Ionic Conductivity Of Composite Electrolytes Research Articles

Molecular coordination induced high ionic conductivity of composite electrolytes and stable LiF/Li3N interface in long-term cycling all-solid-state lithium metal batteries

Composite polymer/oxide electrolyte (CPE) is a promising candidate for all-solid-state lithium metal batteries (ASSLMBs), but controlling the interactions between components in CPEs to achieve high efficient Li+-transport and stable CPE/electrode interface is a challenge. Here, we report a mesoporous black LaxCoO3-δ nanofiber (NF) film with tunable cationic defects to regulate the molecular coordination with PEO/LiTFSI matrix and realize stable operations of ASSLMBs over 1000 cycles. By tuning the A-site defects from x = 1.0 to 0.8, the LaxCoO3-δ NFs show gradually enhanced coordination with PEO/LiTFSI, achieving a high ionic conductivity of 2.5 × 10−4 S/cm at 30 °C. Moreover, the defective La0.8CoO3-δ can catalyze the formation of stable LiF/Li3N interfacial layers, which possess high Li+-conduction kinetics and interfacial energy, thus enabling stable battery operations even at high currents. As a result, the LiFePO4-based ASSLMBs show a long life of >1000 cycles at 0.2 C with a capacity retention of >75%, and they can deliver a high discharge capacity of 142 mA h g−1 at 1 C with a capacity retention of 92.2% over 300 cycles. Importantly, this molecular coordination strategy is still effective when extended to other defective oxides, thus providing a universal method to design high-performance CPEs.

Micro-Structural Design of Soft Solid Composite Electrolytes With Enhanced Ionic Conductivity

Abstract Electrolyte in a rechargeable Li-ion battery plays a critical role in determining its capacity and efficiency. While the typically used electrolytes in Li-ion batteries are liquid, soft solid electrolytes are being increasingly explored as an alternative due to their advantages in terms of increased stability, safety and potential applications in the context of flexible and stretchable electronics. However, ionic conductivity of solid polymer electrolytes is significantly lower compared to liquid electrolytes. In a recent work, we developed a theoretical framework to model the coupled deformation, electrostatics and diffusion in heterogeneous electrolytes and also established a simple homogenization approach for the design of microstructures to enhance ionic conductivity of composite solid electrolytes. Guided by the insights from the theoretical framework, in this paper, we examine specific microstructures that can potentially yield significant improvement in the effective ionic conductivity. We numerically implement our theory in the open source general purpose finite element package FEniCS to solve the governing equations and present numerical solutions and insights on the effect of microstructure on the enhancement of ionic conductivity. Specifically, we investigate the effect of shape by considering ellipsoidal inclusions. We also propose an easily manufacturable microstructure that increases the ionic conductivity of the composite electrolyte by 40 times, simply by the addition of dielectric columns parallel to the solid electrolyte phase.

The Influence of TiO2 on the Proton Conduction and Thermal Stability of CsH2PO4 Composite Electrolytes

Composite Electrolytes (1-x)CsH2PO4/xTiO2(0≤x≤0.4) were prepared and analyzed the structural, thermal, and transport properties. We have investigated the ionic conductivity of composite electrolytes highly pressurized pellets and found that the conductivity of pure CsH2PO4 (CDP) increased three orders of magnitude at the transition temperature. The conductivity value of the composites is greater than pure CDP after 250°C. Arrhenius plots have confirmed the conductive nature of ionic conduction. The dehydration behavior and thermal stability of the materials were observed in terms of differential scanning calorimetry, thermogravimetric analysis, and differential thermal analysis, and found that the minimum weight loss for the composite 0.6CDP/0.4TiO2. The electrodes were prepared with the technique of vapor deposition.

In-Situ Intermolecular Interaction in Composite Polymer Electrolyte for Ultralong Life Quasi-Solid-State Lithium Metal Batteries.

Solid-state lithium metal batteries built with composite polymer electrolytes using cubic garnets as active fillers are particularly attractive owing to their high energy density, easy manufacturing and inherent safety. However, the uncontrollable formation of intractable contaminant on garnet surface usually aggravates poor interfacial contact with polymer matrix and deteriorates Li+ pathways. Here we report a rational designed intermolecular interaction in composite electrolytes that utilizing contaminants as reaction initiator to generate Li+ conducting ether oligomers, which further emerge as molecular cross-linkers between inorganic fillers and polymer matrix, creating dense and homogeneous interfacial Li+ immigration channels in the composite electrolytes. The delicate design results in a remarkable ionic conductivity of 1.43×10-3 S cm-1 and an unprecedented 1000 cycles with 90 % capacity retention at room temperature is achieved for the assembled solid-state batteries.

Flexible, stable, fast-ion-conducting composite electrolyte composed of nanostructured Na-super-ion-conductor framework and continuous Poly(ethylene oxide) for all-solid-state Na battery

Solid-state electrolytes have attracted increasing attentions, as they can solve the safety issues related to the use of flammable liquid electrolytes. However, it is still challenging to achieve high ionic conductivity of solid-state electrolytes and to create low interface impedance between solid electrolyte and solid electrode at room temperature. Herein, we report the development of high-performance NASICON/Poly(ethylene oxide) composite electrolytes (CEs) for all-solid-state Na batteries that can be used at room temperature (23.8 °C). With the novel combination of nanostructured NASICON framework and continuous poly(ethylene oxide) filler, an outstanding room-temperature ionic conductivity of 1.4×10−4 S cm−1 is obtained. The fast Na-ion diffusion pathways at the 3D inter-connected NASICON-Poly(ethylene oxide) interfaces are visually observed for the first time via scanning probe microscopy, contributing to the superior ionic conductivity in CEs. The NASICON framework further strengthens the mechanical structure of CEs and effectively suppresses Na dendrites. Intimate and stable contact is achieved between the solid-state CEs and solid ceramic electrodes at room temperature, along with low electrolyte-electrode interface impedance and good durability, due to the high flexibility of CEs. Prototypes of all-solid-state Na batteries using the CEs are developed, demonstrating excellent electrochemical performance, which verifies that the present solid-state CEs are promising alternatives to the conventional liquid electrolytes.

Ceramic-Polymer Interaction in Solid-State Composite Electrolytes of Lithium Ion Batteries

Based on three dimensional (3D) pervoskite-type Li0.33La0.557TiO3 nanofibers and polymer, a composite solid state electrolyte has been fabricated. Our study shows that the ceramic-polymer interface has significant effect on the ionic conductivity of composite electrolytes and the cyclic performance of symmetric half cells. After a buffer later has been incorporated between the ceramic fibers and polymer matrix, the flexible solid-state electrolyte composite membrane exhibits high ionic conductivity at room temperature, a large electrochemical stability window and good mechanical stability in symmetric Li|electrolyte|Li cell.

Rechargeable solid-state lithium metal batteries with vertically aligned ceramic nanoparticle/polymer composite electrolyte

Composite solid electrolytes are attractive as they combine the high ionic conductivity of ceramic nanoparticles and the excellent mechanical properties of polymer electrolytes. Vertically aligned ceramic nanoparticles in the polymer matrix represent an ideal structure for maximizing ionic conductivity of composite electrolytes. The ice-templating method was used to build rechargeable solid-state lithium metal batteries with a vertically aligned ceramic/polymer composite electrolyte composed of high ionic conductivity Li1.5Al0.5Ge1.5(PO4)3 (LAGP) and polyethylene oxide (PEO) polymer. The vertical LAGP walls provide continuous channels for fast ionic transport, while the PEO matrix renders the composite electrolyte flexible. This solid-state composite electrolyte has a conductivity of 1.67 × 10−4 S cm−1 at room temperature and 1.11 × 10−3 S cm−1 at 60 °C. LiFePO4 (LFP)/vertically aligned LAGP- PEO/Li full cells were also developed with a high capacity retention of 93.3% after 300 cycles. This study demonstrates the successful application of vertically aligned ceramic/polymer composite electrolytes for solid-state batteries with high performance.

A novel solid PEO/LLTO-nanowires polymer composite electrolyte for solid-state lithium-ion battery

In this study, fast ionic conductor Li0.33La0.557TiO3 (LLTO) nanowires with high ionic conductivity were prepared through electrospinning and subsequent high temperature calcination. It was filled in the poly(ethylene oxide) (PEO) matrix as a filler and the novel solid PEO/LiTFSI/LLTO-nanowires polymer composite electrolytes were prepared via solution casting method with low cost. The results showed that the addition of LLTO nanowires could effectively improve the ionic conductivity, electrochemical stability window, transference number, and compatibility with lithium metal of polymer composite electrolytes. The maximum ionic conductivities of composite electrolytes filled with 5 wt% LLTO nanowires at room temperature and 60 °C were 5.53 × 10−5 S cm−1 and 3.63 × 10−4 S cm−1, respectively. Its electrochemical stability window was up to 4.75 V. The LiFePO4/Li solid-state lithium-ion battery assembled with the novel polymer composite electrolytes had good cycling stability. At current rate of 0.5 C, the discharge specific capacity remained about 123 mAh g−1 after 100 cycles at 60 °C.

New Insights into the Compositional Dependence of Li-Ion Transport in Polymer-Ceramic Composite Electrolytes.

Composite electrolytes are widely studied for their potential in realizing improved ionic conductivity and electrochemical stability. Understanding the complex mechanisms of ion transport within composites is critical for effectively designing high-performance solid electrolytes. This study examines the compositional dependence of the three determining factors for ionic conductivity, including ion mobility, ion transport pathways, and active ion concentration. The results show that with increase in the fraction of ceramic Li7La3Zr2O12 (LLZO) phase in the LLZO-poly(ethylene oxide) composites, ion mobility decreases, ion transport pathways transit from polymer to ceramic routes, and the active ion concentration increases. These changes in ion mobility, transport pathways, and concentration collectively explain the observed trend of ionic conductivity in composite electrolytes. Liquid additives alter ion transport pathways and increase ion mobility, thus enhancing ionic conductivity significantly. It is also found that a higher content of LLZO leads to improved electrochemical stability of composite electrolytes. This study provides insight into the recurring observations of compositional dependence of ionic conductivity in current composite electrolytes and pinpoints the intrinsic limitations of composite electrolytes in achieving fast ion conduction.

Cerium doped TiO2 photoanode for an efficient quasi-solid state dye sensitized solar cells based on polyethylene oxide/multiwalled carbon nanotube/polyaniline gel electrolyte

We have synthesized rare earth element cerium (Ce3+) doped TiO2 nanoparticles by using hydrothermal method. This doped TiO2 is used as photoanode in dye sensitized solar cells (DSSCs). The nanoparticles were characterized by using X-ray diffraction (XRD), energy dispersive X-ray (EDX) and UV–visible spectroscopy. From XRD it was found that the anatase crystalline phase keeps unchanged after Ce3+ doping while the crystallite size decreases. There is a decrease in the band gap of doped TiO2 is observed, Ce3+ positively changes the conduction band minimum of TiO2 due to the introduction of unoccupied 4f states of Ce3+. The gel electrolyte was prepared by in situ polymerization of aniline in the mixture of PEO and c-MWCNT. The synthesized gel electrolyte was characterized by Fourier transform infrared spectroscopy (FTIR), SEM, and EDX analyses. The thermal stability of these gels also increased with the addition of c-MWCNT. The present study is concerned with effect of c-MWCNT and Ce3+ on the conversion efficiency of the quasi solid state DSSCs. DSSCs fabricated with 0.1% c-MWCNT c in PEO/PAni and TiO2 as photoanode achieved maximum conversion efficiency of 1.62%. The introduction of c-MWCNT improved ionic conductivity of composite electrolytes and enhanced interfacial contact between electrode and electrolyte. The Ce3+@TiO2 photoanode influences the performance of DSSCs due to the increased electron injection. 0.5wt% Ce3+@TiO2 photoanode gives a maximum PCE of 4.08%, Jsc of 7.36mAcm−2 and Voc of 0.76V.

(Invited) Ion-Transport in Polymer-in-Ceramic Electrolytes

Solid electrolytes could revolutionize battery and supercapacitor technology because of their nontoxicity, stability during operation and enhanced safety. The major limitation of solid electrolytes is their low ionic conductivity at room temperature, and intricate ion transport complicated by grain-boundary phenomena. We have developed, and present here, novel polymer-in-ceramic composite electrolytes with high ion-conduction properties, prepared by electrophoretic deposition. Nanoparticles of LiAlO2, Li10SnP2S12, and some ion-conducting glasses were used as ceramic matrices. Polyethyleneimine (PEI) and polyethylene oxide (PEO) were tested as binders and lithium-ion-conducting media. Our recently developed simplified Poisson-Boltzmann model reveals that the adsorption of PEI on the surface of ceramic particles increases zeta potential, repulsion forces between the particles and their deposition rate. The electrophoretic deposition of PEO and nanoceramic powders occurs from the individual entities. We have succeeded in depositing films containing 5 to 40% PEO which are homogeneous in composition and uniform in thickness. XRD and DSC tests showed that the crystallinity of the polymer confined in the pores of ceramics, is suppressed. This was expected to improve the ionic conductivity of composite electrolytes saturated with LiI salt. However, on the basis of AC-impedance, NMR and high-resolution X-ray tomography data, we suggest that the high ionic conductivity (0.5mS/cm) at room temperature and low activation energy (2.3kJ/mole) are brought about by the grain-boundaries current path between the excess of LiI and ceramic nanoparticles, and not by the confined-in-ceramic polymer. The nanoarchitecturing of ordered, fast-ion-conduction paths and the elimination of perpendicular blocking grain boundaries is expected to reduce the effect of high-resistant grains.

Electrochemical performances of a new solid composite polymer electrolyte based on hyperbranched star polymer and ionic liquid for lithium-ion batteries

A new composite polymer electrolyte membrane composed of hyperbranched star polymers (HBPS-(PMMA-b-PPEGMA)30 (the hyperbranched star polymer with hyperbranched polystyrene as core and polymethyl methacrylate block poly(ethylene glycol) methyl ether methacrylate) as arms)), ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4) or 1-butyl-3-methylimidazolium hexafluorophosphate (BMImPF6)), and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) has been fabricated by solution casting method. This type of solid polymer electrolyte membrane shows an excellent flexibility, transparency, and free-standing properties. Room temperature ionic conductivity of composite electrolytes with 40 wt% BMImBF4 or 40 wt% BMImPF6 can reach 2.5 × 10−4 and 4.1 × 10−5 S cm−1, respectively. The HBPS-(PMMA-b-PPEGMA)30/BMImPF6/LiTFSI (the composite polymer electrolyte with 1-butyl-3-methylimidazolium hexafluorophosphate) composite polymer electrolyte displays better performances including a good thermal stability with decomposition temperature of 350 °C, a wide electrochemical window with oxidation potential of 4.3 V, and the excellent interfacial compatibility with lithium electrode. Moreover, the Li/LiFePO4 batteries based on HBPS-(PMMA-b-PPEGMA)30/BMImPF6/LiTFSI electrolyte retain about 96% of their highest discharge capacity (120.5 mAh g−1) after 100 cycles under a current density of 0.1 C at 60 °C, exhibiting the excellent reversible cyclability.

The “filler effect”: A study of solid oxide fillers with β-Li3PS4 for lithium conducting electrolytes

Solid electrolytes are the subject of intense study partly because of their use in safer, high energy density, all-solid-state lithium-ion batteries. The addition of solid oxide fillers has been previously explored as a way to increase the ionic conductivity in composite electrolytes; however, no comparative study of the effect of both ion-conducting and non-conducting oxides on solid lithium superionic conductor electrolyte is reported. Nano-crystalline β-Li3PS4 (LPS) was recently shown to have anomalous high ionic conductivity, but it was found that this property can be further enhanced. This study examines the effect of three solid oxide fillers (Li6ZnNb4O14, Al2O3, and SiO2) in composites with LPS for the enhancement of the parent electrolyte. The electrolytes' processability, ionic conductivity, activation energy, and stability against metallic lithium are presented to gain a complete understanding on the effect of solid oxide fillers on LPS while elucidating the significant enhancement of LPS through the addition of Li6ZnNb4O14 or Al2O3.

Plastic crystalline-semi crystalline polymer composite electrolyte based on non-woven poly(vinylidenefluoride-co-hexafluoropropylene) porous membranes for lithium ion batteries

The advantageous properties of both solid soft matter electrolytes and polymer gel electrolytes (PGEs) are combined to develop a electrospun polymer composite electrolyte (PCE) for lithium ion batteries, based on addition of butanedinitrile (BDN, the plastic crystal) to poly(vinylidenefluoride-co-hexafluoropropylene) {P(VdF-co-HFP)} (semi crystalline polymer). Polymer composite electrolytes are prepared by activating the fibrous membrane with 1M LiPF6 in EC/DEC. The electrochemical characterization shows that the addition of BDN significantly improves the ionic conductivity of composite electrolytes even at lower temperatures due to the active role played by BDN in ion conduction. Also the compatibility of the polymer composite electrolyte with lithium electrode improves by incorporation of BDN. Galvanostatic cycling test demonstrates the suitability of these polymer composite electrolytes for lithium ion batteries in both Li/PCE/LiFePO4 (half cell) and LTO/PCE/LiFePO4 (full cell) configurations. The addition of BDN improves the charge discharge performance and cycling stability of the polymer composite electrolytes.

Study on All Solid-State Composite Polymer Electrolyte

So far, there has been a large number of high conductivity of solid materials to replace the liquid electrolyte. All solid-state composite polymer electrolyte materials have not yet fully realized industrial production, but many areas are moving in the direction of practical development. With the deepening of the study, the ionic conductivity mechanism and constantly improve, but the ionic conductivity of composite electrolytes should be improved, need to conduct groundbreaking research in the preparation process, structure and properties of the composite electrolyte materials have many problems. The composite polymer electrolyte materials has become an intersection of many disciplines including materials science, chemistry, physics, and the content may lead to the field of new energy materials, in particular, is a new technological revolution in the field of battery materials, which study of the problem will continue and in-depth.

A new carbon nanotubes (CNTs)–poly acrylonitrile (PAN) composite electrolyte for solid state dye sensitized solar cells

A new carbon nanotube (CNTs)–poly acrylonitrile (PAN) composite electrolyte was prepared by the thermal polymerization of acrylonitrile (AN) with CNTs for solid-state dye sensitized solar cells (DSSCs). It was found that the uniform CNT–PAN composite was formed due to the thermal polymerization of AN on CNTs. The strong bonding between CNTs and PAN could be confirmed by the characterization of XPS and Raman spectroscopy, resulting in the lowering of crystallinity and the increasing the ionic conductivity of composite electrolytes. On comparison with bare CNTs and the other composite electrolytes, the formation of triiodide (I3−) ions in CNT–PAN composite electrolytes was drastically increased which was expected from the high ionic conductivity of electrolyte via I3−/I− redox couple. DSSCs fabricated with CNT–PAN composite electrolytes achieved relatively high conversion efficiency of 3.9% with an open circuit voltage (VOC) of 0.57V, short circuit current density (JSC) of 10.9mA/cm2 and fill factor of 63.6%, which attributed to supply the higher extent of I3− ions from CNT–PAN composite electrolyte during the charge transport process.

폴리에틸렌 이민과 혼합된 PEO 복합체 전해질의 이온 전도도에 미치는 실리카 필러 첨가 효과

In this study, poly(ethyleneoxide) and poly(ethylene imine) polymer blends containing fumed silica fillers were studied in order to enhance the ion conductivity and interfacial properties. Lithium perchlorate () as a salt, and silica() as the inorganic filler were introduced into the polymer composite electrolyte composites and the composites were examined to evaluate their ionic conductivity for a possibility test of electrolyte application. As the diameter of semicircle in an impedance test became smaller, ionic conductivity of composite electrolytes had been enhanced by addition of 20 wt% silica filler. However, the conductivity was not greatly changed over 20 wt% content because the silica was sufficiently saturated in the polymer electrolytes. Diffraction peaks of PEO became weaker with the addition of inorganic fillers using XRD analysis. It showed that a crystallinity was proportionally reduced by increasing filler contents. The morphology of composite electrolyte films has been investigated by SEM. The heterogeneous morphology which silica was evenly dispersed by the strong adhesion of PEI was shown at higher contents of silica.

Carbon Nanotube (CNT)–Polymethyl Methacrylate (PMMA) Composite Electrolyte for Solid-State Dye Sensitized Solar Cells

A novel carbon nanotube (CNT)-polymethyl methacrylate (PMMA) composite electrolyte was successfully synthesized by the thermal polymerization of methyl methacrylate (MMA) with CNTs for solid-state dye sensitized solar cells (DSSCs). The prepared CNTs-PMMA composite electrolytes were characterized by Fourior transformed-infrared (FT-IR) spectroscopy, field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and ionic conductivity. A strong bonding was observed between CNT and PMMA through ester bonding in the CNT-PMMA composite, resulting in the lowering of crystallinity and increasing the ionic conductivity of composite electrolyte. DSSCs fabricated with CNTs-PMMA composite electrolytes achieved relatively high conversion efficiency of 2.9% with an open circuit voltage (V(oc)) of 0.567 volt, short circuit current (I(sc)) of 8.9 mA/cm2 and fill factor of 61.8%, which is attributed to enhanced amorphicity and ionic conductivity due to the formation of strong bonding between CNT and PMMA molecules.

Carbon nanotubes–polyethylene oxide composite electrolyte for solid-state dye-sensitized solar cells

Novel carbon nanotubes (CNTs)–polyethylene oxide (PEO) composite electrolyte for dye-sensitized solar cell (DSSC) was prepared and characterized for the first time. The strong bonding and interaction between CNTs and PEO in CNTs–PEO composites was observed by the characterization of X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and Raman spectra. The introduction of CNTs into PEO matrix significantly improved the electrolyte properties of DSSC such as roughness, amorphicity and ionic conductivity. The solid-state DSSC fabricated with the optimum composite electrolyte (added 1% CNTs in PEO matrix, 1%CNT–PEO) achieved maximum conversion efficiency of 3.5%, an open circuit voltage ( V OC ) of 0.589 V, short circuit current density ( J SC ) of 10.64 mA/cm 2 and fill factor ( FF) of 56%. The highest IPCE in the DSSC fabricated with 1%CNT–PEO electrolyte is ascribed to the improved ionic conductivity of composite electrolytes and enhanced interfacial contact between electrode and electrolyte.

Physico- and electrochemistry of composite electrolytes based on PEODME–LiTFSI with TiO 2

The effect of fumed TiO 2 fillers (pure and modified by H 2SO 4) on ionic conductivity of composite electrolytes based on poly(ethylene oxide) dimethyl ether (PEODME) oligomer ( M w = 500) doped with lithium bis-(trifluoromethanesulfonyl)imide LiN(CF 3SO 2) 2 (LiTFSI) are studied by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and complex impedance methods. The electrochemical stability of the electrolytes in the potential range of 4 V versus Li electrode has been confirmed by voltammetric measurements. Li electrode reactions have been followed by means of impedance spectroscopy. The growth in time of the resistance of the interfacial (Li electrode–polymer electrolyte) layers was inhibited upon the addition of fillers.