PEO-based Composite Polymer Electrolytes Research Articles

Synergistic Enhancement of Biaxial Stretching and Multilayer Composites in All-Solid-State Polymer Electrolytes.

As an important component of lithium-ion batteries, all-solid-state electrolytes should possess high ionic conductivity, excellent flexibility, and relatively high mechanical strength. All-solid-state polymer electrolytes (ASSPEs) based on polymers seem to be able to meet these requirements. However, pure ASSPEs have relatively low ionic conductivity, and the addition of inorganic fillers such as lithium salts will reduce their flexibility and mechanical strength. To address the above issues, in this paper, the solvent-free method was used to prepare a poly(vinylidenefluoride-co-hexafluoropropylene)/lithium bis(trifluoromethanesulfonyl) imide/poly(ethylene oxide) all-solid-state polymer electrolyte, which was then subjected to 4 × 4 magnification synchronous bidirectional stretching. Subsequently, it was multilayered with PEO-based composite polymer electrolytes to obtain multilayered composite polymer electrolytes (MCPEs). Bidirectional stretching provides superior in-plane and out-of-plane mechanical properties to MCPEs by inducing molecular chain orientation, which suppresses the growth of lithium dendrites. Concurrently, it facilitates the formation of the β-crystal form of PVDF-HFP, thereby weakening the ion solvation effect and reducing the lithium-ion migration energy barrier. Multilayered compounding improves the interfacial contact between MCPEs and electrodes, thereby reducing the interfacial impedance. Experiments have demonstrated that the MCPEs prepared in this paper exhibit high ionic conductivity at room temperature (1.83 × 10-4 S cm-1), low interfacial resistance (547 Ω cm-2), excellent mechanical properties (26 MPa), and excellent cycling rate performance (a capacity retention rate of 90% after 110 cycles at 0.1 C), which can meet the performance requirements of lithium-ion batteries for ASSPEs.

Advancements in Polyethylene Oxide (PEO)-Active Filler Composite Polymer Electrolytes for Lithium-Ion Batteries: A Comprehensive Review and Prospects.

Polyethylene oxide (PEO) has become a highly sought-after polymer electrolyte for lithium-ion batteries (LIBs) due to its high ionic conductivity, strong mechanical properties, and broad electrochemical stability range. However, its usefulness is hindered by its limited ionic conductivity at typical temperatures (<60 °C). Many researchers have delved into the integration of active fillers into the PEO matrix to improve the ionic conductivity and overall efficiency of composite polymer electrolytes (CPEs) for LIBs. This review delves deeply into the latest developments and insights in CPEs for LIBs, focusing on the role of PEO-active filler composites. It explores the impact of different types and morphologies of active fillers on the electrochemical behavior of CPEs. Additionally, it explores the mechanisms that contribute to the improved ionic conductivity and Li-ion transport in PEO-based CPEs. This paper also emphasizes the present obstacles and prospects in the advancement of CPEs containing PEO-active filler composites for LIBs. It serves as a valuable reference for scientists and engineers engaged in the domain of advanced energy storage systems, offering insights for the forthcoming development and enhancement of CPEs to achieve superior performance in LIBs.

Janus nanofibers with multiple Li+ transport channels and outstanding thermal stability for all-solid-state composite polymer electrolytes

Herein, PEO-based composite polymer electrolytes enhanced by Janus nanofibers with multiple Li+ transport channels and outstanding thermal stability were prepared, which exhibit ultra-long cycle stability in all-solid-state lithium metal batteries.

Impedance analysis of PEG plasticized PEO-based composite polymer electrolytes for sodium-ion batteries

Solid-state sodium-ion batteries (SSIBs) will be the next generation batteries due to the high safety, low price, and availability of sodium resources. Composite polymer electrolytes (CPEs) are promising electrolytes because of easy fabrication, good stability, and high flexibility facilitating a good electrolyte-electrode interface, although their ionic conductivities are still unsatisfied. In this work, a CPE made of polyethylene oxide (PEO), Na3Zr2Si2PO12, and NaClO4 has been fabricated. To further enhance the ionic conductivity and a good electrolyte–electrode interface, polyethylene glycol (PEG) is added as a plasticizer. The electrochemical impedance spectroscopy (EIS) demonstrates effect on conductivity by introducing PEG.

Enhanced Electrochemical Performance of PEO-Based Composite Polymer Electrolyte with Single-Ion Conducting Polymer Grafted SiO2 Nanoparticles.

In order to enhance the electrochemical performance and mechanical properties of poly(ethylene oxide) (PEO)-based solid polymer electrolytes, composite solid electrolytes (CSE) composed of single-ion conducting polymer-modified SiO2, PEO and lithium salt were prepared and used in lithium-ion batteries in this work. The pyridyl disulfide terminated polymer (py-ss-PLiSSPSI) is synthesized through RAFT polymerization, then grafted onto SiO2 via thiol-disulfide exchange reaction between SiO2-SH and py-ss-PLiSSPSI. The chemical structure, surface morphology and elemental distribution of the as-prepared polymer and the PLiSSPSI-g-SiO2 nanoparticles have been investigated. Moreover, CSEs containing 2, 6, and 10 wt% PLiSSPSI-g-SiO2 nanoparticles (PLi-g-SiCSEs) are fabricated and characterized. The compatibility of the PLiSSPSI-g-SiO2 nanoparticles and the PEO can be effectively improved owing to the excellent dispersibility of the functionalized nanoparticles in the polymer matrix, which promotes the comprehensive performances of PLi-g-SiCSEs. The PLi-g-SiCSE-6 exhibits the highest ionic conductivity (0.22 mS·cm-1) at 60 °C, a large tLi+ of 0.77, a wider electrochemical window of 5.6 V and a rather good lithium plating/stripping performance at 60 °C, as well as superior mechanical properties. Hence, the CSEs containing single-ion conducting polymer modified nanoparticles are promising candidates for all-solid-state lithium-ion batteries.

Synergistically reinforced poly(ethylene oxide)-based composite electrolyte for high-temperature lithium metal batteries

Traditional liquid lithium-ion batteries are not applicable for extreme temperatures, due to the shrinkage of separators and volatility of electrolytes. It is necessary to develop advanced electrolytes with desirable characteristics in terms of thermal stability, electrochemical stability and mechanical properties. Solid-state electrolytes, such as polyethylene oxide (PEO), outperform other types and bring the opportunity to realize the high-temperature lithium-ion batteries. However, the softness of PEO at elevated temperatures leads to battery failure. In this work, a three-dimensional fiber-network-reinforced PEO-based composite polymer electrolyte is prepared. The introduced polyimide (PI) framework and trimethyl phosphate (TMP) plasticizer decrease the crystallinity of PEO and increase the ionic conductivity at 30 °C from 8.79 × 10−6 S cm−1 to 4.70 × 10−5 S cm−1. In addition, the PEO bonds tightly with PI fiber network, improving both the mechanical strength and thermal stability of the prepared electrolyte. With the above strategies, the working temperature range of the PEO-based electrolytes is greatly expanded. The LiFePO4/Li cell assembled with the PI-PEO-TMP electrolyte stably performs over 300 cycles at 120 °C. Even at 140 °C, the cell still survives 80 cycles. These excellent performances demonstrate the potential application of the PI-PEO-TMP electrolyte in developing safe and high-temperature lithium batteries.

A sulfur-containing polymer-plasticized poly(ethylene oxide)-based electrolyte enables highly effective lithium dendrite suppression

Herein, a multifunctional S-containing polymer filler to enhance PEO-based composite polymer electrolyte is reported.

3D poly(vinylidene fluoride–hexafluoropropylen) nanofiber-reinforced PEO-based composite polymer electrolyte for high-voltage lithium metal batteries

Solid-state lithium metal batteries (SSLMBs) are considered as a promising energy storage technology due to their high energy density and safety. However, the relatively low conductivity of solid-state electrolytes and the high electrolyte–electrode interfacial resistance seriously limited the development of SSLMBs. In this work, the high-performance PEO-based composite polymer electrolyte (3D CPE-5) was successfully prepared by reinforcing with polyvinylidene fluoride–hexafluoropropylene nanofibers and Li1.3Al0.3Ti1.7(PO4)3 (LATP) particles. The thickness of 3D CPE-5 is only 50 μm with high electrochemical window (5.21 V) and lithium transference number (0.49) at 60 ℃. In addition, the 3D CPE-5 shows excellent stability to Li–metal, so that Li–Li symmetric cells can run stably for more than 300 h under 0.1 mA cm−2 with low voltage polarization value (15 mV) and effective lithium dendrite inhibition. Finally, the high-voltage Li/3D CPE-5/NCM811 (LiNi0.8Co0.1Mn0.1O2) solid-state battery demonstrates excellent cycling stability at 0.1 and 0.5 C (60 ℃). The excellent safety performance of 3D CPE-5 highlights its remarkable advantages over liquid electrolytes and provide an effective design strategy of high-performance polymer electrolytes for SSLMBs.

Enhancement of cycling stability of all-solid-state lithium-ion batteries with composite polymer electrolytes incorporating Li6.25La3Zr2Al0.25O12 nanofibers

Li7La3Zr2O12 (LLZO) with cubic phase structure is a kind of lithium-ion-conducting nanoparticles. According to the previous studies, incorporation of c-LLZO can improve electrochemical properties of PEO-based composite polymer electrolytes (CPEs). Therefore, in our study, we synthesized a kind of room-temperature-stable cubic phase LLZAO (Li6.25La3Zr2Al0.25O12) nanofibers, and we aimed to confirm the optimal content of LLZAO nanofibers in PEO-based CPEs. With the incorporating 10 wt% LLZAO nanofibers, ionic conductivity of CPEs are 9.87×10−5 S cm−1 at 30 °C and 8.66×10−4 S cm−1 at 60 °C. The Li/CPE incorporating 10 wt% LLZAO nanofibers/Li symmetric cell exhibits little voltage fluctuation in 1000 cycles under a current density of 0.5 mA cm−2, demonstrating better cycling stability with long cycle life. The LiFePO4/CPE incorporating 10 wt% LLZAO nanofibers/Li cell has a high initial discharge-specific capacity of 155.6 mAh g−1 under 0.1 C rate at 60 °C and remains 94.5% of capacity after 100 cycles. This cell also has great cycling performance under 0.2 C and 0.5 C rate, indicating good rate performance. Our work indicates that incorporation of LLZAO nanofibers enhances electrochemical properties and cycling stability of PEO-based all-solid-state lithium-ion batteries.

Composite solid electrolyte PEO/SN/LiAlO2 for a solid-state lithium battery

Lithium aluminate (LAO) is known to be an effective filler for improving the conductivity of polyethylene–LiX (PEO–LiX) solid polymer electrolytes (SPEs), while succinonitrile (SN) is an excellent solid plasticizer with plastic crystalline organic molecules. In this work, LAO micro-rods are prepared via a simple hydrothermal method, and a novel PEO-based composite polymer electrolyte is developed by the addition of SN and LAO. The resulting optimal composite PEO:LiTFSI:SN(15%):LAO(10%) (PEOL-SPE) has a maximized ionic conductivity of 1.36 × 10−5 S·cm−1at 30 °C, and the membrane has a wide electrochemical window of 5.2 V. The fabricated cell with LiFePO4 as the cathode, metallic lithium as the anode and PEOL-SPE as the electrolyte membrane delivers an impressive initial charge/discharge capacity of 153.1/141.3 mAh g−1 at 60 °C. The addition of 10 wt% of the LAO micro-rods results in a favorable increase in the ionic conductivity, and no apparent blocking effect is observed to impede the electrochemical performance. These results bring to light the potential of micro-sized additives for use in lithium battery applications.

Innovative High Performing Metal Organic Framework (MOF)-Laden Composite Polymer Electrolytes for All Solid State Lithium Batteries

The unique properties such as high single cell working potential, energy density, long cycle life, etc., have identified secondary Li–ion batteries as the ultimate power source for portable electronic devices such as laptop computers, cellular phones, digital cameras, etc. However, their possible widespread penetration into the large-scale hybrid electric vehicle (HEV) and plug-in HEV markets can be realized only when substantial improvements such as low cost, sustainability, safety, high rate capability and long calendar life are achieved.The advancement in lithium battery technology relies mainly upon replacement of the conventional liquid electrolyte by an advanced solid polymer electrolyte. In order to achieve this goal, many lithium-conducting polymeric networks have been prepared and characterized. Among the polymer hosts explored so far, poly(ethylene oxide) - PEO has been indeed the most extensively studied system [1]. Unfortunately, solid polymer electrolytes comprising a polymer host and a lithium salt (e.g., PEO + LiClO4) exhibit low ionic conductivity at ambient and sub-ambient temperatures. Numerous attempts have been made to enhance the ionic conductivity of PEO-based electrolytes; one of the most common ways is the addition of low molecular weight liquid plasticizers like ethylene carbonate, propylene carbonate, etc. The addition of plasticizers, despite ameliorating the ionic conductivity, it adversely deteriorates the mechanical integrity and safety; moreover, side reactions with lithium metal eventually occur.Recently, new interesting structures have been described in the literature as metal organic frameworks (MOFs) [2]. Generally speaking, they are microporous solids consisting of an infinite network of metal centres (or inorganic clusters) bridged by simple organic linkers through metal–ligand coordination bonds. MOFs are widely used in catalysis, sensors, ion exchange, gas storage, purification, separation and sequestration; they are also used in optoelectronics to improve both electronic and proton conductivity. Nevertheless, to the best of our knowledge, so far no attempt has been made on the development of PEO-based composite polymer electrolytes (CPEs) encompassing an ad hoc synthesized Al-BTC (aluminium benzenetricarboxylate, see Fig. 1) MOF and a proper lithium salt showing an enhanced ionic conductivity of more than two order of magnitude at low temperature and excellent stability towards lithium metal even after a prolonged storage time. The obtained metal organic frameworks and macromolecular composite networks are thoroughly characterized from the structural, morphological and physico-chemical viewpoint of and, for the first time, an excellent long-term electrochemical behaviour in a lab-scale LiFePO4/CPE/Li cell is demonstrated (noteworthy stable even at low 50 °C), thus accounting for the development of high performing, safe all-solid-state lithium batteries. Even though lots of literature data are available on ceramic based fillers, the studies based on MOF encompassed polymer electrolytes are truly interesting due to its tailor-making capability and the broad spectrum of opportunities and possibilities it can bring. If very well-tuned, the MOF based fillers will be a true promising candidate and a vital ingredient which can enforce the intrusion of polymer electrolytes into the huge market of lithium-based batteries. [1] E. Quartarone, P. Mustarelli, Chem. Soc. Rev., 2011, 40, 2525.[2] M. Eddaoudi, H. Li, O.M. Yaghi, J. Am. Chem. Soc., 2000, 122, 1391

Enhancing the ionic transport of PEO-based composite polymer electrolyte by addition of TiO2 nanofiller for quasi-solid state dye-sensitized solar cells

For the application to quasi-solid state dye-sensitized solar cells (QS-DSSCs), we have prepared composite polymer electrolytes with a poly(ethylene oxide) (PEO)-TiO2-LiI-I2 system. Effects of the concentration of TiO2 nanofiller on the electrochemical properties of the PEO-based composite polymer electrolytes have been investigated. The experimental results show that the presence of TiO2 in the PEO-based electrolyte changes the phase of the polymer. Also, the addition of TiO2 noticeably increases the ionic conductivity of the PEO-based electrolytes. At optimized TiO2 concentration of 15 wt%, the composite polymer electrolyte exhibited a maximum value of ionic conductivity, and leads to remarkable enhancement of the photovoltaic performance of the QS-DSSC. This indicates that the incorporation of TiO2 to the PEO-based electrolytes gives rise to the reduction of the crystallinity of the polymer and the enhancement of the mobility of the I−/I3− redox couple, resulting in the increases of the conductivity and the current density of QS-DSSC.

A novel PEO-based composite polymer electrolyte with NaAlOSiO molecular sieves powders

Ion-conducting thin film polymer electrolytes based on poly(ethylene oxide) (PEO) complexes with NaAlOSiO molecular sieves powders has been prepared by solution casting technique. X-ray diffraction, scanning electron microscopy, differential scanning calorimeter, and alternating current impedance techniques are employed to investigate the effect of NaAlOSiO molecular sieves on the crystallization mechanism of PEO in composite polymer electrolyte. The experimental results show that NaAlOSiO powders have great influence on the growth stage of PEO spherulites. PEO crystallization decrease and the amorphous region that the lithium-ion transport is expanded by adding appropriate NaAlOSiO, which leads to drastic enhancement in the ionic conductivity of the (PEO)16LiClO4 electrolyte. The ionic conductivity of (PEO)16LiClO4-12 wt.% NaAlOSiO achieves (2.370 ± 0.082) × 10−4 S · cm−1 at room temperature (18 °C). Without NaAlOSiO, the ionic conductivity has only (8.382 ± 0.927) × 10−6 S · cm−1, enhancing 2 orders of magnitude. Compared with inorganic oxide as filler, the addition of NaAlOSiO molecular sieves powders can disperse homogeneously in the electrolyte matrix without forming any crystal phase and the growth stage of PEO spherulites can be hindered more effectively.

Novel PEO-based composite solid polymer electrolytes incorporated with active inorganic–organic hybrid polyphosphazene microspheres

Inorganic–organic hybrid poly(cyclotriphosphazene- co-4,4′-sulfonyldiphenol) (PZS) microspheres with active hydroxyl groups were incorporated in poly(ethylene oxide) (PEO), using LiClO 4 as a dopant salt, to form a novel composite polymer electrolyte (CPE). The polymer chain flexibility and crystallinity properties are studied by DSC. The effects of active PZS microspheres on the electrochemical properties of the PEO-based electrolytes, such as ionic conductivity, lithium ion transference number, and electrochemical stability window are studied by electrochemical impedance spectroscopy and steady-state current method. Maximum ionic conductivity values of 3.36 × 10 −5 S cm −1 at ambient temperature and 1.35 × 10 −3 S cm −1 at 80 °C with 10 wt.% content of active PZS microspheres were obtained and the lithium ion transference number was 0.34. The experiment results showed that the inorganic–organic hybrid polyphosphazene microspheres with active hydroxyl groups can enhance the ionic conductivity and increase the lithium ion transference number of PEO-based electrolytes more effectively comparing with traditional ceramic fillers such as SiO 2.

A novel PEO-based composite solid-state polymer electrolyte with methyl group-functionalized SBA-15 filler for rechargeable lithium batteries

Functionalized molecular sieve SBA-15 with trimethylchlorosilane was used as an inorganic filler in a poly(ethyleneoxide) (PEO) polymer matrix to synthesize a composite solid-state polymer electrolyte (CSPE) using LiClO4 as the doping salts, which is designated to be used for rechargeable lithium batteries. The methyl group-functionalized SBA-15 (fSBA-15) powder possesses more hydrophobic characters than SBA-15, which improves the miscibility between the fSBA-15 filler and the PEO matrix. The interaction between the fSBA-15 and PEO polymer matrix was investigated by scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry. Linear sweep voltammetry and electrochemical impedance spectroscopy were employed to study the electrochemical stability windows, ionic conductivity, and interfacial stability of the CSPE. The temperature dependence of the change of the PEO polymer matrix in the CSPE from crystallization to amorphous phase was surveyed, for the first time, at different temperature by Fourier transform infrared emission spectroscopy. It has demonstrated that the addition of the fSBA-15 filler has improved significantly the electrochemical compatibility of the CSPE with a lithium metal electrode and enhanced effectively the ion conductivity of the CSPE.

A novel PEO-based composite polymer electrolyte with absorptive glass mat for Li-ion batteries

A novel PEO (polyethylene oxide)-based composite polymer electrolyte (CPE) using absorptive glass mat (AGM) as filler was prepared and characterized. Scanning electronic micrograph (SEM) images showed that the addition of Li salt and modified AGM may improve the surface morphology of CPE. The results of Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and differential scanning calorimeters (DSC) indicated that the inclusion of LiClO4 salt and the addition of AGM filler can reduce the crystallinity of PEO. It was concluded that the addition of AGM plays two roles in PEO-based CPEs, namely, interruption of the PEO recrystallization and reinforcement of CPEs, accordingly enhancing room temperature ionic conductivity of CPEs and improving its mechanical strength and electrochemical stability at high temperatures.

New composite polymer electrolyte comprising mesoporous lithium aluminate nanosheets and PEO/LiClO 4

Mesoporous materials, due to its potential for advanced applications in catalysis and nanoscience, have attracted much attention in the past decade. In this work, mesoporous lithium aluminate (next called MLA) nanosheets with high specific surface area were prepared by a hydrothermal method using hex-adecyltrimethyl ammonium bromide (CTAB) as the template. A novel PEO-based composite polymer electrolyte has been developed by using MLA powders as the filler. The electrochemical impedance showed that the conductivity was improved simultaneously. A high conductivity of 2.24 × 10 −5 S cm −1 at 25 °C was obtained. The lithium polymer battery using this novel composite polymer electrolyte and with lithium metal and LiFePO 4 employed as anode and cathode, respectively, showed high discharge capacity (more than 140 mAh g −1 at 60 °C) and excellent cycling stability as revealed by galvanostastically charge/discharge cycling tests. The excellent electrochemical performances at low temperature of the cells were obtained, which was attributed to the high surface area and channels structure of the filler. The excellent properties of the solid-state lithium battery suggested that, PEO 16–LiClO 4–MLA composite polymer electrolyte can be used as a candidate material for lithium polymer batteries.

Effect of silane-functionalized mesoporous silica SBA-15 on performance of PEO-based composite polymer electrolytes

Silane-functionalized mesoporous silica SBA-15 particles with ultra-high specific surface area and large pore size were used as fillers in PEO-based solid electrolytes. FT-IR results confirmed the silane functionalization of SBA-15. Ionic conductivity and lithium ion transference number of the composite polymer electrolytes were found to simultaneously reach a high value of 5 wt.% silane-functionalized SBA-15 introduced in the matrix. It may be due to the combination effects of the unique structure of SBA-15 (i.e., ultra-high specific surface area and large pore size), the particularly functionalized surface of SBA-15 to promote fast ion transfer, and the good dispersion and compatibility of silane-functionalized SBA-15 in the composite polymer electrolytes. The results suggest an alternative way to improve the performance of solid polymer electrolytes.

Flame-retarding ability and electrochemical performance of PEO-based polymer electrolyte with middle MW cyclic phosphate

In this paper, the PEO-based composite polymer electrolytes are presented, in which phosphonic acid, methyl-, bis[(5-ethyl-2-methyl-2-oxido-1,3,2-dioxaphosphorinan-5-yl)methyl]ester (middle MW cyclic phosphate) works as both the plasticizer and the flame-retarding additive. The flame-retarding ability of middle MW cyclic phosphate was proved through a designed flammability test. The effect of middle MW cyclic phosphate on the thermal stability of CPEs was demonstrated by thermogravimetry (TG) test. Electrochemical measurements prove that the CPEs containing middle MW cyclic phosphate have a very wide electrochemical stability window at both the room temperature and 80 °C, and can be used in lithium batteries with a large choice of redox couples as cathode materials.

Investigations on the enhancement mechanism of inorganic filler on ionic conductivity of PEO-based composite polymer electrolyte: The case of molecular sieves

Polarized optical microscopy (POM) and differential scanning calorimeter (DSC) techniques are used to study the effect of ZSM-5 molecular sieves on the crystallization mechanism of poly(ethylene oxide) (PEO) in composite polymer electrolyte. POM results show that ZSM-5 has great influence on both the nucleation stage and the growth stage of PEO spherulites. ZSM-5 particles can act as the nucleus of PEO spherulites and thus increase the amount of PEO spherulites. POM and DSC results show that ZSM-5 can restrain the recrystallize tendency of PEO chains through Lewis acid–base interactions and hence decrease the growth speed of PEO spherulites. Room temperature ionic conductivity of PEO–LiClO 4-based polymer electrolyte can be enhanced by more than two magnitudes during long time storage with the addition of ZSM-5.