Mixture Of Propylene Carbonate Research Articles

Molecular modeling and simulation of organic electrolyte solutions for lithium ion batteries.

Multi-criteria optimization is used for developing molecular models for ethylene carbonate (EC) and propylene carbonate (PC), organic solvents commonly used in Li-ion batteries. The molecular geometry and partial charges of the solvents are obtained from quantum mechanical calculations. Using a novel optimization strategy that combines systematic variations of the Lennard-Jones parameters with a reduced units approach, the models are fitted to experimental data on the liquid density, vapor pressure, relative permittivity, and self-diffusion coefficient. Since no experimental data for the self-diffusion coefficient of pure EC were available in the literature, they are measured in this work using a gradient-based nuclear magnetic resonance technique. For all pure component properties, excellent agreement between experiment and simulation is obtained. Moreover, the predictive capabilities of the new solvent models are assessed by comparison to experimental data for the liquid density and relative permittivity of mixtures of EC and PC. In addition, molecular models for the anions PF6-, BF4-, and ClO4- in solutions of their lithium electrolytes in PC are developed using experimental data on the solution densities. Finally, the self-diffusion coefficients of LiPF6 in PC and in aqueous solution are predicted and compared, showing that diffusion is much slower in the organic solution due to the formation of larger solvent shells around the ions. Furthermore, an analysis of the radial distribution functions in these solutions suggests that the ions have much less impact on the structure of the solvent PC than on water.

Colloidal dispersions of cobalt ferrite nanoparticles in EMIM TFSI, propylene carbonate and their mixtures

Liquid thermocells are promising devices for the recovery of low-grade waste heat and its conversion into electricity. The present study proposes dispersing charged magnetic nanoparticles in liquids to improve thermoelectric conversion, due to their thermodiffusive and magnetic properties. Core@shell cobalt ferrite@maghemite nanoparticles (NPs) of various sizes with three different kinds of coatings are tested for dispersion in EMIM TFSI (ethyl-methylimidazolium bistriflimide), an ionic liquid (IL) of high electrical conductivity. Among the tested ligands, PAC6MIM±Br− (1-(6-hexylphosphonate) 3-methyl imidazolium bromide) emerges as the most efficient due to its phosphonic group. This ligand leads to dispersions of clusters of a few dozen NPs in water and a few NPs in EMIM TFSI. For improving both the viscosity and the electrical conductivity, dispersions in binary mixtures of propylene carbonate (PC), a polar medium, and EMIM-TFSI are further investigated with the sample based on NPs of ∼ 9 nm diameter. Through a pumping and heating procedure, stable dispersions are obtained with a subsequent reduction of the size of the NP clusters, down to 1 to 2 NPs in EMIM TFSI and a few NPs in PC and their binary mixtures. The mixture with an IL mole fraction ∼0.2–0.3 and maximal electrical conductivity is a promising candidate for further thermoelectric investigations.

High‐Performance Co‐Solvent Engineering Electrolyte for Obtaining a High‐Voltage and Low‐Cost K+ Battery Operating from −25 to 50 °C

AbstractHigh‐safety potassium‐ion batteries (HPIBs) are highly intriguing owing to their green energy, low cost, high voltage, noncombustible, and simple assembly. However, most high‐voltage HPIBs use water‐in‐salt electrolytes (WISE), which lead to several problems, such as a high viscosity, which significantly reduces the performance and increases the cost of HPIBs, thus impeding their development. Unfortunately, studies regarding HPIB electrolytes remain limited, further limiting the development of HPIBs. Herein, a co‐solvent engineering electrolyte (4.0 m KOTf in a mixture of propylene carbonate (PC) and H2O with a volume ratio of 5.0:1.0) featuring low‐cost (1/4 of WISE) and high‐performance (45.43 mS cm−1) characteristics is proposed, which not only achieves a wide electrochemical stability window by reducing the activity of H2O, but also adjusts the solvation structure of K+. Consequently, the HPIBs assembled via co‐solvent engineering electrolyte demonstrated a high energy density of 88.05 Wh kg−1, and sufficiently operated at rates of 0.50–10.0 A g−1 over a wide temperature range (−25–50 °C). This study provides a promising means for developing high‐voltage HPIBs.

Exploring relaxation behaviors in Hydrogen-Bond networks within binary mixtures of propylene carbonate and primary alcohols through broadband dielectric spectroscopy and molecular dynamic simulation

This work investigates the dielectric properties and the relaxation behaviors of propylene carbonate (PC) and its binary mixtures with methanol and ethanol. A coaxial-circular cutoff waveguide junction was employed to characterize broadband dielectric spectra ranging from 0.1 GHz to 18 GHz, and a two-group Debye model was used to extract relaxation parameters. Excess thermodynamic parameters, Kirkwood orientational correlation factors, and Bruggeman factors for PC-alcohol mixtures were also analyzed and presented. These data provide insights into microscopic dynamic processes as the PC concentration in the mixtures gradually increases. These processes include the continuous disassociation of the alcohols’ hydrogen-bond (H-bond) networks, the formation of new PC-alcohol H-bond networks, the parallel alignment of heterogeneous dipoles, and a significant enhancement of the dielectric effect. Furthermore, a series of molecular dynamics (MD) simulations using the TraPPE-UA forcefield were conducted, and the obtained thermodynamic and electromagnetic parameters demonstrated good agreement with experimental results. Based on radial distribution functions, dipole–dipole spatial orientational correlations, and H-bond life times extracted from the MD simulations, we observed the gradual formation of PC-cage and alcohol-cluster microstructures in PC-rich mixtures. The data and physical insights provided in this work are expected to have practical implications in high-energy battery applications and the pharmaceutical industry.

Nafion-Based Quasi-Solid-State Polymer Electrolyte for Lithium-Sulfur Batteries

Lithium-sulfur batteries are considered a strong contender for next-generation high-energy battery systems given their high gravimetric energy density. However, this battery chemistry is still facing challenges such as the polysulfide shuttle effect caused by the high solubility of long-chain lithium polysulfides (Li2Sn) resulting in active material loss and compromised cycle life. Solid-state polymer electrolytes (SPEs) represent a promising pathway to address this issue by preventing the formation and transport of these undesirable polysulfide intermediates.1,2 Moreover, the application of flexible polymer electrolytes promotes safe high energy batteries for smart textiles.In this study, single lithium-ion conducting solid polymer electrolytes (SLIC-SPEs) based on lithiated Nafion membrane have been investigated, utilizing the chemical and thermal stability of this kind of ionomers. Among others, a mixture of ethylene carbonate (EC) and propylene carbonate (PC) was tested as organic aprotic swelling solvent offering advantageous characteristics such as great chemical stability and high ion mobility while avoiding phase separation issues and undesired leaching.Sulfur-infiltrated ultramicroporous carbon composite cathodes were utilized in combination with the investigated SLIC-SPEs, facilitating a quasi-solid-state lithium-sulfur full cell with carbonate-solvent compatibility and high active material utilization.3 Electrochemical performance of the full cell was investigated elaborately and compared with a reference system using solely the liquid EC:PC solvent. While rapid capacity fading can be observed for the liquid electrolyte cell, an enduring high capacity is found in the lithiated-Nafion system. For better understanding of these effects, cycling analysis was accompanied by implementing impedance spectroscopy upon galvanostatic cycling. The electrochemical characterization indicates the formation of a stable film and high degree of reversibility during cycling of the lithiated-Nafion cell whereas an increased film resistance due to sulfur cross-over and electrolyte decomposition was observed within the liquid electrolyte system.(1) Z. Li, W. Lu, N. Zhang, Q. Pan, Y. Chen, G. Xu, D. Zeng, Y. Zhang, W. Cai, M. Yang, J. Mater. Chem. A 2018, 6 (29), 14330-14338.(2) X. Hao, H. Wenren, X. Wang, X. Xia, J. Tu, J. Colloid Interface sci. 2020, 558, 145-154,(3) M. Nojabaee, B. Sievert, M. Schwan, J. Schettler, F. Warth, N. Wagner, B. Milow, K. A. Friedrich, J. Mater. Chem. A 2021, 9 (10), 6508-6519,

Propylene carbonate as an ecofriendly solvent: Stability studies of Ripretinib in RPHPLC and sustainable evaluation using advanced tools

Ripretinib (RPB) is a U.S. Food and Drug Administration approved drug for the treatment of advanced gastrointestinal stromal tumour. According to literature search, there are no RP-HPLC methods developed for the recently approved drug RPB due to its terrible solubility. In this current study, Green Analytical Chemistry (GAC) was employed using the RP-HPLC technique to study the stability of RPB under different stress conditions. Two reported polymorphs of RPB were analysed using the mobile phase mixture of phosphate buffer, propylene carbonate and ethanol (50: 35: 15) on a 250 × 4.6 mm, i.d. 5 μm Inertsil ODS-2 C18 column, at a wavelength of 260 nm. In this study, method development for RPB quantification was accomplished within a linearity range of 1400–2600 ng/mL, yielding an R2 value of 0.9973. The method exhibited a LOD of 103 ng/mL and a LOQ of 312 ng/mL, demonstrating high sensitivity and accuracy. The utilization of assessment tools for evaluating greenness and whiteness offered valuable insights into the environmental impact and sustainability of the proposed methodology. The results substantiated its positive performance in terms of eco-friendliness, thereby emphasizing its alignment with seven sustainable development goals include 7 (Affordable and Clean Energy), 9 (Industry, Innovation, and Infrastructure), 12 (Responsible Consumption and Production), 13 (Climate Action), 14 (Life Below Water), 15 (Life on Land), 17 (Partnerships for the Goals). This further enhances the credibility and significance of the developed method in advancing the cause of a greener and more sustainable future.

Nafion-212 Membrane Solvated by Ethylene and Propylene Carbonates as Electrolyte for Lithium Metal Batteries.

The use of cation-exchange membranes as electrolytes for lithium metal batteries can prevent the formation of lithium dendrites during extended cycling and guarantee safe battery operation. In our study, the Nafion-212 membrane in lithium form solvated by a mixture of ethylene carbonate and propylene carbonate (EC-PC) was used as an electrolyte in a lithium metal battery with the LiFePO4 cathode. The Nafion-212-EC-PC electrolyte is electrochemically stable up to 6 V, indicating its suitability for high-energy density batteries. It has an ionic conductivity of 1.9 × 10-4 S/cm at 25 °C and a high lithium transference number. The symmetric Li|Nafion-212-EC-PC|Li cell shows a very low overvoltage of ~0.3 V at a current density of ±0.1 mA/cm2. At 25 °C, the LiFePO4|Nafion-212-EC-PC|Li battery exhibits a capacity of 141, 136, 125, and 100 mAh/g at 0.1, 0.2, 0.5, and 1C rates, respectively. It maintains a capacity of 120 mAh/g at 0 °C and 0.1C with stable performance for 50 charge/discharge cycles. The mechanism of conductivity and capacity retention at low temperatures is discussed.

Deciphering Electrolyte Degradation in Sodium-Based Batteries: The Role of Conductive Salt Source, Additives, and Storage Condition

This work investigates the stability of electrolyte systems used in sodium-ion-based batteries. The electrolytes consist of a 1:1 (v:v) mixture of ethylene carbonate (EC) and propylene carbonate (PC), a sodium-conducting salt (either NaPF6 or NaTFSI), and fluoroethylene carbonate (FEC), respectively, sodium difluoro(oxalato) borate (NaDFOB), as additives. Through systematic evaluation using gas chromatography coupled with mass spectrometry (GC-MS), we analyze the formation of degradation products under different conditions including variations in temperature, vial material, and the presence or absence of sodium metal. Our results reveal the significant influence of the conductive salt’s source on degradation. Furthermore, we observe that FEC’s stability is affected by the storage temperature, vial material, and presence of sodium metal, suggesting its active involvement in the degradation process. Additionally, our results highlight the role of NaDFOB as an additive in mitigating degradation. The study provides crucial insights into the complex network of degradation reactions occurring within the electrolyte, thus informing strategies for improved electrolyte systems in sodium-based batteries. Since the production, material selection and storage of electrolytes are often insufficiently described, we provide here an insight into the different behavior of electrolytes for Na-ion batteries.

Enhanced Removal of Photoresist Films through Swelling and Dewetting Using Pluronic Surfactants.

Organic photoresist coatings, primarily composed of resins, are commonly used in the electronics industry to protect inorganic underlayers. Conventional photoresist strippers, such as amine-type agents, have shown high removal performance but led to environmental impact and substrate corrosiveness. Therefore, this trade-off must be addressed. In this study, we characterized the removal mechanism of a photoresist film using a nonionic triblock Pluronic surfactant [poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)] in a ternary mixture of ethylene carbonate (EC), propylene carbonate (PC), and water. In particular, the removal dynamics determined by using a quartz crystal microbalance with dissipation monitoring was compared with those determined by performing confocal laser scanning microscopy and visual observation to analyze the morphology, adsorption mass, and viscoelasticity of the photoresist film. In the absence of the Pluronic surfactant, the photoresist film in the ternary solvent exhibited a three-step process: (i) film swelling caused by the penetration of a good solvent (EC and PC), (ii) formation of photoresist particles through dewetting, and (iii) particle aggregation on the substrate. This result was correlated to the Hansen solubility parameters. The addition of the Pluronic surfactant not only prevented photoresist aggregation in the third step but also promoted desorption from the substrate. This effect was dependent on the concentration of the Pluronic surfactant, which influenced diffusion to the interface between the photoresist and the bulk solution. Finally, we proposed a novel photoresist stripping mechanism based on the synergy between dewetting driven by an EC/PC-to-water mixture and adsorption by the Pluronic surfactant.

(Invited) Highly Stable, Crosslinked Polymer Membranes for Non-Aqueous Flow Batteries

Long-term energy storage is a crucial stepping stone for the introduction of renewable sources in the energy mix due to their intermittent nature. Non-aqueous Flow Batteries (NFBs) are expected to operate at higher potential differences in comparison to conventional aqueous systems, thus yielding an improved power density. However, among the several issues of NFBs, it is pivotal to develop ion-conducting separators stable in organic solvents.Here we present a new family of ionomers which proved promising as candidates to implement this crucial function. The ionomers are founded on the strong ionic interactions between the functionalities of a polyamide-based material (P) and a perfluorosulfonic acid macromolecule (N). The latter interactions establish crosslinks between the two starting macromolecules. Consequently, the polymeric structure of the final ionomer is reorganized, improving the mechanical properties and curtailing the swelling upon immersion in organic solvents.The membranes obtained from two of the proposed ionomers, labelled “P-N0.77” and “P-N0.89”, show a swelling < 7% after 1000 hours of immersion both in acetonitrile (ACN) and in a 1:1 vol./vol. mixture of ethylene carbonate and propylene carbonate (EC:PC). Upon exchanging the membranes with tetraethylammonium (TEA+) cations, a common benchmark mobile specie for NFBs, it is shown that: (i) P-N0.77 exhibits a conductivity of 0.4∙10-3 S∙cm-1 and 0.9∙10-3 S∙cm-1 at 25°C in 0.1 M TEA+ in ACN and 0.1 M TEA+ in EC:PC, respectively; and (ii) P-N0.89 shows a conductivity of 1.5∙10-3 S∙cm-1 and 0.5∙10-3 S∙cm-1 in the same conditions.These results suggest that the proposed materials are suitable for application in NFBs, opening the door to the long-term operation of these devices.

Anti-adsorption Mechanism of Photoresist by Pluronic Surfactants: An Insight into Their Adsorbed Structure.

Photoresist stripping is the final step in the photolithography process that forms fine patterns for electronic devices. Recently, a mixture of ethylene carbonate (EC) and propylene carbonate (PC) has attracted attention as a new stripper based on its eco-friendliness and anti-corrosiveness. However, the EC/PC mixture causes re-adsorption of the photoresist during a process of subsequent water rinsing. In this study, we characterized the adsorption/desorption of the photoresist and a triblock Pluronic surfactant [poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)] as a blocking agent on an indium tin oxide (ITO) substrate. In addition, we evaluated the dispersion of photoresist particles. The photoresist polymer formed a thin and rigid adsorption layer on an ITO substrate in the EC/PC mixture. When water was injected into the EC/PC mixture and the photoresist solutions, the photoresist polymer aggregated and was then deposited on the substrate. In contrast, the addition of Pluronic surfactant F-68 (PEO79PPO30PEO79) into the EC/PC mixture remarkably decreased the residual amount of the photoresist on the ITO after water injection. This variation was attributed to the PEO blocks of F-68 extended to the solution phase, whereas the PPO blocks of F-68 functioned as anchors for adsorption onto the photoresist. Therefore, the F-68-adsorbed layer prevented interaction between the photoresist particles or the photoresist and the ITO surface, which provides potential for future applications as new stripping agents with high removal performance.

A comparative analysis of volumetric, viscometric and conductometric properties of Triethylmethylammonium Tetrafluoroborate (TEMABF4) and Tetraethylammonium Tetrafluoroborate (TEABF4) in pure propylene carbonate (PC) and binary aqueous propylene carbonate solvents

Electrolytes play a major role in electrochemical energy storage devices and specifically organic electrolytes are used predominantly over aqueous electrolytes due to wide electrochemical window, high energy density and efficiency. However, aqueous electrolytic systems for energy storage applications still need to be explored as these are non-flammable, environment friendly, non-toxic, carrying high ionic conductivity and low cost as compared to organic counterparts. In this study, an effort has been made in doing a comparative analysis of the physicochemical properties of Triethylmethylammonium Tetrafluoroborate (TEMABF4) and Tetraethylammonium Tetrafluoroborate (TEABF4) in pure propylene carbonate (PC) and binary aqueous mixtures of PC (0.01 &0.02 m) at different temperatures and concentrations. From this data, various volumetric, viscometric, and conductometric parameters have been calculated and the results obtained are analysed and compared in terms of solute–solute and solute–solvent interactions. From the analysis of thermo physical parameters, we have found that both the salts act as structure breaker in PC whereas structure maker in binary aqueous mixtures of PC (0.01 & 0.02 m). FTIR studies have also been done to see the intermolecular interactions and structural alterations. Furthermore, results from Cyclic Voltammetry (CV) studies suggested that a binary aqueous organic electrolytic system can also be a potential electrolytic system as its electrochemical window is comparable to that of pure electrolytic organic solvents.

Ultraviolet Spectrophotometry of Lignin Revisited: Exploring Solvents with Low Harmfulness, Lignin Purity, Hansen Solubility Parameter, and Determination of Phenolic Hydroxyl Groups.

In this article, we explored solvents with lower harmfulness than established systems for UV spectrophotometry of lignin. By measuring the absorptivity in DMSO solvent at 280 nm, the purity of the lignin samples was addressed and compared with Klason and acid-soluble lignin. The general trend was an increasing absorptivity with increasing lignin purity; however, considerable scattering was observed around the sample mean. The Hansen solubility parameter (HSP) of four technical lignins was furthermore determined. The model was in line with the UV measurements, as solvents closer in HSP correlated with a higher absorptivity. Ethylene glycol was identified as a good solvent for lignin with low UV-cutoff. In addition, mixtures of propylene carbonate, water, and ethanol showed good suitability and a low cutoff of 215 nm. While DMSO itself was poorly suited for recording alkali spectra, blending DMSO with water showed great potential. Comparing three methods for determining phenolic hydroxyl units by UV spectrophotometry showed some discrepancies between different procedures and solvents. It appeared that the calibrations established with lignin model compounds may not be fully representative of the lignin macromolecule. More importantly, the ionization difference spectra were highly affected by the solvent of choice, even when using what are considered "good" solvents. At last, a statistical comparison was made to identify the most suitable solvent and method, and the solvent systems were critically discussed. We thus conclude that several solvents were identified, which are less harmful than established systems, and that the solubility of lignin in these is a crucial point to address when conducting UV spectrophotometry.

High‐performance sodium ion conducting gel polymer electrolyte based on a biodegradable polymer polycaprolactone

AbstractGel polymer electrolytes (GPEs) are gaining recent focus for high‐performance quasi‐solid‐state energy storage devices owing to their high ionic conductivity, good interfacial properties, flexibility with high safety in comparison to liquid electrolytes. Among various polymer hosts, developed so far, polycaprolactone (PCL) is attractive for its biodegradable and biocompatible nature. In this report, we demonstrate a novel GPE composition incorporating a liquid electrolyte 1 M sodium triflurosulfonate (NaTf) in ethylene carbonate (EC):propylene carbonate (PC) mixture, immobilized in PCL as the host polymer in the form of mechanically stable, free‐standing and flexible thick films. The GPE films are characterized using various physicochemical and electrochemical techniques. The GPE comprising an approximately 80 wt.% concentration of liquid electrolyte offers an optimum ionic conductivity of ~1.3 × 10−3 S cm−1, wide electrochemical stability window up to approximately 4.3 V and high sodium ion transport number (tNa+ ~ 0.67) at room temperature. Besides, the GPE film is thermally stable up to approximately 100°C. The sodium stripping/plating tests reveal highly stable cycling under ±46 mV for over 100 hours followed by ±30 mV at a current density of 0.05 mA cm−2 indicating reversible Na‐plating/stripping behavior. The high Na+‐conductivity and suitable Na‐storage properties make a favorable biodegradable electrolyte for practical sodium‐ion battery applications.

Gel Polymer Electrolytes with Mixture of Triazolium Ionic Liquids and Propylene Carbonate.

This study is focused on the structural influence of 1,2,4-triazolium ionic liquid (IL), that is, the effect of the length of the substituent and the type of substitution (1-methyl-4-alkyl or 1-alkyl-4-methyl) used in the mixture with propylene carbonate (PC) on the properties of thiol–ene polymer ionogels and on the preparation of an ionogel with satisfactory mechanical and conductive properties. PC allows for higher conductivity but also causes electrolyte leakage from the gel. When using triazolium IL (instead of the imidazolium one), because of the stronger interactions between components of the system, the ionogels do not leak. In this study, 1,4-dialkyl-1,2,4-triazolium ILs were successfully synthesized by the alkylation of 1,2,4-triazole. Subsequently, gel polymer electrolytes were obtained by one-pot thiol–ene photopolymerization reactions of tetrafunctional thiols with different chemical structures: pentaerythritol tetra(3-mercaptopropionate) (PETMP) or pentaerythritol tetra(3-mercaptobutyrate) (PETMB) and trifunctional ene (TATT) in the presence of a mixture of 1,4-dialkyl-1,2,4-triazolium IL with PC. Measurements made by electrochemical impedance spectroscopy showed that all ionogels with TATT+PETMB as a polymer matrix presented smaller relative ionic conductivity compared to ionogels containing TATT+PETMP. The puncture resistance and elongation at puncture, measured by the puncture resistance method, were higher for ionogels with poly(TATT+PETMB) than for those with poly(TATT+PETMP). Moreover, ILs containing a methyl group in position N1 of the 1,2,4-triazole ring presented lower puncture resistance than ionogels with ILs containing a methyl group in position N4, especially for shorter alkyl chains. Additionally, the photo-differential scanning calorimetry method was employed to characterize the course of photopolymerization. The compositions and their constituents were characterized by UV and IR spectroscopy.

Thermodynamic, excess Properties and Intermolecular interactions of ionic liquid 1- Ethyl-3-Methylimidazolium thiocyanate and propylene carbonate mixtures

Thermodynamic, excess Properties and Intermolecular interactions of ionic liquid 1- Ethyl-3-Methylimidazolium thiocyanate and propylene carbonate mixtures

Glyoxal-based electrolytes for potassium-ion batteries

In this study we reported for the first time the use of an electrolyte containing 1.5 M KFSI (potassium(bis)-fluorosulfonylimide) dissolved in a mixture of propylene carbonate (PC), tetraethoxy-glyoxal (TEG) and vinyl-ethylene carbonate (VEC) in potassium-ion batteries (KIB). We showed that this electrolyte displays good transport properties, high thermal stability and broad electrochemical stability. Graphite and Prussian White (PW) electrodes used in combination with 1.5 M KFSI in PC/TEG display high capacity, even at high C-rates, and remarkable cycling stability. These electrodes can be successfully combined in a KIB displaying high efficiencies and high stability for more than 500 cycles. Considering these results, glyoxal-based electrolytes can be therefore considered as an attractive new class of electrolyte for KIBs.

Sodium ion conducting flame-retardant gel polymer electrolyte for sodium batteries and electric double layer capacitors (EDLCs)

We report a trimethyl phosphate (TMP) based sodium ion conducting flame-retardant gel polymer electrolyte for safer electrochemical applications. The physical investigations reveal superior amorphicity and thermal stability of electrolyte utilizing TMP solvent as compared to the conventionally used binary mixture of ethylene carbonate (EC) and propylene carbonate (PC). The TMP based electrolyte membrane displays better ionic conductivity (∼ 1.40 mS cm−1) as compared to the membrane with EC:PC solvent mixture (∼ 0.72 mS cm−1) at 30°C with higher electrochemical stability window of ∼ 4.5 V and superior Na+ transport characteristics. The TMP based electrolyte has been utilized for proto-type sodium battery and EDLC application. The proto-type Na battery displays an open circuit potential of ∼ 2.3 V and specific discharge capacity of ∼ 225 mA h g−1. The electric double layer capacitor (EDLC) fabricated using the TMP based electrolyte and activated carbon electrodes shows specific capacitance of ∼100 F g−1 and is stable up to 4000 charge–discharge cycles.

Gel Polymer Electrolytes Based on Cross-Linked Poly(ethylene glycol) Diacrylate for Calcium-Ion Conduction.

Calcium batteries are promising alternatives to lithium batteries owing to their high energy density, comparable reduction potential, and mineral abundance. However, to meet practical demands in high-performance applications, suitable electrolytes must be developed. Here, we report the synthesis and characterization of polymer gel electrolytes for calcium-ion conduction prepared by the photo-cross-linking of poly(ethylene glycol) diacrylate (PEGDA) in the presence of solutions of calcium salts in a mixture of ethylene carbonate (EC) and propylene carbonate (PC) solvents. The results show room-temperature conductivity between 10–5 and 10–4 S/cm, electrochemical stability windows of ∼3.8 V, full dissociation of the salt, and minimal coordination with the PEGDA backbone. Cycling in symmetric Ca metal cells proceeds but with increasing overpotentials, which can be attributed to interfacial impedance between the electrolyte and calcium surface, which inhibits charge transfer. Calcium may still be plated and stripped yielding high-purity deposits and no indication of significant electrolyte breakdown, indicating that high overpotentials are associated with an electrically insulating, yet ion-permeable solid electrolyte interface (SEI). This work provides a contribution to the study and understanding of polymer gel materials toward their improvement and application as electrolytes for calcium batteries.

Interfacial Degradation in NMC811-Graphite Batteries during Extended Cycling

To improve the energy density in Li-ion batteries, development of cathode materials with higher capacities are required, where much of the current focus is on Ni-rich lithium nickel manganese oxides (NMC). However, higher Nickel content is typically accompanied by accelerated degradation and thus poor cycle life, with undesired reactions at the electrode-electrolyte interfaces strongly implicated. There have been numerous attempts to mitigate this, using various methods including surface coatings, structural doping and advanced synthesis techniques such as core-shell or concentration gradient particles with much lower nickel concentrations at their surface. Designing improved solutions, requires a deeper mechanistic understanding of the underlying interfacial processes involved in degradation and their relative contributions. In this study these reactions are investigated in LiNi0.8Mn0.1Co0.1O2–graphite cells cycled using LP57 electrolyte (1 M LiPF6 in EC:EMC, 3:7) for different number of cycles, providing information about how interfacial degradation proceeds. Electrochemical measurements are combined with post mortem techniques including surface sensitive soft X-ray absorption spectroscopy, and photoelectron spectroscopy measured with different excitation energies. Based on fitted differential voltage analysis (DVA) data from the cells it is shown how the initial capacity fading during the first 300 cycles is almost fully attributable to excessive electrolyte reduction exhibited as SEI thickening, whereas further cycling leads to a larger contribution to capacity fading from loss of active NMC material. The initial capacity fading due to electrolyte reduction can be correlated with more plating of manganese, as compared to nickel, onto the graphite electrode, see figure. However, after 600 cycles both nickel and manganese are found in similar concentrations within the SEI. The changing ratio between the amount of plated nickel and manganese with cycle number indicates that manganese on the NMC surface initially dissolves more easily than the nickel, but as the unstable manganese ions are dissolved more and more nickel will contribute to the transition metal dissolution. The nickel ions in the SEI are also found to change their chemical surrounding as the cycling proceeded, showing that they do not form stable species and are thus likely to contribute to continued breakdown of the SEI. We compare the observed evolution of the SEI that results from cross talk between the NMC and graphite electrodes, to the case where EC-free electrolytes are used and graphite is replaced with Li4Ti5O12 (LTO) such that contributions from electrolyte reduction at the anode are expected to be minimised [1,2].In addition to the side reactions at the graphite other important side reactions take place on the NMC, some of which are potentially initiated by the graphite electrode [3]. For instance it was found that the Li2CO3 impurities present on the NMC surface decompose throughout the cells’ cycle life rather than just during the initial cycles. Previous studies have shown how Li2CO3 coatings severely decrease the cycle life, and therefore the observations here show that decomposition related to Li2CO3 is a problem that does not disappear during the formation cycling. Instead minimizing the initial Li2CO3 formation is critical. The insights obtained here on the evolution of surface layers coupled with the individual electrochemical degradation of the electrodes will advance the understanding of the Ni-rich NMC’s capacity retention behaviour and inform future efforts to achieve longer cycle lifetimes.[1] Björklund, E., Göttlinger, M., Edström, K., Younesi, R. & Brandell, D. Sulfolane‐Based Ethylene Carbonate‐Free Electrolytes for LiNi0.6Mn0.2Co0.2O2−Li4Ti5O12 Batteries. Batter. Supercaps 3, 201– 207 (2020).[2] Björklund, E., Göttlinger, M., Edström, K., Brandell, D. & Younesi, R. Investigation of Dimethyl Carbonate and Propylene Carbonate Mixtures for LiNi0.6 Mn0.2Co0.2O2-Li4 Ti5 O12 Cells. ChemElectroChem 6, 3429–3436 (2019).[3] Björklund, E., Brandell, D., Hahlin, M., Edström, K. & Younesi, R. How the Negative Electrode Influences Interfacial and Electrochemical Properties of LiNi1/3Co1/3Mn1/3O2 Cathodes in Li-Ion Batteries. J. Electrochem. Soc. 164, A3054–A3059 (2017). Figure 1