Poly Ethylene Oxide Research Articles

Sustained dual delivery of metronidazole and viable Lactobacillus crispatus from 3D-printed silicone shells

Bacterial vaginosis (BV) is an imbalance of the vaginal microbiome in which there are limited lactobacilli and an overgrowth of anaerobic and fastidious bacteria such as Gardnerella. The propensity for BV recurrence is high, and therapies involving multiple treatment modalities are emerging to meet this need. However, current treatments requiring frequent therapeutic administration are challenging for patients and impact user compliance. Three-dimensional (3D)-printing offers a novel alternative to customize platforms to facilitate sustained therapeutic delivery to the vaginal tract. This study designed a novel vehicle intended for dual sustained delivery of both antibiotic and probiotic. 3D-printed compartmental scaffolds consisting of an antibiotic-containing silicone shell and a core containing probiotic Lactobacillus were developed with multiple formulations including biomaterials sodium alginate (SA), polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyethylene oxide (PEO), and kappa-carrageenan (KC). The vehicles were loaded with 50 μg of metronidazole/mg polymer and 5 × 107 CFU of L. crispatus/mg scaffold. Metronidazole-containing shells exhibited cumulative drug release of 324.2 ± 31.2 μg/mL after 14 days. Multiple polymeric formulations for the probiotic core demonstrated cumulative L. crispatus recovery of >5 × 107 CFU/mg scaffold during this timeframe. L. crispatus-loaded polymeric formulations exhibited ≥2 log CFU/mL reduction in free Gardnerella in the presence of VK2/E6E7 vaginal epithelial cells. As a first step towards the goal of facilitating patient compliance, this study demonstrates in vitro effect of a novel 3D-printed dual antibiotic and probiotic delivery platform to target BV.

Magnetic field-assisted vertically aligned NiFe2O4 nanosheets in composite solid polymer electrolytes for advanced all solid-state lithium metal batteries

Two-dimensional materials (2D Ms) as fillers have been applied in polyethylene oxide (PEO)-based electrolyte to enhance the low ionic conductivity and poor interface compatibility. However, the randomly dispersed fillers in PEO matrix result in anisotropy of Li+ transportation and insufficent ionic conductivity. Herein, NiFe2O4 (NFO) nanosheets are firstly introduced in polymer matrix to form vertically aligned NFO-PEO (ANFO-PEO) composite solid-state electrolytes (CSEs) through magnetic field-assisted alignment strategy. The vertically aligned NFO/PEO interface in CSEs can construct oriented Li+ transport channels and maximize the utilization of high in-plane conductivity. Meanwhile, the NFO nanosheets with abundant oxygen vacancies could effectively anchor TFSI− to promote the dissociation of Li salts. Furthermore, the optimized Li+ transport flux in CSEs enables homogeneous Li deposition and effectively mitigates the growth of dendrites. Owing to the synergistic effects, the ANFO-PEO CSEs exhibit high ionic conductivity (9.16 × 10−4 S cm−1 at 60 °C) and stable potential window up to 5.0 V vs Li/Li+. Therefore, LiFePO4 in the full cell and pouch cell with ANFO-PEO CSEs could deliver excellent cycling performance (92.78 % capacity retention after 1000 cycles at 0.5C; 96.88 % capacity retention after 105 cycles at 0.1C).

On the rheological properties of Silica – Poly(ethylene-oxide) dispersions: "Shake-gels" II The effect of silica concentration and molecular weight of polymer

Using rheological techniques, the effect of silica concentration and polyethylene oxide molecular weight has been investigated to follow the gelation/shear thickening behaviour of PEO silica water mixtures, a phenomenon which has become known as "shake gels”. By monitoring the viscosity as a function of the shear rate it was observed that at a critical shear rate the viscosity increased by many orders of magnitude. The higher the silica concentration and the higher the polymer molecular weight the lower the shear rate required for the gel to form. Once formed by dropping the shear rate to a low value or by monitoring the viscoelastic moduli the relaxation of the gel back into the liquid state could be followed. It was noted that the lower the polymer molecular weight or the lower the silica concentration the faster the relaxation process was. It is postulated that the silica particles effectively cross link the gel so that the more silica particles per polymer molecule would result in slower relaxation. Conversely in the gel formation stage the more silica particles per polymer the faster the gel forms are a consequence of the ease by which the silica particles can cross link to form the gel.

Metal-organic frameworks Derived frustrated Lewis acid-base pairs accelerate ion dynamics to dendrite-free solid-state lithium batteries

The Poly(ethylene oxide) (PEO)-based polymer electrolytes exhibit the drawbacks of high crystallinity and low ionic conductivity (<10−5 S m−1), which significantly restrict their application in solid-state lithium metal batteries. This study presents the bismuth metal-organic frameworks (MOFs) as a PEO-based electrolyte filler, incorporating frustrated Lewis acid-base pairs, which is formed in-situ through the coordination of ellagic acid (EA) and bismuth ions (Bi3+). The simultaneous presence of Lewis acids (unsaturated Bi3+) and bases (free nitrate, NO3−) in the MOFs, which effectively transfers and transports the lithium ions through the synergistic interaction based on the polymer matrix and the lithium salts, resulting in the high durable solid-state lithium batteries. Meanwhile, NO3− can further promote the dissociation of lithium ion (Li+) and the formation of inorganic solid electrolyte interfaces (SEIs) with lithium metal, which is conducive to the dynamic repair of SEIs. Characterizations and calculations show that Bi-MOFs promote the increase of composite ionic conductivity (6.4 × 10−4 S cm−1, 60 °C) and lithium transference number (0.52, 60 °C). At a current density of 0.4 mA cm−2, the assembled Li–Li symmetric battery can be continuously cycled for more than 500 h. This strategy opens a new window for improvement of solid-state electrolyte performance.

A novel approach for the atomic scale characterization of Li-ion battery components probed by positron annihilation lifetime spectroscopy

Recent research has focused on solid polymer electrolytes (SPEs) as the best liquid electrolyte replacements. Poly(ethylene oxide) (PEO) is the most frequent one because of its fast segmental movements in the free volume which controls lithium-ion transport between electrodes. Therefore, PEO-based copolymer electrolytes that can be tailored for mechanical strength and ionic conductivity are often studied. The most popular material is PEO chains containing PMMA because PEO transports ions, and PMMA has good mechanical properties. Further investigations on PEO-based solid polymer electrolytes (SPEs) have shown that chain designs with more nonlinear branches prevent crystallinity and maintain fast segmental dynamics. For this purpose, we worked on PEO-grafted-PMMA copolymers in which the free volume probed by positron annihilation lifetime spectroscopy considerably affects the structure-ionic conductivity relationship. Finally, we investigated the free volume theory of ionic condcutivity using Yahsi-Ulutas-Tav (YUT) theory.

Study on the effect and mechanism of polyethylene oxide and alum in flotation separation of fine smithsonite/calcite

The flotation separation of fine smithsonite and calcite has always been a challenging issue in the mineral processing industry. Both minerals are microfine particle distribution in nature, requiring ultra-fine grinding to maximize their liberation, which makes their flotation separation difficult. This study investigated the effects of PEO (Polyethylene oxide) and alum as combination agent on the flotation separation of fine smithsonite and calcite. The research results showed that using PEO and alum as combination agent can effectively separate fine smithsonite and calcite. PEO has a flocculation effects on both minerals, and Alum has better selective adsorption and flocculation effects on calcite, thereby effectively reducing the recovery of calcite. After treatment with PEO and alum, soluble starch tends to adsorb on the surface of calcite more than smithsonite, selectively depressing calcite in flotation separation, thus allowing for the effective flotation separation of fine smithsonite and calcite.

Enhanced performance of ambient-air processed CsPbBr3 perovskite light-emitting electrochemical cells via synergistic incorporation of dual additives

Metal halide perovskite light-emitting electrochemical cells (MHP-LECs) are promising due to their facile solution processability and exceptional optoelectrical properties. However, commercialization is hindered by poor thin-film coverage and the need for glovebox processing. This study addresses these issues by incorporating poly(ethylene oxide) (PEO) and potassium hexafluorophosphate (KPF6) into cesium lead bromide perovskite (CsPbBr3) emitting layers (EML), processed under ambient-air conditions. These perovskite composite thin films were spin-coated on a preheated substrate, and the device structure was ITO/PEDOT:PSS/EML/Al. Notably, the MHP-LEC based on CsPbBr3:PEO:KPF6 (100:65:0.2, weight ratio) exhibited pure-green emission with a peak at 524 nm and a narrow full width at half-maximum of 27 nm. Compared to a reference device (CsPbBr3:PEO (100:65, weight ratio)), the new device showed 1.5-, 4-, and 5-fold improvements in current density, electroluminescence (EL) intensity, and lifetime, respectively. These enhancements are attributed to reduced non-radiative current leakage, improved film surface coverage and passivation, and balanced charge carrier injection and transportation. This study offers a straightforward approach for processing CsPbBr3 thin films under ambient-air conditions, enhancing the EL performance of MHP-LECs.

Electropolishing of Magnesium and Its Alloys using a Safe Glycol Solution containing Sodium Chloride

Abstract The electropolishing behavior of pure magnesium and its alloys in ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TrEG), and tetraethylene glycol (TeEG) solutions containing sodium chloride was investigated using electrochemical measurements, microscopic observations, and reflectance measurements. Large light-grayish cloudy areas with micrometer-scale linear irregularities were formed on the magnesium surface via constant-voltage electrolysis in the EG solution, whereas mirror-finished magnesium surfaces were successfully obtained in the DEG and TeEG solutions. Among these, the DEG solution is considered appropriate for electropolishing because of its lower viscosity and market price. The reflectance of the entire visible wavelength region gradually increased with time during electrolysis in the DEG solution at 308 K. We found that short-term electrolysis for 3 min at the higher voltage of 75 V should be selected if a moderately polished surface is to be rapidly obtained, whereas long-term electrolysis for 60-300 min at 50 V should be performed if a highly polished surface with an extremely high reflectivity measuring more than 80% can be obtained. Three-dimensional magnesium specimens with curved and spiral shapes and an LZ91 magnesium alloy consisting of a simple solid-solution matrix can also be electropolished via electrolysis in a DEG solution.

Lewis-basic nitrogen-rich covalent organic frameworks enable flexible and stretchable solid-state electrolytes with stable lithium-metal batteries

Designing flexible and stretchable solid-state electrolytes (SSEs) holds promise but challenge in flexible all-solid-state lithium-metal batteries (LMBs) owing to their insufficient ion conductivity and mechanical strength. Herein, we develop nitrogen-rich covalent organic frameworks (NCOF) with abundant Lewis-basic N atoms as lithiophilic sites to incorporate Lewis-acidic Li+ into its inner order structure for fabricating flexible and stretchable PEO-LI+@NCOF SSEs with the crosslinking of polyethylene oxide (PEO). The SSE film displays high mechanical strain (2.2 MPa), Young's modulus (689 MPa), stretchability (1000 %), ion conductivity (2.4 × 10–4 S cm-1), good flame resistance, and wide electrochemical window (4.8 V). Owing to the rich Lewis-basic N atoms with strong Li+ adsorption energy, orderly nanochannels, and negative charge environment within NCOFs, the SSE film endows orderly and rapid ion migration, low Li-ion diffusion barrier, and significantly enhanced ion conductivity for uniform lithium plating/stripping and suppressing Li-dendrite growth. The crosslinking of Li+@NCOF with PEO greatly enhances the mechanical stretchability, flame resistance, and electrochemical window of PEO-based SSEs. Consequently, the Li/PEO-LI+@NCOF/Li symmetrical cell exhibits stable cycling without short-circuiting for 1200 h at 0.1 mA cm-2/0.1 mAh cm-2. The LiFePO4/PEO-LI+@NCOF/Li battery exhibits a 500-cycle long lifespan at 1 C (78 % capacity retention), and its pouch cell verifies promising applications in flexible all-solid-state LMBs. Therefore, introducting Lewis-basic N-rich COFs verifies an effective strategy to design a flexible and stretchable SSE film with high mechanical strength, superior ion conductivity and flame resistance.

A Simple Method for the Study of Heteroionic Interface Impedances in Solid Electrolyte Multilayer Cells Containing LLZO.

Hybrid battery cells that combine a garnet-type Li7La3Zr2O12 (LLZO) solid electrolyte with other solid, polymer or liquid electrolytes are increasingly investigated. In such cells with layered electrolytes, ensuring a low-resistive heteroionic interface between neighboring electrolytes is crucial for preventing major additional overpotentials during operation. Electrochemical impedance spectroscopy is frequently used to extract such parameters, usually on multilayer symmetrical model cells that contain the different electrolytes stacked in series. Unfortunately, the impedance contributions of the heteroionic interfaces often overlap with those of the electrolyte|electrode interfaces, necessitating the use of sophisticated four-point cells that probe the electrochemical potential away from the polarization source. In this work, an alternative solution to this problem is demonstrated by taking advantage of the inherent fast charge transfer kinetics of LLZO with its parent metal electrode. The "resistance-free" nature of a reversible Li|LLZO interface enables a precise evaluation of the heteroionic interface impedance in symmetric two-point cells of the type Li|LLZO|electrolyte|LLZO|Li with negligible electrode contribution. This is exemplified for symmetric multilayer cells containing tantalum-doped LLZO and a poly(ethylene oxide) (PEO)-based dry polymer electrolyte. Validation and comparison of impedance data with results from symmetric four-point cells and two-point cells with ion-blocking electrodes demonstrate the advantage of the proposed method. Overall, this study presents a simple and reliable method for studying heteroionic interface impedances in LLZO-containing multilayer cells.

A multi-step discharge/charge model of Li[sbnd]O2 batteries coupled with electrolyte decomposition and carbon electrode corrosion reactions

Electrolyte decomposition and electrode corrosion stand as two primary side reactions in lithium‑oxygen (LiO2) batteries during their discharge/charge cycles. In this work, a comprehensive LiO2 battery model combining multi-step lithium peroxide (Li2O2) formation, electrolyte decomposition, and electrode corrosion is proposed. Based on this model, the deposition behaviors and cycling performance of the LiO2 battery under deep discharge/charge cycles are investigated. The stop of discharge is mainly ascribed to the loss of active surface area for the battery using tetraethylene glycol dimethyl ether (TEGDME) electrolyte, while both O2 transport limitation and active surface area loss lead to the discharge termination for battery using dimethyl sulfoxide (DMSO) electrolyte. The incomplete decomposition of Li2O2 and lithium carbonate (Li2CO3) clogs electrode pores, leading to a continuous decline in the discharge capacity of the LiO2 battery. For the TEGDME-based battery, the undecomposed Li2CO3 gradually dominates the deposition with cycles, wherein electrode corrosion becomes the primary source of the undecomposed Li2CO3 after 3 cycles. For the DMSO-based battery, undecomposed Li2O2 is always a dominant trigger for battery discharge capacity degradation, although electrode corrosion remains a key contributor to Li2CO3 generation. Despite the DMSO-based battery exhibiting lower rates of electrolyte decomposition and electrode corrosion, it demonstrates poorer cyclic performance than the TEGDME-based battery due to the generation of more toroidal Li2O2. Moreover, when the charging cut-off voltage is reduced to 4.2 V, discharge capacity diminishes more rapidly due to the increased accumulation of undecomposed Li2O2, despite suppressed Li2CO3 deposition. Finally, the results confirm that thick electrodes lead to deteriorating cycling performance, stemming from increased discharge/charge overpotential and extended discharge/charge times, thus intensifying the side reactions.

Cleaner and Sustainable Production of Core-Sheath Polymer Fibres.

The amalgamation of sustainable practises throughout the fabrication process with advanced material engineering holds promise not only for eco-conscious manufacturing but also for promoting technological advancements in versatile material design and application. Moreover, technological innovation serves as a catalyst for sustainability initiatives, driving innovation and enabling the adoption of greener practises across industries. This study investigates redefining the production protocol of pressure spinning to produce core-sheath polymer fibres, deepening sustainable practises. It aims to explore innovative approaches such as modifying spinning parameters, optimising polymer solvent configurations and understanding fluid behaviour to curtail material wastage and maintain minimal energy consumption without compromising production efficiency. Utilising Polyvinylpyrrolidone (PVP) for the core and Polyethylene oxide (PEO) for the sheath, production rates of up to 64 g/h were achieved with a fibre diameter range of 3.2 ± 1.7 µm to 4.6 ± 2.0 µm. Energy consumption per mass of fibres produced showed a decreasing trend overall with increasing applied gas pressure. These findings highlight the potential for the efficient and scalable production of core-sheath fibres with applications in various advanced materials fields.

Effect of Grafting Density on the Crystallization Behavior of Molecular Bottlebrushes.

A unique case of sterically constrained crystallization arises in bottlebrush polymers bearing semicrystalline side chains. Bottlebrushes with grafted side chains can form crystalline structures governed by the complex interplay between side chain packing and backbone confinement. The confinement effect can be readily tuned by varying the side chain grafting density, thus affording control over the crystallization behavior of these systems. In this work, the grafting density effect on the crystallization behavior of molecular bottlebrushes comprising poly(ethylene oxide) (PEO) side chains grafted to a methacrylate backbone was systematically studied. Thermal analysis using differential scanning calorimetry showed that the bottlebrush polymers displayed suppressed crystallization temperatures, lower melting temperatures, and reduced crystallinities compared to linear homopolymer PEO. The crystalline morphology was investigated using polarized light, atomic force, and scanning electron microscopy. Isothermal crystallization experiments revealed a nonmonotonous dependence of the nucleation density on the side chain grafting density. The grafting density effect was also investigated using self-seeding experiments, revealing an increased clearing temperature and memory retention at higher grafting densities. This work highlights how grafting density influences the crystallization behavior of semicrystalline bottlebrushes, providing information for the processing and application of these unique polymers.

Amphiphilic silica monomers induced superhydrophilic and flexible silica aerogels for radiative cooling and atmospheric water harvesting

Silica aerogels have attracted extensive attention owing to their exceptional porous structures and crucial applications for sustainable environments. However, the inherent fragility and complex manufacturing process of silica aerogels present a challenge for their prolonged applications. In this study, an amphiphilic silica monomer, triethoxysilane end-capped poly(ethylene oxide) (PEO-TES), is designed and synthesized, which can co-gelled with methyltrimethoxysilane in water and gives birth to flexible and superhydrophilic silica aerogels via ambient pressure drying (APD). PEO-TES plays a dual role as both co-monomers and surfactants, effectively stabilizing the sol–gel transition, adjusting the porous structure of hydrogels, and imparting superhydrophilicity. The silica aerogel has low density (0.147 g cm−3), zero water contact angle, high elasticity (80 % compression), high solar reflectance (0.888), and high IR emissivity (0.967). These features make them robust all-day passive radiative cooling materials with 10.5 °C sub-ambient cooling capacity and atmospheric water harvesting capacities for both vapor (a water harvesting rate of 0.041 kg m−2h−1) and fog (harvesting capacity of 2.9 g g−1). The strategy provides a simple APD method for synthesizing flexible and superhydrophilic silica aerogels with controllable porous structures, passive cooling, and water harvesting performance, which may help address global climate change and water scarcity challenges.

Vertical channel‐structured cyanoethylated bacterial cellulose/polyethylene oxide composite solid electrolyte for all‐solid‐state lithium batteries

AbstractSolid polymer electrolytes (SPEs) have gained remarkable development within the realm of new energy resources. With its improved electrochemical stability and environmental‐friendly sustainability, bacterial cellulose (BC) has emerged as a promising candidate for applications in SPEs. Herein, bacterial cellulose was chemically cyanoethylated and integrated with lithium bis(trifluoromethanesulphonyl)imide/polyethylene oxide (PEO) based SPE. Some vertical channels are formed when trace amounts (0.5 wt%) of cyanoethylated bacterial cellulose (BC‐CN) are added to PEO‐based SPE, as revealed by SEM. This formula's corresponding PEO‐based SPE presents the highest ion conductivity of 5.7 × 10−4 S cm−1 at 60°C. The ion migration activation (Ea) deduced from the Arrhenius equation is 0.48 eV, lower than the value of 0.82 eV for the pristine PEO SPE. Besides, the Li+ migration number of this modified PEO‐based solid electrolyte is calculated to be a relatively high value of 0.33, while that of its counterpart, the pristine PEO SPE, is as low as 0.06. The all‐solid‐state lithium battery with PEO/0.5%BC‐CN SPE can operate stably for 115 cycles, which is longer than the 80 cycles achieved with the pristine PEO SPE. This study introduces a novel strategy for creating modified BC composites PEO‐based SPE.Highlights Bacterial cellulose was chemically cyanoethylated. Cyanoethylated bacterial cellulose composite polyethylene oxide (PEO)‐based solid polymer electrolytes (SPEs) are prepared in DMF. Opening pores penetrate the surface of the PEO/0.5% cyanoethylated bacterial cellulose (BC‐CN) SPE membrane. PEO/0.5% BC‐CN shows ionic conductivity of 5.7 × 10−4 S cm−1 at 60°C. Full cell with PEO/0.5% BC‐CN performs stably for 115 cycles.

Novel non-fluorinated surfactants for emulsion polymerization of fluorinated monomers

In order to replace toxic fluorinated surfactants such as PFOA and GenX, herein we report a series of non-fluorinated surfactants (NFS) for the emulsion polymerization of fluorinated monomers. The surfactant is a statistic copolymer synthesized from free radical polymerization of poly(ethylene oxide) methacrylate (PEGMA) as hydrophilic monomer with methyl methacrylate (MMA) or tert-butyl methacrylate (TBMA) as hydrophobic comonomer. With properly designed hydrophile lipophile balance (HLB), monomer ratio, and the length of PEG segments, the polymeric NFS form unimolecular micelles in water, which facilitates the emulsion polymerization of fluorinated monomers including vinyl difluoride (VDF) where the solid content of emulsion can be higher than 25 wt% without the occurrence of significant coagulation. The optimized loading ratio of NFS is as low as 88 ppm which is ten times lower than that of fluorinated surfactants. The results demonstrate that the statistic copolymers construct unimolecular micelles to be powerful NFS for the emulsion polymerization of fluorinated monomers.

Challenges in XPS Analysis of PEO‐LiTFSI‐based Solid Electrolytes: How to Overcome X‐ray‐Induced Photodecomposition

AbstractThe cycle life of poly(ethylene oxide) (PEO) batteries containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is hindered by interfacial (electro)chemical electrolyte decomposition, a process traditionally examined via X‐ray photoelectron spectroscopy (XPS). Our research presents a critical examination of X‐ray induced photodecomposition, commonly misinterpreted as (electro)chemical electrolyte decomposition, in PEO‐LiTFSI systems and those with NCM cathodes. We provide novel insights into this X‐ray induced photodecomposition process and show that it is particularly pronounced when LiTFSI is dissolved and not in its pure state. Most importantly, we reveal that cryogenic measurement conditions can almost completely mitigate this photodecomposition. This insight not only deepens the understanding of photodecomposition within XPS analyses but also provides a transformative approach to the accurate characterization of electrolyte materials in lithium batteries.

Electrospun Cerium Oxide Nanoparticle/Aloe Vera Extract-Loaded Nanofibrous Poly(Ethylene Oxide)/Polyurethane Mats As Diabetic Wound Dressings.

Currently the prevalence of diabetic wounds brings a huge encumbrance onto patients, causing high disability and mortality rates and a major medical challenge for society. Therefore, in this study, we are targeting to fabricate aloe vera extract infused biocompatible nanofibrous patches to facilitate the process of diabetic wound healing. Additionally, clindamycin has been adsorbed onto the surface of in-house synthesized ceria nanoparticles and again used separately to design a nanofibrous web, as nanoceria can act as a good drug delivery vehicle and exhibit both antimicrobial and antidiabetic properties. Various physicochemical characteristics such as morphology, porosity, and chemical composition of the produced nanofibrous webs were investigated. Bacterial growth inhibition and antibiofilm studies of the nanofibrous materials confirm its antibacterial and antibiofilm efficacy against Gram-positive and Gram-negative bacteria. An in vitro drug release study confirmed that the nanofibrous mat show a sustained drug release pattern (90% of drug in 96 h). The nanofibrous web containing drug loaded nanoceria not only showed superior in vitro performance but also promoted greater wound contraction (95 ± 2%) in diabetes-induced mice in just 7 days. Consequently, it efficaciously lowers the serum glucose level, inflammatory cytokines, oxidative stress, and hepatotoxicity markers as endorsed by various ex vivo tests. Conclusively, this in-house-fabricated biocompatible nanofibrous patch can act as a potential medicated suppository that can be used for treating diabetic wounds in the proximate future.

Revealing Phase Transitions in Poly(Ethylene Oxide)‐Based Electrolyte for Room‐Temperature Solid‐State Batteries

AbstractSolid‐state electrolytes (SSEs) offer enhanced safety, extended cycle life, and increased energy density when replacing flammable liquid electrolytes in lithium‐ion batteries. Poly(ethylene oxide) (PEO)‐based SSE is the only candidate that has been commercially implemented in electric vehicles. However, the equipped battery needs to operate at temperatures above 50 °C, and its phase transitions at room temperature are still unclear. Herein, the solidification of the PEO‐lithium bis(trifluoromethanesulfonyl)imide (PEOn‐LiTFSI) system is revisited. Contrary to the prevailing view of forming PEO(6)‐LiTFSI spherulites, the presence of crystalline PEO(8)‐LiTFSI complexes is quantitatively confirmed. The nucleation and growth processes of crystalline PEO and PEO(8)‐LiTFSI spherulites are also visually elucidated, and phase transitions with the impedance change are correlated. In addition, it is demonstrated that the crystalline PEO shell surrounding the PEO(8)‐LiTFSI spherulites hinders the kinetics of crystal growth, thereby enabling the highest ionic conductivity at n = 10. Importantly, it is pointed out that instead of the poor ionic conductivity of the electrolyte layer, the heterogeneous nucleation of PEO(8)‐LiTFSI within the electrodes is the limiting factor in constructing room‐temperature all‐solid‐state batteries.

Quasi-Gel Polymer Electrolyte Interfaced with Electrodes through Solvent-Swollen Poly(ethylene oxide) for High-Performance Lithium/Lithium-Ion Batteries.

Solid polymer electrolytes (SPEs) are regarded as a superior alternative to traditional liquid electrolytes of lithium-ion batteries (LIBs) due to their improved safety features. The practical implementation of SPEs faces challenges, such as low ionic conductivity at room temperature (RT) and inadequate interfacial contact, leading to high interfacial resistance across the electrode and electrolyte interfaces. In this study, we addressed these issues by designing a quasi-gel polymer electrolyte (QGPE), a blend of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), poly(ethylene oxide) (PEO), and succinonitrile (SN), with the desired mechanical strength, ionic conductivity, and interfacial stability through a simple solution casting technique. The QGPE features a thin solvated PEO layer on its surface, which wets the electrode, reducing the interfacial resistance and ensuring a homogeneous Li-ion flux across the interface. The optimized QGPE exhibits a good lithium-ion conductivity of 1.14 × 10-3 S cm-1 with a superior lithium-ion transference number of 0.7 at 25 °C. The Li/QGPE/Li symmetric cell exhibits a highly reversible lithium plating/stripping process for over 1300 h with minimal voltage polarization of ∼20 mV. The Li/QGPE/LiFePO4 full cell demonstrates good rate capability and excellent long-term cycling performance at a 0.1 C rate at 25 °C, maintaining a specific discharge capacity of 148 mAh g-1 over 200 cycles. The effectiveness of QGPE for LIBs is proven using a graphite/QGPE/LiFePO4 4 × 4 cm pouch cell, showcasing outstanding flexibility and tolerance against intentional abuse.