, the key problems and challenges of NASICON-type solid electrolyte are described from the aspects of ionic conductivity, electrode interface, and electrochemical stability. Firstly, the migration mechanism of lithium ion is analyzed from the three-dimensional structure of NASICON-type solid electrolyte, and progress in the research of conductivity and stability is summarized. Then, the effective methods to reduce interface impedance and improve the cycle stability of all-solid-state lithium batteries (ASSLBs) with NASICON-type solid electrolyte are introduced. Finally, solutions to improve the conductivity of electrolytes and deal with electrode/electrolyte interface problems are summarized, and the development prospects of ASSLBs are discussed.

Journal ArticleDOI
TL;DR: In this article, a quasi-solid-state supercapacitor with high energy density and low self-discharge is synthesized by the addition of 1-butyl-3-methylimidazolium bromide (BMIMBr) ionic liquid (IL) and carbon nanotubes (CNTs) into a PVA aqueous solution.

Journal ArticleDOI
TL;DR: Li2Sc2/3Cl4 as discussed by the authors is a spinel-type superionic halide that exhibits an ionic conductivity of 1.5 mS cm−1 with a low activation energy barrier for Li+ ion diffusion.
Abstract: We report a new Li-superionic chloride, Li2Sc2/3Cl4, that crystallizes in a disordered spinel structure, and exhibits an ionic conductivity of 1.5 mS cm−1 with a low activation energy barrier for Li+ ion diffusion of 0.34 eV. This material is the first spinel-type superionic halide. Structural elucidation via powder neutron diffraction reveals a significantly disordered Li+-ion distribution over available tetrahedral and octahedral sites within the lattice, forming an infinitely 3D connected Li+ ion diffusion pathway comprised of face-sharing octahedra and tetrahedra. Due to the high oxidative stability of Li2Sc2/3Cl4, all solid state lithium batteries employing Li2Sc2/3Cl4 and high voltage cathodes (LiCoO2, LiNi0.6Mn0.2Co0.2O2 or high-Ni LiNi0.85Mn0.1Co0.05O2) – without any coating – exhibit excellent electrochemical performance up to 4.6 V in terms of capacity retention and cycle life.

Journal ArticleDOI
TL;DR: The undoped hexagonal perovskite Ba 7 Nb 4 MoO 20 supports pure ionic conduction with high proton and oxide ion conductivity at 510 °C (the bulk conductivity is 4.0 mS cm −1 ), and hence is an exceptional candidate for application as a dual-ion solid electrolyte in a ceramic fuel cell that will combine the advantages of both oxide ion and proton-conducting electrolytes.
Abstract: Oxide ion and proton conductors, which exhibit high conductivity at intermediate temperature, are necessary to improve the performance of ceramic fuel cells. The crystal structure plays a pivotal role in defining the ionic conduction properties, and the discovery of new materials is a challenging research focus. Here, we show that the undoped hexagonal perovskite Ba7Nb4MoO20 supports pure ionic conduction with high proton and oxide ion conductivity at 510 °C (the bulk conductivity is 4.0 mS cm−1), and hence is an exceptional candidate for application as a dual-ion solid electrolyte in a ceramic fuel cell that will combine the advantages of both oxide ion and proton-conducting electrolytes. Ba7Nb4MoO20 also showcases excellent chemical and electrical stability. Hexagonal perovskites form an important new family of materials for obtaining novel ionic conductors with potential applications in a range of energy-related technologies. Fast oxide ion and proton conductors at intermediate temperature are required to improve the performance of ceramic fuel cells. An undoped hexagonal perovskite Ba7Nb4MoO20 electrolyte with high proton and oxide ion conductivity (4.0 mS cm−1) at 510 °C is now reported.

Journal ArticleDOI
TL;DR: In this article, a polyethylene oxide (PEO) based solid electrolyte is used for safe and high energy density lithium-metal batteries owing to its good flexibility and high degree of safety.
Abstract: A solid polymer electrolyte is expected to be useful for safe and high energy density lithium-metal batteries owing to its good flexibility and high degree of safety. The development of a polyethylene oxide (PEO) based solid electrolyte is still restrained by low ionic conductivity and unsatisfactory mechanical strength. Since MnO2 could combine with PEO chains and Li ions could undergo long-range migration on MnO2 nanosheets, MnO2 nanoflakes are chosen as fillers to improve the electrochemical and mechanical properties of a solid polymer electrolyte. A PEO/MnO2 composite solid polymer electrolyte (CSPE) displays a higher lithium ion transference number (0.378), higher ionic conductivity (1.5 times higher at 60 °C) and better tensile strength (2.3 times) than a PEO solid electrolyte. Density functional theory calculations reflect the fact that the binding energy between the PEO/Li complex and MnO2 is small and there is easy desorption of Li from PEO and migration on MnO2 nanosheets, indicating enhanced lithium ion transport in the electrolyte system. A solid-state lithium metal battery using a PEO/MnO2 CSPE delivers higher capacity (143.5 mA h g−1 after 300 cycles) than an electrolyte without fillers (61.2 mA h g−1 after 90 cycles). Soft-package lithium metal batteries with an MnO2 CSPE reveal high safety after cutting, nail and bending tests.

Journal ArticleDOI
TL;DR: In this article, a poly(vinyl ethylene carbonate) polymer electrolyte for polymer lithium metal battery by in-situ polymerization method was designed, which provides superior ionic conductivity with 2.1 × 10−3−S cm−1 at 25°C, wide electrochemical window up to 4.5 V and excellent interfacial compatibility to electrodes.

Journal ArticleDOI
TL;DR: This work systematically investigates the hydrolysis and reduction reactions in Li- and Na-containing sulfides and chlorides by applying thermodynamic analyses based on first principles computation database, revealing the stability trends among different chemistries and identifying promising materials systems to simultaneously achieve the moisture stability and electrochemical stability.
Abstract: Sulfide solid electrolytes are promising inorganic solid electrolytes for all-solid-state batteries Despite their high ionic conductivity and desirable mechanical properties, many known sulfide solid electrolytes exhibit poor air stability The spontaneous hydrolysis reactions of sulfides with moisture in air lead to the release of toxic hydrogen sulfide and materials degradation, hindering large-scale manufacturing and applications of sulfide-based solid-state batteries In this work, we systematically investigate the hydrolysis and reduction reactions in Li- and Na-containing sulfides and chlorides by applying thermodynamic analyses based on a first principles computation database We reveal the stability trends among different chemistries and identify the effect of cations, anions, and Li/Na content on moisture stability Our results identify promising materials systems to simultaneously achieve desirable moisture stability and electrochemical stability, and provide the design principles for the development of air-stable solid electrolytes

Journal ArticleDOI
TL;DR: Sulfide solid electrolytes have recently attracted significant interest for use in all-solid-state lithium batteries (ASSLBs) due to their high ionic conductivity as discussed by the authors, however, one of the main challeng...
Abstract: Sulfide solid electrolytes have recently attracted significant interest for use in all-solid-state lithium batteries (ASSLBs) due to their high ionic conductivity. However, one of the main challeng...

Journal ArticleDOI
Gaozhan Liu1, Wei Weng1, Zhihua Zhang1, Liping Wu1, Jing Yang1, Xiayin Yao1 
TL;DR: Li et al. as discussed by the authors proposed a flat-surface Li6PS5Cl nanorod pellet with high density, which exhibits an ionic conductivity as high as 6.11 mS cm-1 at 25 °C.
Abstract: Solid electrolytes are receiving great interest owing to their good mechanical properties and high lithium-ion transference number, which could potentially suppress lithium dendrites. However, lithium dendrites can still penetrate solid electrolytes even at low current densities. In this work, a flat-surface Li6PS5Cl nanorod pellet with high density is achieved, which exhibits an ionic conductivity as high as 6.11 mS cm-1 at 25 °C. The flat surface of the pellet is beneficial for the homogeneous lithium deposition, and the dense pellet microstructure can suppress the growth of lithium dendrites along the grain boundaries, leading to a significantly improved critical current density of 1.05 mA cm-2 at 25 °C. The resultant dense Li6PS5Cl pellet is further employed in a LiCoO2/Li6PS5Cl/Li all-solid-state lithium battery, showing an initial discharge capacity of 115.3 mAh g-1 at 1C (0.35 mA cm-2, 25 °C) with a capacity retention of 80.3% after 100 cycles.

Journal ArticleDOI
TL;DR: The advantages of ultralow cost and high universality enable a great practical application potential of the super-concentrated sugar-based aqueous electrolytes, which can also provide great experimental and theoretical assistance for further research in water chemistry.
Abstract: Aqueous energy-storage systems have attracted wide attention due to their advantages such as high security, low cost, and environmental friendliness. However, the specific chemical properties of water induce the problems of narrow electrochemical stability window, low stability of water-electrode interface reactions, and dissolution of electrode materials and intermediate products. Therefore, new low-cost aqueous electrolytes with different water chemistry are required. The nature of water depends largely on its hydroxyl-based hydrogen bonding structure. Therefore, the super-concentrated hydroxyl-rich sugar solutions are designed to change the original hydrogen bonding structure of water. The super-concentrated sugars can reduce the free water molecules and destroy the tetrahedral structure, thus lowering the binding degree of water molecules by breaking the hydrogen bonds. The ionic electrolytes based on super-concentrated sugars have the expanded electrochemical stability window (up to 2.812 V), wide temperature adaptability (-50 to 80 °C), and fair ionic conductivity (8.536 mS cm-1 ). Aqueous lithium-, sodium-, potassium-ion batteries and supercapacitors using super-concentrated sugar-based electrolytes demonstrate an excellent electrochemical performance. The advantages of ultralow cost and high universality enable a great practical application potential of the super-concentrated sugar-based aqueous electrolytes, which can also provide great experimental and theoretical assistance for further research in water chemistry.

Journal ArticleDOI
04 Mar 2020
TL;DR: In this article, two 2D conductive metal-organic frameworks (MOFs) were constructed via combination of [In(COO)4]− metal nodes and tetratopic tetrathiafulvalene (TTF)-based linkers, with ultrahigh proton conductivity.
Abstract: Summary Two-dimensional (2D) conductive metal-organic frameworks (MOFs), whose advanced electrical properties accompany their intrinsic structural characteristics, represent an exciting new class of 2D atomic crystals for the van der Waals integration of novel heterostructures and the development of novel nano/quantum devices. Guided by topology, we report two 2D MOFs (1 and 2) constructed via combination of [In(COO)4]− metal nodes and tetratopic tetrathiafulvalene (TTF)-based linkers, with ultrahigh proton conductivity (6.66 × 10−4 and 1.30 × 10−2 S cm−1 for 1 and 2, respectively). Additionally, high electrical conductivity was simultaneously achieved with the pure protonic nature of the 2D MOF 2. The electrical conduction at the MOF-metal interface is enabled by the redox-switchable behavior of the TTF-based ligands. This unique charge-transport mechanism, protonic/pseudo-capacitance coupling, offers a new strategy for utilizing the ionic conductivity from MOFs to construct functional electronic devices.

Journal ArticleDOI
TL;DR: This work offers an ionic engineering strategy to enable fast and durable charge transfer in materials, holding great promise for providing guidance for the material design of related energy storage systems.
Abstract: Boosting charge transfer in materials is critical for applications involving charge carriers. Engineering ionic channels in electrode materials can create a skeleton to manipulate their ion and electron behaviors with favorable parameters to promote their capacity and stability. Here, tailoring of the atomic structure in layered potassium niobate (K4 Nb6 O17 ) nanosheets and facilitating their application in lithium and potassium storage by dehydration-triggered lattice rearrangement is reported. The spectroscopy results reveal that the interatomic distances of the NbO coordination in the engineered K4 Nb6 O17 are slightly elongated with increased degrees of disorder. Specifically, the engineered K4 Nb6 O17 shows enhanced electrical and ionic conductivity, which can be attributed to the enlarged interlamellar spacing and subtle distortions in the fine atomic arrangements. Moreover, subsequent experimental results and calculations demonstrate that the energy barrier for Li+ /K+ diffusion is significantly lower than that in pristine K4 Nb6 O17 . Interestingly, the diffusion coefficient of K+ is one order of magnitude higher than that of Li+ , and the engineered K4 Nb6 O17 presents superior electrochemical performance for K+ to Li+ . This work offers an ionic engineering strategy to enable fast and durable charge transfer in materials, holding great promise for providing guidance for the material design of related energy storage systems.

Journal ArticleDOI
TL;DR: In this article, an improved polyethylene oxide (PEO)-LiTFSI electrolytes with 3D aramid nanofibers (ANFs) network frames are achieved through the hydrogen-bond interactions between the 1D ANFs.

Journal ArticleDOI
TL;DR: In this paper, the authors performed an uncertainty evaluation via a Round Robin approach using different Li-argyrodites exhibiting orders of magnitude different ionic conductivities as reference materials and measured the conductivities and activation barriers by impedance spectroscopy.
Abstract: Owing to highly conductive solid ionic conductors, all-solid-state batteries attract significant attention as promising next-generation energy storage devices. A lot of research is invested in the search and optimization of solid electrolytes with higher ionic conductivity. However, a systematic study of an interlaboratory reproducibility of measured ionic conductivities and activation energies is missing, making the comparison of absolute values in literature challenging. In this study, we perform an uncertainty evaluation via a Round Robin approach using different Li-argyrodites exhibiting orders of magnitude different ionic conductivities as reference materials. Identical samples are distributed to different research laboratories and the conductivities and activation barriers are measured by impedance spectroscopy. The results show large ranges of up to 4.5 mScm-1 in the measured total ionic conductivity (1.3 – 5.8 mScm-1 for the highest conducting sample, relative standard deviation 35 – 50% across all samples) and up to 128 meV for the activation barriers (198 – 326 meV, relative standard deviation 5 – 15%, across all samples), presenting the necessity of a more rigorous methodology including further collaborations within the community and multiplicate measurements.

Journal ArticleDOI
TL;DR: A judicious analysis of these emerging ionic soft materials, their properties and applications open in energy, (bio)electronics, drug delivery, analytical chemistry, and wastewater treatment is provided.
Abstract: In the last 5 years, the use of deep eutectic solvents (DESs) have been opening new perspectives toward the creation of novel ionic soft materials as alternatives to expensive ionic liquids. This M...

Journal ArticleDOI
TL;DR: In this article, an ionic liquid (IL)- incorporated redox-active gel polymer electrolyte (GPE) based on polymer blend of poly(vinyl alcohol) (PVA) and polyvinyl pyrrolidone (PVP) is presented for application in carbon supercapacitors, comprising IL 1-ethyl-3methylimidazolium hydrogen-sulphate (EMIHSO4), added with redoxadditive hydroquinone (HQ), immobilized in PVA/PVP, exhibits excellent flexibility, thermal

Journal ArticleDOI
TL;DR: In this article, a redox-active ionic liquid-based ionogel electrolyte (IGE) consisting of 1-butyl-3-methylimidazolium iodide (BMIMI) IL, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and carbon nanotubes (CNTs) was prepared by a solution-casting method.

Journal ArticleDOI
TL;DR: In this article, a quasi-solid-state battery was constructed by combining the MgVO cathode with polyvinyl alcohol/glycerol gel electrolyte, which shows high ionic conductivity in a wide temperature range (e.g., 10.7 mS cm−1 at −30 °C).
Abstract: Aqueous zinc-ion batteries (AZIBs) are promising due to their intrinsic safety and low cost. However, the unsatisfactory cathode materials with low mass loading (<3 mg cm−2) and high freezing point of aqueous electrolytes severely limit the application prospects of AZIBs. Herein, Mg0.19V2O5·0.99H2O (δ-MgVO) with a large interlayer spacing of 13.4 A is synthesized through a facile pre-intercalation strategy, and is used to construct a cathode with a commercial-level mass loading of 10 mg cm−2. At such a high mass loading, the δ-MgVO shows reversible charge storage behavior, high Zn2+ ion diffusion coefficients, and fast electrochemical kinetics. Moreover, a quasi-solid-state battery is assembled by combining the δ-MgVO cathode with polyvinyl alcohol/glycerol gel electrolyte, which shows high ionic conductivity in a wide temperature range (e.g., 10.7 mS cm−1 at −30 °C) and excellent compatibility with a Zn foil anode. Thanks to that, the quasi-solid-state battery exhibits great performances from −30 to 60 °C. Remarkably, at a rather low temperature of −30 °C, an admirable energy density of 48.14 mW h cm−3 (1940 μW h cm−2) can be achieved at 17.83 mW cm−3 (0.72 mW cm−2). Overall, this work opens new opportunities for developing environmentally adaptive aqueous energy storage devices towards practical applications.