Ion Transport In Electrolytes Research Articles

Novel layered polyaniline-poly(hydroquinone)/graphene film as supercapacitor electrode with enhanced rate performance and cycling stability

It is a challenge to fabricate polyaniline (PANI) materials with high rate performance and excellent stability. Herein a new special supercapacitor electrode material of polyaniline-poly(hydroquinone)/graphene (PANI-PHQ/RGO) film with layered structure was prepared by chemical oxidative polymerization of aniline and hydroquinone (H2Q) in the presence of RGO hydrogel film. The synergistic effect and loose layered structure of the composite film facilitate fast diffusion and transportation of electrolyte ions through unimpeded channels during rapid charge-discharge process, resulting in high rate capability and stable cycling performance. As a result, the PANI-PHQ/RGO-61 film electrode exhibited 356 F g−1 at a current density of 0.5 A g−1 and high capacitance retention of 83% from 0.5 to 30 A g−1. Moreover, it presented an excellent cycling stability with 94% of capacitance retention in comparison with 60% of pure PANI electrode and an outstanding Coulombic efficiency of 99% after 1000 cycles of galvanostatic charge-discharge. These superior electrocapacitive properties make it one of promising candidates for electrochemical energy storage.

Studies on AC Electrical Conductivity, Dielectric Properties and Ion Transport in PVA polymeric Electrolytes

Studies on AC Electrical Conductivity, Dielectric Properties and Ion Transport in PVA polymeric Electrolytes

Hierarchically porous carbon with high-speed ion transport channels for high performance supercapacitors

Abstract Hierarchically porous carbons (HPC) are considered as promising electrode materials for supercapacitors, due to their outstanding charge/discharge cycling stabilities and high power densities. However, HPC possess a relatively low ion diffusion rate inside the materials, which challenges their application for high performance supercapacitor. Thus tunnel-shaped carbon pores with a size of tens of nanometers were constructed by inducing the self-assembly of lithocholic acid with ammonium chloride, thereby providing high-speed channels for internal ion diffusion. The as-formed one-dimensional pores are beneficial to the activation process by KOH, providing a large specific surface area, and then facilitate rapid transport of electrolyte ions from macropores to the microporous surfaces. Therefore, the HPC achieve an outstanding gravimetric capacitance of 284 F g−1 at a current density of 0.1 A g−1 and a remarkable capacity retention of 64.8% when the current density increases by 1000 times to 100 A g−1.

Modeling the Effect of Mechanics on Ion Transport and Reaction Kinetics in Solid Electrolytes

Solid state batteries are gaining increasing attention due to their potential for high energy densities and their enhanced safety properties when using a solid electrolyte separator with a metal anode such as Lithium or Sodium. The solid electrolyte can be designed as a single ion conductor or as a solid solvent with both mobile anions and cations. Especially for the description of the latter case, the influence of mechanics on ion transport and reaction kinetics cannot be neglected or treated in a simplified manner as is usually done for liquid electrolytes, see e.g. [1]. In this contribution we present a coupled electro-chemo-mechanical modeling framework for ion transport in solid electrolytes and investigate the influence of mechanics on both ion transport and reaction kinetics. Drawing on ideas from Bucci et al. [2], we formulate a fully coupled large strain theory for ionic transport in terms of electric field, mechanical deformation and anion and cation concentrations. We derive suitable constitutive relations based on the Helmholtz energy and thermodynamic restrictions for the species fluxes of the different ionic constituents as done in the context of liquid electrolytes e.g. by Dreyer et al. [3]. We propose a constitutive formulation that allows the calculation of the electrochemical transport in the deformed state and consistently predicts the coupling between species transport and gradients of stress and material properties based on the choice of the Helmholtz energy, similar to e.g. lithium diffusion in active particles [4] or the swelling of polymeric gels [5]. Using the framework of the newly derived transport theory, we investigate the effect of mechanics on the interfacial kinetics at the metal anode/solid electrolyte interface. Based on energetic considerations as presented in [6] or [7], we propose a modified Butler-Volmer relation that not only establishes a relation between the exchange current density and potential/concentration differences across the interface but also takes into account the mechanical state of both solid electrolyte and metal anode. To illustrate the features of the model and to highlight cases where the electro-chemo-mechanical coupling plays an important role for ion transport and kinetics, we show numerical examples for a Lithium symmetric solid state cell with binary solid electrolyte. [1] NEWMAN, J. S.; THOMAS-ALYEA, K. E. [2004]: Electrochemical systems. J.Wiley, Hoboken, N.J., 3rd ed Edition. [2] BUCCI, G.; CHIANG, Y.-M.; CARTER, W. C. [2016]: Formulation of the coupled electrochemical mechanical boundary value problem, with applications to transport of multiple charged species. Acta Materialia, 104:33–51. [3] DREYER, W.; GUHLKE, C.; MÜLLER, R. [2013]: Overcoming the shortcomings of the Nernst–Planck model. Physical Chemistry Chemical Physics, 15(19):7075. [4] BOHN, E.; ECKL, T.; KAMLAH, M.; MCMEEKING, R. [2013]: A model for lithium diffusion and stress generation in an intercalation storage particle with phase change. Journal of the Electrochemical Society, 160(10):A1638–A1652. [5] HONG, W.; ZHAO, X.; ZHOU, J.; SUO, Z. [2008]: A theory of coupled diffusion and large deformation in polymeric gels. Journal of the Mechanics and Physics of Solids, 56(5):1779–1793. [6] BOCKRIS, J. O.; REDDY, A. K. N.; GAMBOA-ALDECO, M. [2000]: Modern Electrochemistry 2A: Fundamentals of Electrodics. [7] MONROE, C.; NEWMAN, J. [2004]: The effect of interfacial deformation on electrodeposition kinetics. Journal of The Electrochemical Society, 151(6):A880.

(Invited) Ion Transport in Polymerized Ionic Liquids: Structure-Morphology-Property Relationships

Polymerized ionic liquids (PolyILs) are a novel class of functional polymers that combine the unique physicochemical properties of molecular ionic liquids with the outstanding mechanical characteristics of polymers. This special mix of features might help to circumvent the key limitations of low molecular weight ionic liquids, namely, leakage and poor mechanical properties while utilizing their outstanding characteristics such as low vapor pressures, wide liquidus ranges, high thermal stability, high ionic conductivity, and wide electrochemical windows. PolyILs have shown remarkable advantages when employed in electrochemical devices such as dye-sensitized solar cells, lithium batteries, actuators, field-effect transistors, light emitting electrochemical cells, and electrochromic devices, among others. Despite their promising prospects as ideal polymer electrolytes, the role of molecular structure, morphology, and polymer dynamics on charge transport in PolyILs remains poorly understood. According to classical theories, the self-diffusion and ion transport in electrolytes are controlled by structural relaxation. These approaches predict similar temperature dependence for the dc conductivity and structural dynamics. Although this prediction has been shown to hold reasonably well for low molecular weight aprotic ionic liquids, it fails for PolyILs. In addition, the impact of morphology on charge transport is not considered within the framework of these theories. This talk will focus on new insights obtained from experimental studies employing broadband dielectric spectroscopy, temperature-modulated differential scanning calorimetry, rheology, and scattering techniques to elucidate the impact of morphology on charge transport and structural dynamics in systematic series of polymerized ammonium- and imidazolium- based ionic liquids. Detailed analyses reveal strong decoupling of these processes in the PolyILs, implying the limitation of the classical theories in describing charge transport and molecular dynamics in these materials, in contrast to low molecular weight systems. In addition, the strong correlation observed between ionic conductivity from dielectric experiments and morphologies from scattering and computational studies will be discussed.

MnO2 nanotubes assembled on conductive graphene/polyester composite fabric as a three-dimensional porous textile electrode for flexible electrochemical capacitors

A three-dimensional (3D) electrode material was successfully synthesized through a facile ZnO-assisted hydrothermal process in which vertical MnO2 nanotube arrays were in situ grown on the conductive graphene/polyester composite fabric. The morphology and structure of MnO2 nanotubes/graphene/polyester textile electrode were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The 3D electrode structure facilitates to achieve the maximum number of active sites for the pesudocapacitance redox reaction, fast electrolyte ion transportation and short ion diffusion path. The electrochemical measurements showed that the electrode possesses good capacitance capacity which reached 498F/g at a scan rate of 2mV/s in Na2SO4 electrolyte solution. The electrode also showed stable electrochemical performances under the conditions of long-term cycling, and mechanical bending and twisting.

Nonlinear ion transport in liquid and solid electrolytes

This paper describes nonlinear ion transport properties of liquid and solid electrolytes. Typically, the relation between ionic current density and electric field becomes nonlinear at electric fields above 50–100 kV/cm. We review the 1st and 2nd Wien effect found in classical strong and weak electrolyte solutions as well as the strong nonlinear ion transport effects observed for inorganic glasses and for polymer electrolytes. Furthermore, we give an overview over models describing nonlinear ion transport in electrolyte solutions, in glasses and in polymers. Recent results are presented for the nonlinear ionic conductivity of supercooled ionic liquids. We show that supercooled ionic liquids exhibit anomalous Wien effects, which are clearly distinct from the classical Wien effects. We also discuss the frequency dependence of higher-order conductivity and permittivity spectra of these liquids.

An Ideal Electrode Material, 3D Surface-Microporous Graphene for Supercapacitors with Ultrahigh Areal Capacitance.

The efficient charge accumulation of an ideal supercapacitor electrode requires abundant micropores and its fast electrolyte-ions transport prefers meso/macropores. However, current electrode materials cannot meet both requirements, resulting in poor performance. Herein, we creatively constructed three-dimensional cabbage-coral-like graphene as an ideal electrode material, in which meso/macro channels are formed by graphene walls and rich micropores are incorporated in the surface layer of the graphene walls. The unique 3D graphene material can achieve a high gravimetric capacitance of 200 F/g with aqueous electrolyte, 3 times larger than that of commercially used activated carbon (70.8 F/g). Furthermore, it can reach an ultrahigh areal capacitance of 1.28 F/cm2 and excellent rate capability (83.5% from 0.5 to 10 A/g) as well as high cycling stability (86.2% retention after 5000 cycles). The excellent electric double-layer performance of the 3D graphene electrode can be attributed to the fast electrolyte ion transport in the meso/macro channels and the rapid and reversible charge adsorption with negligible transport distance in the surface micropores.

Bioinspired Ultrastrong Solid Electrolytes with Fast Proton Conduction along 2D Channels.

Solid electrolytes have attracted much attention due to their great prospects in a number of energy- and environment-related applications including fuel cells. Fast ion transport and superior mechanical properties of solid electrolytes are both of critical significance for these devices to operate with high efficiency and long-term stability. To address a common tradeoff relationship between ionic conductivity and mechanical properties, electrolyte membranes with proton-conducting 2D channels and nacre-inspired architecture are reported. An unprecedented combination of high proton conductivity (326 mS cm-1 at 80 °C) and superior mechanical properties (tensile strength of 250 MPa) are achieved due to the integration of exceptionally continuous 2D channels and nacre-inspired brick-and-mortar architecture into one materials system. Moreover, the membrane exhibits higher power density than Nafion 212 membrane, but with a comparative weight of only ≈0.1, indicating potential savings in system weight and cost. Considering the extraordinary properties and independent tunability of ion conduction and mechanical properties, this bioinspired approach may pave the way for the design of next-generation high-performance solid electrolytes with nacre-like architecture.

Hierarchical flower-like C/NiO composite hollow microspheres and its excellent supercapacitor performance

Abstract Nickel (II) oxide (NiO) nanosheet grown on N-doped carbon hollow spheres (NiO/NCHS) with hierarchical pore structure are obtained via facile chemical bath deposition followed by calcination at 350 °C under nitrogen atmosphere. Phase structure measurements indicate that the material is composed of NiO and N-doped carbon. The NiO/NCHS composite exhibits a unique flower-like morphology, where ultrathin NiO nanosheets are vertically grown on the surface of NCHS. This hierarchical nanostructure is beneficial for facilitating electron and electrolyte ion transport and accelerating the reversible redox reaction. The specific capacitance of the NiO/NCHS composite (585 F g −1 at 1 A g −1 ) is higher than that of pure NiO particle (453 F g −1 at 1 A g −1 ). Meanwhile, the NiO/NCHS composite exhibits excellent rate performance and superior cycling stability over 6000 cycles. The enhanced supercapacitive performance of the NiO/NCHS nanocomposite indicates that it can be an appealing candidate electrode material for supercapacitors.

New Avenue for Appendage of Graphene Quantum Dots on Halloysite Nanotubes as Anode Materials for High Performance Supercapacitors

Graphene quantum dots (GQDs) are a newly developed graphene family with good electrical conductivity and high theoretical capacitance, while halloysite nanotubes (HNTs) are naturally occurring layered mineral materials containing high active sites for energy storage support. The combination of HNTs and GQDs can offer a new strategy on the fabrication of eco-friendly electrode materials for high performance supercapacitor applications. Herein, an environmentally friendly GQD-HNT nanocomposite is fabricated in the presence of (3-aminopropyl)-triethoxysilane to provide increased charge storage sites as well as to allow for the fast charge transport for supercapacitor application. Morphological and surface analytical results show that 5–10 nm GQDs are homogeneously distributed on the surface of APTES-coated HNTs via amide linkage. This new and novel layered nanocomposite can provide accessible electroactive sites and low resistance to accelerate the electrons and electrolyte ion transport, resulting in excell...

A novel approach for supercapacitors degradation characterization

Abstract A novel approach to analyze electrochemical impedance spectroscopy (EIS), based on evolutionary programming, has been utilized to characterize supercapacitors operation mechanism and degradation processes. This approach poses the ability of achieving a comprehensive study of supercapacitors via solely AC measurements. Commercial supercapacitors were examined during accelerated degradation. The microstructure of the electrode-electrolyte interface changes upon degradation; electrolyte parasitic reactions yield the formation of precipitates on the porous surface, which limit the access of the electrolyte ions to the active area and thus reduces performance. EIS analysis using Impedance Spectroscopy Genetic Programming (ISGP) technique enables identifying how the changing microstructure is affecting the operation mechanism of supercapacitors, in terms of each process effective capacitance and time constant. The most affected process is the transport of electrolyte ions at the porous electrode. Their access to the whole active area is hindered, which is shown in our analysis by the decrease of the capacitance gained in the transport and the longer time it takes to penetrate the entire pores depth. Early failure detection is also demonstrated, in a way not readily possible via conventional indicators. ISGP advanced analysis method has been verified using conventional and proven techniques: cyclic voltammetry and post mortem measurements.

(Invited) Flexible Mxene/Graphene Films for Ultrafast Supercapacitors

Due to their unique properties and a great diversity, various two-dimensional nanomaterials have attracted interest from scientific community for energy storage applications in recent years. Herein, we present a facile strategy to prepare MXene/graphene films with excellent flexibility and electrical conductivity for supercapacitors by using layer-by-layer electrostatic self-assembly from solution between positively charged graphene and negatively charged MXene nanosheets. Graphene nanosheets are intercalated in-between MXene layers after electrostatic assembly. As a result, the face-to-face self-restacking of MXene nanosheets is effectively prevented, leading to the considerably increased interlayer spacing of MXene layers and more active sites accessible to electrolyte ions, which ensures high diffusion rate and transport of electrolyte ions during the charge/discharge process. The as-prepared freestanding MXene/graphene (5wt.%) film displays outstanding volumetric capacitance of 1040 F cm-3 at a scan rate of 2 mV s-1 and impressive rate capability with 61% capacitance retention at 1000 mV s-1. Meanwhile, the film electrode exhibits a long cycle life with almost no capacitance decay after 20,000 cycles. More importantly, our fabricated symmetric supercapacitor shows a maximum volumetric energy density of 34.6 Wh L-1 and an ultrahigh volumetric power density up to 74.4 kW L-1, which is among the highest values reported for carbon and MXene based materials in aqueous electrolytes so far. This work not only provides fundamental insights to the effect of interlayer spacing on the electrochemical performance of emerging MXene materials but also sheds light on future design of next-generation flexible, portable and highly integrated supercapacitors with high volumetric and rate performances. Figure 1

(Invited) Decoupling Effective Li+ Ion Conductivity from Electrolyte Viscosity for Improved Room-Temperature Cell Performance

Ionic liquids are attractive materials for alternative electrolytes to combat the safety issues associated with conventional organic carbonate-based electrolytes. However, the performance of ionic liquid-based cells is generally not competitive as the high viscosity and low conductivity limits the rate performance. The work presented here demonstrates that the drawbacks in terms of rate capability can be overcome through the use of the high lithium concentration Pyr12O1FTFSI0.6LiFTFSI0.4 electrolyte. Despite an order of magnitude difference in the conductivity and viscosity, this high concentration electrolyte outperforms the lithium-dilute electrolyte with the same components in terms of rate capability in LTO and LFP half and full cells. The results suggest that the effective Li ion transport in the concentrated electrolyte is higher than in the dilute solution.

(Invited) Liquid and Solid State NMR Investigations of Electrolytes for Beyond Lithium Ion Applications

Nuclear magnetic resonance (NMR) has been productively employed to investigate ion transport and solvation in standard carbonate-based Li ion battery electrolytes and in solid polymer electrolytes based on poly(ethylene oxide) (PEO). Future electrochemical power sources require new electrolytes to adapt to disruptive changes in the basic working chemistry, such as moving from Li ion to Na ion, or to Li metal electrodes. We highlight two recent collaborative activities on electrolytes in our group (i) Na ion; (ii) Li metal polymer. Using a combination of 23Na, 19F and natural abundance 17O NMR, and pulsed field gradient diffusion in a collaboration with the U.S. Army Research Lab, we have examined NaPF6 solutions in binary solvent mixtures ethylene carbonate (EC) and ethylmethyl carbonate (EMC) for possible cation solvation preference as a function of EC/EMC ratio. Spectroscopic evidence demonstrate that the Li+ and Na+ cations share a number of similar ion–solvent and ion-ion interaction trends, such as a preference for a solvation shell rich in cyclic carbonates over linear carbonates and fluorinated carbonates. However some differences are noted, in particular a somewhat weaker ion-solvent interaction for Na+. Ionic Materials, Inc. has invented a novel polymer with extremely high ionic conductivity over a range of temperatures, even surpassing that of a commercial porous separator containing the standard liquid carbonate-based electrolyte at room temperature. This solid polymer can be reliably extruded into very thin films, is non-flammable, has attractive mechanical properties for lithium dendrite suppression, is electrochemically stable against Li, and is compatible with a variety of different anodes and cathodes. The polymer electrolyte is based on an inexpensive semicrystalline commercially available polymer such as polyether ether ketone or polyphenylene sulfide and Li salts familiar to the battery and polymer electrolyte communities. The ionic transport mechanism is unlike that which characterizes the PEO salt complexes – that is ion mobility is completely decoupled from polymer host motion, as verified by differential scanning calorimetry and NMR. In fact NMR pulsed gradient measurements reveal Li self-diffusion coefficients at room temperature that are an order of magnitude higher than in the ceramic ion conductors of the Li10GeP2S12 class and thus the highest in any known solid. Furthermore, the Li+ transference number determined electrochemically and by NMR is > 0.6.

Effects of Mesoscopic Microstructural Features on the Effective Ionic Diffusivity of Solid Electrolytes for Li Batteries

The kinetics of ion transport in solid electrolytes is known to be highly sensitive to the topological characteristics of ion conduction pathways. The conduction mechanisms usually involve concurrent ionic diffusion along a variety of mesoscopic features of internal microstructures such as bulk grain, structural domains, and associated boundaries as well as their network. Due to the complexity of these structural features of the solid electrolytes during operation, it is significantly challenging to characterize the microstructure-ionic diffusion property relationship. For better mechanistic understanding of relevant conduction mechanisms, it is necessary to thoroughly explore the impacts of individual microstructural factors on the overall kinetic properties and performances. In this presentation, we will present our development of an efficient mesoscopic computational method for extracting the effective diffusivity of the solid electrolyte containing arbitrarily distributed microstructural inhomogeneities such as differently oriented multiple grains, several structural variants of phase domains, and grain/domain boundaries. Using two- and three-dimensional digital microstructures generated by phase-field simulations as well as the fundamental diffusivity tensors of reference phases and boundaries derived from atomistic calculations as inputs, the method enable us to efficiently compute the effective diffusivity tensor of the entire system. We will then discuss the applications of this framework to investigating the relationship between relevant individual microstructural features and effective diffusivity of highly conductive solid electrolytes (e.g., LLTO and LLZO) focusing on the impacts of topological features of grains, internal mesoscopic structures of high- and low-temperature phase domains, and grain/phase boundary networks. *This work of was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Modulating Ion Transport and Self-Assembly of Polymer Electrolytes via End-Group Chemistry

We report a rational design of solid-state dry polymer electrolytes with high conductivity, high mechanical strength, and improved cation transference number. Thiol–ene click chemistry provided orthogonal control over the type and number of end groups in poly(styrene-b-ethylene oxide) (PS-b-PEO) block copolymers. This approach permitted the synthesis of PEO chains with reduced crystallinity, reminiscent of PEO oligomers, thereby playing a key role in improving the room temperature conductivity. Intriguingly, the incorporation of diol or dicarboxylic acid end groups in PS-b-PEO produced a well-defined gyroid structure, leading to order of magnitude improvements in the storage modulus. Out of the various samples examined, the electrolytes bearing terminal diol displayed the highest ionic conductivity and a 2-fold increase in lithium transference number. The improvements in performance are attributed to the reduced interchain aggregation and the anion stabilization mediated by the terminal diol group. The fa...

Supramolecular Assembly of 1D Pristine Carbon Nanotubes and 2D Graphene Oxides into Macroscopic All‐Carbon Hybrid Sponges for High‐Energy‐Density Supercapacitors

AbstractThe rational design and targeted synthesis of macroscopic and ultralight all‐carbon sponges with satisfying electron/proton conductivity through a simple and environmentally friendly approach is challenging. Herein, three‐dimensional carbon nanotube‐graphene oxide (CNT‐GO) hybrid hydrogels have been constructed by the gelation of an aqueous dispersion of graphene oxide (GO) induced by pristine carbon nanotubes (CNTs) without any additives or other crosslinkers. Upon reduction of CNT‐GO hydrogels and removal of water by freeze‐drying, the resulting carbon nanotube‐graphene (CNT‐G) aerogels exhibit a unique all‐carbon continuous framework with a hierarchical porosity that allows high‐rate transport of electrolyte ions and electrons throughout the electrode matrix. As a result, they show high specific energy (31.3 Wh kg−1), high specific capacitance with excellent rate performance (≈71 % retention at 10 A g−1) and cycling stability (≈100 % retention at 10 A g−1 for 5000 cycles) in two electrode systems, and thus great potential as promising electrode materials for next‐generation supercapacitors.

Enhanced lithium ion transport in garnet-type solid state electrolytes

Al-substituted Li7La3Zr2O12 samples processed under argon show enhanced Li-ion transport and interfacial properties in symmetrical cells with lithium electrodes, compared to those prepared in air. In particular, the samples prepared under argon have higher ionic conductivities and lower interfacial impedances in symmetrical lithium cells, and show better DC cycling characteristics. The electronic conductivities are also somewhat higher. Pellets subjected to thermal treatment under the two types of atmospheres have different colors but exhibit similar microstructures. X-ray diffraction experiments suggest that there are slight structural differences between the two types of samples, but few dissimilarities were observed in elemental composition, distribution of ions, oxidation states, or bond lengths using laser-induced breakdown spectroscopy (LIBS), x-ray photoelectron spectroscopy (XPS), and extended x-ray absorption fine structure spectroscopy (EXAFS) to analyze the materials. Additionally, there was no evidence that La or Zr were reduced during the processing under Ar. Possible explanations for the improved electrochemical properties of the sample prepared under Ar compared to the one prepared in air include differences in grain boundary chemistries and conductivities and/or a small concentration of oxygen vacancies in the former.

Diffusion of Lithium Ions in Amorphous and Crystalline Poly(ethylene oxide)3:LiCF3SO3 Polymer Electrolytes

The PEO3:LiCF3SO3 polymer electrolyte has attracted significant research due to high conductivity and enhanced stability in lithium polymer batteries. Most experimental studies have shown that amorphous PEO lithium salt electrolytes have higher conductivity than the crystalline ones. Other studies, however, have shown that crystalline PEO salt complexes can conduct ions. As a result, further theoretical investigations are warranted to help clarify the issue. In this work, we use density functional theory with the climbing image nudged elastic band method to investigate the atomic-scale mechanism of lithium ion transport in the polymer electrolytes. We also use density functional theory and ab initio molecular dynamics simulations to obtain the amorphous structure of PEO3:LiCF3SO3. The diffusion pathways and activation energies of lithium ions in both crystalline and amorphous PEO3:LiCF3SO3 are determined. In crystalline PEO3:LiCF3SO3, the activation energy for the low-barrier diffusion pathway is approximately 1.0eV. In the amorphous phase, the value is 0.6eV. This result would support the experimental observation that amorphous PEO3:LiCF3SO3 has higher ionic conductivity than the crystalline phase.