Propylene Carbonate Research Articles

Swelling of lignin-based gel in salt-containing organic solvents and its application as gel electrolyte

Abstract A lignin-based gel prepared by the chemical crosslinking of hardwood acetic acid lignin (AL) with poly(ethylene glycol) diglycidyl ether has been reported to shrink in water and organic solvents but swell specifically in aqueous binary solutions. In this study, the AL-based gel was also found to swell in lithium-salt-containing organic solvents, namely, liquid electrolytes. The uptake of salt solutions reached five times the dry weight of the gel. The ionic conductivity of the gel swollen with 1 M LiBF4 in propylene carbonate or a mixed solution (1:1, v/v) of ethylene carbonate and dimethyl carbonate exceeded 1 mS cm−1 at room temperature (25 °C), suggesting that this gel can be applied as a gel electrolyte for lithium-ion batteries (LIBs). A prototype LIB was assembled with the AL-based gel electrolyte and LiCoO2/graphite-based electrodes and exhibited low bulk and charge transfer resistances of 4.1 and 9.7 Ω, respectively. Moreover, its initial specific capacity reached 104 mAh g−1 at a current density of 28 mA g−1, which is comparable to that of a reference LIB assembled using a commercial polyethylene separator. These results indicate the significant potential of this lignin-based gel for application in energy storage devices.

Insights into Electrolyte Reactivity and Solid Electrolyte Interphase Formation at the Li Metal Anode Surface from DFT Simulations

Solid electrolyte interphase (SEI) is a critical component of lithium ion batteries, yet is poorly characterized and not well understood. We use plane wave density functional theory simulations to perform a comprehensive study of the degradation reaction mechanisms of four electrolyte solvents and additives, ethylene carbonate (EC), propylene carbonate (PC), fluoroethylene carbonate (FEC), and vinylene carbonate (VC), at the Li (001) metal anode surface. The calculations provide fundamental insights into electrolyte decomposition and spontaneous SEI formation. Utilizing automated workflows implemented in the Schrödinger Materials Science Suite, we compute the adsorption energies and calculate the reaction energies for each decomposition pathway. Furthermore, we employ nudged elastic band calculations to compute the decomposition reaction barriers and provide mechanistic insights into the onset of SEI formation. We analyze trends in decomposition reaction energies and the relationships between the reaction energies and the activation barriers for the various electrolyte molecules as a function of applied bias potential. We find that the preferred decomposition pathways are different for the solvent molecules (EC and PC) than for the additives (FEC and VC). Calculations also suggest that applied bias reduces decomposition reaction barriers thus enhancing SEI formation. Such a comprehensive dataset of reaction energies and activation barriers provides useful benchmarks for the development and validation of reactive machine learned force fields for modeling advanced battery chemistries at a larger scale.

A Model for Lithium-Ion Battery Electrolyte Mixture Densities

Lithium-ion battery (LIB) electrolytes are generally composed of an organic hydrocarbon and lithium salt (e.g., LiPF6). The effect of salt addition to the electrolyte solvent increases its density. Experimental density data for basic and realistic, multicomponent mixtures are scarce in the literature, and a predictive model for electrolyte solution density is not yet available. This work resolves to create a predictive method that can be used to estimate the density of these mixtures. A predictive method which accounts for intramolecular forces in the electrolyte mixture was developed and fit to the sparse density data available in the literature. The model exhibited high accuracy for single component electrolyte mixtures with most predictions falling within 1% of measured values and all predictions falling within 5%. The model was further extended to more realistic, multi-solvent electrolyte mixtures which exhibited similar accuracy, seen in Fig. 1. It was noted that the multi-component predictions were moderately worse than for the single component mixtures. The source of this disparity is not clear but may be derived from uncertainty in the data reported by electrolyte vendors and/or the presence of solvent-to-solvent interactions in the solution which are not accounted for in the current modeling framework. In addition to the density model, an accurate method for computing absolute molar and mass fractions of multi-solvent mixtures with specified volumetric concentrations (e.g., 1.2 M LiPF6 in 1:1:1 %vol. EC/ DEC/DMC) is also described for when that is the only known relation for a solution. Computed mass concentration values yielded an average error of 1.4% with a maximum value of 9.6%. The molar and mass approaches were combined to yield a modeling framework capable of computing molar concentrations and densities of all LIB electrolyte solutions based on LiPF6 loaded in any combination of ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and propylene carbonate (PC). The largest fault with the final modeling system is that it suffers from a lack of sufficient, high-quality experimental data for validation of its accuracy over a wide range of electrolyte formulations and conditions. This model’s accuracy is dependent on the experimental data utilized for correlation. Accordingly, more data from differing sources will help increase the accuracy and confidence of the model developed herein and allow it for expansive use in LIB fields. Future work will be required to extend the current approach to any novel electrolyte formulations developed in the research and development sector. Figure 1

Solvent Co-Intercalation for Electrochemical Energy Storage

One of the major differences between sodium- and lithium-ion batteries (SIBs and LIBs) is how the ions electrochemically react with graphite, where large amounts of lithium can be stored in the graphite galleries, but sodium cannot form thermodynamically stable, high capacity binary graphite intercalation compounds (b-GICs).[1] In 2014, however, it was discovered that graphite had a much greater capacity to reversibly store sodium-ions than previously thought – but only when using ether based electrolytes.[2] The increased storage capabilities in ether based electrolytes comes about by the formation of a ternary graphite intercalation compound (t-GIC), whereby the sodium-ion is intercalated along with it solvation shell. Thus, graphite can store solvated sodium-ions, but not bare ones. This unconventional mechanism is already known to occur for certain solvents, such as propylene carbonate, but was always thought to be accompanied by complete destruction of the graphite.[3]Since then, several studies have been conducted on electrochemical solvent co-intercalation for energy storage,[4] but the topic is still unexplored. Several fundamental questions have received quite conflicting answers – Especially with regards to the SEI and the reaction mechanism - the system displaying both clear staging in graphite, with at least one well defined plateau for stage I formation, but also large pseudocapacitive features. Following development on electrochemical double-layers and confined electrolytes,[5] it appears in systems where reversible electrochemical co-intercalation occurs the system will display both clear faradaic and non-faradaic properties. This is indeed what is seen, as the system offers a moderate amount of energy density, similar to batteries, while still being highly reversible and extremely fast, even at low temperatures, similar to capacitors.[6,7] Moreover, the reaction is tunable by altering the electrolyte composition - opening up for a great deal of exploration.[8] These properties, along with using abundant materials, makes the system applicable to problems where both the properties of capacitors and batteries are needed, such as in grid storage.This talk purport to summarize our research activity on electrochemical solvent co-intercalation phenomena, ranging from fundamental questions such as how to detect solvent co-intercalation, to the nature of the electrochemical reaction. We also present our work on using solvent co-intercalation in full cells, as well as a new type of battery where both the anode and cathode operate by a solvent co-intercalation mechanism – the solvent co-intercalation battery (CoIB).[9] References [1] O. Lenchuk, P. Adelhelm, D. Mollenhaur, Phys. Chem. Chem. Phys., 21 (2019) 19378-19390.[2] B. Jache, P. Adelhelm, Angewandte Chemie, 126 (2014) 10333-10337.[3] K. Xu, Chemical reviews 104 (2004), 4303-4418[4] J. Park, Z-L. Xu, K. Kang, Frontiers in Chemistry, 8 (2020), 2296-2646[5] S. Fleischmann, Y. Zhang, X. Wang, P. T. Cummings, J. Wu, P. Simon, Y. Gogotsi, V. Presser, V. Augustyn, Nature Energy, 7 (2022),222-228.[6] J. Chen, Y. Peng, Y. Yin, Z. Fang, Y. Cao, Y. Wang, X. Dong, Y. Xia, Angew. Chem. Int. Ed. 60 (2021) 23858.[7] Z-L. Xu, G. Yoon, K-Y. Park, H. Park, O. Tamwattana, S. J. Kim, W. M. Seong, K. Kang, Nat. Commun. 10 (2019) 2598.[8] B. Jache, J. O. Binder, T. Abe, P. Adelhelm, Phys. Chem. Chem. Phys., 18 (2016) 14299-14316[9] G. A. Ferrero, G. Åvall, K. A. Mazzio, Y. Son, K. Janßen, S. Risse, P. Adelhelm, Adv. Energy Mater. 12 (2022) 2202377

(Invited) 2D Mxenes for Energy Storage Applications

MXenes are a family of two-dimensional (2D) transition metal carbides and nitrides, with a general structure of Mn+1XnT x , where M is the transition metal, X is carbon and/or nitrogen, and T represents the surface terminations (F, O, OH). MXenes have attracted attention in a multitude of energy storage applications due to their high electronic conductivity, tunable interlayer spacing, redox-active transition metals, and hydrophilic surface groups. In this talk, we discuss the use of MXene electrodes in supercapacitor applications, including aqueous, non-aqueous, and water-in-salt electrolytes. The variability of MXenes is demonstrated with each electrolyte system showing unique electrochemical responses, not limited to redox and/or intercalation pseudocapacitance, and hydrated cation intercalation. Furthermore, the versatility of the hydrophilic, 2D morphology of MXenes is demonstrated through its use in multiple form factors, not limited to flexible free-standing films, multilayer powder electrodes, interdigitated microsupercapacitors, knitted textiles, and more. New directions and perspectives for MXenes in energy storage are discussed, including MXenes’ use as passive components (separators, current collectors, binders, scaffolds, conductive additives) in energy storage systems. Figure 1 (A) Schematic illustration showing MXenes’ electrochemical properties for ion storage applications. (B) Cyclic voltammetry (CV) data collected at scan rates from 10 to 100,000 mV·s−1 for a 90-nm-thick Ti3C2T x film. (C) Influence of an electrolyte’s solvent on the lithium-ion storage capacity of Ti3C2T x ; CV curves of microporous Ti3C2T x electrode in 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in DMSO, acetonitrile (ACN), or propylene carbonate (PC) electrolytes. (D) A digital photograph showing the wafer scale fabrication of an array of 143 MXene microsupercapacitors. (E) Photograph of a knitted textile with an interdigitated pattern made using Ti3C2T x MXene-coated cotton yarn to produce electrodes for wearable textile supercapacitor.Reference[1] A. VahidMohammadi, J. Rosen, Y. Gogotsi, Science, 2021, 372, eabf1581. Figure 1

(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.

Using Ambient Pressure Photoelectron Spectroscopy to Investigate the Time Dependence of Electrostatic Potential Difference over the Interphase between an Electrode and an Electrolyte

Ambient pressure photoelectron spectroscopy (APPES) is a method well-suited for measuring the change ∆φ in electrostatic potential difference φ over an interphase between an electronic conductor and an insulator. APPES had previously been used to compare ∆φ over an interphase between an electrode and an electrolyte with the change in electrochemical potential difference ∆UWE-RE between the working and the reference electrode UWE-RE .[1] The relationship between ∆φ and ∆UWE-RE at low current-transient had been shown to follow two distinct trends depending on whether charge transfer of Li+ ions between an electrode and an electrolyte occurs or not.[1,2] In this work, APPES was used to investigate the time dependence of ∆φ after changing UWE-RE . The studied electrochemical system consisted of Au (working electrode), Li4Ti5O12 (reference electrode) and a second Li4Ti5O12 (counter electrode) with 0.008 M LiClO4 in propylene carbonate (PC) as the electrolyte. Pressure in the sample compartment was equal to the saturated PC pressure. APPES experiments were performed at HIPPIE beamline at MAX IV in Lund and were conducted as follows. After applying a potential step ∆UWE-RE , a C 1s spectrum was measured every 7 s. Incident photon energy was 1800 eV. Each spectrum was fitted using a Python code written especially for the obtained C 1s spectra. Time dependence of ∆φ was extracted from the shift in the kinetic energy ∆KE of the C=O peak (∆φ = ∆KE). Experiments were performed in both regimes, i.e. when the working electrode behaves as an ideal polarizable electrode and when it behaves as an ideal non-polarizable electrode, and have shown the time dependence of ∆φ to differ for the two regimes. Behaviour of ∆φ(t) as well as the experimental setup and spectral fitting using the Python code will be discussed.Figure 1: a) Schematic depiction of the electronic electrostatic potential φ between a working (WE) and a reference electrode (RE). Electrostatic potential profile is not to scale. b) An example of the experimentally obtained time dependence of the C=O peak kinetic energy KE(t). KE(t) is related to φ(t) as ∆φ(t) = ∆KE(t).

Sustainable composites from Carbon Dioxide-Derived Poly (propylene carbonate) and biosourced poly(3-hydroxybutyrate-co-3-hydroxyvalerate) fiber with enhancing mechanical properties and heat resistance

Biodegradable and biosourced poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) fibers were used as reinforcing materials, and sustainable Carbon Dioxide-Derived Poly (propylene carbonate) composites with balanced strength and ductility were prepared by melt compounding. The PHBV fiber was proved to be an effective reinforcing agent. With the addition of PHBV fibers, the PPC composites showed a significant increase in Young's modulus and tensile strength. When the PHBV fiber content was 40 wt%, the Young's modulus and tensile strength were 317% and 145% higher than that of neat PPC. Especially, the composites still exhibited a certain level of ductility. With increasing the PHBV fiber content, the dynamic storage modulus and glass transition temperature of PPC composite were also increased. The Vicat softening temperature (VST) of PPC/PHBV fiber composites was increased significantly, suggesting the heat resistance of PPC was improved after composites preparation. Such sustainable composites from PHBV fiber reinforced PPC could be used in packaging field, which will promote the practical application of PPC.

Facile and direct synthesis of oligocarbonate diols from carbon dioxide and their application as sustainable feedstock for polyurethane

Oligocarbonate diols (PPCDL) with carbonate content higher than 90% were successfully synthesized by the direct copolymerization of propylene oxide (PO) and carbon dioxide (CO2) using metal-free Lewis acid-base catalysts in the presence of 1,4-butanediol (BDO) as proton exchange agent (PEA). The effects of molar ratio of PO to BDO, temperature, pressure and reaction time on the copolymerization were systematically investigated. The molecular weight of the prepared oligocarbonate diols is in good linear relationship to PO/BDO feeding ratio and can be easily and precisely controlled in the range of 1000–4000 g mol−1. The detailed structures of the oligocarbonate diols were fully investigated by 1H NMR, 13C NMR, MALDI-TOF analysis. The rheological properties of synthesized PPCDL were also studied using a rheometer. Finally, polycarbonate urethanes were designed and successfully prepared using the PPCDLs as soft segment and 4,4′-diphenylmethane diisocyanate (MDI) and BDO as hard segment. The comprehensive evaluation of thermal and mechanical properties of the synthesized poly(carbonate urethane)s (PCUs) demonstrates their complete feasibility in the application of polyurethane industry.

Zinc Iodide-Metal Chloride-Organic Base: An Efficient Catalytic System for Synthesis of Cyclic Carbonates from Carbon Dioxide and Epoxides under Ambient Conditions

Development of an effective catalytic system for the cycloaddition of carbon dioxide to epoxides for the preparation of cyclic carbonates under mild conditions is of great importance. Herein, a mixture of zinc iodide, metal chlorides, and strong organic bases is demonstrated to be a useful catalytic system that works at room temperature under atmospheric pressure. The most efficient combination, zinc iodide-niobium chloride-7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (1.2-0.3-3.0 mol%), gave styrene carbonate (95%) from styrene oxide and CO2 (balloon) at 25 °C for 24 h. Another combination, zinc iodide-zinc chloride-1,8-diazabicyclo[5.4.0]undec-7-ene (1.2-0.8-4.0 mol%), kept the catalytic activity for the preparation of propylene carbonate until the fourth run. Therefore, the reaction system was operationally simple, highly efficient, and proceeded under ambient conditions. The catalyst is composed of readily available reagents and is reusable. Thus, the method presented is a powerful tool for utilizing CO2 as the starting material for the production of valuable chemicals.

Systematic Approach to Constructing Safe and High-Performance Supercapacitors with Nonflammable Electrolytes.

The successful implementation of supercapacitors in large-scale applications necessitates careful consideration of safety aspects, along with factors such as energy density, power density, working voltage, and cycling performance. One effective method for ensuring safety is the utilization of nonflammable trimethyl phosphate (TMP) electrolyte in supercapacitors. However, this approach suffers from the drawback of low power density due to its low ionic conductivity. To overcome this limitation, we propose the addition of co-solvents, namely propylene carbonate, acetonitrile, and propionitrile (PN), to enhance limited electrochemical properties of TMP-based electrolytes. We systematically investigate the impact of incorporating TMP into various organic solvents on physical and electrochemical properties. Binary electrolytes show improved ionic conductivity, capacitance, power density, energy density, and working voltage compared to the single TMP-based electrolyte. Notably, our result highlights that the carbon-based supercapacitors using TMP-PN with 70 : 30 volume ratio electrolyte provide the best compromise between ionic conductivity (13.5 mS cm-1 ), capacitance (24.0 F g-1 ), energy density (13.2 Wh kg-1 ), power density (2.3 kW kg-1 ), working voltage (3.5 V), and safety. By combining the nonflammable properties of TMP with co-solvents, we can overcome the trade-off between safety and electrochemical performances, presenting advancement in the development of supercapacitors for energy storage applications.

Effect of Mo content on oxidative dehydrogenation of propane with CO2 over ZnOx catalysts supported on Mo–Zr mixed–oxides

The production of propylene from readily available propane sources is of great importance as it serves as a crucial building block for producing numerous value-added chemicals. Oxidative dehydrogenation of propane with carbon dioxide (ODPC) has been proposed as a viable and eco-friendly approach for simultaneous propylene production and carbon dioxide reduction. In this study, ZnOx catalysts were prepared by supporting them on a range of molybdenum–zirconium (Mo–Zr) mixed–oxides with varying Mo contents, aiming to utilize them for ODPC applications. The incorporation of suitable quantities of Mo in zirconium dioxide (ZrO2) supports increases the surface concentration and enhances the dispersion of ZnOx, thereby demonstrating promotional effects on the surface properties of the supported ZnOx catalysts. Notably, the ZnOx catalyst supported on a Mo–Zr mixed–oxide, with an optimized Mo content, exhibits a propane conversion rate more than two-fold higher than that of the catalyst without Mo in ODPC. Furthermore, the introduction of Mo into the ZrO2 supports effectively inhibits the formation of coke by suppressing the cleavage of C–C bonds in propane. In comparison, the supported ZnOx catalysts with higher Zn loadings, show that a Mo–Zr mixed–oxide support effectively suppresses the formation of bulk ZnOx more than an unmodified ZrO2 support, leading to improved ODPC performance. The promoting effects of Mo emphasize the potential of utilizing mixed–oxide supports for ZnOx catalysts in ODPC, demonstrating a promising opportunity for enhancing catalytic performance.

Development of Electrochromic Devices, Based on Polymeric Gel, for Energy Saving Applications.

In this work, the implementation of an electrochromic device (10 cm × 10 cm in size) for energy saving applications has been presented. As electrochromic system has been used with an electrochromic solution (ECsol) made by ethyl viologen diperchlorate [EV(ClO4)2], 1,1'-diethyl ferrocene (DEFc) and propylene carbonate (PC), as solvent. The final system has been obtained by mixing the ECsol, described above, with a polymeric system made by Bisphenol-A glycerolate (1 glycerol/phenol) diacrylate (BPA) and 2,2-Dimethoxy-2-phenylacetophenone (Irgacure 651) in a weight percentage equal to 60:40% w/w, respectively. Lithography has been used to make a spacer pattern with a thickness of about 15-20 µm between the two substrates. Micro-Raman spectroscopy confirmed the presence of the EV•+ as justified by the blue color of the electrochromic device in the ON state. Electrochemical and optical properties of the electrochromic device have been studied. The device shows reversible electrochromic behavior as confirmed by cyclic color variation due to the reduction and oxidation process of the EV2+/EV•+ couple. The electrochromic device shows a variation of the % transmittance in the visible region at 400 nm of 59.6% in the OFF state and 0.48% at 3.0 V. At 606 nm the transmittance in the bleached state is 84.58% in the OFF state and then decreases to 1.01% when it is fully colored at 3.0 V. In the NIR region at 890 nm, the device shows a transmittance of 74.3% in the OFF state and 23.7% at 3.0 V while at 1165 nm the values of the transmittance changed from 83.21% in the OFF state to 1.58% in the ON state at 3.0 V. The electrochromic device shows high values of CCR% and exhibits excellent values of CE in both visible and near-infrared regions when switched between OFF/ON states. In the NIR region at 890 nm, electrochromic devices can be used for the energy-saving of buildings with a promising CE of 120.9 cm2/C and 420.1 cm2/C at 1165 nm.

Enhanced efficiency and stability of 3.3 V Cu-Li batteries by tuning the cation-anion interaction in the electrolyte

Cu-Li battery with Cu metal cathode and Li metal anode is a candidate for next-generation energy storage system. While self-discharge of the battery can be suppressed with an anion exchange membrane, the voltage polarization depends strongly on the electrolyte. Specifically, when an electrolyte with 3 M LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) in dimethyl carbonate (DMC) is used, overpotential increases with cycling. In this work, we reveal why the voltage polarization changes, and reduce and stabilize it by replacing DMC solvent with a mixed solvent composed of dimethoxyethane (DME) and propylene carbonate (PC). The new electrolyte has higher ionic conductivity and stable solvation structure with more free TFSI− anions upon cycling, which also facilitates uniform plating of metal ions on the metal electrodes. These characteristics enable a stable Cu-Li battery with minimal change in overpotential for more than 1500 cycles at a current density of 2 mA cm−2.

Insight into the Desolvation of Organic Electrolyte Cations with Propylene Carbonate as a Solvent in Flat Pores: A First-Principles Calculation

Supercapacitors have many applications in new energy and other high-tech fields. The desolvation effect on ions affects the capacity size of supercapacitors, and there are few relevant studies published in this field at present. In this experiment, bilayer graphene (BG) with a layer spacing of 4–10 Å was used as a model of flat pores and was calculated with first-principles calculations, which can effectively simulate the adsorption behaviour of porous carbon. The reaction energies of ions, propylene carbonate, and ionic complexes in bilayer graphene with different layer spacings were calculated, and the desolvation behaviour of lithium salt cations (Li+), tetraethyl quaternary ammonium salt cations (TEA+), triethyl methyl quaternary ammonium salt cations (TEMA+), and bipyrrolidinium quaternary ammonium salt cations (SBP+) was investigated. The calculation was based on density functional compact bound (DFTB+) software. The calculated results show that in the stacked system, the complete desolvation size of the TEA+ reaches 5.6 Å, the complete desolvation size of the TEMA+ reaches 4.9 Å, the complete desolvation size of the SBP+ reaches 4.8 Å, and the complete desolvation size of the Li+ reaches 5.4 Å, with the organic electrolyte cations showing a positive trend in the complete desolvation size as the ion radius increases. An in-depth analysis of the data shows that Li+, TEA+, TEMA+, and SBP+ ion radii play a dominant role in the size of desolvation. The results of this paper provide an effective aid for the selection of organic electrolytes to increase the capacity of supercapacitors.

Novel extended viologen derivatives for photochromic and electrochromic dual-response smart windows

Smart windows, which could save building energy consumption by modulating indoor thermal and light intensity, have attracted considerable attention in recent years. Photochromic (PC) and electrochromic (EC) are two representative working modes of smart windows. Integrating PC and EC on a single smart window is beneficial for adapting to various environments and meeting individual needs. However, it remains challenging to develop PC and EC dual-responsive materials. In this work, we reported two extended viologen derivatives, EV-1 and EV-2, with both PC and EC properties. Photochromic devices (PCDs) and electrochromic devices (ECDs) based on these materials were fabricated successfully. Under UV light irradiation, the PCDs exhibited a significant color change from transparent to green (PCD-1) and blue (PCD-2) color, and the colored state can maintain a long time (2.73 h for PCD-1 and 41.72 h for PCD-2) after removing the UV light. Owing to the extension of the conjugate length of the chromophore as compared with traditional viologens using bipyridine as chromophores, the spectra response range of the devices was extended to the near-infrared (NIR) region. To obtain different light modulation capabilities, we fabricated electrochromic devices using propylene carbonate as solvent. These devices display different colored states (red for ECD-1 and purple for ECD-2) and spectra absorption compared to PCD-1 and PCD-2. Furthermore, a photo/electrochromic device (PECD) smart window system was developed to enhance light and thermal regulation. This system offers four working modes, including off mode, photochromic mode, electrochromic mode, and photo-electrochromic mode, which opens up new possibilities for expanding its applications.

Organic carbonates as green and sustainable complexing agents for double metal cyanide catalysts for the synthesis of polyether and poly(ether-carbonate) polyols

We investigated various linear carbonates, including dimethyl carbonate and diethyl carbonate, and cyclic carbonates such as ethylene carbonate, propylene carbonate (PC), butylene carbonate, and glycerol carbonate, as complexing agents (CAs) for the preparation of double metal cyanide (DMC) catalysts. The DMC catalysts bearing carbonate complexing agents exhibited good to excellent activities for the ring-opening polymerization of epoxides (turnover frequencies of up to 467 min−1) and the copolymerization of epoxides and CO2, producing polyether polyols with moderate molecular weights (1700–9700 g mol−1), narrow polydispersity indexes (1.1–1.2), very low unsaturation values (0.002–0.009), and low viscosities (438 −997 cP). The DMC catalyst bearing PC also afforded linear and branched polycarbonate polyols in high yields (up to 83%) and carbonate contents (up to 36 mol%). Density functional theory calculations were also performed to understand the effect of the CAs on the structural properties and activities of the corresponding DMC catalysts.

Intensity Ratio Distribution in Different Dielectric Liquids using Kerr Effect Method

Light intensity is the result from the Kerr effect measurement that can be used in determining the electric field distributions in dielectric liquids as the analysis continues afterwards. One of the most important parameters to consider in designing the Kerr effect experiment is the Kerr constant of the test liquid. This paper aims to study and compare light intensity distribution in different dielectric liquids using Kerr effect method. Propylene carbonate, transformer oil and purified water are used as the test liquids. From the results obtained, the light intensities as a function of electric field of the test liquids are compared. With higher Kerr constant, low voltages can be applied to the test liquid but with larger optical signals. Furthermore, the length of the electrodes can be designed accordingly to suit the experimental setup.

Effect of Temperature on Breakdown Characteristics of Propylene Carbonate in Nonuniform Fields Under Microsecond Pulse

Effect of Temperature on Breakdown Characteristics of Propylene Carbonate in Nonuniform Fields Under Microsecond Pulse

Molecular Adsorption‐Induced Interfacial Solvation Regulation to Stabilize Graphite Anode in Ethylene Carbonate‐Free Electrolytes

AbstractMany organic solvents have excellent solution properties, but fail to serve as lithium‐ion batteries (LIBs) electrolyte solvents, due to their electrochemical incompatibility with graphite anodes. Herein, a new strategy is proposed to address this issue by introducing a surface‐adsorbed molecular layer to regulate the interfacial solvation structure without the alteration of electrolyte composition and properties. As a proof‐of‐concept study, it is demonstrated for the first time that the intrinsically incompatible propylene carbonate (PC)‐based electrolyte becomes completely compatible with graphite anodes by introducing a layer of adsorbed hexafluorobenzene (HFB) molecules to weaken the Li+‐PC coordination strength and facilitate the interfacial desolvation process. As a consequence, the graphite/ NCM811 pouch cells using the PC‐based electrolyte containing only 1 vol.% HFB demonstrate excellent long‐term cycling stabilities over 1150 cycles. This strategy is also proved to be applicable to other ethylene carbonate (EC)–free electrolytes, thus providing a new avenue for developing advanced LIB electrolytes.