PEO-based Polymer Electrolytes Research Articles

In-situ modification of ultrathin and uniform layer on LiCoO2 particles for 4.2 V poly(ethylene oxide) based solid-state lithium batteries with excellent cycle performance

Poly(ethylene oxide) based polymer electrolytes(PEO-SPEs) suffer from a narrow electrochemical window and deliver poor electrochemical performance when coupling with 4.2 V cathode. This severely limits the scope of its application. Here, a combination of physical stirring and electrochemistry is used to form an ultrathin and uniform cladding layer on the LiCoO2 particles. The results show that in addition to the decomposition of LiPO2F2 during the charge/discharge cycling, decomposition reactions occur during the stirring and drying process by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). This novel method effectively improves the electrochemical performance of 4.2 V PEO based solid-state lithium batteries. In particular, the cell shows excellent and stable electrochemical performance, exhibiting a discharge capacity of 112.0 mAh g−1 after 200 cycles, a capacity retention rate of 79.4% and a capacity decay rate of approximately 0.1% per cycle when the surface of LiCoO2 is coated with 2 wt% LiPO2F2. In comparison, the discharge capacity of the unmodified LiCoO2 cathode is found to be only 75.6 mAh g−1 after 100 cycles, with a poor capacity retention rate of 56.8%. Based on the basis of the above research, a new process was explored and also shows excellent interfacial stability by dispersing LiPO2F2 directly inside the binder which with a discharge capacity of 109.2 mAh g−1 and a capacity retention rate of 84.5% after 145 cycles. This novel approach opens up a new pathway for solving the problem of interfacial stability between PEO based polymer electrolytes and high-voltage cathode.

Engineering a High-Voltage Durable Cathode/Electrolyte Interface for All-Solid-State Lithium Metal Batteries via In Situ Electropolymerization.

Poly(ethylene oxide) (PEO)-based polymer electrolytes have been widely studied as a result of their flexibility, excellent interface contact, and high compatibility with a lithium metal anode. Owing to the poor oxidation resistance of ethers, however, the PEO-based electrolytes are only compatible with low-voltage cathodes, which limits their energy density. Here, a high-voltage stable solid-state interface layer based on polyfluoroalkyl acrylate was constructed via in situ solvent-free bulk electropolymerization between the LiNi0.8Mn0.1Co0.1O2 (NCM811) cathode and the PEO-based solid polymer electrolyte. The electrochemical oxidation window of the as-synthesized electrolyte was therefore expanded from 4.3 V for the PEO-based matrix electrolyte to 5.1 V, and the ionic conductivity was improved to 1.02 × 10-4 S cm-1 at ambient temperature and 4.72 × 10-4 S cm-1 at 60 °C as a result of the improved Li+ migration. This fabrication process for the interface buffer layer by an in situ electrochemical process provides an innovative and universal interface engineering strategy for high-performance and high-energy-density solid-state batteries, which has not been explicitly discussed before, paving the way toward the large-scale production of the next generation of solid-state lithium batteries.

Effects of lithium salts on PEO-based solid polymer electrolytes and their all-solid-state lithium-ion batteries

Effects of lithium salts on PEO-based solid polymer electrolytes and their all-solid-state lithium-ion batteries

Poly(ionic liquid)-functionalized graphene oxide towards ambient temperature operation of all-solid-state PEO-based polymer electrolyte lithium metal batteries

Endowing polyethylene oxide (PEO)-based electrolyte with low crystallinity and high efficient Li+ transport channels is urgently required for next generation all-solid-state lithium metal batteries (LMBs). Herein, a new type of oxyethyl containing poly(ionic liquid) modified graphene oxide nanoparticles (ox-PIL@GO) is coincidentally proposed for preparing PEO based organic–inorganic composite electrolyte membranes (CPEs). Both experimental and DFT simulation results indicate that the dissociation of the LiTFSI is significantly enhanced by the anticipated electrostatic interaction between imidazolium cation and TFSI- anions in CPEs. In addition, the formed electrostatic interaction can also inhibit the movement of TFSI-, giving rise to the increased lithium transference number of 0.61 from 0.21 for the neat PEO/LiTFSI electrolyte. Furthermore, the ion–dipole interaction between imidazolium cation and PEO chain largely reduces the crystallinity of PEO and the ionic conductivity of 1.01 × 10-4 S cm−1 at 40 °C is successfully obtained. As a result, the ox-PIL@GO incorporated PEO electrolyte enables the Li||Li symmetric cell with long-term, square-wave galvanostatic cycling test of 800 h at current density of 0.1 mA cm−2 at 50 °C and the solid-state LiFePO4|CPE|Li battery with high discharge specific capacity of 116 mAh g−1 at 40 °C at 1C for 300 cycles.

Modification of PEO-based polymer electrolytes by electron beam irradiation for energy storage applications

Modification of PEO-based polymer electrolytes by electron beam irradiation for energy storage applications

Influence of Nano Filler (ZrO2) on Optical and Thermal Studies of Potassium Doped Polyethylene Oxide Solid Polymer Electrolytes

Solid polymer electrolyte films made with potassium doped Polyethylene oxide using ZrO2 as nanofiller (70PEO-30KBF4-x ZrO2 where x = 1, 2.5, 5, 7.5, & 10 wt% ­­) were prepared by solution casting technique. Optical and thermal properties of polymer electrolyte films were studied by using Optical absorption and DSC techniques. From Optical absorption spectra, it is observed that fundamental absorption edge is shifted towards the higher wavelength side (range 259- 297 nm) with increase of nano filler (ZrO­2) concentration (1-10 wt %). Optical band gap for all electronic transitions (p=1/2, 2, 2/3 and 1/3) are found to be increased as incorporation of nano filler (ZrO2) which confirms the structural rearrangements takes place in polymer electrolyte films. Optical band gap for indirect allowed transitions (p=1/2) are found to be in the range of 1.93-3.34eV. Decrease in Urbach energy (4.8eV- 1.4eV) is associated with decrease in defect formation in host polymeric matrix (PEO-KBF4) as a result of embedded nano filler (ZrO2). DSC spectra analysis of polymer electrolytes has showed melting temperatures in the range 63.63-73.71°C and highest crystallinity is found to be 85 % (10 wt % ZrO­2). Enthalpy values are elevated with increase in nanofiller composition (ZrO2) in the present polymer electrolyte films.Keywords: PEO based polymer electrolytes, Solid polymer electrolytes, Optical and Thermal studies.

Enabling high-performance all-solid-state hybrid-ion batteries with a PEO-based electrolyte.

All-solid-state hybrid-ion batteries exhibiting a synergistic Na+/Li+ de/intercalation mechanism were designed and assembled, by using modified PEO-based solid polymer electrolyte, Na2V2(PO4)2O2F cathode, and Li metal anode. The batteries exhibited a high average working voltage of 3.88 V, and an energy density of 432.37 W h kg-1, providing a new avenue for the development of high-safety and low-cost secondary batteries.

The effect of [EMIm]BF4/Li+ Ionic liquid on PEO-based solid polymer electrolyte membranes characteristics as lithium-ion batteries separator

Lithium-ion batteries have liquid electrolytes, which are corrosive and volatile, that would cause leakage and explosion during the rechargeable process at high temperatures. To overcome these problems, it is necessary to change the liquid electrolyte into a solid one, namely a solid polymer electrolyte. This work has prepared the solidpolymer electrolyte membranes by casting various 1-ethyl-3-tetrafluoroborate, [EMIm]BF4/Li+ ionic liquid, and PEO. In this study, [EMIm]BF4/Li+ , a Li+ ion-attached ionic liquid, has been synthesized using a simple metathesis reaction between 1-ethyl-3- methylimidazolium-bromide, [EMIm]Br, and lithium tetrafluoroborate, LiBF4 salt. [EMIm]Br has been synthesized from 1- methylimidazole and bromoethane precursors using Microwave Assisted Organic Synthesis (MAOS) method. The functional groups and structures of [EMIm]Br and [EMIm]BF4/Li+ have been confirmed by Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectra analysis. The analysis of ionic conductivities, crystallinities, mechanical properties, surface morphologies, and thermal stabilities have been confirmed by using Electrochemical Impedance Spectroscopy (EIS), X-ray Diffraction (XRD), and tensile tester, Scanning Electron Microscopy (SEM), and Thermogravimetry Analysis (TGA), respectively. The highest ionic conductivity is 1.83 x 10-3 S.cm-1 at room temperature for polymer electrolyte membrane with 16% weight of the [EMIm]BF4/Li+ ionic liquid and also exhibits good mechanical flexibility and thermal stability

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.

Enhancing Li ion transfer efficacy in PEO-based solid polymer electrolytes to promote cycling stability of Li-metal batteries

Li+ transfer efficacy enhancement of PEO-based electrolyte, determined via constructing fast Li+ transfer channel and weakened interaction between Li+ and PEO, leading to significant improvement of electrochemical performance of Li-metal batteries.

Poly(Ionic Liquid)-Functionalized Graphene Oxide Towards Ambient Temperature Operation of All-Solid-State Peo-Based Polymer Electrolyte Lithium Metal Batteries

Poly(Ionic Liquid)-Functionalized Graphene Oxide Towards Ambient Temperature Operation of All-Solid-State Peo-Based Polymer Electrolyte Lithium Metal Batteries

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.

Organic ionic plastic crystal enhanced interface compatibility of PEO-based solid polymer electrolytes for lithium-metal batteries

Polyethylene oxide (PEO)-based solid polymer electrolytes (SPEs) are appealing solid electrolytes for lithium-metal batteries (LMBs) due to their high safety, low cost and flexibility. However, PEO'snarrow electro-chemical potential window and poor interfacial compatibility with the electrode restrict PEO-based SPE development. Herein, we used a solution-casting method to prepare PEO-based SPE membranes reinforced with an organic ionic plastic crystal—N,N-diethylpyrrolidinium bis(fluorosulfonyl)amide (C2epyrFSI). The as-prepared SPE exhibits high ionic conductivity of 3.02 × 10−4 S cm−1 at 50 °C, an extremely wide electro-chemical window (5.1 V) and flexible mechanical properties. Using SPE, the Li symmetric cells can cycle for 2000 h at a current density of 0.1 mA cm−2 without short circuiting at 50 °C. Furthermore, the Li|SPE|LiFePO4 all-solid-state LMBs have a high initial discharge specific capacity of 157.3 mAh g−1 at 0.2C and a capacity retention rate of 96% after 120 cycles. This study shows that the PEO-C2epyrFSI SPE is a promising electrolyte for all-solid-state LMBs.

Improved mechanical and electrochemical properties of PVDF/PEO/LiClO4 based solid polymer electrolyte by using TiO2 and MgO nanoparticles

The poly (vinylidene fluoride) PVDF and poly (ethylene oxide) PEO-based solid polymer electrolytes are gaining popularity due to their good electrochemical and mechanical characteristics. In the present work the polymer electrolyte is prepared by taking 80% PVDF, 20% PEO, and 20% LiClO4 through rigorous mixing. Further, the properties of PVDF/PEO/LiClO4 based electrolyte are improved by adding TiO2 and MgO nanoparticles in different proportions. The results show that the addition of TiO2 and MgO nanoparticles has a significant effect on the electrochemical characteristics and mechanical properties of the electrolyte. The maximum current onset potential of 4.97 V is observed with a 4% concentration of TiO2 nanoparticles. Also, the mechanical properties such as ultimate stress and failure stress are increased with the addition of nanoparticles. The ionic conductivity of the electrolyte first increases with an increase in the concentration of nanoparticles but it starts decreasing after 2% concentration.

Application of a Modified Porphyrin in a Polymer Electrolyte with Superior Properties for All-Solid-State Lithium Batteries.

Porphyrins and their derivatives are a unique class of multifunctional and modifiable π-conjugated heterocyclic organic molecules, which have been widely applied in the fields of optoelectronic devices and catalysis. However, the application of porphyrins in polymer electrolytes for all-solid-state lithium-ion batteries (ASSLIBs) has rarely been reported. Herein, porphyrin molecules modified by polyether chains are used for composite solid-state polymer electrolytes (CSPEs) for the first time. The introduction of a modified porphyrin in an electrolyte can not only promote the electrochemical properties by constructing ordered ion channels via the intermolecular interaction between π-conjugated heterocyclic porphyrins, but also significantly improve the mechanical strength and interface contact between the electrolyte membrane and the lithium metal anode. Consequently, the all-solid-state batteries assembled by the modified porphyrin composite polymer electrolyte, LiFePO4 cathodes, and Li anodes deliver a higher discharge capacity of 158.2 mA h g-1 at 60 °C, 0.2 C, which remains at 153.6 mA h g-1 after 120 cycles with an average coulombic efficiency of ∼99.60%. Furthermore, the flexible porphyrin-based composite polymer electrolyte can also enable a Li || LiCoO2 battery to exhibit a maximum discharge capacity of 108.6 mA h g-1 at 60 °C, 0.1 C with an active material loading of 2-3 mg cm-2, which is unable to realize for the corresponding batteries with a pure PEO-based polymer electrolyte. This work not only broadens the application scope of porphyrins, but also proposes a novel method to fabricate CSPEs with improved electrochemical and mechanical properties, which may shed new light on the development of CSPEs for next-generation high-energy-density lithium-ion batteries.

Research Progress and Application of PEO-Based Solid State Polymer Composite Electrolytes

As a high-efficiency energy storage and conversion device, lithium-ion batteries have high energy density, and have received widespread attention due to their good cycle performance and high reliability. However, currently commercial lithium batteries usually use organic solutions containing various lithium salts as liquid electrolytes. In practical applications, liquid electrolytes have many shortcomings and shortcomings, such as poor chemical stability, flammability, and explosion. Therefore, the liquid electrolyte has a great safety hazard. The use of solid electrolyte ensures the safety of lithium-ion batteries, and has the advantages of high energy density, good cycle performance, long life, and wide electrochemical window, making the battery safer and more durable, with higher energy density and simple battery Structural design. Solid electrolytes mainly include inorganic solid electrolytes and organic polymer solid electrolytes. Although both inorganic solid electrolytes and polymer solid electrolytes have their own advantages, as far as the existing research work is concerned, whether it is an inorganic system or a polymer system, a single-system solid electrolyte can never achieve the full performance of an ideal solid electrolyte. The composite solid electrolyte composed of active or passive inorganic filler and polymer matrix is considered as a promising candidate electrolyte for all-solid-state lithium batteries. Among many polymer systems, PEO-based is considered to be the most ideal polymer substrate. In this review article, we first introduced the structure, properties, and preparation methods of PEO-based polymer electrolytes. Furthermore, the researches related to the modification of PEO-based polymer solid electrolytes in recent years are summarized. The contribution of polymer structural modification and the introduction of additives to the ionic conductivity, electrochemical stability and mechanical properties of PEO-based solid electrolytes is described. Examples of different composite solid electrolyte design concepts were extensively discussed, such as inorganic inert nanoparticles/PEO, oxide/PEO, and sulfide/PEO. Finally, the future development direction of composite solid electrolytes was prospected.

Self-Healing Solid Polymer Electrolyte for Room-Temperature Solid-State Lithium Metal Batteries.

Poor room-temperature ionic conductivities and narrow electrochemical stable windows severely hinder the application of conventional poly(ethylene oxide)-based (PEO-based) solid polymer electrolytes (SPEs) for high-energy-density lithium metal batteries (LMBs). Herein, we designed and synthesized a PEO-based self-healing solid polymer electrolyte (SHSPE) via dynamically cross-linked imine bonds for safe, flexible solid LMBs. The constructed dynamic networks endow this SPE with fascinating intrinsic self-healing ability and excellent mechanical properties (extensibility > 500% and stress >130 kPa). More importantly, this SHSPE exhibits ultrahigh ionic conductivity (7.48 × 10-4 S cm-1 at 25 °C) and wide ESW (5.0 V vs Li/Li+). As a result, Li||Li symmetrical cells with the SHSPE showed reliable stability in a >1200 h cycling test under room temperature. The assembled Li|SHSPE|LiFePO4 cell maintained a discharge capacity of 126.4 mAh g-1 after 300 cycles (0.1C, 27 °C). This work highlights a promising strategy for next-generation room-temperature solid-state LMBs.

Thermal, Structural and Morphology Studies of PEO-LICF3SO3-DBP-ZrO2 Nanocomposite Polymer Electrolytes

This work represents thermal study of PEO-based polymer electrolyte films that were prepared by the solution cast technique. The melting temperature Tm, glass transition temperature Tg and degree of crystallinity χc were measured by diffraction scanning calorimetry (DSC). Thermogravimetric (TGA) was used to determine the initial and final degradation temperatures. The structural was also performed to characterize the vibrational wavelength and phase characteristic (crystalline/amorphous). While the morphological study was emphasized to examine the features appearance for pure polymer electrolyte system as well as after addition salt, plasticizer and filler. The zirconium oxide particles were measured after the milling process by using the transmission electron microscopy (TEM), and the particles obtained in the range of 9 – 54 nanometer size.

Enhancing Sodium Ion Transport in a PEO-Based Solid Polymer Electrolyte System with NaAlO2 Active Fillers

Enhancing Sodium Ion Transport in a PEO-Based Solid Polymer Electrolyte System with NaAlO2 Active Fillers

Non-flammable super-concentrated polymer electrolyte with “solvated ionic liquid” for lithium-ion batteries

The ambient temperature application of PEO-based polymer electrolytes has been restrained by their poor ionic conductivity. Herein, we report a super-concentrated polymer in “solvated ionic liquid” which is composed of polyethylene oxide (PEO), LiN(SO2CF3)2 (LiTFSI), and solvent with low viscosity. It is found that the maximum coordination during Li, polymer, and the solvent can be formed by the molar ratio of PEO/Li = 1:1 with 25 wt% of solvent, left no free solvent exits in the mixture. The electrochemical performance of the designed electrolyte was evaluated by using a LiFePO4/Li cell. Comparing to the conventional carbonate liquid electrolyte, the designed electrolyte achieves comparable rate performance (155.4 and 157.8 mAh g−1 discharge at 1 C for the designed and carbonate electrolyte, respectively) and higher cycle performance (capacity retention of 95.5% and 75.5% after 100 cycles for the designed and carbonate electrolyte, respectively). It has been further proven that incombustibility can be obtained by only adding ~15 wt% fire-retardant. We believe that the developed electrolyte is promising and practical for being applied in the polymer lithium-ion battery.