Crystallization Of Polyethylene Oxide Research Articles

Regulating Li+ transport behavior by cross-scale synergistic rectification strategy for dendrite-free and high area capacity polymeric all-solid-state lithium batteries

The inability to effectively inhibit the lithium (Li) dendrite growth is identified as the real culprit hindering the practical application of polyethylene oxide (PEO)-based electrolytes. Herein, a novel PEO composite electrolyte with ion rectifier is developed based on the cross-scale synergistic rectification strategy. At the micro-scale, the array structure of the ion rectifier suppresses the growth of PEO crystals and their distribution in the non-ionic conduction direction through space confinement, alleviating ion-migration crosstalk and enabling polymer chain rectification. Furthermore, the matrix contains abundant copper ions and oxygen-containing groups that inhibit anion conduction and accelerate Li+ migration at the nanoscale, respectively, to achieve ion flow rectification. Implementing this strategy results in a uniform, fast, and stable Li+ migration/diffusion behavior from the electrolyte to anode interface. The critical current density of the PEO electrolyte is increased to 2.5 mA cm−2, indicating a significant improvement in dendrite growth inhibition. Impressively, the composite electrolytes exhibit long-term stability (>4000 h at 0.2 mA cm−2) and ultra-high current-density tolerance (>200 h at 1 mA cm−2). Moreover, the composite electrolytes enable stable cycling of high-area-capacity (3.11 mAh cm−2, 20 mg cm−2) LiFePO4/Li pouch cells, highlighting the importance of this strategy for the practical application of PEO electrolytes.

Construction of PEO@g-C3N4 supported ionic liquid membrane with interactive network structure for enhanced carbon capture efficiency

Polyethylene oxide (PEO) shows a high CO2-philic due to its dipolar-quadrupolar interaction with CO2 molecules. As a result, it is an excellent candidate for gas separation applications, yet it faces problems such as crystallization and low permeance. Herein, we show a versatile strategy to enhance gas permeation fluxes, which is mainly achieved by hindering the crystallization of PEO and the stacking of nanosheets. Specifically, graphite-like phase carbon nitride (g-C3N4) nanosheets are introduced and interaction networks (PGCN) are constructed by taking full advantage of the dipole-level quadrupole moment interactions between the ether-oxygen groups contained in PEO and CO2. In order to compensate the membrane surface defects for enhancing gas selectivity, we used the suspension coating method to create a PEO@g-C3N4 supported ionic liquid membrane (PGCN/ILX SILM) by coating IL on the surface of membrane. The results show that, when the IL concentration is 30 wt%, the PGCN/IL30 % membrane separates CO2/N2 with a CO2 permeance of 1396 GPU and an optimal selectivity of 58. While overcoming the “Trade-off” effect, it has demonstrated good thermal stability and long-term stable operation for 72 h. The development of this work will generate solutions for overcoming PEO crystallization and achieving efficient CO2 capture.

Zwitterionic Cellulose-Based Polymer Electrolyte Enabled by Aqueous Solution Casting for High-Performance Solid-State Batteries.

Polyethylene oxide (PEO)-based solid-state batteries hold great promise as the next-generation batteries with high energy density and high safety. However, PEO-based electrolytes encounter certain limitations, including inferior ionic conductivity, low Li+ transference number, and poor mechanical strength. Herein, we aim to simultaneously address these issues by utilizing one-dimensional zwitterionic cellulose nanofiber (ZCNF) as fillers for PEO-based electrolytes using a simple aqueous solution casting method. Multiple characterizations and theoretical calculations demonstrate that the unique zwitterionic structure imparts ZCNF with various functions, such as disrupting PEO crystallization, dissociating lithium salts, anchoring anions through cationic groups, accelerating Li+ migration by anionic groups, as well as its inherent reinforcement effect. As a result, the prepared PL-ZCNF electrolyte exhibits remarkable ionic conductivity (5.37×10-4 S cm-1) and Li+ transference number (0.62) at 60 °C without sacrificing mechanical strength (9.2 MPa), together with high critical current density of 1.1 mA cm-2. Attributed to these merits of PL-ZCNF, the LiFePO4|PL-ZCNF|Li solid-state full-cell delivers exceptional rate capability and cycling performance (900 cycles at 5 C). Notably, the assembled pouch-cell can maintain steady operation over 1000 cycles with an impressive 93.7 % capacity retention at 0.5 C and 60 °C, highlighting the great potential of PL-ZCNF for practical applications.

Composite Electrolytes with Li2CO3‐Free Garnets Achieved by One‐Step Poly(propylene carbonate) Treatment for High‐Rate and Long‐Life Solid Lithium Batteries

AbstractGarnet‐based composite electrolytes show great potential in building high‐energy‐density solid lithium batteries. However, naturally formed Li2CO3 on garnets owing to air exposure hinders the Li‐ion transport and triggers undesirable performance deterioration. Based on the reaction between basic Li2CO3 and poly(propylene carbonate) (PPC) with a product of propylene carbonate (PC), composite electrolytes with homogeneously distributed Li2CO3‐free garnets as well as PC are fabricated in one step without the post‐treatment of garnet powders in both polyethylene oxide (PEO) and polyvinylidene fluoride (PVDF)‐based electrolytes. The formed PC component further decreases the crystallization of PEO and reduces the grain size of PVDF, leading to improved ion transport in PEO and the suppression of PVDF dehydrofluorination. Consequently, the PPC‐treated garnets enable high ionic conductivities of 3.40 × 10−4 and 1.75 × 10−4 S cm−1 at 30 °C, respectively, in PEO:garnet and PVDF:garnet electrolytes, as well as great electrochemical stability against Li‐metal with a lifespan over 1000 h in Li symmetrical cells at 0.1 mA cm−2. Superior stable cycles are thus realized in both LiFePO4|PEO:garnet|Li and LiNi0.6Co0.2Mn0.2O2|PVDF:garnet|Li cells. These above results demonstrate that the one‐step treatment used here helps the enhancement of Li‐ion transport in composite electrolytes, thus essential for building high‐rate and long‐life solid lithium batteries (SLBs).

Well‐Dispersed Polydopamine In Situ Coated Lithium Montmorillonite Nanofillers Composite Polyethylene Oxide‐Based Solid Electrolyte for All‐Solid‐State Lithium Batteries

In lithium batteries, composite solid electrolytes gain their reputation owing to their great safety, excellent mechanical properties, and remarkably improved electrochemical performance. Herein, composite polyethylene oxide (PEO)‐based solid electrolytes with well‐dispersed in situ polydopamine‐coated lithium montmorillonite (PDA@LiMMT) nanofillers are successfully fabricated. The involvement of PDA@LiMMT retards significantly the crystallization of PEO, addressing a manifest enhancement in the ionic conductivity of the modified composite solid electrolyte. A conducive ionic conductivity value of 3.06 × 10−4 S cm−1 at 60 °C is reached, while the electrochemical window widens to 4.7 V. The assembled Li/solid polymer electrolytes/LiFePO4 battery exhibits a 158.2 mA h g−1 high discharge specific capacity at a current density of 0.5C; besides, the capacity retention rate keeps 86% after 200 cycles. The enhancement of the cycle stability of the solid‐state batteries highlights the excellent interfacial stability between the modified solid electrolytes and the lithium electrode, which originates from lithiophilicity of PDA.

Defect-free PEO membrane fabrication by hydrogen bonding coupling thermal annealing for carbon capture

Reduction of CO2 emission is an urgent global demand to deal with the current extreme climate and ecosystem destruction. Polyethylene oxide (PEO) is an ideal material for CO2 separation membranes, because of its moderate affinity for CO2. However, due to its high tendency of crystallization, the mass transfer of CO2 is significantly hampered, resulting in poor separation performance. This study proposed of employment of trehalose as the filler to PEO membrane with subsequent thermal annealing, that is hydrogen-bond suppression crystallization coupling thermal annealing healing defects strategy, to simultaneously enhance the gas transport and selectivity. The trehalose plays the role of suppressing PEO crystallization while thermal annealing charges for healing defects. Consequently, the optimized trehalose-loaded PEO membrane exhibits a CO2 permeability of 117 Barrer and an ideal CO2/N2 selectivity of 51, which is superior to the pure PEO membrane. Moreover, the membrane offers merits of anti-plasticization feature and long-term running stability.

Polyethylene Oxide/Sodium Sulfonamide Polymethacrylate Blends as Highly Conducting Single-Ion Solid Polymer Electrolytes

In this work, blends of polyethylene oxide (PEO) and poly(sodium 1-[3-(methacryloyloxy)propylsulfonyl]-1-(trifluoromethanesulfonyl) imide) (PNaMTFSI) in different compositions were investigated for their application as solid electrolytes for sodium batteries. PNaMTFSI and PEO are miscible, exhibiting only one Tg in the whole range of compositions. PNaMTFSI was shown to reduce the crystal growth rate of PEO crystals but increase PEO nucleation, making the overall crystallization rate higher in blends with 15 and 30 wt % PNaMTFSI. The ionic conductivity is also affected by the blend composition. The highest values of ionic conductivity were observed with 15 and 30 wt % PNaMTFSI at high temperatures equal to 5.84 × 10–5 and 7.74 × 10–5 S cm–1 at 85 °C, respectively, with values of sodium-ion transference numbers of higher than 0.83 and electrochemical stability between 3.5 and 4.5 V versus Na+/Na0 depending on the composition, which opens the possibility of its use in sodium batteries. Finally, a comparison was made between the effect of sodium and lithium on these types of electrolytes, showing that sodium electrolytes have a lower ionic conductivity due to the larger size of the Na cation. The differences in the spherulitic growth rate and overall crystallization rate between Li and Na-containing electrolytes were compared and rationalized in terms of the blends’ intermolecular interactions and the relative contribution of primary nucleation and growth.

Influence of the Polymer Structure and its Crystallization on the Interface Resistance in Polymer-LATP and Polymer-LLZO Hybrid Electrolytes

For many years, composite electrolytes (CEs) consisting of a mixture of inorganic solid electrolytes (ISEs) and polymer electrolytes (PEs) have been investigated as promising materials for the scalable production of solid-state batteries (SSBs). It is believed that CEs can overcome limitations of the single components, namely the low room-temperature conductivity and lithium ion transference number of PEs and the poor mechanical properties and high temperature processing necessary for ISE ceramics. To facilitate ion transport in the CE between the electrodes a low and stable charge transfer resistance between PEs and ISEs is required. In this study, we investigate by means of electrochemical impedance spectroscopy (EIS) how polymer crystallinity influences the charge-transfer resistance of hetero-ionic interfaces between polyethylene oxide (PEO)-based electrolytes and Li1.5Al0.5Ti1.5(PO4)3 (LATP) as well as Li6.25Al0.25La3Zr2O12 (LLZO) as ISEs. Crystallization of PEO based electrolytes below their melting temperature leads to an increased charge-transfer resistance. On the other hand, electrolytes based on the amorphous poly[2-(2-(2-methoxyethoxy)ethoxy)ethyl glycidyl ether (PTG) do not show an increased charge transfer resistance. Finally, the conductivity of ISE-rich CEs is measured as a function of their temperature and composition for elucidating how the interface resistance influences charge transport in ISE-rich composite electrolytes.

Flexible ion-conducting membranes with 3D continuous nanohybrid networks for high-performance solid-state metallic lithium batteries

Polyethylene oxide (PEO)-based electrolytes are considered as one of the most promising solid-state electrolytes for next-generation lithium batteries with high safety and energy density; however, the drawbacks such as insufficient ion conductance, mechanical strength and electrochemical stability hinder their applications in metallic lithium batteries. To enhance their overall properties, flexible and thin composite polymer electrolyte (CPE) membranes with 3D continuous aramid nanofiber (ANF)–Li1.4Al0.4Ti1.6(PO4)3 (LATP) nanoparticle hybrid frameworks are facilely prepared by filling PEO–LiTFSI in the 3D nanohybrid scaffolds via a solution infusion way. The construction of the 3D continuous nanohybrid networks can effectively inhibit the PEO crystallization, facilitate the lithium salt dissociation and meanwhile increase the fast-ion transport in the continuous LATP electrolyte phase, and thus greatly improving the ionic conductivity (∼3 times that of the pristine one). With the integration of the 3D continuity and flexibility of the 3D ANF networks and the thermostability of the LATP phase, the CPE membranes also show a wider electrochemical window (∼5.0 V vs. 4.3 V), higher tensile strength (∼4–10 times that of the pristine one) and thermostability, and better lithium dendrite resistance capability. Furthermore, the CPE-based LiFePO4/Li cells exhibit superior cycling stability (133 mAh/g after 100 cycles at 0.3 C) and rate performance (100 mAh/g at 1 C) than the pristine electrolyte-based cell (79 and 29 mAh/g, respectively). This work offers an important CPE design criteria to achieve comprehensively-upgraded solid-state electrolytes for safe and high-energy metal battery applications.

Hydroxyl-rich single-ion conductors enable solid hybrid polymer electrolytes with excellent compatibility for dendrite-free lithium metal batteries

Polyethylene oxide (PEO) based solid polymer electrolytes (SPEs) are promising candidates for constructing the safety and high-performance of lithium metal batteries (LMBs). However, a number of obstacles have limited its further application, such as low ionic conductivity, undesired mechanical properties, and low lithium-ion transference number (tLi+). Herein, a hydroxyl-rich single conductor polymer (lithium sulfonated polyvinyl alcohol, SPVA-Li) was introduced as a polymeric filler into PEO SPEs network via a simple and scalable solution casting method to fabricate the composite SPEs. The hydrogen bond interactions between SPVA-Li and PEO enable the polymer chains to be more disordered that effectively suppress PEO crystallization, endowing the SPVA-Li SPEs with high ionic conductivity (1.76 × 10−4 S cm−1) and tLi+ (0.59) at 60 °C. Moreover, such cross-linking structures also can significantly improve the mechanical strength and thermal stability of the SPVA-Li SPEs. These performances are all superior to the PEO SPEs. Thus, based on the composite SPEs, Li/Li symmetric cells run for 400 h without any short circuits, and the LiFePO4/Li batteries also can be stably operated for 100 cycles at 0.2 and 0.5 C rates, respectively. These merits enable the SPVA-Li SPEs to be very promising for developing high-performance LMBs.

Molecular composite electrolytes of polybenzimidazole/polyethylene oxide with enhanced safety and comprehensive performance for all-solid-state lithium ion batteries

Polyethylene oxide (PEO)-based solid polymer electrolyte (SPE) is recognized as the most promising candidate in the commercialization process of all solid lithium ion battery (LIB). However, the crystallization of PEO results in low ionic conductivity, and the poor mechanical property and flammable feature of PEO lead to potential safety hazards in practical use. Here, we propose a cost-efficient, scalable, and facile approach for safe and high-performance SPE based on molecular composite of aromatic polybenzimidazole (PBI) and PEO. The strong intermolecular interactions effectively inhibit the crystallization of PEO, and significantly improve the modulus, strength, and ionic conductivity of PEO electrolyte by 16.6, 11.4, and 3.1 times with the addition 20% PBI. The thermal stability and flame retardancy are also simultaneously improved thanks to the outstanding heat-resistance and noninflammability of PBI. The PBI/PEO electrolyte exhibits excellent interfacial stability to lithium negative electrodes (500 h at 0.3 mA cm−2), and the LiFePO4//Li cell with PBI/PEO electrolyte shows a high-rate performance (152 mAh g−1 at 0.2 C) as well as cycling performance (100 cycles at 0.2 C) at 60 °C. We believe that the PBI/PEO molecular composite electrolytes hold great promising for practical application in safe and high-performance all-solid-state LIB.

Heterogeneous Crystal Nucleation from the Melt in Polyethylene Oxide Droplets on Graphite: Kinetics and Microscopic Structure

It is well known that the crystallization of liquids often initiates at interfaces to foreign solid surfaces. In this study, using polarized light optical microscopy, atomic force microscopy (AFM), and wide-angle X-ray scattering (WAXS), we investigate the effect of substrate–material interactions on nucleation in an ensemble of polyethylene oxide (PEO) droplets on graphite and on amorphous polystyrene (PS). The optical microscopy measurements during cooling with a constant rate explicitly evidenced that the graphite substrate enhances the nucleation kinetics, as crystallization occurred at approximately an 11 °C higher temperature than on PS due to changes in the interactions at the solid interface. This observation allowed us to conclude that graphite induces heterogeneous nucleation in PEO. By employing the classical nucleation theory for analysis of the data with reference to the amorphous PS substrate, the obtained results indicated that the crystal nuclei with contact angles in the range of 100–117° were formed at the graphite interface. Furthermore, we show that heterogeneous nucleation led to a preferred orientation of PEO crystals on graphite, whereas PEO crystals on PS had isotropic orientation. The difference in crystal orientations on the two substrates was also confirmed with AFM, which showed only edge-on lamellae in PEO droplets on graphite compared to unoriented lamellae on PS.

Comprehensively-modified polymer electrolyte membranes with multifunctional PMIA for highly-stable all-solid-state lithium-ion batteries

Polyethylene oxide (PEO)-based electrolytes have obvious merits such as strong ability to dissolve salts (e.g., LiTFSI) and high flexibility, but their applications in solid-state batteries is hindered by the low ion conductance and poor mechanical and thermal properties. Herein, poly(m-phenylene isophthalamide) (PMIA) is employed as a multifunctional additive to improve the overall properties of the PEO-based electrolytes. The hydrogen-bond interactions between PMIA and PEO/TFSI− can effectively prevent the PEO crystallization and meanwhile facilitate the LiTFSI dissociation, and thus greatly improve the ionic conductivity (two times that of the pristine electrolyte at room temperature). With the incorporation of the high-strength PMIA with tough amide-benzene backbones, the PMIA/PEO-LiTFSI composite polymer electrolyte (CPE) membranes also show much higher mechanical strength (2.96 MPa), thermostability (419 °C) and interfacial stability against Li dendrites (468 h at 0.10 mA cm‒2) than the pristine electrolyte (0.32 MPa, 364 °C and short circuit after 246 h). Furthermore, the CPE-based LiFePO4/Li cells exhibit superior cycling stability (137 mAh g−1 with 93% retention after 100 cycles at 0.5 C) and rate performance (123 mAh g−1 at 1.0 C). This work provides a novel and effective CPE structure design strategy to achieve comprehensively-upgraded electrolytes for promising solid-state battery applications.

Probing the Dynamics of Li+ Ions on the Crystal Surface: A Solid-State NMR Study.

Polyethylene oxide-based solid polymer electrolytes (SPEs) are of research interest because of their potential applications in all-solid-state Li+ batteries. However, despite their advantages in terms of compatibility with the electrodes and easy processing, polyethylene oxide (PEO)/Li+ complexes often suffer from low conductivity at room temperature. Understanding the conduction mechanism and, in turn, developing strategies to improve the conductivity have long been the main objectives underlying research into PEO/Li+ complex electrolytes. Here, we prepared several special PEO/Li+ complex samples where the PEO/Li+ complex structures were located on the surfaces of PEO crystals and consisted of high content chain ends. We found two different Li+ species in the PEO/Li+ complex structures via solid-state nuclear magnetic resonance (NMR). The 2D 7Li exchange NMR showed the exchange process between the different Li+ species. The exchange dynamics of the Li+ ions provide a molecular mechanism of the Li+ transportation in the surface of PEO crystal lamella, which is further correlated with the ionic conduction mechanism of the PEO/Li+ complex structure.

Comprehensively-upgraded polymer electrolytes by multifunctional aramid nanofibers for stable all-solid-state Li-ion batteries

Satisfactory ionic conductivity and mechanical stability are the prerequisites for the applications of solid polymer electrolytes in Li-ion batteries. Herein, by using aramid nanofibers (ANFs) as multifunctional nano-additives, comprehensively-upgraded polyethylene oxide (PEO)-LiTFSI electrolytes with 3D ANF network frames are achieved through the hydrogen-bond interactions between the 1D ANFs. The hydrogen-bond interactions between the ANFs and the PEO chains and TFSI‒ anions can greatly prevent the ANF agglomeration, suppress the PEO crystallization, facilitate the LiTFSI dissociation, and prolong the ion transport paths at the 3D ANF framework/PEO-LiTFSI interfaces. Thus, the ANF-modified electrolytes show superior room-temperature conductivity of 8.8 × 10−5 S cm−1. The ANF-containing composite electrolytes also display greatly-enhanced mechanical strength, thermostability, electrochemical stability and interfacial resistance against Li dendrites, attributed to the 3D ANF framework. In consequence, the composite electrolyte-based LiFePO4/Li cells exhibit better rate performance and cycling stability (e.g., 135 mAh g−1 after 100 cycles at 0.4 C). This work offers a novel and effective strategy to comprehensively upgrade polymer electrolytes by employing organic nanofillers in the composite electrolyte design and revealing the ion transport mechanism for promising all-solid-state Li-ion battery applications.

High performance all-solid-state sodium batteries actualized by polyethylene oxide/Na2Zn2TeO6 composite solid electrolytes

To address sluggish kinetics of ions in all-solid-state sodium batteries, composite solid electrolytes (CSEs), i.e. polyethylene oxide (PEO) with dispersed Ga doped-Na2Zn2TeO6 (NZTO) particles, and a nanostructured Na2V3(PO4)3 cathode are applied to assemble batteries. The conductivity of the PEO/NZTO CSE is increased by a factor of ~40 from 1 × 10−6 S cm−1 to 4 × 10−5 S cm−1 at 30 °C and 1 × 10−3 S cm−1 at 80 °C, due to the high conductivity of doped-NZTO and the suppressed crystallization of PEO. In addition, CSEs own excellent thermal and electrochemical stabilities, and are more resistant to the penetration of sodium dendrites. The CSE allying with nanostructured Na2V3(PO4)3 confers upon the all-solid-state sodium battery an initial discharge capacity of ~106 mA h g−1 (99 mA h g−1 after 100 cycles) at 0.2C and 80 °C, remarkably better than those of the batteries using the PEO:NaTFSI electrolyte.

Semi-Interpenetrating Networks for All-Solid-State Lithium Metal Batteries

In the past two decades, exponentially growing markets of mobile consumer electronics and electric vehicles caused an increasing demand towards higher energy and power density in energy storage technologies. Aiming to overcome the intrinsic limitations of state of the art liquid organic carbonate-based electrolytes with regard to higher energy densities and cost efficient cells solid state electrolytes are a promising topic of research. Enabling not only the use of electrolyte layers in the range of a few micrometers and a reduction of needed security features of the cell housing, but also the utilization of lithium metal as anode. Besides the prominent classes of oxidic ceramic and sulfidic glassy electrolytes, the class of lithium ion conducting polymer electrolytes comprises a large variety of different subclasses. The subclass of semi-interpenetrating networks (s-IPNs) defines a combination of at least two polymer networks penetrating each other without a covalent bonding between the different polymer species. Thanks to its excellent interface wetting ability, processability and lithium metal compatibility, polyethylene oxide (PEO) was selected as lithium ion conducting polymer.[1] This combination of different polymer types allows the tailoring of vital physicochemical and electrochemical properties of the resulting s-IPN membranes. Possible benefits of a second interwoven polymer matrix refer to the reduction/suppression of PEO crystallization inside of confinements, thus allowing the utilization of polymer membranes at ambient temperature, an enhanced mechanical stability of thin film membranes compared to single polymer materials and the improved homogeneity of lithium precipitation by a more defined interface structure.[2] Depending on the preparation route of the s-IPN, not only the polymer itself but also the polymer interfaces can be tuned selectively by introduction of, for example, highly hydrophobic substances like siloxanes, which tend to accumulate at the membrane surfaces.[3] The prepared s-IPN membranes in this work were investigated by means of selected thermal, electrochemical and spectroscopy techniques including differential scanning calorimetry, galvanostatic and potentiostatic experiments as well as impedance spectroscopy. This work aims for an economic approach to tailor vital physicochemical properties of s-IPN electrolyte membranes by utilization of PEO as lithium ion conductor and lithium metal as anode material using a single-step solution casting synthesis route towards advanced all-solid-state lithium metal batteries.

Composite polymer electrolytes based on electrospun thermoplastic polyurethane membrane and polyethylene oxide for all‐solid‐state lithium batteries

AbstractTo improve the electrochemical properties and enhance the mechanical strength of solid polymer electrolytes, series of composite polymer electrolytes (CPEs) were fabricated with hybrids of thermoplastic polyurethane (TPU) electrospun membrane, polyethylene oxide (PEO), SiO2 nanoparticles and lithium bis(trifluoromethane)sulfonamide (LiTFSI). The structure and properties of the CPEs were confirmed by SEM, XRD, DSC, TGA, electrochemical impedance spectroscopy and linear sweep voltammetry. The TPU electrospun membrane as the skeleton can improve the mechanical properties of the CPEs. In addition, SiO2 particles can suppress the crystallization of PEO. The results show that the TPU‐electrospun‐membrane‐supported PEO electrolyte with 5 wt% SiO2 and 20 wt% LiTFSI (TPU/PEO‐5%SiO2‐20%Li) presents an ionic conductivity of 6.1 × 10−4 S cm−1 at 60 °C with a high tensile strength of 25.6 MPa. The battery using TPU/PEO‐5%SiO2‐20%Li as solid electrolyte and LiFePO4 as cathode shows an attractive discharge capacity of 152, 150, 121, 75, 55 and 26 mA h g−1 at C‐rates of 0.2C, 0.5C, 1C, 2C, 3C and 5C, respectively. The discharge capacity of the cell remains 110 mA h g−1 after 100 cycles at 1C at 60 °C (with a capacity retention of 91%). All the results indicate that this CPE can be applied to all‐solid‐state rechargeable lithium batteries. © 2018 Society of Chemical Industry

Highly selective multi-block poly(ether-urea-imide)s for CO2/N2 separation: Structure-morphology-properties relationships

Polyethylene oxide (PEO)-containing multi-block copolymers are good candidates for CO2 membrane separations because of their strong affinity for CO2 but PEO crystallization and weak mechanical properties are two limitations to be overcome at high PEO content. In this work, PEO block incorporation within new linear multi-block copolymers avoided PEO crystallization. The copolymers consisted in Jeffamine soft blocks (SB) and particularly stiff urea-imide hard blocks for improved physical cross-linking and excellent film-forming ability. Varying the SB content from 41 to 70 wt% led to different copolymer physical properties, morphology and CO2 permeation properties. The copolymer with the lowest SB content was a rigid glassy material with very weak phase separation. Its soft and hard blocks formed large interpenetrated domains, resulting in low CO2 permeability (2 Barrer) but extreme selectivity (αCO2/N2 = 207) for CO2/N2 separation at 2 bar and 35 °C. CO2 permeability greatly improved with the SB content due to strong phase separation. The copolymer with the highest SB content was a thermoplastic elastomer with soft blocks forming well-separated highly permeable percolating nano-domains. Its CO2 permeability (57 Barrer) and high selectivity (αCO2/N2 = 50) are among the best properties reported for PEO-containing multi-block copolymers for CO2 capture.

Synthesis and properties of ionic conduction polymer for anodic bonding

Abstract In this study, powders of polyethylene oxide (PEO) and lithium perchlorate (LiClO 4 ) were used as the raw materials for producing the ionic conduction polymer PEO–LiClO 4 with different complex-ratios and used for anodic bonding through high energy ball milling method, and meanwhile, X-ray diffraction, differential scanning calorimetry (DSC), ultraviolet absorption spectrum test analysis, and other relevant methods were adopted to research the complexation mechanism of PEO and LiClO 4 and the impact of the ionic conduction polymer with different complex-ratios on the anodic bonding process under the action of the strong static electric field. The research results showed that the crystallization of PEO could be effectively obstructed with increased addition of LiClO 4 , thus increasing the content of PEO–LiClO 4 in amorphous area and continuously improving the complexation degree and the room-temperature conductivity thereof, and that the higher room-temperature conductivity enabled PEO–LiClO 4 to better bond with metallic aluminum and have better bonding quality. As the new encapsulating material, such research results will promote the application of new polymer functional materials in micro-electro-mechanical system (MEMS) components.