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In this Note, the heat-proofing and anti-plasticizing nature of poly(ethylene carbonate) by the addition of a defibered plant (DP) is presented. The DP was obtained via simple wet-milling treatment of water-dispersed Japanese cedar. The presented results encourage us to use plants as functional fillers without a special chemical/biological reaction. In this Note, the heat-proofing and anti-plasticizing nature of poly(ethylene carbonate) by the addition of a defibered plant (DP) is presented. The DP was obtained via simple wet-milling treatment for water-dispersed Japanese cedar. The presented results encourage us to use plants as functional fillers without a special chemical/biological reaction.

In this paper, phase behavior, ionic conductivity, and current-voltage response were evaluated for gels consisting of imogolite nanotubes crosslinked by dicarboxylic acid in ionic liquid to obtain ...

We applied a slide-ring (SR) gel to a Mg2+ ion gel electrolyte and clarified the electrical and mechanical properties in order to achieve a Mg2+ ion gel electrolyte with both sufficient mechanical strength and high ionic conductivity. The SR gel is made from polyrotaxane, which has a structure that consists of cyclic molecules, α-cyclodextrins (CDs), threaded by an axial polymer chain, polyethylene glycol (PEG), and cross-linked by divinyl sulfone. Pure glymes and tetraethylene glycol dimethyl ether (tetraglyme: G4) dissolving Mg2+ ions had no ability to swell the SR gel, whereas diethylene glycol dimethyl ether (diglyme: G2) and triethylene glycol dimethyl ether (triglyme: G3) dissolving Mg2+ ions were able to swell the SR gel. The swelling behavior was strongly dependent on the interaction between Mg2+ ions complexed with glymes and ether oxygens of a PEG-based hydroxypropyl PR (HyPR) network. Upon tensile elongation, SR gel swollen with G3 solution dissolving Mg2+ ions could be extended by 300%, which indicated the unique property of high ductility. The ionic conductivity of SR gel swollen with G3 dissolving Mg2+ ions, which approximately satisfied a Vogel-Tamman-Fulcher (VTF) dependence, was 1.73 mS cm−1 at room temperature, and the molar conductivity was 67% of that for a pristine G3 solution dissolving Mg2+ ions.

Random copolymers of ethylene carbonate (EC) and ethylene oxide (EO) having various EC/EO ratios were synthesized using double metal cyanide catalyst, and their LiFSI electrolytes were prepared. All of the copolymer electrolytes had greater conductivity and lower Tg than the EC homopolymer system, and the copolymer with 53% EO content (LiFSI 120 mol%) exhibited the highest conductivity of 2.9 × 10−4 S cm−1 at 60 °C, with an excellent Li-ion transference number of nearly 0.7. FT-IR measurement showed that the carbonate groups of the copolymer interact preferentially with Li ions without the formation of any stable coordination structure, while free FSI anions decrease and the aggregated ions increase with increasing salt concentration. A Li/LiFePO4 coin cell with copolymer electrolyte having LiFSI 120 mol% had a discharge capacity of approximately 160 mAh g−1 for the first few cycles at 40 °C. Electrochemical impedance spectroscopy measurement on the cell after discharge found two semicircles in the Nyquist diagrams based on the passivation layer and charge-transfer resistance between the electrode and electrolyte gradually increase in size with increasing charge-discharge cycling.

We report an electrochemical study of end-capped glymes dissolving lithium salts as electrolyte solutions for lithium metal batteries. Various electrolyte formulations including triethylene and diethylene glycol dimethyl ethers as solvents and lithium salts employing bis(fluorosulfonyl)imide (FSI−), bis(trifluoromethanesulfonyl)imide (TFSI−), and bis(pentafluoroethanesulfonyl)imide (BETI−) anions are explored. The ion transport properties, the lithium/electrolyte interphase characteristics and the electrochemical stability window are investigated by means of chronoamperometry, electrochemical impedance spectroscopy, galvanostatic cycling, and voltammetry measurements. The comparative study suggests electrochemical properties well suitable for lithium battery application which enable long cycling. The electrolyte solutions are studied in cells using an insertion cathode material, i.e., lithium iron phosphate (LiFePO4), and the high-energy lithium metal anode. The results reveal that the electrolyte composition has a remarkable effect on the cell performances, and indicate the solutions of LiTFSI salt in either glymes as the most adequate formulations for possible applications among the ones herein investigated.

The effect of the melt-quench process on the thermal, structural and mechanical properties of partially miscible poly(ethylene carbonate) (PEC)/poly (lactic acid) (PLA) blends was investigated. The differential scanning calorimetry (DSC) and X-ray diffraction (XRD) measurements found a largely amorphous phase of melt-quenched PEC/PLA blends, with crystallinity in the range 6–12%, depending on the PEC and PLA ratios. The high chain mobility of PEC reduces the cold-crystallization temperature of PLA for the melt-quenched PEC/PLA blends by more 12 °C, as in the PEC60/PLA40 blend. Upon the rapid cooling, however, the morphology of PEC/PLA blend changes to enhance the toughness, especially for the PLA-rich blend. Addition of 10 wt% PEC to PLA slightly improved the tensile toughness, from 5.1 MJ/m3 to 5.5 MJ/m3, in which ductile PEC improves the toughness of PLA. SEM images of the quenched fracture cross-section of melt-quenched PEC/PLA blends confirmed that PEC and PLA are compatible, with a two-phase structure in which small PLA domains are distributed in the continuous PEC phase. This structure is responsible for the high interfacial adhesion in the sea-island morphology of PEC-rich blends, giving improved resistance to failure of PEC.

We study the ion-conductive and electrochemical properties of concentrated poly (ethylene carbonate) (PEC)-based electrolytes with Li salt concentrations greater than 100 mol%. An end-capped PEC having acetate groups (PEC-Ac) was synthesized as a novel polymer matrix for improving the thermal stability and oxidative stability. A concentrated PEC-Ac electrolyte with 120 mol% of LiFSI had a good conductivity of approximately 10−6 S/cm at 40 °C with an excellent Li transference number (t+) of 0.8. Linear sweep voltammetry measurement for the PEC-Ac electrolyte indicates that the oxidation tolerance is more than 5 V, and is greater than that of the original PEC-based electrolyte. A battery test for the LiFePO4 cell using the PEC-Ac electrolyte was conducted for the first time, finding good capacities ranging from 130 to 160 mAh/g and stable cyclability for more than 60 cycles.

Electrochemical and ion-transport properties of polymer blend electrolytes comprising poly(ethylene carbonate) (PEC), poly(trimethylene carbonate) (PTMC) and lithium bis(fluorosulfonyl) imide (LiFSI) were studied in this work, and the electrolyte with the best blend composition was applied in all-solid-state Li batteries. The ionic conductivity of both PEC and PTMC single-polymer electrolytes increased with increasing Li salt concentration. All PEC and PTMC blend electrolytes show ionic conductivities on the order of 10−5 S cm−1 at 50 °C, and the ionic conductivities increase slightly with increasing PEC contents. The PEC6PTMC4-LiFSI 150 mol% electrolyte demonstrated better Li/electrolyte electrochemical and interfacial stability than that of PEC and PTMC single-polymer electrolytes and maintained a polarization as low as 5 mV for up to 200 h during Li metal plating and stripping. A Li|SPE|LFP cell with the PEC6PTMC4-LiFSI 150 mol% electrolyte exhibited reversible charge/discharge capacities close to 150 mAh g−1 at 50 °C and a C/10 rate, which is 88% of the theoretical value (170 mAh g−1). Concentrated poly(ethylene carbonate) (PEC) and poly(trimethylene carbonate) (PTMC) blend electrolytes with 150 mol% of LiFSI were prepared and the PEC6PTMC4 electrolyte was applied in all-solid-state Li batteries. The blend electrolyte has an ionic conductivity of 10−5 S cm−1 and a Li+ transference number (t+) of 0.73. Meanwhile, the PEC6PTMC4 electrolyte exhibits a good electrochemical stability with Li electrode than those of PEC and PTMC single-polymer electrolytes. An LFP half-cell exhibits a discharge capacity of 150 mAh g−1 at 50 °C and a C/10 rate.

Thin films of PEC/PLA blend exhibiting improved toughness and biodegradability in alkaline solutions were prepared by a simple solution casting method. With the addition of 50 wt% PEC, the toughness of PEC/PLA blend was improved to a peak value of 45.8 MJ/m3, in contrast to 6.7 MJ/m3 for neat PLA. Young's modulus of PEC/PLA blends at low PEC ratio were fairly similar to that of neat PLA. Addition of more than 40 wt% of PEC enhanced the biodegradability of PLA in alkaline solution. The weight loss of hydrolysed PEC/PLA blends changed non-linearly with the addition of PEC, and depended strongly on PLA crystallinity and the ratio of PEC to PLA. This enhancement was attributed to the high toughness and degradability of PEC/PLA blends induced by partial miscibility, as reported previously.

Solid polymer electrolytes consisting of CO2-derived poly(ethylene carbonate) (PEC), LiPF6, and plasticizers (glycerol or 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide, EMImTFSI) were prepared by a simple casting method, and their dielectric relaxation behavior was evaluated using broadband electric spectroscopy (BES), which clarified the correlation between the polymer motion and ionic conduction. From the DSC and BES results, it was revealed that the addition of plasticizer decreased the glass transition temperature and increased the dc conductivity (σdc) of the PEC electrolyte. The BES results also revealed that the plasticizer increased the segmental motion of PEC and improved σdc, and the plasticizing effect of EMImTFSI on the PEC electrolyte was larger than that of glycerol. From the results of the Walden plot and fragility analysis, it was expected that the degree of decoupling e and fragility m would increase with the addition of plasticizer because these plasticizers weaken the interactions between the PEC chains and Li ions in the electrolyte. Plasticized poly(ethylene carbonate) (PEC)/LiPF6 electrolytes were prepared and evaluated their ion-conductive and dielectric relaxation behavior using broadband electric spectroscopy (BES). The BES results indicated that the plasticizer accelerates segmental motion of PEC and improve the dc conductivity, and the plasticizing effect of ionic liquid (EMImTFSI) on the PEC electrolyte is larger than that of glycerol. From the results of the Walden plot and fragility analysis, it was revealed that the degree of decoupling and the value of fragility increase by the addition of plasticizer, and these plasticizers weaken interactions between PEC chains and Li ions in the electrolyte.

High‐performance lithium‐metal batteries are achieved by using a glyme‐based electrolyte enhanced with a LiNO3 additive and a LiFePO4 cathode. An optimal electrolyte formulation is selected upon detailed analysis of the electrochemical properties of various solutions formed by dissolving respectively lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium bis(pentafluoroethanesulfonyl)imide (LiBETI) either in diethylene glycol dimethyl ether or in triethylene glycol dimethyl ether and by adding LiNO3. A thorough investigation shows evidence of efficient ionic transport, a wide stability window, low reactivity with lithium metal, and cathode/electrolyte interphase characteristics that are strongly dependent on the glyme chain length. The best Li/LiFePO4 battery delivers 154 mAh g−1 at C/3 (1 C=170 mA g−1) without any decay after 200 cycles. Tests at 1 C and 5 C show initial capacities of about 150 and 140 mAh g−1, a retention exceeding 70 % after 500 cycles, and suitable electrode/electrolyte interphases evolution.

Poly(ethylene carbonate) (PEC)-based polymer electrolytes incorporated with magnesium bis(trifluoromethanesulfonyl) imide (Mg(TFSI)2) and triethylene glycol dimethylether (triglyme, G3) were invest...

Magnesium (Mg) electrolytes are presently under investigation for their promising performance capabilities in the next generation of batteries. The present work studies Mg-ion transport in polymers using different types of Mg salts. Polymer electrolytes comprising poly(ethylene carbonate) (PEC) with Mg salts (MgX2; X = TFSI, ClO4) were prepared by solution casting. The structural, thermal, and electrochemical properties of flexible self-standing membranes were studied as potential Mg electrolytes. The impedance results at 90 °C found the highest conductivities of 6.0 × 10−6 S cm−1 for PEC-Mg(TFSI)2, and 5.2 × 10−5 S cm−1 for PEC-Mg(ClO4)2, at 40 mol%. FT-IR measurements revealed changes in the peak fraction from the region of carbonyl group, which explain the interaction with Mg ions. The glass transition temperature of the TFSI system decreased with increasing salt concentration due to the plasticizing effect of TFSI anions. Thermal gravimetric analysis revealed that the highest values of the 5% weight-loss temperature at 40 mol% are 174 °C for PEC-Mg(TFSI)2 and 160 °C for PEC-Mg(ClO4)2. The electrochemical stability of PEC-Mg(TFSI)2 at 40 mol% was up to 2.2 V. To confirm the redox reaction of Mg ions in PEC, CV measurement was carried out using symmetrical cells with quasi Mg electrodes. Cathodic and anodic current peaks were clearly observed, and the presence of these peaks indicates Mg-ion conduction in PEC.

We prepared a ternary composite polymer electrolyte from poly(ethylene carbonate) (PEC), lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) and non-calcined silica nanofibers (SNFs) having 3 average diameters (300, 700, and 1000 nm). The SNF composite electrolytes were obtained as homogeneous, self-standing membranes. The ionic conductivity of PEC/LiTFSI 100 mol% was increased by the addition of SNFs, and the thinner SNFs with average diameter 300 nm were most effective in improving the conductivity. The conductivity was of the order of 10−4 S/cm at 60°C. The lithium transference number of the SNF300 composite was greater than 0.7. Stress-strain curves of the composites indicated significant increases in Young's modulus and maximum stress for the PEC electrolytes. The 5% weight-loss temperature of the composites also improved with the addition of SNF.

We propose using a slide-ring (SR) gel electrolyte to achieve a gel polymer electrolyte with both sufficient mechanical strength and high ionic conductivity. The SR gel is made from polyrotaxane, which has a structure that consists of cyclic molecules, α-cyclodextrins (CDs), threaded by an axial polymer chain, polyethylene glycol (PEG), and cross-linked by divinyl sulfone. The SR gel electrolyte was made from SR gels which were swollen by an electrolyte solution (ES) prepared with lithium salt and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMITFSI). The swelling behavior of SR gel in the ES by the formation of coordination bonds between lithium cations and oxygen atoms on CDs was investigated. The swelling behavior and ionic conductivity of the SR gel swollen with ES had a peak at 0.8 M lithium ion in the ES and the molar conductivity of the SR gel swollen with ES was 85% more than that of pristine ES. The puncture resistance of the SR gel electrolyte was also investigated; the puncture elongation was more than 1000% and the Young’s modulus increased with the lithium ion concentration due to an increase in the coordination bonds between lithium cations and the oxygen atoms on CDs.

Here we found that a small amount of non-deteriorated lignin enhanced the heat-tolerance properties of a synthetic polymer without the need for inorganic, halogen, or phosphorus compounds. Non-deteriorated lignin's radical scavenging properties and its platelet-like nanoparticle shape make it an excellent heatproof filler that is unmatched by conventional heatproof fillers.

A crosslinked poly(tetrahydrofuran) (c-PTHF) was synthesized as a novel polymer matrix for gel polymer electrolyte (GPE) swelled with Mg(TFSI)2/triglyme solution to develop Mg-ion battery. Two GPE based on c-PTHF with different crosslinking structure and crosslinker ratio were obtained as free-standing membranes with excellent heat resistance. From the CV measurement, the Pt/GPE/AZ31 cell clearly showed Mg redox reaction, and the values of current densities in reduction/oxidation peaks and the Coulombic efficiency were larger than those of the triglyme electrolyte solution. This may be due to the changes in the solvation structure of Mg2+ ions by the presence of crosslinking structures in the network framework.

Ion-conductive polymer electrolytes are remarkable materials that have recently been proposed for use as flexible solid electrolytes in next-generation energy storage devices. In particular, the author has proposed the synthesis of novel polymer electrolytes with very high ionic conductivities and the essential properties of polymeric materials. This review describes the synthesis of alternating copolymers of CO2 with epoxides and their application as novel ion-conductive polymers in the place of typical polyether-based systems. The Li salt electrolytes of poly(ethylene carbonate) (PEC) and of other polycarbonates with different side groups exhibit unique ion-conductive properties, such as increasing conductivity with higher salt concentrations, very high Li transference numbers and good electrochemical stability. The Li-ion conductivity of a PEC-lithium bis(fluorosulfonyl)imide LiFSI electrolyte was estimated to be greater than 10−4 S cm−1, and excellent battery performance of this material was also demonstrated at room temperature. In this focus review, alternating copolymers of carbon dioxide with epoxides have been synthesized and studied as novel ion-conductive polymers. The Li salt electrolytes of poly(ethylene carbonate) (PEC) and of other polycarbonates having different side groups exhibited remarkable ion-conductive properties including the following: increased conductivity with increasingly higher salt concentrations, very high values for the Li+ transference number, and good electrochemical stability. The Li-ion conductivity of a highly concentrated PEC-LiFSI electrolyte was estimated to be greater than 10−4 S cm−1, and excellent battery performance was demonstrated at room temperature.

We report preparation and improvement in photovoltaic performance of N719-based dye-sensitized solar cells (DSSCs) using pressurized carbon dioxide (CO2) as a co-solvent for the absorption process on the TiO2 photoelectrode surface. Effective absorption of the N719 molecules on the TiO2 surface was achieved using CO2 processing, and the absorption time was shortened drastically from 24 h (in the dip process) to less than 3 h. The cells prepared under pressurized CO2 for the absorption showed greater photovoltaic performance, especially higher short-circuit current density and conversion efficiency, compared with that from typical dip method. It was revealed that the suitable CO2 pressure for the absorption was 5 MPa and the efficiency was achieved to be more than 7.5 %. Prevention of back electron transfer reactions from TiO2 to oxidized dyes or iodides was caused currently, because the homogeneous coverage of N719 molecules on the TiO2 surface was obtained by the use of pressurized CO2.

To study the ion-conductive and dielectric properties of polymer electrolytes based on poly(ethylene carbonate) (PEC) with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), the complex permittivity and conductivity were measured using broadband dielectric spectroscopy. The temperature dependence of the relaxation frequency and ionic conductivity for PEC-LiTFSI electrolytes (1 – 200 mol%) indicates that the segmental motion of PEC chains decreases with the addition of just 1 mol% of Li salt and increases with increasing concentration above 10 mol%. According to the Walden rule for PEC-based electrolytes, the value of deviation from the reference line increased, and the fragility and decoupling exponents decreased with increasing salt concentration. These results indicate that there are large numbers of ion pairs and aggregated ions, which imply low ionicity and reduced fragility in highly concentrated PEC-based electrolytes. Copyright © 2016 John Wiley & Sons, Ltd.

Solid polymer electrolytes are important materials in realizing safe and flexible energy storage devices. The present study looks at correlation between solvation structure and the ion-conductive behavior of poly(ethylene carbonate) (PEC)/lithium bis(fluorosulfonyl)imide (LiFSI) electrolytes which have high Li transference number (t+) and show unusual salt-concentration dependence of conductivity. From FT-IR and Raman spectroscopy, we determined that Li ions interact with carbonyl (C═O) groups and also with FSI ions, which can be referred to as contact ion pair or aggregate. 7Li magic-angle-spinning NMR spectroscopy and density functional theory calculations for model species suggest that a loose coordination structure, in which Li ions interact with C═O groups and FSI ions with appropriate strength, allows the electrolytes to have both reasonable conductivity and high t+ with a flexible and transparent character. A high salt dissociation rate is generally considered essential in SPEs, but the presence of...

We have synthesized polycarbonates having oxyethylene (OE) end groups from alternating copolymerization of CO 2 with glycidyl ether monomers, and studied the effect of OE length on the ion-conductive properties of electrolytes with lithium bis-(fluorosulfonyl) imide (LiFSI). Polycarbonate-based electrolytes exhibited obvious dependence of the ion-conductive behavior on the salt concentration; the conductivity of PEtGEC (polycarbonate possessing ethoxy side groups) electrolyte increased with increasing salt concentration, and the conductivity of PME1C (polycarbonate possessing 2-methoxyethoxy side groups) and PME2C (polycarbonate possessing 2-(2-methoxy)ethoxy side groups) electrolytes decreased at low salt concentration but then increased dramatically with increasing concentration. PME2C-LiFSI (376 mol%) had the greatest conductivity of all the electrolytes. We also measured the Li transference numbers ( t Li+ ) of polycarbonate-based electrolytes; the values of t Li+ for LiFSI electrolytes (188 mol%) decreased with increasing number of OE chains. This indicates that dissociated Li ions are trapped and that migration is inhibited by the OE side groups. For the PEtGEC electrolyte, t Li+ was very high, more than 0.7, because the polymer has only one ether oxygen atom in the side chain, making it difficult to form stable solvation structures. This study suggests a new polymer matrix combining ether units to give high conductivity at low salt concentrations with a carbonate main chain for high t Li+ .

In this paper, we reveal a synthetic polymer heatproofing mechanism of a lignin derivative extracted by simultaneous enzymatic saccharification and comminution (hereafter referred to as “SESC lignin”). First, the prevention of back-biting on the thermal degradation of poly(ethylene carbonate) by SESC lignin is experimentally verified via chromatograph/spectroscopic approaches. Second, we explore the applicable scope (e.g., the limiting temperature) of SESC lignin as a heatproof filler by comparing the heatproof properties of a conventional heat stabilizer and SESC lignin. Finally, we confirm that the combination of “preferential pyrolysis” and “radical scavenging” of SESC lignin induces its synthetic polymer heatproof properties, which can be determined using thermochemical/kinetical approaches.

A composite electrolyte consisting of polyethylene-glycol dimethyl-ether (MW 2000 g mol-1), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) conducting salt, lithium nitrate (LiNO3) film-forming additive, and nanometric silica (SiO2) filler, is herein obtained by a scalable solvent casting pathway and thoroughly investigated for application in lithium metal polymer battery. Structure and morphology of the electrolyte are investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively, while its electrochemical features are revealed by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), chronoamperometry, and galvanostatic cycling tests in lithium cell. The room-temperature structure of the composite electrolyte reflects the combination into a complex of the membrane components, while its morphology appears smooth with uniform distribution of salts and ceramic. The electrolyte shows an ionic conductivity over 10-4 S cm-1 above 40 °C promoted by repeated heating and cooling, lithium transference number ranging from 0.22 at 45 °C to 0.27 at 70 °C, low interphase resistance and polarization in lithium cell, and an electrochemical stability window extending above 4.4 V. These optimal features allow the membrane to operate in a lithium cell with LiFePO4 cathode at 50 °C, with specific capacity exceeding 150 mAh g-1 and coulombic efficiency approaching 100% over prolonged cycling. Figure 1

Poly(ethylene carbonate)/poly(lactic acid) blends were successfully prepared by means of a solution film-casting method, and their physicochemical properties were investigated. PEC/PLA blends exhibit partial miscibility and are characterized by the interaction of the ester and carbonic ester groups. One such interaction is between partial charges in –C–O– in –O–C=O of PLA and the carbonyl –C=O of PEC. Another is between –C–O– in –O–C=O of PLA and –C–O– in –CH2–O– of PEC. The value of Tg varies by more than 10 °C across the blends. PEC does not significantly influence the melting temperature of neat PLA, but non-spherical spherulites are formed in PEC-rich blends, whereas the spherulites are spherical with an average size of 30 μm in PLA-rich blends. Crystallization of PLA is influenced by the addition of flexible PEC and by the proportion of PLA in the blends. Interestingly, addition of at least 10 wt% PLA increased Tg, with a crystallinity, Xc of 47% and better thermal degradation properties, with the temperature at 5 wt% weight loss (Td5) more than 30 °C higher than for neat PEC.

Ion-conductive elastomer blends of commercial acrylonitrile-butadiene rubbers (NBR) rubber with polyether-based electrolyte were prepared as potential antistatic materials. Polyether-based electrolytes are usually very sensitive to humidity, because the electrolyte consists of hydrophilic polyether and metal salt. Here, we generated a nano-ordered phase-separated structure in the NBR blends so as to improve their stability against varying humidity environment. For better control of the conductivity in the semi-conductive region under differing conditions, we prepared NBR/polyether-based electrolyte blends with differing acrylonitrile (AN) content of NBR, and studied the effects of CN groups on the conductive properties and structures using a DC conductivity system, differential scanning calorimetry, Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). We found that the conductivity of the blends increased with increasing AN content of NBR, implying that CN groups having strong electron withdrawing properties interact with the dissociated K ions. The FT-IR and TEM measurements show that the concentration of the CN groups is a crucial factor in determining the morphology of each blends and the improvement in conductivity between the NBR and polyether phases.

A new class of polymer electrolytes, consisting of poly(ethylene carbonate) (PEC) and metal salts, is expected to find application in all-solid-state batteries because of its excellent performance as an electrolyte. To study the ion-conductive mechanism in PEC-based electrolytes, broadband dielectric spectroscopy is used to analyze the correlation between dielectric relaxation and ionic conduction in PEC-lithium bis-(trifluoromethanesulfonyl) imide electrolytes over a broad range of salt concentration (0–150 mol%) at 40 °C. The PEC system has two relaxation modes, α and β, associated respectively with the segmental motion and the local motion of PEC chains. The conductivity increases exponentially with increasing salt concentration, while the α relaxation frequency (fα) decreases with increasing strength (Δeα) at low salt concentrations, whereas in contrast fα increases with Δeα being saturated at high salt concentrations above 10 mol%. It is believed that the mobility of PEC segment at high concentration is enhanced by two factors. The first is that intermolecular interactions decrease, given the existence of many ion pairs and aggregated ions around saturated PEC domains where the dissociated ions are highly concentrated. The second is that intramolecular interactions between CO and CH2 are lowered by the ion–dipole interaction.

Polymer gel electrolytes with both high ionic conductivity and mechanical ductility are produced using a slide-ring (SR) gel swollen with an electrolyte solution (ES) composed of propylene carbonate (PC) and lithium salt. The SR gel was derived from polyrotaxane (PR), in which cyclic molecules known as cyclodextrins (CDs) are threaded on the axial polymer chain of polyethylene glycol (PEG) capped by bulky ends, through intermolecular crosslinking between the CDs. The molar conductivity of the SR gel electrolyte with a high swelling ratio and small crosslinking density was more than 95% for pristine ES, and the activation energy and potential window of the SR gel electrolyte was close to that of pristine ES. The compressive properties of the SR gel electrolyte were also investigated; the Young's modulus of the SR gel electrolyte decreased with the crosslinking density and the SR gel electrolyte with a low crosslinking density was not fractured under compression to almost half of the original thickness.

Poly(ethylene carbonate)-based polymer electrolytes with lithium salts (LiX; X=TFSI, ClO4, BF4 and PF6) were prepared and measured their lithium transference numbers (t +) for the comparison between different anion radius and salt concentrations. The LiTFSI electrolytes showed highest t + and Li-ion conductivities of all samples at 80 oC, and these values increased with increasing salt concentration. From the results of FT-IR measurements for all concentrated samples, it was revealed that the changes of a band fraction divided at around 1720 cm-1 for interacted carbonyl groups with Li+ (C=O --- Li+) strongly relate to the mobility of Li+.

We report an all-solid-state Li rechargeable battery based on a hybrid membrane comprising a highly-concentrated poly(ethylene carbonate) (PEC) electrolyte with 80 wt.% of lithium bis(fluorosulfonyl)imide (LiFSI) and a three-dimensionally ordered macroporous polyimide matrix operating at room temperature. The PEC-LiFSI 80 wt.% electrolyte showed an ionic conductivity of the order of 10−5 S cm−1 at 30 °C and a quite high Li transference number, and was employed as a good ion-conductive solid polymer membrane for all-solid-state Li battery. To assure the mechanical stability, the polyimide matrix was combined as a porous substrate to support the electrolyte. A Li|PEC-LiFSI|LiFePO4 cell with the hybrid membrane delivered a reversible charge–discharge capacity close to 120~130 mAh g−1 at 30 °C and C/20 rate. Keywords: Polymer electrolytes, Poly(ethylene carbonate), Li battery, Li transference number, Polyimide matrix, Hybrid electrolyte membrane

In the present study, surface amino-functionalized silica nanofibers (f-SiO2NFs, average diameter = 400 and 1000 nm) are used as one-dimensional (1-D) fillers of ionic liquid (IL)-based quasisolid electrolytes. On adding f-SiO2NFs to an IL (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide, EMITFSA) containing lithium bis(trifluoromethanesulfonyl)-amide (LiTFSA), the well-dispersed 1-D nanofillers easily form a three-dimensional network structure in the IL, function as physical cross-linkers, and increase the viscosity of the composites, consequently providing a quasisolid state at a 3.5 wt % fraction of the NFs. Rheological measurements demonstrate that the prepared composites exhibit “gel-like” characteristics at 40–150 °C. All prepared composites show high ionic conductivities, on the order of 10–3 S cm–1, around room temperature. To investigate the additive effect of f-SiO2NFs in the composites, the lithium transference numbers are also evaluated. It is found that thinner NFs enhance the transference numbers of the composites. In addition, quasisolid lithium-ion cells containing the prepared composites demonstrate relatively high rate characteristics and good cycling performance at high temperature (125 °C).

We report a quasi-solid electrolyte comprising a transparent thixotropic gel swelled by an ionic liquid that is formed by a framework of single-walled aluminosilicate cylindrical inorganic “imogolite” nanotubes. The quasi-solid electrolyte shows moldability, thermal stability, and high ionic conductivity, and has potential applications in free-moldable conductive and anti-icing coatings, or electrolytes for batteries.

Ion-conductive behavior of a novel polymer electrolyte without oxyethylene units, poly(ethylene carbonate) (PEC)-Li salt system, was reported. Salt-concentration dependence revealed that the LiCF3SO3 and LiClO4 electrolytes exhibit typical polyether-like conduction behavior. However, the LiBETI, LiBF4 and LiTFSI electrolytes were much different, and the conductivity increased and Tg decreased with increasing salt concentration. This behavior of salt-rich PEC electrolytes relates to the ‘polymer-in-salt’ system. Li+ transference number of PEC-LiBF4 (44.4 wt%) electrolyte was measured, and the value was estimated to be ∼0.5 at 100 oC.

Highly ordered mesoporous silica (MPS) and sulfonated mesoporous organosilicate (s-MPOs) were synthesized as novel inorganic additives derived for use in PEM-FCs, and were added to the non-protonic polymer matrix, poly(ethylene- co -vinyl alcohol) (EVOH). The proton conductivities of EVOH composites were measured at 50–100 °C under controlled high humidity values. The EVOH27 (ethylene content: 27 mol%) composite membranes filled with s-MPOs gave a proton conductivity more than 50-times higher than composites filled with simple treated MPS (t-MPS). The s-MPOs having many SO 3 H groups was able to form effective proton conductive passages via its periodic structure and so improve conductivity in the polymer. We also investigated the temperature dependence of the conductivity for EVOH composites with ethylene content of 27 and 44 mol%. The EVOH44/s-MPOs composites had better conductivity than EVOH27 at higher temperatures. The greatest value was estimated to be 1.67 × 10 −3 S cm −1 without extra acid additives, at 80 °C and more than 96%RH.

For creation of a novel candidate for the polymer electrolytes without ethylene oxide units in the main chain, we considered polycarbonates obtained from the copolymerization of CO 2 with epoxy monomers. In this study, we synthesized six types of polycarbonates possessing glycidyl ethers (phenyl, tert -butyl, n -butyl, ethyl and isopropyl) and ethyl side groups using zinc glutarate, and measured the ionic conductivity of their electrolytes including LiTFSI. The electrolyte possessing ethyl glycidyl side groups had the highest conductivity and the value was 2.9 × 10 −7 S/cm at room temperature. DSC measurement showed that some of polycarbonates possessing glycidyl ethers decrease in T g by the addition of salt, whereas the polycarbonate (P(EP-C)) possessing non-ether side group increase in the T g . FT-IR measurement revealed that the P(EP-C) electrolyte clearly makes interaction between Li ions and carbonyl groups on the main chain, which is related to the main factor of the increase in T g .

To overcome the low ionic conduction of existing poly(ethylene oxide)-based polymer electrolytes, we consider polycarbonates obtained from the copolymerization of CO2 and epoxy monomers. We synthesized four types of polycarbonates possessing phenyl, n-butyl, t-butyl and methoxyethyl side groups using zinc glutarate, and measured the ionic conductivity of their electrolytes, including 10 mol% of LiTFSI. The electrolyte possessing methoxyethyl side groups had the highest conductivity, of the order of 10−6 S cm−1 at room temperature. The activation energy (Ea) for ionic conduction in the polycarbonate electrolytes was estimated from the VTF equation, and the Ea of the electrolyte possessing n-butyl side groups was almost the same with the polyether-based electrolytes. An interesting feature of our study is that the polycarbonate is a unique candidate for ion-conductive polymers because of its flexible and hydrophobic properties.

Electrolytes comprising poly(ethylene carbonate) (PEC)/poly(trimethylene carbonate) (PTM C) with lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) are prepared by a simple solvent casting method. Although PEC and PTMC have similar chemical structures, they are immiscible and two glass transitions are present in the differential scanning calorimetry (DSC) measurements. Interestingly, these two polymers change to miscible blends with the addition of LiTFSI, and the ionic conductivity increases with increasing lithium salt concentration. The optimum composition of the blend electrolyte is achieved at PEC6PTMC4, with a conductivity as high as 10(-6) S cm(-1) at 50 degrees C. This value is greater than that for single PEC- and PTMC-based electrolytes. Moreover, the thermal stability of the blend-based electrolytes is improved as compared to PEC-based electrolytes. It is clear that the interaction between C=O groups and Li+ gives rise to a compatible amorphous phase of PEC and PTMC.

Novel ion-conductive elastomer blends containing polyether-based solid polymer electrolyte (SPE) were prepared by the radical polymerization of oligo[(ethylene oxide)-co-(propylene oxide)] methacrylate (M(EO/PO)) monomer with LiClO4 in NBR. Obtained samples showed micro- (or nano-) scale Sea-Island phase separation, which was revealed from the TEM observation in case of NBR18/PM(EO/PO)mono-LiClO4 50/50 wt% blend, and the DC conductivity under dry N2 (σdry) was approximately 10–8 S cm–1 at 25 °C. The difference in the conductivity of blend samples between dry and wet conditions was very small, whereas the conductivity of PM(EO/PO)-LiClO4 without NBR under wet condition (σwet) was 10-times higher than σdry. Moreover, the σdry of NBR43 blend sample (NBR43/electrolyte = 30/70 wt%) was higher than that of the neat electrolyte. The complex impedance measurement revealed that AC ionic conductivity of the NBR43 blend sample was 6.7 × 10–6 S cm–1 at 25 °C and the value was approximately 6-times higher than that of the neat electrolyte. This may be caused by accelerated ion-conduction between the electrolyte islands or on the NBR/electrolyte interface where the resistance is very small because of the electrical interactions between Li ions (or Li+−polyether complex domains) and nitrile groups of NBR.

Hyperbranched poly(ether sulfone) polymers having sulfonyl chloride end-groups is blended at up to 30 w% with linear poly(ether ether ether sulfone)s and a two-phase system is generated via spinodal decomposition upon drying from a DMAc solution. Conversion of the end-groups from sulfonyl chloride to sulfonic acid is accomplished using 16 M H 2 SO 4 that is also believed to introduce additional sulfonic acid groups at the interface of the linear polymer. The blend films before and after conversion to sulfonic acid have similar tensile strengths as films composed of solely linear polymer (yield stress >40 MPa and Young's modulus >3 GPa m). These films are designed to test the viability of hyperbranched polymers as fuel cell membranes. Proton conductivities of up to 0.03 S cm −1 are observed at 80 °C and 90% R.H indicating a good potential for use of hyperbranched polymers as a proton conduction material.

イオン伝導性を示す固体高分子電解質(SPEs)は，既存物質に替わりフレキシブルで薄型の次世代リチウム電池における基幹物質となりうる新しい固体電解質として期待されている．しかしながら，SPE は既存の液体，ゲル，無機系の固体電解質と比べるとイオン伝導度が劣る．固体高分子中で速いイオン輸送を実現するために，筆者は高密度の二酸化炭素流体，特に超臨界二酸化炭素(scCO2)に着目し，そのユニークな溶媒特性を SPE のイオン伝導性改善に活かすことを初めて試みた．その結果，scCO2 処理は Li 塩を含むポリエチレンオキシド(PEO)のようなポリエーテル系電解質のイオン伝導度を著しく増加させた．また，SPE に対する CO2 処理は，イオン伝導性の改善につながるガラス転移温度(Tg)の劇的な低下を引き起こした．さらに，高圧 CO2 中における SPE のイオン伝導挙動を圧力容器中で直接測定した結果，CO2 圧力の上昇に伴うイオン伝導度の増加が認められた．本研究では，CO2 が SPE 中に溶解し，高分子を可塑化させ，さらには系内に存在する凝集イオンの解離を促進する効果を有することが示唆されている．

The structure and properties of highly stereoregular isotactic poly(methyl methacrylate) ( it -PMMA) and syndiotactic poly(methyl methacrylate) ( st -PMMA) blends with crystalline stereocomplex formed by supercritical CO 2 treatment at temperatures ranging from 35 to 130 °C were investigated by means of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and dynamic mechanical analysis (DMA) measurements. The melting temperature, T m , and the heat of fusion, Δ H m , had maximum values at about 200 °C and 25 J/g, respectively. The degree of crystallinity evaluated by WAXD ranged in value from 32 to 38%. The fringed-micellar stereocomplex crystallites were formed in case of treatment temperatures below 90 °C, and the orderliness perpendicular to the helix axis of the fringed-micellar crystallites was considered to be increased with increasing treatment temperature. In case of treatment temperature of 130 °C, the fringed-micellar crystallites and the lamellar crystallites with high orderliness parallel to the helix axis coupled with the perpendicular orderliness were formed, and the respective double endothermic peaks, T m 1 and T m 3 , were observed in DSC due to the melting of the two kinds of stereocomplex crystallites. The it -PMMA/ st -PMMA blends containing the fringed-micellar crystallites maintained high values of storage modulus, E ′, up to higher temperature compared with the amorphous blends. The E ′ of the blend treated with CO 2 at 130 °C decreased twice at temperatures corresponding to T m 1 and T m 3 .

Poly( l -lactide) (PLLA) was melt-blended with poly( p -vinyl phenol) (PVPh) using a two-roll mill, and the miscibility between PLLA and PVPh and degradation of the blend films were investigated. It was found that PLLA/PVPh blend has miscibility in the amorphous state because only single T g was observed in the DSC and DMA measurements. The T g of the PLLA/PVPh blend could be controlled in the temperature range from 55 °C to 117 °C by changing the PVPh weight fraction. In alkaline solution, degradation rate of PLLA/PVPh blends was faster than that of neat PLLA because PVPh could dissolve in alkaline solution. The surface morphology of degraded PLLA and PLLA/PVPh blend were observed by SEM. The surface morphology of degraded PLLA/PVPh blend was finer than that of PLLA. Young's modulus of PLLA/PVPh blend increased with increasing PVPh content. Yield stress of PLLA/PVPh blends whose PVPh content was less than 30 wt% kept the level of about 55 MPa and that of PLLA/PVPh blend whose PVPh content was 40 wt% is much lower than that of neat PLLA.