Ethylene Oxide Research Articles

Ternary Solid Polymer Electrolytes at the Electrochemical Interface: A Computational Study.

Polymer-based solid-like gel electrolytes have emerged as a promising alternative to improve battery performance. However, there is a scarcity of studies on the behavior of these media at the electrochemical interface. In this work, we report classical MD simulations of ternary polymer electrolytes composed of poly(ethylene oxide), a lithium salt [lithium bis(trifluoromethanesulfonyl)imide], and different ionic liquids [1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide] confined between two charged and uncharged graphene-like surfaces. The molecular solvation of Li+ ions and their diffusion as well as the polymer conformational picture were characterized in terms of the radial distribution functions, coordination numbers, number density profiles, orientations, displacement variance, polymer radius of gyration, and polymer end-to-end distance. Our results show that the layering behavior of the ternary electrolyte in the interfacial region leads to a decrease of Li+ mobility in the direction perpendicular to the electrodes and high energy barriers that hinder lithium cations from coming into direct contact with the graphene-like surface. The nature of the ionic liquid and its concentration were found to influence the structural and dynamic properties at the electrode/electrolyte interface, the electrolyte with low amounts of the pyrrolidinium-based ionic liquid being that with the best performance since it favors the migration of Li+ cations toward the negative electrode when compared to the imidazolium-based one.

Distribution of Mechanical Properties in Poly(ethylene oxide)/silica Nanocomposites via Atomistic Simulations: From the Glassy to the Liquid State

Distribution of Mechanical Properties in Poly(ethylene oxide)/silica Nanocomposites via Atomistic Simulations: From the Glassy to the Liquid State

Covalent vs. Non covalent chemical modification of multiwalled carbon nanotubes based-nanofluids: Stability and thermal conductivity steadiness over temperature

Thermal conductivity enhancement coupled to nanoparticle dispersion stability over time are the two main conflicting requirements to overcome to develop carbon nanomaterial-based nanofluids. Both covalent and non-covalent approaches, having their own advantages and disadvantages, are commonly used for carbon nanotube based nanofluids development. However, they are rarely compared regarding their impact on stability and thermal conductivity performances for the same kind of nanofluid. In this work, multiwalled carbon nanotubes have been chemically modified by both covalent and non-covalent functionalization. For the covalent functionalization, a simple oxidation method is applied. It consists of refluxing the powdered MWCNTs in H2SO4/HNO3 at 5 M concentration. For the non-covalent approach, both an anionic (sodium dodecyl sulfate) and a non-ionic (Pluronic P123, comprising poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) in an alternating linear fashion, PEO-PPO-PEO) surfactants were employed at a concentration of 1 wt%. Nanofluids were prepared with multiwalled carbon nanotubes at a fixed concentration of 0.2 wt% for both chemical modification approaches. The oxidation reaction occurs without significant structure damaging as shown by transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. UV–visible spectrophotometry analysis shows a remarkable stability with temperature in the 293.15–303.15 K range over one-week and for a longer period of 49 days for all the three types of nanofluids. Their thermal conductivity has been investigated in the same temperature range. For all the three nanofluid series prepared with a fixed concentration of carbon nanomaterials, a thermal conductivity enhancement compared to that of the base fluid has been observed. The thermal conductivity evolution with temperature is different for each type of nanofluid. The covalently oxidized multiwalled carbon nanotube based nanofluids showed the better thermal conductivity enhancement steadiness (around 7 %) with temperature. The discussion on the surfactant-based nanofluid behavior proposes the possible involved mechanisms as temperature increases for each surfactant.

A Versatile Synthesis Platform Based on Polymer Cubosomes for a Library of Highly Ordered Nanoporous Metal Oxides Particles.

Polymer cubosomes (PCs) have well-defined inverse bicontinuous cubic mesophases formed by amphiphilic block copolymer bilayers. The open hydrophilic channels, large periods, and robust physical properties of PCs are advantageous to many host-guest interactions and yet not fully exploited, especially in the fields of functional nanomaterials. Here, the self-assembly of poly(ethylene oxide)-block-polystyrene block copolymers is systematically investigated and a series of robust PCs is developed via a cosolvent method. Ordered nanoporous metal oxide particles are obtained by selectively filling the hydrophilic channels of PCs via an impregnation strategy, followed by a two-step thermal treatment. Based on this versatile PC platform, the general synthesis of a library of ordered porous particles with different pore structures , tunable large pore size (18-78nm), high specific surface areas (up to 123.3m2g-1 for WO3) and diverse framework compositions, such as transition and non-transition metal oxides, rare earth chloride oxides, perovskite, pyrochlore, and high-entropy metal oxides is demonstrated. As typical materials obtained via this method, ordered porous WO3 particles have the advantages of open continuous structure and semiconducting properties, thus showing superior gas sensing performances toward hydrogen sulfide.

Development of robust polysesquioxane/polymer dual-network hybrid membranes for flue gas carbon capture

In the present study, robust organic/inorganic dual-network membranes were designed by combining the advantages of polysesquioxane with superior thermal and structural stabilities, and polyether with outstanding CO2-philic and film-forming abilities. Specifically, a typical polysesquioxane precursor, bis(triethoxysilyl)ethane (BTESE), was selected to generate the inorganic-based amorphous network via a hydrolysis and condensation process, during which polyethylene glycol (PEG) was introduced to form the organic network. The Si-O-Si network derived from BTESE could provide excellent mechanical stability, while the repeat polar ethylene oxide units contained in PEG were expected to furnish a strong affinity toward CO2 through dipolar-dipolar interactions. In comparison to individual membranes, the dual-network membranes presented both attractive CO2/N2 separation performance and improved structural stability. These dual-network membranes proposed in this work hold great potential in industrial flue gas carbon capture and the strategies for designing such inorganic–organic dual-network membranes could be extended to other robust inorganic–organic hybrid films/materials.

Multipolar Conjugated Polymer Framework Derived Ionic Sieves via Electronic Modulation for Long-Life All-Solid-State Li Batteries.

Here, we build a tunable multipolar conjugated polymer framework platform via pore wall chemistry to probe the role of electronic structure engineering in improving the Li+ conduction by theoretical studies. Guided by theoretical prediction, we develop a new cyano-vinylene-linked multipolar polymer framework namely CNF-COF, which can act as efficient ion sieves to modify solid polymer electrolytes to simultaneously tune Li+ migration and stable Li anodes for long-lifespan all-solid-state (ASS) Li metal batteries at high rate. The dual-decoration of cyano and fluorine groups in CNF-COF favorably regulates electronic structure via multipolar donor-acceptor electronic effects to afford proper energy band structure and abundant electron-rich sites for enhanced oxidative stability, facilitated ion-pair dissociation and suppressed anion movements. Thus, the CNF-COF incorporation into poly (ethylene oxide) (PEO) electrolytes not only renders fast selective Li+ transport but also facilitates the Li dendrite suppression. Specifically, the constructed PEO composite electrolyte with an ultra-low CNF-COF content of only 0.5 wt % is endowed with a wide electrochemical window, a high ionic conductivity of 0.634 mS cm-1 at 60 °C and a large Li+ transference number of 0.81-remarkably outperforming CNF-COF-free counterparts (0.183 mS cm-1 and 0.22). As such, the Li symmetric cell delivers stable Li plating/stripping over 1400 h at 0.1 mA cm-2. Impressively, by coupling with LiFePO4 (LFP) cathodes, the assembled ASS Li battery under 60 °C allows for stable cycling over 2000 cycles at 1 C and over 1000 cycles even at 2 C with a large capacity retention of ~75 %, surpassing most reported ASS Li batteries using PEO-based electrolytes.

Multipolar Conjugated Polymer Framework Derived Ionic Sieves via Electronic Modulation for Long‐Life All‐Solid‐State Li Batteries

AbstractHere, we build a tunable multipolar conjugated polymer framework platform via pore wall chemistry to probe the role of electronic structure engineering in improving the Li+ conduction by theoretical studies. Guided by theoretical prediction, we develop a new cyano‐vinylene‐linked multipolar polymer framework namely CNF‐COF, which can act as efficient ion sieves to modify solid polymer electrolytes to simultaneously tune Li+ migration and stable Li anodes for long‐lifespan all‐solid‐state (ASS) Li metal batteries at high rate. The dual‐decoration of cyano and fluorine groups in CNF‐COF favorably regulates electronic structure via multipolar donor‐acceptor electronic effects to afford proper energy band structure and abundant electron‐rich sites for enhanced oxidative stability, facilitated ion‐pair dissociation and suppressed anion movements. Thus, the CNF‐COF incorporation into poly (ethylene oxide) (PEO) electrolytes not only renders fast selective Li+ transport but also facilitates the Li dendrite suppression. Specifically, the constructed PEO composite electrolyte with an ultra‐low CNF‐COF content of only 0.5 wt % is endowed with a wide electrochemical window, a high ionic conductivity of 0.634 mS cm−1 at 60 °C and a large Li+ transference number of 0.81—remarkably outperforming CNF‐COF‐free counterparts (0.183 mS cm−1 and 0.22). As such, the Li symmetric cell delivers stable Li plating/stripping over 1400 h at 0.1 mA cm−2. Impressively, by coupling with LiFePO4 (LFP) cathodes, the assembled ASS Li battery under 60 °C allows for stable cycling over 2000 cycles at 1 C and over 1000 cycles even at 2 C with a large capacity retention of ~75 %, surpassing most reported ASS Li batteries using PEO‐based electrolytes.

Lignin Derived Ultrathin All-Solid Polymer Electrolytes with 3D Single-Ion Nanofiber Ionic Bridge Framework for High Performance Lithium Batteries.

The lignin derived ultrathin all-solid composite polymer electrolyte (CPE) with a thickness of only 13.2µm, which possess 3D nanofiber ionic bridge networks composed of single-ion lignin-based lithium salt (L-Li) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as the framework, and poly(ethylene oxide)/lithium bis(trifluoromethanesulfonyl)imide (PEO/LiTFSI) as the filler, is obtained through electrospinning/spraying and hot-pressing. t. The Li-symmetric cell assembled with the CPE can stably cycle more than 6000h under 0.5mA cm-2 with little Li dendrites growth. Moreover, the assembled Li||CPE||LiFePO4 cells can stably cycle over 700 cycles at 0.2 C with a super high initial discharge capacity of 158.5 mAh g-1 at room temperature, and a favorable capacity of 123 mAh g-1 at -20°C for 250 cycles. The excellent electrochemical performance is mainly attributed to the reason that the nanofiber ionic bridge network can afford uniformly dispersed single-ion L-Li through electrospinning, which synergizes with the LiTFSI well dispersed in PEO to form abundant and efficient 3D Li+ transfer channels. The ultrathin CPE induces uniform deposition of Li+ at the interface, and effectively inhibit the lithium dendrites. This work provides a promising strategy to achieve ultrathin biobased electrolytes for solid-state lithium ion batteries.

Colloidal and Biological Characterization of Dual Drug-Loaded Smart Micellar Systems.

Smart polymeric micelles (PMs) are of great interest in drug delivery owing to their low critical micellar concentration and sizes. In the present study, two different pH-sensitive poly(2-vinyl pyridine)-b-poly(ethylene oxide) (P2VP-b-PEO) copolymer samples were used for the encapsulation of paclitaxel (PTX), ursolic acid (UA), and dual loading of PTX and UA. Based on the molecular features of copolymers, spherical PMs with sizes of around 35 nm and 140 nm were obtained by dialysis for P2VP55-b-PEO284 and P2VP274-b-PEO1406 samples, respectively. The micellar sizes increased after loading of both drugs. Moreover, drug encapsulation and loading efficiencies varied from 53 to 94% and from 3.2 to 18.7% as a function of the copolymer/drug ratio, molar mass of copolymer sample, and drug type. By FT-IR spectroscopy, it was possible to demonstrate the drug loading and the presence of some interactions between the polymer matrix and loaded drugs. In vitro viability was studied on 4T1 mammary carcinoma mouse cells as a function of time and concentration of drug-loaded PMs. UA-PMs and free PMs alone were not effective in inhibiting the tumor cell growth whereas a viability of 40% was determined for cells treated with both PTX- and PTX/UA-loaded PMs. A synergic effect was noticed for PTX/UA-loaded PMs.

Self-assembly mechanism and application performance in aqueous solutions mediated by ethylene oxide chains in alcohol ether carboxylates and cocamidopropyl betaine

Zwitterionic Cocoamidopropyl Betaine (CAB) and anionic alcohol ether carboxylates have garnered significant attention within the realms of green and colloid chemistry owing to their inherent biocompatibility, multi-responsiveness, and diverse applications. Systematic inquiry into the physicochemical properties, self-assembly mechanisms, and application efficacy of complex systems comprising alcohol ether carboxylate salts with varying ethylene oxide (EO) units (AECnH, n = 5, 7, 9) and CAB-35 in aqueous solutions was undertaken. It was discerned that the optimum physicochemical attributes of the complex system are attained at a molar ratio of AEC of 0.5 (αAEC = 0.5). Incremental augmentation in the number of EO units facilitated the formation of rod-like micelles, exhibiting relatively unstable characteristics, while a reduction in the number of EO units led to the generation of comparatively stable spherical micelles. The self-assembly of micelles in these hybrid systems predominantly hinges upon hydrogen bonding, electrostatic interactions, and hydrophobic forces. Furthermore, kinetic analysis validated that the genesis of micelles in all three hybrid systems is propelled by enthalpy, with the adsorption process entailing a mechanism characterized by mixed diffusion-kinetic adsorption. The optimal wetting performance of the complex system was observed at αAEC = 0.5, while the foam performance demonstrated a diminishing trend with escalating αAEC. This comprehensive discourse delineates the synergistic mechanisms and application efficacy of two distinct classes of green surfactants with disparate charges in aqueous solutions, while contemplating the influence of varying numbers of ethylene oxide chains. Not only does it furnish fundamental insights into their properties, but it also proffers a novel standpoint for the exploration of green surfactants.

Catalytic Hydroxyethylation of Phenols with Renewable Ethylene Glycol Diester as an Alternative to Ethylene Oxide

Polyol esters are abundant bio‐based resources. Integration of polyol esters into the production chain of fine chemicals would reduce carbon emission and improve the sustainability of the chemical industry. An efficient synthetic route towards phenoxyethanols was developed through catalytic hydroxyethylation of phenols with ethylene glycol diacetate as the reagent. This method showed the potential of ethylene glycol diester as a safe and sustainable substitute for ethylene oxide, a useful but toxic reagent. A variety of phenoxyethanol esters were produced in high yield under simple catalytic conditions. Mechanism studies revealed the reaction underwent a neighboring group participation process.

Ultrathin, Mechanically Robust Quasi-Solid Composite Electrolyte for Solid-State Lithium Metal Batteries.

Herein, we present the preparation and properties of an ultrathin, mechanically robust, quasi-solid composite electrolyte (SEO-QSCE) for solid-state lithium metal battery (SLB) from a well-defined polystyrene-b-poly(ethylene oxide) diblock copolymer (SEO), Li6.75La3Zr1.75Ta0.25O12 nanofiller, and fluoroethylene carbonate plasticizer. Compared with the ordered lamellar microphase separation of SEO, the SEO-QSCE displays bicontinuous phases, consisting of a Li+ ion conductive poly(ethylene oxide) domain and a mechanically robust framework of the polystyrene domain. Therefore, the 12 μm-thick SEO-QSCE membrane exhibits an exceptional ionic conductivity of 1.3 × 10-3 S cm-1 at 30 °C, along with a remarkable tensile strength of 5.1 MPa and an elastic modulus of 2.7 GPa. The high mechanical robustness and the self-generated LiF-rich SEI enable the SEO-QSCE to have an extraordinary lithium dendrite prohibition effect. The SLB of Li|SEO-QSCE|LiFePO4 reveals superior cycling performances at 30 °C for over 600 cycles, maintaining an initial discharge capacity of 145 mAh g-1 and a remarkable capacity retention of 81% (117 mAh g-1) after 400 cycles at 0.5 C. The high-voltage SLB of Li|SEO-QSCE|LiNi0.5Co0.3Mn0.2O2 displays good cycling stability for over 150 cycles at 30 °C. Moreover, the exceptional robustness of SEO-QSCE enables the high-voltage solid-state pouch cell of Li|SEO-QSCE|LiNi0.5Co0.3Mn0.2O2 with high flexibility and excellent safety features. The current investigation delivers a promising and innovative approach for preparing quasi-solid electrolytes with features of ultrathin design, mechanical robustness, and exceptional electrochemical performance for high-voltage SLBs.

Tailored efficient and reliable double luminescent layer hybrid WOLEDs via doping engineering

Doping engineering has been widely utilized to increase the efficiency of White organic light-emitting diodes (WOLEDs). In this study, a blue phosphor material named DMAC-DPS and an orange phosphor material named PO-01 are integrated into the host materials Bis[2-(diphenylphosphino)phenyl] ether oxide (DPEPO) and carbazole-based 4,4′-biscarbazole-p-biphenyl (CBP) by incorporating the principle of complementary color luminescence, resulting in a doped double-luminescent layer hybrid WOLED. The developed device structure consists of ITO/MoO3/TCTA/DPEPO:DMAC-DPS/CBP:PO-01 (or CBP:PO-01/DPEPO:DMAC-DPS)/TAZ/Alq3/LiF/Al. The transfer of energy between the host and guest materials is achieved by controlling the thickness and position of the emitting layer, leading to a more balanced emission of blue and yellow light and an overall increase in device efficiency. The developed WOLED exhibits a maximum current efficiency of 26.8 cd A−1, a power efficiency of 16.8 lm W−1, and an external quantum efficiency of 10.95%. The stable color coordinates of the device remains consistent, varying from (0.34, 0.40) to (0.33, 0.39) at brightness levels ranging from 100 to 1000 cd m−2. Technically, the incorporation of blue and orange phosphor materials into the host materials DPEPO and CBP, respectively, resulting in a doped double-luminescent layer hybrid WOLED, has shown a more balanced emission of blue and yellow light and resulted in increased efficiency. The reliable color coordinates corroborate the good color stability, making it a promising candidate for various applications. Furthermore, the controlled transfer of energy between the host and guest materials has led to a more balanced emission of blue and yellow light. Our developed doping engineering methods have shown potential for increased efficiency and good color stability, making the developed WOLED a promising candidate for various applications.

Preventing Staphylococci Surgical Site Infections with a Nitric Oxide-Releasing Poly(lactic acid-co-glycolic acid) Suture Material.

Of the 27 million surgeries performed in the United States each year, a reported 2.6% result in a surgical site infection (SSI), and Staphylococci species are commonly the culprit. Alternative therapies, such as nitric oxide (NO)-releasing biomaterials, are being developed to address this issue. NO is a potent antimicrobial agent with several modes of action, including oxidative and nitrosative damage, disruption of bacterial membranes, and dispersion of biofilms. For targeted antibacterial effects, NO is delivered by exogenous donor molecules, like S-nitroso-N-acetylpenicillamine (SNAP). Herein, the impregnation of SNAP into poly(lactic-co-glycolic acid) (PLGA) for SSI prevention is reported for the first time. The NO-releasing PLGA copolymer is fabricated and characterized by donor molecule loading, leaching, and the amount remaining after ethylene oxide sterilization. The swelling ratio, water uptake, static water contact angle, and tensile strength are also investigated. Furthermore, its cytocompatibility is tested against 3T3 mouse fibroblast cells, and its antimicrobial efficacy is assessed against multiple Staphylococci strains. Overall, the NO-releasing PLGA copolymer holds promise as a suture material for eradicating surgical site infections caused by Staphylococci strains. SNAP impregnation affords robust antibacterial properties while maintaining the cytocompatibility and mechanical integrity.

Multifunctional Additive Enables a "5H" PEO Solid Electrolyte for High-Performance Lithium Metal Batteries.

The solid-state battery with a lithium metal anode is a promising candidate for next-generation batteries with improved energy density and safety. However, the current polymer electrolytes still cannot fulfill the demands of solid-state batteries. In this work, we propose a "5H" poly(ethylene oxide) (PEO) electrolyte via introducing a multifunctional additive of tris(pentafluorophenyl)borane (TPFPB) for high-performance lithium metal batteries. The addition of TPFPB improves the ionic conductivity from 6.08 × 10-5 to 1.54 × 10-4 S cm-1 via reducing the crystallinity of the PEO electrolyte and enhances the lithium-ion transference number from 0.19 to 0.53 via anion trapping due to its Lewis acid nature. Furthermore, the fluorine and boron segments from TPFPB can optimize the composition of the solid-electrolyte interphase and cathode-electrolyte interphase, providing a high electrochemical stability window over 4.6 V of the PEO electrolyte along with significantly improved interface stability. At last, TPFPB can ensure improved safety through a self-extinguishing effect. As a result, the "5H" electrolyte enables the Li/Li symmetric cells to achieve a stable cycle over 2200 h at the current density of 0.2 mA cm-2 with a capacity of 0.2 mA h cm-2; the LiFePO4/Li full cells with a high LFP loading of 8 mg cm-2 exhibits decay-free capacity of 140 mA h g-1 (99% capacity retention) after 100 cycles; and the NCM811/Li cells exhibit a high capacity of 160 mA h g-1 after 50 cycles at 0.5 C. This work presents an innovative approach to utilizing a "5H" electrolyte for high-performance solid-state lithium batteries.

Neuron‐Like Silicone Nanofilaments@Montmorillonite Nanofillers of PEO‐Based Solid‐State Electrolytes for Lithium Metal Batteries with Wide Operation Temperature

Poly(ethylene oxide) (PEO)‐based composite solid electrolytes (CSEs) are promising to accelerate commercialization of solid‐state lithium metal batteries (SSLMBs). Nonetheless, this is hindered by the CSEs' limited ion conductivity at room temperature. Here, we propose design, synthesis, and application of the bioinspired neuron‐like nanofillers for PEO‐based CSEs. The neuron‐like superhydrophobic nanofillers are synthesized by controllably grafting silicone nanofilaments onto montmorillonite nanosheets. Compared to various reported fillers, the nanofillers can greatly improve ionic conductivity (4.9 × 10−4 S cm−1, 30 °C), Li+ transference number (0.63), oxidation stability (5.3 V) and mechanical properties of the PEO‐based CSEs because of the following facts. The distinctive neuron‐like structure and the resulting synaptic‐like connections establish numerous long‐distance continuous channels over various directions in the PEO‐based CSEs for fast and uniform Li+ transport. Consequently, the assembled SSLMBs with the CSEs and LiFePO4 or NCM811 cathodes display superior cycling stability over a wide temperature range of 50 °C to 0 °C. Surprisingly, the pouch batteries with the large‐scale prepared CSEs kept working after being repeatedly bent, folded, cut or even punched in air. We believe that design of neuron‐like nanofillers is a viable approach to produce CSEs with high room temperature ionic conductivity for SSLMBs.

Neuron-Like Silicone Nanofilaments@Montmorillonite Nanofillers of PEO-Based Solid-State Electrolytes for Lithium Metal Batteries with Wide Operation Temperature.

Poly(ethylene oxide) (PEO)-based composite solid electrolytes (CSEs) are promising to accelerate commercialization of solid-state lithium metal batteries (SSLMBs). Nonetheless, this is hindered by the CSEs' limited ion conductivity at room temperature. Here, we propose design, synthesis, and application of the bioinspired neuron-like nanofillers for PEO-based CSEs. The neuron-like superhydrophobic nanofillers are synthesized by controllably grafting silicone nanofilaments onto montmorillonite nanosheets. Compared to various reported fillers, the nanofillers can greatly improve ionic conductivity (4.9 × 10-4 S cm-1, 30 °C), Li+ transference number (0.63), oxidation stability (5.3 V) and mechanical properties of the PEO-based CSEs because of the following facts. The distinctive neuron-like structure and the resulting synaptic-like connections establish numerous long-distance continuous channels over various directions in the PEO-based CSEs for fast and uniform Li+ transport. Consequently, the assembled SSLMBs with the CSEs and LiFePO4 or NCM811 cathodes display superior cycling stability over a wide temperature range of 50 °C to 0 °C. Surprisingly, the pouch batteries with the large-scale prepared CSEs kept working after being repeatedly bent, folded, cut or even punched in air. We believe that design of neuron-like nanofillers is a viable approach to produce CSEs with high room temperature ionic conductivity for SSLMBs.

External Pressure in Polymer-Based Lithium Metal Batteries: An Often-Neglected Criterion When Evaluating Cycling Performance?

Solid-state batteries based on lithium metal anodes, solid electrolytes, and composite cathodes constitute a promising battery concept for achieving high energy density. Charge carrier transport within the cells is governed by solid-solid contacts, emphasizing the importance of well-designed interfaces. A key parameter for enhancing the interfacial contacts among electrode active materials and electrolytes comprises externally applied pressure onto the cell stack, particularly in the case of ceramic electrolytes. Reports exploring the impact of external pressure on polymer-based cells are, however, scarce due to overall better wetting behavior. In this work, the consequences of externally applied pressure in view of key performance indicators, including cell longevity, rate capability, and limiting current density in single-layer pouch-type NMC622||Li cells, are evaluated employing cross-linked poly(ethylene oxide), xPEO, and cross-linked cyclodextrin grafted poly(caprolactone), xGCD-PCL. Notably, externally applied pressure substantially changes the cell's electrochemical cycling performance, strongly depending on the mechanical properties of the considered polymers. Higher external pressure potentially enhances electrode-electrolyte interfaces, thereby boosting the rate capability of pouch-type cells, despite the fact that the cell longevity may be reduced upon plastic deformation of the polymer electrolytes when passing beyond intrinsic thresholds of compressive stress. For the softer xGCD-PCL membrane, cycling of cells is only feasible in the absence of external pressure, whereas in the case of xPEO, a trade-off between enhanced rate capability and minimal membrane deformation is achieved at cell pressures of ≤0.43 MPa, which is considerably lower and more practical compared to cells employing ceramic electrolytes with ≥5 MPa external pressure.

Molecular and electrostatic origins of mixed salt partitioning phenomena in uncharged poly(ethylene oxide)-based membranes

Despite the increasing interest in membranes for water purification and resource recovery from aqueous electrolyte mixtures, few studies rigorously investigate the influence of salt solution composition (e.g., mole fraction and total salt concentration) on membrane material properties such as partition coefficients. Here, we systematically investigate the influence of solution composition on the partitioning of ionic species from binary aqueous salt solutions into crosslinked poly(ethylene glycol) diacrylate membranes at fixed ionic strength. These results are compared to partition coefficients observed for pure salt solutions. We observe large systematic deviations between the pure salt and mixed salt ion partition coefficients, indicating that the single salt partition coefficients that are often reported do not describe the more complex and realistic mixed salt scenario. Free energy calculations from molecular dynamics simulations, coupled with equilibrium thermodynamic modeling, indicate that mixed salt partitioning trends result from (i) different ions exhibiting different affinities for the membrane and (ii) the constraint of global electrical neutrality within the membrane. With this physical insight, we develop a simple approach to predicting the concentration of various ions in a membrane equilibrated with a mixed salt solution which requires no adjustable parameters.

Sulfur-containing soft Lewis base polymers for improved lithium-ion conductivity under polymer-in-salt conditions

Abstract Solid polymer electrolytes have been intensively studied to improve the safety and energy density of lithium-ion batteries (LiBs). Although high-rate performance of LiBs has been reported in electrolytes under polymer-in-salt conditions with an excess of lithium salts and polymers, effective conditions for achieving high ionic conductivity remain unresolved. In this study, we elucidate the mechanism and high Li-ion transportability of poly(sulfone-thioether) under polymer-in-salt conditions. In particular, the composition of the polymer with an asymmetric Li salt, lithium(fluorosulfonyl)(trifluoromethane sulfonyl)imide (LiFTFSI), induced a high ionic conductivity above 10−5 S/cm, which is higher than that of the poly(ethylene oxide) (PEO)-Li salt system. Under polymer-in-salt conditions, the enhanced conductivity of poly(sulfone-thioether) contrasts with the conductivity drop observed in the conventional PEO system. These results show the superiority of polymers with soft Lewis bases, such as sulfur donor atoms, for Li-ion transport under polymer-in-salt conditions.