Blend Electrolytes Research Articles

Ion association as a main shortcoming in polymer blend electrolytes based on CS:PS incorporated with various amounts of ammonium tetrafluoroborate

This work presents a successfulness of the methodology of solution cast technique for fabrication of polymer blend electrolytes based on chitosan (CS): potato starch (PS) doped with various amounts of ammonium tetrafluoroborate (NH4BF4). In this work we demonstrated that association of ions is the main drawback for the NH4BF4 salt. Low DC conductivity of the films displays the non availability of the present system for applications. To look at the electrical properties, structural, and morphological properties, electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD), and Field emission scanning electron microscopy (FESEM), respectively were used. From the EIS measurement the highest conductivity of the system was found to be 3.07 × 10−8 S/cm which is too low for device applications including batteries and supercapacitors. The increase of bulk resistance is an indication for the recombination of cation and anion of the salt at high concentration. Sharp peaks were observed in the XRD spectra at high salt concentration. The morphological outcomes display protruded salts with large size at high salt concentration. The large value of dielectric constant at low frequency region is associated to electrode polarization (EP) while their decline with increasing frequency is ascribed to the lag of polarization of ion with respect to the quick orientation of dipole species because of the applied AC field. The M″ peak asymmetry displays the distribution of relaxation time.

Achieving Stable Cycling of Li-Metal Anodes in Li-O2 Batteries: Optimizing Solvation Environment in Ionic Liquid/Solvent Blend Formulations

The realization of a truly rechargeable, high capacity lithium-oxygen (Li-O2) battery faces serious technological barriers relating to material/intermediate stability, electrochemical reversibility of the cathode discharge processes, and gas supply challenges.1 Furthermore, to maximize energy densities of Li-O2 cells, the utilization of Li-metal anodes is highly desired, thus introducing additional and serious interfacial challenges in the form of electrolyte degradation and susceptibility to dendrite formation on cycling. These factors ultimately create serious safety issues and further contribute to the reduced cyclability of Li-O2 cells that is already limited by the poor reversibility of Li2O2 formation at the cathode. Without introducing artificial anode protection or isolation of Li from a cathoylte compartment, the electrolyte for a high-performance Li-O2 device must exhibit complementary stability at both reactive interfacial regions of the two different electrodes. In many cases, the solvents that mediate good performance at the Li-O2 cathode exhibit poor stability at Li-metal and, consequently, new electrolyte formulations geared towards good stability and performance at both the cathode and the anode are required.In this work, we report on the development of blend electrolytes of ionic liquids (ILs) and molecular solvents for improving cell performance in Li-O2 batteries with considered focus on enhancing stability at the Li-metal anode. Through combined experimental and theoretical investigations, we present how the electrochemical stability of Li-O2-cathode relevant molecular solvents at the Li-metal anode can be regulated by tuning formulation properties. Wide formulation ranges, including dilute to highly concentrated Li-salt mixtures are explored within the ternary formulations of IL, molecular solvent and Li-salt. Good performance in symmetrical Li|electrolyte|Li cells is achieved through improving the Coulombic efficiency of the electroplating/stripping processes, as quantified in asymmetric Li|Cu cells. In lieu of strong SEI forming additives, these observed stability enhancements are found to be highly reliant on Li+-solvent solvation interactions within the liquids. Shifts in vibrational modes associated with changes in coordination, as measured by Raman and IR spectroscopy, provide insights into the nature of these important solvent and salt interactions. These experimental insights are supported by computational modelling of local solvation environments in select exemplary mixtures. Pulsed-field gradient NMR techniques are also utilized to understand what information the diffusional motion of differing species within the IL/solvent blends further reveals about the nature of these stabilizing coordination interactions. The implications of complete formulation design towards achieving mutual stability at anode and cathode interfaces is demonstrated within full cell (Li-O2) testing using composite air-cathodes. 1. D. Aurbach, B. D. McCloskey, L. F. Nazar, and P. G. Bruce, Nat. Energy, 1 16128 (2016).

Reduced Gassing in Lithium-Ion Batteries with Organosilicon Additives

The battery industry is constantly seeking to improve battery capacity, lifetime, and safety. Electrolytes are a key development focus in achieving these goals, as traditional carbonate-based electrolytes cause capacity fade and gassing through degradation processes, as well as representing a safety risk due to flammability. The release of gasses through electrolyte decomposition is a problem of prominent concern in the battery industry, due to the negative impact of gassing on cell safety and performance. Studies on battery gassing have been reported for a wide range of battery systems,1-3 but the mechanisms and conditions of gas release are complex and not fully understood. Gaining a greater understanding of gassing mechanisms, and the specific electrolyte components that cause them, will allow for precise design of battery electrolyte formulations that optimize performance and minimize gassing.In addition to understanding traditional electrolyte blends, the investigation of new electrolytes and additives is essential in developing low-gassing batteries. Organosilicon (OS) materials have been developed by Silatronix® as critical high stability additions to conventional carbonate electrolytes to enable next-generation Li-ion batteries. This novel organosilicon chemistry involves the merging of a silane with a Li+ coordinating functionality. For example, the OS3® solvent family contains a nitrile functionality. The adoption of new Li-ion battery electrolyte materials is driven by the desire to deploy higher energy density batteries capable of performing under broader operating conditions of temperature and voltage, and the design of OS solvents results in low molecular-weight molecules that have demonstrated superior thermal and electrochemical stability,4,5 as well as good safety properties with a high flash point and low vapor pressure.Silatronix® has conducted commercially relevant performance testing and fundamental mechanistic studies to investigate gassing phenomena in advanced Li-ion chemistries under both cycling and storage test conditions. In these studies, commercially relevant electrolytes were evaluated as well as electrolytes designed to specifically isolate the effect of selected electrolyte components, including OS3® and other industry-relevant solvents. The dependence of gassing on storage and voltage conditions was investigated, and connections between gas analysis and the electrode surface chemistry are also reported. Gas component analysis was performed with a calibrated dual-column GC-TCD, a similar analytical system to that utilized in previous studies,6 which provides excellent resolution and quantification of every gaseous product. Key experimental results show that all OS3® concentrations reduce gas generation after 60°C storage and higher OS3® content provides greater benefit. Overall, we show that organosilicon additives substantially reduce gassing from carbonate-based electrolytes while maintaining good cell performance. 1. Zhang, S.S., Insight into the Gassing Problem of Li-ion Battery. Frontiers in Energy Research 2014, 2, 59.2. Self, J.; Aiken, C.P.; Petibon, R.; Dahn, J.R., Survey of Gas Expansion in Li-Ion NMC Pouch Cells. Journal of the Electrochemical Society 2015, 162, A796-A802.3. Jung, R.; Metzger, M.; Maglia, F.; Stinner, C., Chemical vs Electrochemical Electrolyte Oxidation on NMC111, NMC622, LNMO, and Conductive Carbon. The Journal of Physical Chemistry Letters 2017, 8, 4820-4825.4. Guillot, S.L.; Peña-Hueso, A.; Usrey, M.; Hamers, R.J., Thermal and Hydrolytic Decomposition Mechanisms of Organosilicon Electrolytes with Enhanced Thermal Stability for Lithium-Ion batteries. Journal of the Electrochemical Society 2018, 164, A1907-A1917.5. Chen, X.; Usrey, M.; Peña-Hueso, A.; West, R.; Hamers, R.J., Thermal and Electrochemical Stability of Organosilicon Electrolytes for Lithium-Ion Batteries. Journal of Power Sources 2013, 241, 311-319.6. Xiong, D.J.; Ellis, L.D.; Petibon, R.; Hynes, T.; Liu, Q.Q.; Dahn, J.R., Studies of Gas Generation, Gas Consumption and Impedance Growth in Li-Ion Cells with Carbonate or Fluorinated Electrolytes Using the Pouch Bag Method. Journal of the Electrochemical Society 2017, 164, A340-A347.

Proton (H+) transport properties of CMC–PVA blended polymer solid electrolyte doped with NH4NO3

This present work investigated the proton (H+) conduction behavior of the blended polymer solid electrolyte (BPSE) derived from carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVA) that was doped with ammonium nitrate (NH4NO3). The properties of this CMC-PVA-AN BPSE were evaluated using Fourier transform infrared spectroscopy (FTIR), transference number measurement (TNM), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrical impedance spectroscopy (EIS). We found that doping (NH4NO3) improved the chemical and thermal stability of the CMC-PVA BPSE. The highest ionic conductivity (~10−3 S/cm) of the BPSE at ambient temperature was achieved with a CMC:PVA:NH4NO3 composition of 56:14:30 wt%. This was due to the interplay of segmental motion between the CMC and PVA and also the H+ hopping mechanism as revealed by FTIR. XRD and morphology analysis showed that the peak intensity decreased which implied an increase in its amorphous nature. Based on the transport properties, the CMC-PVA-AN BPSE conduction mechanism was governed by number of ions, ionic mobility and also free ions diffusion coefficient. The proton transference number (tH+= 0.42) in the present study indicated that the charge transport in the BPSE was predominantly due to the H+ carrier conduction.

Structural, Morphological, Electrical and Electrochemical Properties of PVA: CS-Based Proton-Conducting Polymer Blend Electrolytes.

Polymer blend electrolytes based on poly(vinyl alcohol):chitosan (PVA:CS) incorporated with various quantities of ammonium iodide were prepared and characterized using a range of electrochemical, structural and microscopic techniques. In the structural analysis, X-ray diffraction (XRD) was used to confirm the buildup of the amorphous phase. To reveal the effect of dopant addition on structural changes, field-emission scanning electron microscope (FESEM) was used. The protrusions of salt aggregates with large quantity were seen at the surface of the formed films at 50 wt.% of the added salt. The nature of the relationship between conductivity and dielectric properties was shown using electrochemical impedance spectroscopy (EIS). The EIS spectra were fitted with electrical equivalent circuits (EECs). It was observed that both dielectric constant and dielectric loss were high in the low-frequency region. For all samples, loss tangent and electric modulus plots were analyzed to become familiar with the relaxation behavior. Linear sweep voltammetry (LSV) and transference number measurement (TNM) were recorded. A relatively high cut-off potential for the polymer electrolyte was obtained at 1.33 V and both values of the transference number for ion (tion) and electronic (telec) showed the ion dominant as charge carrier species. The TNM and LSV measurements indicate the suitability of the samples for energy storage application if their conductivity can be more enhanced.

Protonic EDLC cell based on chitosan (CS): methylcellulose (MC) solid polymer blend electrolytes

In this work, preparation and application of solid polymer blend electrolytes (SPBEs) based on chitosan: methylcellulose (CS:MC) incorporated with various amounts of ammonium iodide (NH4I) salt are described. Solution cast technique was adapted for the preparation of the SPBE films. Structural investigation and extent of interaction of the NH4I salt with the CS:MC film surface were conducted through X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy measurements. Electrical DC conductivity of the prepared samples was studied by electrochemical impedance spectroscopy. It is confirmed through transference number (TNM) analysis that ions are the dominant charge carrier in the polymer electrolyte system, in which the ionic (tion) and electron (tel) transference numbers were found to be 0.934 and 0.036, respectively. Through the use of linear sweep voltammetry (LSV), the CS:MC:NH4I system is found to experience electrolyte degradation at 2.1 V. The polymer blend electrolyte sample with highest DC conductivity property was also used as separator in electrical double-layer capacitor (EDLC) cell. Two identical activated carbon electrodes were used to sandwich the electrolyte film. Cyclic voltammetry (CV) was used to show the capacitive behavior of the fabricated EDLC cell, in which no redox peaks were observed. The EDLC was examined for 100 cycles at current density of 0.2 mA/cm2. The values of specific capacitance and equivalent series resistance were determined to be 1.76 F/g, and 650 to 1050 Ω, respectively.

Effect of ohmic-drop on electrochemical performance of EDLC fabricated from PVA:dextran:NH4I based polymer blend electrolytes

Proton conducting solid polymer blend electrolytes based on poly(vinyl alcohol)(PVA):dextran that were doped with different quantities of ammonium iodide (NH4I) were prepared. The X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) study were carried out to examine the compatibility of NH4I withPVA:dextran polymers. FTIR spectroscopy assessment was used to establish the presence of a complex formation between the PVA:dextran and added salt through the modification and reduction in the intensity of FTIR bands relevant to the functional groups. The field emission scanning electron microscopy (FESEM) examination was used to assess the channels for proton transport. Electrical impedance spectroscopy (EIS) was used to analyse the samples conductivity behaviour. The sample with 20 wt.% of added salt has shown a high DC conductivity which can be employed in electrochemical devices such as EDLC. It is also demonstrated by the transference number (TNM) and linear sweep voltammetry (LSV) that it is appropriate to use the largest conducting sample for electrochemical device. There was electrochemical stability of the electrolyte sample with voltage sweeping linearly to 1.3 V. It is shown by the outcome of cyclic voltammetry (CV) plot that charge storage at the site of electrode-electrolyte is non-Faradiac. A high drop voltage (Vd=IR) is implied by the usual galvanostatic charge-discharge. The equivalent series resistance (Res) increases as a result of the increase in Vd all the way through the charge-discharge cycle. Specific capacitance (Csp) is nearly constant from the foremost cycle to the 100th cycle, with average of 4.2 F/g.

Effect of Host Incompatibility and Polarity Contrast on Ion Transport in Ternary Polymer-Polymer-Salt Blend Electrolytes

We study ternary polymer-polymer-salt blend electrolytes using coarse-grained molecular dynamics. We specifically examine the influence of the polymer hosts’ incompatibility and polarity contrast o...

The Effect of Electrolyte Additives upon Lithium Plating during Low Temperature Charging of Graphite-LiNiCoAlO2 Lithium-Ion Three Electrode Cells

The effects of lithium-ion electrolyte additives in ester-rich low temperature electrolyte blends, including vinylene carbonate (VC), lithiuma bis(oxalato) borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), propane sultone (PS) and lithium bis(fluorosulfonyl)imide (LiFSI), upon the likelihood of lithium plating are investigated in graphite-LiNiCoAlO2 three-electrode cells. Although metallic lithium is generally absent in lithium-ion cells, certain conditions, particularly charging at low temperature and/or at high rate, can lead to lithium metal plating on the surface rather than intercalating into the carbon anode. Metallic lithium reacts with the electrolyte and forms dendrites upon continuous plating, which can lead to cell shorting and capacity loss. The type of carbon anode, electrolyte, and solid-electrolyte-interphase (SEI) all influence this behavior. SEI stabilizing additives are generally detrimental to low temperature charging performance, however, 0.1 M LiFSI was found to be advantageous to low temperature charging. When charged at a C/5 rate to 4.10 V, lithium plating was evident at ∼20 °C higher temperature with VC and LiBOB additives compared to the baseline electrolyte without any additives (plating appears at −10 °C rather than −30 °C with the baseline electrolyte). In contrast, the cell containing 0.10 M LiFSI as an additive did not display lithium plating until −40 °C, or 10 °C lower than the baseline cell.

Quasi-solid-state dye-sensitized indoor photovoltaics with efficiencies exceeding 25%

Quasi-solid-state dye-sensitized indoor photovoltaics fabricated using polymer blend electrolytes, judicious cosensitization and polymeric catalysts show efficiencies beyond 25% under 1000-lux artificial lighting.

Structural and Impedance Enquiry on Biodegradable Blend Polymer Electrolytes of Cornstarch and Polyvinyl Pyrrolidone

Biopolymer based Solid polymer blend electrolytes had been prepared utilizing Cornstarch (CS) and Poly vinyl pyrrolidone (PVP) by the technique of solution casting. The readied electrolytes were described by XRD, FTIR and Impedance investigation. The structural properties of CS and PVP blend Polymer Electrolytes (PEs) are dissected by XRD. The interaction among PVP and CS is considered by FTIR investigation. The electrical conductivity is calculated utilizing impedance analyser. The blend of 80wt% CS and 20wt% PVP is having the high conductivity (4.90217 x 10-9 S cm-1 ) and low activation energy (0.16 eV). The temperature dependent conductivity obeys the Arrhenius behaviour.

Dielectric behaviour of PVA and Cornstarch Polymer Blend Electrolytes

Simple film preparation method of solution casting has been used for making of biodegradable PVP and Cornstarch blend polymer electrolytes. Ion dynamics in polymer film membranes has been understood by conductivity and dielectric studies. The combination of 60wt% PVA and 40wt% Corn Starch is having the high conductivity value of 1.56 x 10-9 S cm-1 at ambient temperature and when the temperature increases, the conductivity also linearly increases to obtain 4.93 x 10-9 S cm-1 at 363 K which due to ion hopping mechanism in the polymer matrix. The frequency dependence of dielectric permittivity, dissipation factor (tangent loss) and electrical modulus have been used to know about dielectric behaviours of the polymer blend electrolytes. In dielectric studies, Non-Debye behaviour was observed in all samples.

Structural and ionic conductivity characterization of PEO:MC-NH4I proton-conducting polymer blend electrolytes based films

In the present work, series of proton-conducting polymer electrolyte films based on polyethylene oxide/methylcellulose complexed with different concentrations of ammonium iodide (NH4I) as doping salt were prepared by solution cast technique. The produced films were characterized by X-ray diffraction (XRD), Polarized optical microscope (POM), Fourier transform infrared (FTIR), and electrical impedance spectroscopy (EIS). The XRD and POM results reveal that the sample with 30 wt% NH4I (PBE-30) has the lowest degree of crystallinity. The observed shift in the IR peak position of the N–H stretching band at regions 3000–3300 cm−1 as a function of NH4I concentration suggested clear evidence of an interaction between host polymers and NH4I. The highest value of electrical conductivity was found to be 7.62×10-5S.cm-1 at 303K for PBE-30. The temperature-dependent of electrical conductivity and ion transport properties was described using both the Arrhenius and Vogel-Tammann-Fulcher (VTF) relations. The activation energy values decrease with increasing DC conductivity and vice-versa.

Investigations of lithium ion conducting polymer blend electrolytes using biodegradable cornstarch and PVP

Solid polymer electrolytes used in energy storage devices based on Cornstarch and Poly (vinyl Pyrrolidone) blend incorporated with lithium acetate was prepared using the solution casting method. XRD results confirmed that the amorphous nature of the as-prepared polymer electrolyte was increased by addition of salt. 80 wt % Cornstarch/20 wt % PVP/60 wt % lithium acetate added polymer blend system attains better amorphous nature than others. At ambient temperature, 60 wt % of lithium acetate added system has better bulk conductivity of 3.52 × 10−5Scm−1 over the frequency range of 42 Hz to 1 MHz using AC impedance spectroscopy studies. The dielectric analysis is confirmed that the higher conducting sample was having high dielectric constant and low relaxation time for enhancing ions dynamic behaviour. The conduction mechanism of the higher conducting polymer electrolyte is explained by small polaron hopping and overlapping large polaron tunnelling conduction mechanism. From the argand plot, it is confirmed that higher conducting sample has low relaxation time.

Fabrication of high performance energy storage EDLC device from proton conducting methylcellulose: dextran polymer blend electrolytes

This paper reports Methylcellulose:Dextran (MC:Dex) polymer blend based electrolyte system with NH4I salt for electrical double layer capacitor (EDLC) application. The structural and electrochemical properties of the electrolyte systems were investigated using X-ray diffraction (XRD), Fourier transformed infra-red (FTIR) spectroscopy, Field emission scanning electron microscope (FESEM), impedance spectroscopy, transference number measurement (TNM) and linear sweep voltammetry (LSV). The FTIR studies revealed the complexation between MC:Dex polymer blend and NH4I salt. The reduction in the crystallinity of MC:Dex polymer blend with the increasing salt concentration was observed in XRD analysis. The electrolyte system was observed to be predominantly ionic in nature. The electrolyte composition with 40 wt.% of NH4I showed the maximum ionic conductivity as 1.12 × 10−3 S/cm with electrochemical stability window of 1.27 V. The highest conducting composition of the electrolyte system was used to prepare EDLC with activated carbon electrodes. The EDLC exhibited initial specific capacitance as 79 F/g, energy density as 8.81 Wh/kg and power density as 1111.1 W/kg at a current density of 0.2 mA/cm2.

Studies on ionics conduction properties of modification CMC-PVA based polymer blend electrolytes via impedance approach

In this study, the modification of cellulose derivative namely carboxymethyl cellulose (CMC) blended with polyvinyl alcohol (PVA) and doped with different content of NH4Br based solid polymer electrolytes (SPEs) prepared via solution casting method is investigated. The FTIR analysis demonstrated the interaction between CMC-PVA and NH4Br via COO−. The optimum ionic conductivity at ambient temperature is found to be 3.21 × 10−4 S/cm for the sample containing 20 wt% NH4Br with the lowest percentage of crystallinity and total weight loss. The conductivity-temperature relationship for the entire SPEs system obeys Arrhenius behaviour. Besides that, based on the Nyquist fitting analysis, it is shown that the ionic conductivity of the SPEs is primarily influenced by the ionic mobility as well as the ions diffusion coefficient. The H+ transference number obtained using non-blocking reversible electrode is 0.31, which further indicates that the conduction species is predominantly due to the cationic conduction.

Ion dynamics and dielectric relaxation behavior of PVA-PVP-NaI-SiO2 based nano-composites polymer blend electrolytes

In this paper we have reported the loading effect of SiO2 nano-particles on the electrical transport properties and dielectric relaxation behavior of the PVA-PVP-NaI based nano composite polymer blend electrolytes (NCPBEs). Solution cast technique has been used for the preparation of PVA-PVP-NaI-SiO2 based NCPBE films. AC impedance spectroscopic technique is used for the study of electrical conductivity and dielectric properties. The frequency dependence of AC conductivity with different SiO2 concentration for all prepared NCPBEs obeys the Jonscher power law (JPL) with exponent, n ≥ 1. The dielectric permittivity (ε′&ε″), electric modulus (M′&M″) vs. frequency plots at different concentrations and temperatures were reported. Mobility (μ), dc conductivity (σdc) and total number of charge carriers (N) were estimated and found that mobility varies with the SiO2 concentration. Sample containing 0.6 wt% of SiO2 shows optimum dc conductivity, σdc ~5.07 × 10−6 S/cm with μ ~4.60 × 10−7 and N ~6.98 × 1021. Dielectric relaxation peaks have been observed for all samples and relaxation time (τ) is minimum for 0.6 wt%SiO2 based NCPBE film.

Ion Transport Study in CS: POZ Based Polymer Membrane Electrolytes Using Trukhan Model.

In this work, analysis of ion transport parameters of polymer blend electrolytes incorporated with magnesium trifluoromethanesulfonate (Mg(CF3SO3)2) was carried out by employing the Trukhan model. A solution cast technique was used to obtain the polymer blend electrolytes composed of chitosan (CS) and poly (2-ethyl-2-oxazoline) (POZ). From X-ray diffraction (XRD) patterns, improvement in amorphous phase for the blend samples has been observed in comparison to the pure state of CS. From impedance plot, bulk resistance (Rb) was found to decrease with increasing temperature. Based on direct current (DC) conductivity (σdc) patterns, considerations on the ion transport models of Arrhenius and Vogel–Tammann–Fulcher (VTF) were given. Analysis of the dielectric properties was carried out at different temperatures and the obtained results were linked to the ion transport mechanism. It is demonstrated in the real part of electrical modulus that chitosan-salt systems are extremely capacitive. The asymmetric peak of the imaginary part (Mi) of electric modulus indicated that there is non-Debye type of relaxation for ions. From frequency dependence of dielectric loss (ε″) and the imaginary part (Mi) of electric modulus, suitable coupling among polymer segmental and ionic motions was identified. Two techniques were used to analyze the viscoelastic relaxation dynamic of ions. The Trukhan model was used to determine the diffusion coefficient (D) by using the frequency related to peak frequencies and loss tangent maximum heights (tanδmax). The Einstein–Nernst equation was applied to determine the carrier number density (n) and mobility. The ion transport parameters, such as D, n and mobility (μ), at room temperature, were found to be 4 × 10−5 cm2/s, 3.4 × 1015 cm−3, and 1.2 × 10−4 cm2/Vs, respectively. Finally, it was shown that an increase in temperature can also cause these parameters to increase.

Additives for Cycle Life Improvement of High‐Voltage LNMO‐Based Li‐Ion Cells

AbstractIn this empirical study, five electrolyte additives, namely, lithium bis(oxalato) borate, lithium difluoro(oxalato) borate, 1‐vinyl‐1,2,4‐triazole, 1‐vinyl imidazole and dimethyl‐2,5‐dioxahexane dioate are described and compared regarding their effect in LNMO//graphite cells. The additives were selected from a preliminary study of 59 potential additives. The basis electrolyte mixture is DMC/EC+1 M LiPF6 (LP30) for all cells. All additives are able to enhance the cycle life at room temperature and at elevated temperatures (50 °C) significantly compared to the non‐additive electrolyte blend (basis electrolyte). The cell enhancement is discussed based on the solid‐electrolyte interface (SEI) and metal‐ion content on anode side. The aim of the study is to suggest promising already known as well as new additives that are able to overcome the issue of rapid capacity fading of LNMO‐based cells when the cells are cycled up to 4.8–5.0 V vs. Li/Li+, especially at higher temperatures.

Effect of PEG as a plasticizer on the electrical and optical properties of polymer blend electrolyte MC-CH-LiBF4 based films

Plasticized polymer blend electrolyte films based on methylcellulose (MC), chitosan (CH), lithium tetrafluoroborate (LiBF4), and polyethylene glycol (PEG) as a plasticizer were prepared and investigated. The effect of different concentrations of PEG was studied using AC impedance spectroscopy, and UV–Visible spectroscopy. The electrical and optical properties of polymer electrolytes have been improved upon addition of PEG. The DC conductivity was evaluated from the bulk resistance achieved from Nyquist impedance plots. Results from temperature studies reveal that all samples comply with the Arrhenius formula in the investigated temperature range. The sample with 10 wt% of PEG exhibits the highest ionic conductivity of 2.12×10-5S/cm with the minimum activation energy of 0.528eV at ambient temperature. The lowest relaxation time for highest ion conductive sample indicates the faster ion dynamics. The frequency-dependence AC conductivity was found to follows the Jonscher’s power law at various temperatures, and the conduction mechanism for this system followed the overlapping large polaron tunneling (OLPT) model. The increase in absorption and a decrease in optical band-gap in the UV region was confined by UV–Visible spectroscopy.