Polymer Segmental Motion Research Articles

Organic Cationic-Coordinated Perfluoropolymer Electrolytes with Strong Li+-Solvent Interaction for Solid State Li-Metal Batteries.

The practical application of solid-state polymer lithium-metal batteries (LMBs) is plagued by the inferior ionic conductivity of the applied polymer electrolytes (PEs), which is caused by the coupling of ion transport with the motion of polymer segments. Here, solvated molecules based on ionic liquid and lithium salt with strong Li+-solvent interaction are inserted into an elaborately engineered perfluoropolymer electrolyte via ionic dipole interaction, extensively facilitating Li+ transport and improving mechanical properties. The intensified formation of solvation structures of contact ion pairs and ionic aggregates, as well as the strong electron-withdrawal properties of the F atoms in perfluoropolymers, give the PE high electrochemical stability and excellent interfacial stability. As a result, Li||Li symmetric cells demonstrate a lifetime of 2500 h and an exceptionally high critical current density above 2.3 mA cm-2, Li||LiFePO4 batteries exhibit consistent cycling for 550 cycles at 10 C, and Li||uncoated LiNi0.8Co0.1Mn0.1O2 cells achieve 1000 cycles at 0.5 C with an average Coulombic efficiency of 98.45 %, one of the best results reported to date based on PEs. Our discovery sheds fresh light on the targeted synergistic regulation of the electro-chemo-mechanical properties of PEs to extend the cycle life of LMBs.

Phase behavior of rubber and supercritical CO2: Operating parameters and swelling characteristics

AbstractThis study aims to compare the difference in the swelling process between styrene butadiene rubber (SBR) and natural rubber (NR) in ScCO2. A high‐pressure visual stainless‐steel autoclave was used to carry out swelling measurements based on the sample dimensions. The swelling rates for both rubbers followed a first‐order kinetic model. The diffusion coefficient for CO2 was determined from the change in the swelling degree with time. The shrinking process for the expanded rubber obeyed a second‐order kinetic model. A 2‐level full factorial experimental design was employed to discuss the influence of variables on rubber swelling and CO2 diffusion. Temperature and pressure were found to have a great influence on the equilibrium swelling degree, swelling rate and diffusion coefficient. For both SBR and NR, the maximum equilibrium swelling degrees were observed at 120°C and 20 MPa, yielding values of 1.18 and 1.16, respectively. The maximum diffusion coefficient reached approximately 3 × 10−9 m2 s−1 for both types of rubber at 120°C and 8 MPa. The crosslink density failed to affect these three responses, but the volume of expansion and the shrinkage rate were found to significantly decrease and increase, respectively, with increasing crosslink density. The motion of polymer segments forced by ScCO2 led to rearrangement of the material structure, which governed the nature of swelling, expansion, and shrinkage. Due to a lower number of entanglements and a weak electrostatic interaction exists between CO2 and the π‐system, SBR can absorb more CO2 and easily restructure than NR under the same conditions, resulting in higher equilibrium swelling degree, larger expansion and faster shrinkage than NR.Highlights Swelling of nature rubber and styrene‐butadiene rubber in ScCO2 is compared. Swelling degree is positively correlated with temperature and pressure. Diffusion coefficient increases with temperature but decreases with pressure. Swelling degree varies with rubber type, while CO2 diffusion dose not. Crosslink density significantly affects expansion and shrinkage of rubber.

Incorporating LLTO ceramic into PVDF/PEO polymer electrolyte for lithium-ion capacitor

Hybrid supercapacitors are a prominent energy storage option for electric vehicles because they have high power and energy densities. Electrolyte plays a major role in hybrid supercapacitor performance. Our report is on a ceramic composite polymer electrolyte made from poly (vinylidene fluoride) (PVDF)/poly (ethylene oxide) (PEO)/ Lithium Lanthanum titanate (LLTO), which we analyzed for its structure, thermal behavior, and electrical characteristics. The different weight percentages (10 wt%, 20 wt%, 30 wt% and 40 wt%) of LLTO were incorporated into the PVDF/PEO polymer blends to study the performance of the electrolyte by FTIR, microscopic analysis, TGA, and impedance spectroscopy. Based on the results, 40 wt% of LLTO containing CPE showed high liquid electrolyte uptake behaviour (275 %) and a high ionic conductivity value (3.94 mS/cm). In addition, incorporating LLTO affects the PVDF/PEO polymer backbone and enhances the amorphicity of polymer blends. This result enhances the polymer segmental motion and reduces the relaxation time. We fabricated hybrid supercapacitor coin cells using 10 wt% and 40 wt% of LLTO containing composite polymer electrolyte and tested them. The 40 wt% LLTO-containing CPE-based hybrid supercapacitor possesses a high specific capacitance value (182F/g) and a long cycle life (upto10000 cycles).

Lamellar Ionenes with Highly Dissociative, Anionic Channels Provide Lower Barriers for Cation Transport.

Solid polymer electrolytes have the potential to enable safer and more energy-dense batteries; however, a deeper understanding of their ion conduction mechanisms, and how they can be optimized by molecular design, is needed to realize this goal. Here, we investigate the impact of anion dissociation energy on ion conduction in solid polymer electrolytes via a novel class of ionenes prepared using acyclic diene metathesis (ADMET) polymerization of highly dissociative, liquid crystalline fluorinated aryl sulfonimide-tagged ("FAST") anion monomers. These ionenes with various cations (Li+, Na+, K+, and Cs+) form well-ordered lamellae that are thermally stable up to 180 °C and feature domain spacings that correlate with cation size, providing channels lined with dissociative FAST anions. Electrochemical impedance spectroscopy (EIS) and differential scanning calorimetry (DSC) experiments, along with nudged elastic band (NEB) calculations, suggest that cation motion in these materials operates via an ion-hopping mechanism. The activation energy for Li+ conduction is 59 kJ/mol, which is among the lowest for systems that are proposed to operate via an ion conduction mechanism that is decoupled from polymer segmental motion. Moreover, the addition of a cation-coordinating solvent to these materials led to a >1000-fold increase in ionic conductivity without detectable disruption of the lamellar structure, suggesting selective solvation of the lamellar ion channels. This work demonstrates that molecular design can facilitate controlled formation of dissociative anionic channels that translate to significant enhancements in ion conduction in solid polymer electrolytes.

Solid polymer electrolytes: Ion conduction mechanisms and enhancement strategies

Solid polymer electrolytes (SPEs) possess comprehensive advantages such as high flexibility, low interfacial resistance with the electrodes, excellent film-forming ability, and low price, however, their applications in solid-state batteries are mainly hindered by the insufficient ionic conductivity especially below the melting temperatures, etc. To improve the ion conduction capability and other properties, a variety of modification strategies have been exploited. In this review article, we scrutinize the structure characteristics and the ion transfer behaviors of the SPEs (and their composites) and then disclose the ion conduction mechanisms. The ion transport involves the ion hopping and the polymer segmental motion, and the improvement in the ionic conductivity is mainly attributed to the increase of the concentration and mobility of the charge carriers and the construction of fast-ion pathways. Furthermore, the recent advances on the modification strategies of the SPEs to enhance the ion conduction from copolymer structure design to lithium salt exploitation, additive engineering, and electrolyte micromorphology adjustion are summarized. This article intends to give a comprehensive, systemic, and profound understanding of the ion conduction and enhancement mechanisms of the SPEs for their viable applications in solid-state batteries with high safety and energy density.

Composite electrolyte with polyethylene oxide and metal–organic framework for lithium‐ion conduction

AbstractPolyethylene oxide based solid polymer electrolytes (SPEs) are safer alternatives to the current flammable liquid electrolytes used in lithium‐ion batteries. Lithium ions are typically thought to conduct through the amorphous regions of SPEs with the aid of polymer segmental motion, which is correlated with the glass transition temperature (Tg). The ionic conductivity is generally increased by making the polymer more flexible (decreasing Tg) and/or by increasing the amorphous regions of the SPE, at the cost of compromising its stiffness. This trade‐off makes it impossible to optimize both ionic conductivity and stiffness of SPEs. By incorporating a metal–organic framework (MOF) nanowhisker with the composition EO:Li = 6:1 [EO = ether oxygen, Li = lithium], we synthesized a unique composite electrolyte. We observed an atypical conductivity mechanism in this composite electrolyte, where lithium ions conduct through the crystalline regions without decreasing Tg or increasing amorphous fraction. The room‐temperature ionic conductivity of the 6:1 polymer electrolyte increased by almost 400% when 2 wt% MOF nanowhisker was added. Our results supported the potential of a composite electrolyte, which enables simultaneous improvement in both conductivity and stiffness.

Spectroscopic investigations of solvent assisted Li-ion transport decoupled from polymer in a gel polymer electrolyte

We present here a gel polymer electrolyte, where the Li+-ion transport is completely decoupled from the polymer host solvation and dynamics. A free-standing gel polymer electrolyte with a high volume content (nearly 60%) of xM LiTFSI in G4 (tetraglyme) (x = 1–7; Li+:G4 = 0.2–1.5) liquid electrolyte confined inside the PAN (polyacrylonitrile)-PEGMEMA [poly (ethylene glycol) methyl ether methacrylate oligomer] based polymer matrix is synthesized using a one-pot free radical polymerization process. For LiTFSI concentrations, x = 1–7 (Li+:G4 = 0.2–1.5), Raman and vibrational spectroscopies reveal that like in the liquid electrolyte, the designed gel polymer electrolytes (GPEs) also show direct coordination of Li+-ions with the tetraglyme leading to the formation of [Li(G4)]+. Coupled with the spectroscopic studies, impedance and nuclear magnetic resonance investigations also show that the ion transport is independent of the polymer segmental motion and is governed by the solvated species {[Li(G4)]+}, very similar to the scenario in ionic liquids. As a result, the magnitude of ionic conductivity and activation energies of the gel polymer electrolyte are very similar to that of the liquid electrolyte. The Li+-ion transport number for the GPE varied from 0.44 (x = 1) to 0.5 (x = 7) with the maximum being 0.52 at x = 5.

Interfacial Selective Study on the Gelation Behavior of Aqueous Methylcellulose Solution via a Quartz Crystal Microbalance.

It is important to understand the interfacial structure and physical properties of a polymer material to improve its function. In this study, we used a quartz crystal microbalance (QCM) and neutron reflectivity (NR) measurements to evaluate the viscoelasticity and structure of an aqueous methylcellulose solution near the gold interface. The apparent shear modulus, which was calculated from the complex frequency, was used to assess gelation behavior. The apparent shear modulus determined via the QCM suggested high-frequency rheological properties that reflected the relaxation of skeletal stretching and rotational motion of polymer segments, as well as cooperative motion of the various functional groups. The gelation temperature was found to be lowered at the interface in comparison with that of the bulk. It is suggested that the QCM can evaluate the shear modulus accompanying the gelation near the interface. The interfacial segregation on the gold substrate caused by the surface free energy and long-range van der Waals interaction was observed from NR measurements.

EIS and FTIR approaches to study the ion transport parameters and relaxation dynamics of Na+1 ion in SPE based on MC polymer inserted with sodium salt

In this work deep insights on ion transport parameters based on EIS and FTIR were presented. MC based biopolymer was used as the host material to prepare solid polymer electrolyte (SPE). The XRD equipment was used to study the structural changes happening in the SPE films upon addition of various rate of NaSCN salt. The polymer-salt interactions were observed from the shifting and changing of intensity of FTIR transmittance peaks. The EIS plots were fitted with EECs to detect the electrical properties of the films. Transport parameters including number density (n), mobility (μ) and diffusion coefficient (D) were evaluated using impedance and FTIR methodologies. The percentage of free ions was found to influence the transport parameters utilizing FTIR approach. The maximum DC conductivity of 3.6 × 10−6 Scm−1 was obtained for the MC film incorporated with 40 wt% of NaSCN salt. The temperature variation of DC conductivity follows Arrhenius behavior model. The dielectric properties of the films were studied at ambient temperature. The effects of temperature on dielectric properties were examined on the highest conducting sample. The relaxation processes were analyzed in terms of loss tangent and electric modulus. Broad peaks of M'' pattern and tanδ plot are marks for non-Debye type relaxation of Na+ ions. The ion conduction mechanisms as a complicated subject in SPEs were focused in this work. The noticeable results achieved from the dielectric properties and electric modulus indicated the coupled motion between cations of the dissolved salt and polymer segmental motions. The transport of ions followed Arrhenius model in which polymer chains assist ion jumping.

Ionic conductivity study of Camphor Sulphonic Acid doped PMMA-PVC blends as polyelectrolyte

Blends of PMMA and PVC were synthesized using film cast and doped with Camphor Sulphonic Acid (CSA). In order that the mechanical properties do not deteriorate, plasticizers were not added. The amorphous nature of the doped samples was confirmed through XRD and ac electrical conductivity of these blends was studied as a function of frequency in the range 100 Hz to 1 MHz at eight different temperatures from 30 °C to100 °C. The nonlinearity observed indicates that the ion transport in polymer electrolyte is dependent on polymer segmental motion. The slight increase in conductivity with temperature was due to the hopping mechanism between the coordinating sites and the linear variation of conductivity with frequency for all the temperatures and the samples and was attributed to the polarization of electrodes.

Dielectric Study of Gel Polymer Electrolyte Based on PVA-K2CO3-SiO2

In this study, effect of filler (SiO2) on dielectric and electrical properties of gel polymer electrolyte (GPE) based on PVA-K2CO3 has been investigated and reported. The electrolyte were prepared by incorporating silica particle as a filler into the un-plasticized electrolyte (PVA-K2CO3). The prepared electrolyte were characterized physicochemically (FTIR) and electrochemically based on electrochemical impedance spectroscopy (EIS). Based on the impedance spectroscopy, complex permittivity (ε*) (dielectric constant and loss) and complex electrical modulus (M*) (real and imaginary modulus) were calculated. Characterization result indicate that SiO2 particles has successfully interacts with PVA-K2CO3 in the form of a three dimensional polymeric network. At low frequencies, high values of complex permittivity (dielectric constant and dielectric loss) were observed, which increased with increasing temperature, signifying an increase in ionic conductivity of the electrolyte. With the incorporation of filler, the peaks of both ε* and M* shifts towards higher frequency side suggesting the speed up the relaxation time. From the electrical modulus, the developed electrolyte is shown to be highly capacitive in nature. Based on the peak shape of the imaginary part of electric modulus, the non-Debye type relaxation predicted. Analysis of both dielectric permittivity and electrical modulus suggest that ionic and polymer segmental motions are strongly coupled. An optimum ionic conductivity of 3.25 × 104 mScm1 was achieved at ambient temperature at a composition of 15 wt.% SiO2 (PKS15).

Solid Polymer Electrolytes from Copolymers Based on Vinyl Dimethyl Phosphonate and Vinylidene Fluoride

AbstractSolid polymer electrolytes are prepared by mixing various amounts of lithium bis(trifluoromethanesulfonyl)imide with poly(vinylidene fluoride‐co‐vinyl dimethyl phosphonate) statistical copolymers with different compositions. Such copolymers are obtained by conventional radical copolymerization of vinylidene fluoride (VDF) with vinyl dimethyl phosphonate (VDMP) initiated by peroxides. A morphological study of the obtained solid polymer electrolytes (SPEs) shows that only samples prepared from the copolymer with the lower amount of VDMP (16 mol%) result in the formation of homogeneous electrolytes while aggregates of lithium salts are observed for the other copolymers. The best ionic conductivity values are accordingly observed for the copolymers with the lower VDMP amount and are reaching 5 × 10−3 mS cm−1 at 100 °C. The dependence of the ionic conductivity versus temperature suggests that the ionic conductivity is controlled by the motion of polymer segments. Indeed, the ionic conductivity can be increased by adding a small amount of trimethylphosphate plasticizer and can reach 1.9 × 10−2 mS cm−1 at 20 °C. Finally, the prepared SPEs exhibit a high electrochemical stability and a good resistance to flame because of the presence of fire‐retardant phosphate groups in their structure.

Ionic Transport Properties in Sulfone-Based Solid Polymer Electrolytes

Solid polymer electrolytes (SPEs) consist of polymers and metal salts, which are safer than liquid electrolytes owing to non-leakage of electrolytes. They have many practical advantages compared with inorganic solid electrolytes; for instance, flexibility and processability. However, SPEs have several challenges: low ionic conductivity and Li+ transference number. Typical SPEs such as a polyethylene oxide (PEO)-based electrolyte show low ionic conductivity of ~10−5 S cm−1 and low Li+ transference number of ~ 0.2 at room temperature 1, 2. Therefore, it is essential to design novel SPEs with high ionic conductivity and Li+ transference number for practical battery applications.Recently, our group has focused on highly concentrated liquid electrolytes and found that sulfolane (SL)-based molten Li salt solvates show high Li+ transference number (0.7 ~ 0.8) via Li+ hopping/exchange conduction mechanism 3. In the SL-based electrolytes, oxygen atoms of the sulfone groups coordinate to two different neighbouring lithium cations to form a unique chain-like Li+ coordination structure, which enables predominant Li+ hopping/exchange conduction between the coordination sites. This was considered to accelerate Li+ transport and result in the high Li+ transference number despite relatively high viscosity of the electrolytes.Here, we expect that high Li+ transference number can be achieved in SPEs containing the sulfone moieties similar to the SL-based molten Li salt solvates. In this study, we attempted to incorporate the sulfone groups into the polymer side chains to achieve high Li+ transference number. Thermal, ionic transport and electrochemical properties of the prepared sulfone-based SPEs were investigated. We synthesised poly(3-acryloyl sulfolane) (PASL) containing the sulfone groups into the side chains of polyacrylates as polymer matrix of SPEs and prepared two types of SPEs: Li[TFSA] (lithium bis(trifluoromethanesulfonyl)amide)/PASL = 1:2 and Li[TFSA]/PASL/SL = 1:1:1. Li[TFSA]/PASL was prepared by mixing Li[TFSA] and PASL at a molar ratio of 1:2 using DMF (N,N-dimethylformamide) as co-solvent followed by vacuum drying for five days. Li[TFSA]/PASL/SL was prepared by mixing equimolar amounts of Li[TFSA], PASL and SL.In addition to ionic conductivity, we have also evaluated Li+ transference number in these electrolytes by the potentiostatic polarization method using a Li metal symmetric cell. 4, 5 As shown in Figure (a), ionic conductivity of Li[TFSA]/PASL/SL is higher than that of Li[TFSA]/PASL. The plasticization of the SPE in the presence of SL molecules resulted in the higher ionic mobility for Li[TFSA]/PASL/SL. The ionic conductivity of Li[TFSA]/PASL at the glass transition temperature (T g : 45 °C) was 3.9×10−8 S cm−1 and that of Li[TFSA]/PASL/SL(T g : −45 °C) was 1.7×10−14 S cm−1. The ionic conductivity at T g of Li[TFSA]/PASL is much higher than that of PEO-based polymer electrolytes of about 10−14 S cm−1 as well as that of Li[TFSA]/PASL/SL. Ionic conduction behavior in SPEs can be discussed in terms of coupling/decoupling of Li+ conduction with/from polymer segmental motions 1. In the coupling system, ionic motions are coupled with the segmental motions of polymer chains and therefore ionic conductivity becomes very low at T g (~10−14 S cm−1). On the other hand, in the decoupling system, the ionic motions is decoupled from the polymeric motions, and ionic conductivity at T g is higher than that in the coupling system. Whilst Li+ conduction is dominated by the polymeric segmental motions in PEO-based electrolytes, Li[TFSA]/PASL can be classified as the decoupling system owing to its much higher ionic conductivity at T g of ~10−8 S cm−1. Li+ transference number of Li[TFSA]/PASL/SL was found to 0.75 at 80 °C, which is higher than that of PEO-based polymer electrolytes (t Li = 0.2 at 70 °C). This suggests that the unique Li+ hopping/exchange mechanism contributes to ionic conduction in the solfone-containing SPE as well as a SL-based molten Li salt solvates.References Seki et al., J. Phys. Chem. B 2005, 109, 3886-3892.Rosenbach, et al., ACS Appl. Energy Mater. 2019, 2, 3373-3388Dokko et al., J. Phys. Chem. B, 2018, 122, 47, 10736-10745.G. Bruce et al., Solid State Ionics, 1988, 28-30, 918-922.Watanabe et al., Solid State Ionics, 1988, 28-30, 911-917. Figure 1

Ion Transport in Solvated Sodium-Ion Conducting Gel Polymer Electrolytes

Single ion conducting gel polymer electrolytes (GPEs) are characterized as having a certain amount of ionic liquid or solvent incorporated into a single ion-conducting polymer matrix and may afford the advantages of high conductivity and low electrolyte polarization under battery operation. Single ion conducting polymers often suffer from low conductivity due to their reliance on polymer segmental motion to achieve sufficient ion mobility. However, by incorporating specific solvents into a single ion conducting matrix, mobility of the polymer can be enhanced while still maintaining the advantages of single ion conduction. Although many of the solvents used to swell GPEs are mixtures of flammable organic solvents (such as dimethyl carbonate), there are many potential non-reactive, low vapor pressure solvents that could effectively solvate alkali-ion based GPEs and plasticize the polymer matrix to enhance ion conductivity. Adipate-based solvents are a group of non-volatile plasticizers with low viscosities and low vapor pressures at room temperature derived from adipic acid. The ester groups in these solvents may effectively solvate alkali ions such as Na+, leading to higher conductivity, while circumventing issues of flammability found in current alkali-ion conducting electrolytes. This study investigates the properties of sodium-ion conducting GPEs that have been swollen with varying adipate-based solvents and the subsequent dielectric response from the solvent addition. Dielectric relaxation spectroscopy was used to characterize the Na+ conductivity, static dielectric constant, ion-conducting content, and mobility of the membranes before and after the non-volatile solvent uptake. Understanding this relationship will pave the path toward safer, more efficient solid-state polymer electrolytes for battery applications.

Ionic liquid-based novel polymer electrolytes: electrical and thermal properties

New polymer electrolytes have been prepared from room temperature ionic liquid (IL) and poly(vinylidene fluoride)-hexafluoropropylene copolymer [PVdF-HFP]. The variation of thermal and electrical properties with varying polymer to IL concentration was investigated. The electrolytes had high thermal stabilities. The IL-PVdF-HFP electrolytes were freestanding, flexible films with room temperature conductivities of the order of 10−3 S cm−1. Increase in conductivity was found with increasing IL and also with increasing temperature. Increase in conductivity can be attributed to the fact that with increasing IL amorphicity increases as evident from XRD result. Dielectric studies showed decrease in relaxation time with increasing IL concentration indicating increase in polymer segmental motion which result in increase in conductivity.

Segmented Phosphonium Ionenes As Solid Polymer Electrolytes for Lithium Ion Batteries

All-solid-state lithium ion batteries replace the traditional liquid electrolyte with a conductive solid polymer electrolyte. Replacing the liquid electrolyte in batteries has the potential to improve safe use of batteries without the need for hermetic sealing, extending the operating temperature range, and extending the lifetime of the battery. However, solid polymer electrolytes often have non-competitive conductivity compared to liquid electrolytes. Improving the conductivity of solid polymer electrolytes based on an understanding of structure-property relationships is not yet well understood, but it is believed to depend heavily on the localized segmental motion of polymer chains. This work attempts to describe the role of polymer segmental motion on lithium ion transport through the synthesis and characterization of phosphonium ionenes that include poly(ethylene oxide) “soft” segments. Synthetically, these segmented polymers offer an opportunity to systematically control the segmental motion of polymer chains (i.e. glass transition temperature) through control of PEO incorporation. Prepared by step-growth polymerization, these segmented phosphonium ionenes achieve molecular weights up to 40,000 g/mol. Also, the degradation and glass transition temperatures are dependent on the percent incorporation of PEO as determined by thermogravimetric analysis and differential scanning calorimetry, respectively. The ability to influence the physical properties of this unique class of polyelectrolyte provides a unique opportunity to systematically probe the impact of glass transition temperature on the ion transport properties of solid polymer electrolytes in lithium ion batteries. Our initial results from electrochemical impedance as well as the charge/discharge performance of these novel solid polymer electrolytes in coin cell battery assemblies will also be presented.

High positive temperature coefficient effect of resistivity in conductive polystyrene/polyurethane composites with ultralow percolation threshold of MWCNTs via interpenetrating structure

In this work, a novel interpenetrating system including amorphous polystyrene/polyurethane and multiwall carbon nanotubes (PS/PU-MWCNTs) was in-situ constructed by the homogeneous bulk polymerization. The ultralow percolation threshold (about 0.01 wt%) and high electrical conductivity were achieved owing to the unique conductive networks of MWCNTs in the interconnected “island chain” of PU. Surprisingly, the high positive temperature coefficient (PTC) effect of resistivity of amorphous PS/PU-MWCNTs composites, which was caused by the polymer segment motion, was achieved, such as PTC intensity of six orders of magnitude, fantastic reproducibility and favorable mechanical properties. Finally, this work provided a new promising in the development of excellent PTC materials.

Nanoscale Mapping of Extrinsic Interfaces in Hybrid Solid Electrolytes

Summary Inorganic-organic hybrid solid electrolytes are promising material systems for all solid-state batteries (ASSBs). These electrolytes contain numerous solid | solid interfaces that govern transport pathways, electrode | electrolyte compatibility, and durability. This paper evaluates the role that electrode | electrolyte interfaces and electrolyte structure have on electrochemical performance. Atomic force microscopy techniques reveal how mechanical, adhesion, and morphological properties transform in a series of model hybrid solid electrolytes. These measurements are mapped to sub-surface microstructural features using synchrotron nano-tomography. Hybrid solid electrolytes with shorter polymer chains demonstrate a higher adhesion ( > 100 nN), Young's Modulus (6.4 GPa), capacity (114.6 mAh/g), and capacity retention (92.9%) than hybrid electrolytes with longer polymer chains (i.e., higher molecular weight). Extrinsic interfacial properties largely dictate electrochemical performance in ASSBs. Microstructural control over inorganic constituents may provide a means for tailoring interfacial properties in hybrid solid electrolytes.

Role of Multiferroic Filler on the AC Response of Bi1‐xBaxFeO3 doped PVA:NH4CH3COO Nanocomposite Gel Polymer Electrolytes

AbstractThe frequency dependent AC conductivity and dielectric studies of multiferroic filler (Bi1‐xBaxFeO3) doped nanocomposite gel polymer electrolyte (NCGPEs) based on PVA:(NH4CH3COO) are investigated in the present work. The nano composite gel polymer electrolyte systems are synthesized for various filler concentrations by solution cast method. The effect of filler concentration on ionic conductivity is studied using AC impedance technique in the frequency range 1–106 Hz. X‐ray diffraction studies reveal the formation of nanocomposite gel polymer electrolyte. The low frequency dispersion in the dielectric response of electrolytes shows the relaxation contribution is superimposed with electrode polarization effects. The relaxation peaks in the NCGPEs are found to shift toward higher frequency side with increasing filler concentration and are suitably correlated to change in morphology of the gel electrolyte system. The variation of AC conductivity with frequency is seen to obey Jonscher's universal power law with the exception of small deviation in the low frequency regime. Modulus formalism of dielectric response suggests that the ion transport is strongly coupled to the polymer segmental motion.

Probing Intermittent Motion of Polymer Chains in Weakly Attractive Nanocomposites

In this study, we investigate the motion of polymer segments in polymer/nanoparticle composites by varying nanoparticle (NP) volume fractions. By studying the probability distribution of segment displacement, segment trajectory, and the square displacement of segment, we find the intermittent motion of segments, accompanied with the coexistence of slow and fast segments in polymer nanocomposites (PNCs). The displacement distribution of segments exhibits an exponential tail, rather than a Gaussian form. The intermittent dynamics of chain segments is comprised of a long-range jump motion and a short-range localized motion, which is mediated by the weakly attractive interaction between NP and chain segment and the strong confinement induced by NPs. Meanwhile, the intermittent motion of chain segments can be described by the adsorption-desorption transition at low particle loading and confinement effect at high particle loading. These findings may provide important information for understanding the anomalous motion of polymer chains in the presence of NPs.