PEO-based Composite Polymer Electrolytes Research Articles

Effect of molecular sieves ZSM-5 on the crystallization behavior of PEO-based composite polymer electrolyte

Polarized optical microscopy (POM) results show that ZSM-5 has great influence on both the nucleation stage and the growth stage of PEO spherulites. Part of ZSM-5 particles can act as the nucleus of PEO spherulites and thus increase the amount of PEO spherulites. On the other hand, ZSM-5 can restrain the recrystallization tendency of PEO chains through Lewis acid–base interaction and hence decrease the growth speed of PEO spherulites. The increasing amount of PEO spherulites, decreasing size of PEO spherulites and the incomplete crystallization are all beneficial for creating more continuous amorphous phases of PEO, which is very important for the transporting of Li + ions. An adequate amount of ZSM-5 can enhance the room temperature ionic conductivity of PEO-LiClO 4 based polymer electrolyte for more than two magnitudes.

Enhanced electrochemical properties of poly(ethylene oxide)-based composite polymer electrolyte with ordered mesoporous materials for lithium polymer battery

Ordered mesoporous materials (OMMs), due to its potential for advanced applications in separation technologies, catalysis, and nanoscience, have attracted much attention in the past decade. In this work, a novel PEO-based composite polymer electrolyte has been developed by using ordered mesoporous silica (OMS) as the filler. The interactions between OMS and PEO matrix are studied by XRD, DSC, and POM techniques in detail. The effects of OMS on the electrochemical properties of the PEO-based polymer electrolyte, such as ionic conductivity, lithium ion transference number, and electrochemical stability windows are studied by electrochemical impedance spectroscopy and steady-state current method. The experimental results show that the addition of OMS can enhance the ionic conductivity and increase the lithium ion transference number of PEO-based polymer electrolyte at the same time. The excellent performances such as high ionic conductivity, good mechanical stability, and broad electrochemical stability window suggest that PEO–LiClO 4/OMS composite polymer electrolyte can be used as candidate electrolyte material for lithium polymer batteries.

Enhanced electrochemical properties of PEO-based composite polymer electrolyte with shape-selective molecular sieves

ZSM-5 molecular sieves, usually known as shape-selective catalyst in a great deal of catalysis fields, due to its special pore size and two-dimensional interconnect channels. In this work, a novel PEO-based composite polymer electrolyte by using ZSM-5 as the filler has been developed. The interactions between ZSM-5 and PEO matrix are studied by DSC and SEM techniques. The effects of ZSM-5 on the electrochemical properties of the PEO-based electrolyte, such as ionic conductivity, lithium ion transference number, and interfacial stability with lithium electrode are studied by electrochemical impedance spectroscopy and steady-state current method. The experiment results show that ZSM-5 can enhance the ionic conductivity and increase the lithium ion transference number of PEO-based electrolyte more effectively comparing with traditional ceramic fillers such as SiO 2 and Al 2O 3, resulting from its special framework topology structure. The excellent performances such as high ionic conductivity, good compatibility with lithium metal electrode, and broad electrochemical stability window suggesting that PEO–LiClO 4/ZSM-5 composite polymer electrolyte can be used as candidate electrolyte materials for lithium polymer batteries.

Novel composite polymer electrolyte comprising poly(ethylene oxide) and triblock copolymer/mesostructured silica hybrid used for lithium polymer battery

Ordered mesoporous materials, due to its potential applications in catalysis, separation technologies, and nano-science have attracted much attention in the past few years. In this work, a novel PEO-based composite polymer electrolyte by using organic–inorganic hybrid EO 20PO 70EO 20 @ mesoporous silica (P123 @ SBA-15) as the filler has been developed. The interactions between P123 @ SBA-15 hybrid and PEO chains are studied by X-ray diffraction (XRD), differential scanning calorimeter (DSC), and FT-IR techniques. The effects of P123 @ SBA-15 on the electrochemical properties of the PEO-based electrolyte, such as ionic conductivity, lithium ion transference number are studied by electrochemical ac impedance spectroscopy and steady-state current method. The experiment results show that P123 @ SBA-15 can enhance the ionic conductivity and increase the lithium ion transference number of PEO-based electrolyte, which are induced by the special topology structure of P123 in P123 @ SBA-15 hybrid, at the same time. The excellent lithium transport properties and broad electrochemical stability window suggesting that PEO–LiClO 4/P123 @ SBA-15 composite polymer electrolyte can be used as candidate electrolyte materials for lithium polymer batteries.

Composite polymer electrolyte doped with mesoporous silica SBA-15 for lithium polymer battery

SBA-15, due to its ordered mesoporous structure and potential for advanced applications in separation technologies, catalysis, and nanoscience, has attracted much attention in the past few years. In this work, a novel PEO-based composite polymer electrolyte has been developed by using SBA-15 as the filler. The interactions between SBA-15 and PEO matrix are studied by XRD, DSC, and FT-IR techniques in detail. The effects of SBA-15 on the electrochemical properties of the PEO-based polymer electrolyte, such as ionic conductivity, lithium ion transference number, and interfacial stability with lithium electrode, are studied by electrochemical impedance spectroscopy and steady-state current method. The experiment results show that the addition of SBA-15 can enhance the ionic conductivity and increase the lithium ion transference number of PEO-based polymer electrolyte at the same time. The excellent performances such as high mechanical stability, good compatibility with lithium metal electrode, and broad electrochemical stability window suggest that PEO–LiClO 4/SBA-15 composite polymer electrolyte can be used as candidate electrolyte material for lithium polymer batteries.

Selective Transporting of Lithium Ion by Shape Selective Molecular Sieves ZSM-5 in PEO-Based Composite Polymer Electrolyte

To elucidate the mechanism of the enhancement of lithium ion transference numbers, TLi+, induced by ZSM-5 in PEO-based composite polymer electrolyte, different types of other fillers, such as ceramic fillers (SiO2 and Al2O3), solid superacid (SO42-/ZrO2), layered materials (montmorillonite), and mesoporous materials (MCM-41, HMS, and SBA-15), are selected to compare with ZSM-5 molecular sieves. The experimental results suggest that ZSM-5 may enhance the TLi+ of PEO-based composite polymer electrolytes in three ways: (1) Lewis acid−base interactions, resulting in the release of more “free” Li+ cations; (2) selective passing of Li+ cations due to the special pore size of ZSM-5 and electrostatic repulsion for ClO4- anions due to the negative environment in the channels of ZSM-5; (3) the cation-exchange centers in the framework of ZSM-5, suggesting that the Li+ cation can be ion-exchanged into the channels for charge balance, namely, provide a special conducting pathway for Li+ cation. In addition, room temperature ionic conductivity of the composite polymer electrolyte can also be increased by about 2 orders of magnitude. The high lithium ion transference numbers combined with a suitable ionic conductivity of PEO−LiClO4−ZSM5 composite polymer electrolyte suggest that it can be used as candidate electrolyte material for all solid-state rechargeable lithium polymer batteries.

Effect of organic-inorganic hybrid P123-em-SBA15 on lithium transport properties of composite polymer electrolyte

A novel PEO-based composite polymer electrolyte by using organic-inorganic hybrid EO20PO70EO20-emmesoporous silica (P123-em-SBA15) as the filler has been developed. The experiment results show that P123-em-SBA15 can enhance the lithium-ion transference number of the composite polymer electrolyte, which is induced by the special topology structure of P123 in P123-em-SBA15 hybrid. In addition, room temperature ionic conductivity of the composite polymer electrolyte can also be increased by about two orders of magnitude. The excellent lithium transport properties suggest that PEO-LiClO4-P123-em-SBA15 composite polymer electrolyte can be used as electrolyte materials for all solid-state rechargeable lithium polymer batteries.

Study on Electrochemical Properties of PEO-based Composite Polymer Electrolytes

Study on Electrochemical Properties of PEO-based Composite Polymer Electrolytes

NMR and conductivity study of PEO-based composite polymer electrolytes

The influence of the space charge created by the presence of TiO 2 nanoparticles on the lithium and polymer chain mobility have been investigated in solid composite polymer electrolytes (CPE), poly(ethylene oxide) (PEO) LiClO 4, by using complex impedance spectroscopy and nuclear magnetic resonance (NMR). Special care was taken with the synthesis and the characterization of the TiO 2 particles and with the composite preparation. The conductivity and NMR measurements were undertaken in composite samples nanoparticles having constant total surface area. Proton ( 1H) and lithium ( 7Li) lineshapes and spin-lattice relaxation times were measured as a function of temperature. Activation energies extracted from the 7Li relaxation data are in the range 0.20–0.22 eV. The NMR decoupling experiment suggests that the Li–Li interactions are stronger in the composites when compared with those of the ceramic free electrolytes.

Effects of alumina whisker in (PEO) 8–LiClO 4-based composite polymer electrolytes

This paper reports the morphological, electrical and mechanical characteristics of the PEO-based composite polymer electrolytes with alumina whisker as fillers. The SEM results showed that serious microcracks occurred in the pristine PEO–LiClO 4 polymer electrolytes when they were quenched at room temperature and spherulites were allowed to form in the electrolytes. Addition of alumina whisker effectively prevented the formation of the microcracks. The whiskers were homogeneously dispersed in the polymer electrolyte matrix and exhibited excellent interconnection with PEO–LiClO 4 polymer electrolyte. The addition of whisker additives improved the ionic conductivity of the PEO–LiClO 4 polymer electrolytes to some extent when the content of the whisker was less than 20 wt.%. Moreover, the whisker could remarkably improve the mechanical performance of the PEO–LiClO 4 polymer electrolyte especially at the temperatures higher than its melting point.

Ion-transport phenomena in concentrated PEO-based composite polymer electrolytes

The enhancement of the ionic conductivity of Li–P(EO) n -based polymer electrolytes by the addition of finely divided inorganic oxides is the subject of considerable discussion. The increase in ionic conductivity in concentrated composite solid polymer electrolytes (CSPE) is related both to the suppression of the formation of crystalline PEO and PEO-salt phases and to interfacial conduction. In the case of polycrystalline or polyparticle solid electrolytes, however, grain-boundary (GB) resistance, which is associated with the crossover of ions from particle to particle across grain boundaries orthogonal to the direction of current flow (or parallel to the field lines), must be considered. The conduction across grain boundaries in polymer appears to be ignored so far. In this work, we provide SEM and ECS experimental data on LiI–P(EO)–Al 2O 3 CSPEs. The effects of plasticizers, doping by CaI 2, change in Li/EO ratio, and nanosize alumina concentration on the interior grain ionic conductivity and on the resistance of the orthogonal grain boundaries are addressed.

Role of the ceramic fillers in enhancing the transport properties of composite polymer electrolytes

A model to account for the role of the ceramic fillers in enhancing the transport properties of PEO-based composite polymer electrolytes is here proposed. The model is supported by a series of specifically addressed electrochemical tests which included the determination of the conductivity and of the lithium transference number of various composite electrolyte samples differing from the type of the surface states of the ceramic filler.

Nuclear magnetic resonance study of PEO-based composite polymer electrolytes

The effect of carbon black and ceramic (α-Al 2O 3 and γ-Al 2O 3) particles on the cationic and polymer chain mobility have been investigated in poly(ethylene oxide)–lithium salt (LiClO 4 and LiBF 4) solid composite polymer electrolytes by using nuclear magnetic resonance (NMR) techniques. Proton ( 1H) and lithium ( 7Li) lineshapes and spin–lattice relaxation times were measured as a function of temperature. The 7Li data indicates that the lineshape and relaxation is affected by the coupling of its quadrupolar moment to the surrounding electric field gradients. Activation energies extracted from the 7Li relaxation data are in the range 0.20–0.25 eV. Results show that the addition of α-Al 2O 3 influenced both, the relative cation mobility and the polymer chain motion. Calculation shows that this result is in quantitative agreement with the conductivity data.

PEO-based composite polymer electrolytes

Poly(ethylene oxide) (PEO)-based composite polymer electrolytes have been widely studied during the last ten years. At present, systems with room temperature conductivity up to 10 −4 ohm −1 cm −1 have been synthesized and tested in electrochemical devices like lithium-ion rechargeable batteries. In this paper, we will chiefly focus on the experimental work, whereas the theoretical models for ion transport will be only summarized. The systems are classified as `blend-based' and `mixed-phase' composite electrolytes. We call blend-based systems those systems obtained from homogeneous solutions of two components in an appropriate common solvent. Mixed-phase systems are inhomogeneous mixtures of polymer and inorganic or organic additives not dissolved in a common solvent. Effective Medium Theories (EMT) are useful for modelling the conductivity behaviour in these composite electrolytes.

The sei model—application to lithium-polymer electrolyte batteries

In this work we studied interfacial phenomena in PEO-based composite polymer electrolytes ( cpe) which were stabilized by a high-surface-area oxide matrix such as alumina or magnesia. In order to avoid both consumption of the electrolyte salt (by reaction with Li) and anode passivation, we used only thermodynamically stable anions such as I − and Br −. Two types of solid electrolytes have been studied: composite solid electrolytes ( cse)—salt-rich electrolytes which have an n to LiI ratio of 2.5–3 (n in P(EO)n), and t + close to unity and cpes which have an n to LiI ratio of 6–20. Using an ac technique and assuming a simple equivalent circuit, we determined the apparent thickness of the SEI (L SEI), its resistance (R SEI), apparent conductivity ( σ SEI ) and the apparent energy of activation for conduction (Ea SEI). The effects of: inorganic oxide matrix, LiX salt, co-polymers and plasticizers on σ SEI , Ea SEI , L SEI and R SEI were determined. L SEI and R SEI, were found to be low and stable up to 3000 h of storage at 120 °C (less than 10 nm and typically 3–8 Ωcm 2).

The lithium polymer electrolyte battery VI. Design and characterization of prototypes

Flat, thin-film prototypes of rechargeable lithium batteries have been realized using a PEO-based composite polymer electrolyte and composite cathodic mixtures. The performance and the characteristics of these batteries have been investigated by electrochemical and impedance analysis.