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As one of the main components of ionic liquid-based composite electrolytes, nanoparticles play a major role in determining the performance of such electrolytes. In this study, four different TiO2-b...

Two types of ionic liquids (ILs), 1-(3-hexenyl)-3-methyl imidazolium iodide and 1-(3-butenyl)-3-methyl imidazolium iodide, are synthesized by introducing an unsaturated bond into the side alkyl chain of the imidazolium cation. These new ionic liquids exhibit high thermal stability and low viscosity (104 cP and 80 cP, respectively). The molecular dynamics simulation shows that the double bond introduced in the alkane chain greatly changes the molecular system space arrangement and diminishes the packing efficiency, leading to low viscosity. The low viscosity of the synthesized ionic liquids would enhance the diffusion of redox couples. This enhancement is detected by fabricating dye-sensitized solar cells (DSSCs) with electrolytes containing the two ILs and I2 . The highest efficiency of DSSCs is 6.85 % for 1-(3-hexenyl)-3-methyl imidazolium iodide and 5.93 % for 1-(3-butenyl)-3-methyl imidazolium iodide electrolyte, which is much higher than that of 5.17 % with the counterpart 1-hexyl-3-methyl imidazolium iodide electrolyte.

To obtain a rapid processible LED encapsulant that leads to high and stable light extraction efficiency (LEE), UV curable ZrO2/phenyl-siloxane nano-composite (ZSC) double-layer encapsulants were prepared and optimized. The highly crystalline ZrO2 nanoparticles with a diameter of ∼14 nm were synthesized through a modified hydrothermal method at mild conditions, and a UV curable methacryl-diphenyl-polysiloxane (MDPS) with a refractive index (RI) of 1.54 (at 633 nm) was synthesized from self-condensation of diphenylsilanediol and an end-capping reaction. High refractive indexes (RIs) from 1.54–1.61 have been obtained for ZSC composites by adding 0–20 wt% ZrO2. Before and after sulfur vapor erosion, the double-layer encapsulated sample (M-10/M) showed 11.2% and 64.8% higher LEE respectively than that of Dow Corning OE-7662. Meanwhile, the variation of LED light color temperature (Tc) was less than 1%. The effect of the ZrO2 nanoparticle content on LEE of double-layer and single-layer encapsulation were compared and discussed based on Fresnel loss and Rayleigh scattering theories. The double-layered UV curing processing took only 1/6 of the time needed for common thermal curing.

In this paper, a novel kind of functional NH2-rich silica nanoparticle (A-SiO2) as an electrolyte additive is reported, which is employed to assemble high-efficiency quasi-solid-state dye-sensitized solar cells (DSCs) and quantum dot sensitized solar cells (QDSCs), while the additional solidifying character of A-SiO2 makes it superior to the common additives. It is found that the A-SiO2 nanoparticle as an additive for ionic-liquid electrolyte can significantly improve the photovoltaic performance of quasi-solid-state DSCs, especially the open-circuit photovoltage (Voc) and fill factor (FF) through (1) negatively shifting the TiO2 conduction band (CB) edge, (2) effectively facilitating the ions transport and (3) remarkably inhibiting the charge recombination. Notably, DSC fabricated using the A-SiO2 based ionic-liquid gel electrolytes achieves a power conversion efficiency (PCE) of 7.30% under 1 sun illumination (AM 1.5 G, 100 mW cm−2), which is higher than that of DSC with the ionic-liquid electrolyte employing N-methylbenzimidazole (NMBI) and Guanidinium thiocyanate (GuNCS) as additives (PCE = 6.23%). Moreover, the A-SiO2 additive is of the universality in organic electrolytes for DSCs and polysulfide electrolytes for QDSCs. The PCE of CdS/CdSe co-sensitized QDSCs using A-SiO2 additives is improved by 34.9% due to the enhancement of short-circuit current density (Jsc) and Voc, resulting in a champion PCE of 7.11%, which is one of the best results for CdS/CdSe co-sensitized QDSCs.

Polyaniline-grafted silica nanocomposites (PANI-SiO 2 ), which are synthesized through in-situ surface chemical oxidative polymerization of aniline with the NH 2 -modified silica nanoparticles, are exploited as gelators in the ionic-liquid electrolytes for dye-sensitized solar cells (DSCs). It can be clearly seen that the PANI-SiO 2 nanocomposites have the well-interconnected network structure, which not only serve as gelators to effectively solidfy the ionic-liquid electrolytes, but also significantly improve the ion conductivity of electrolytes and the diffusion coefficient of I 3 − ions. As a result, an optimal efficiency of 7.15% for DSC using gel electrolyte is achieved due to the enhancement of photocurrent density ( J sc ) and fill factor ( FF ), which is increased by 18.99% than that of the cell using ionic-liquid electrolyte.

The surface properties of nanoparticles have a significant influence on the properties of the gel electrolytes. Herein, the surface NH2-rich nanoparticle (A-SiO2), with a tightening network, is synthesized by silanizing SiO2 nanoparticles with pre-polymerized aminopropyltriethoxysilane, which is further employed to prepare ionic-liquid gel electrolytes for dye-sensitized solar cells. The addition of a small amount of A-SiO2 can effectively solidify the ionic-liquid, whereas a large number of NH2 groups on the SiO2 surface leads to a large negative shift of the TiO2 conduction band edge, and can react with I3− in the form of a Lewis complex, resulting in an increase in the concentration of I− and a decrease in the concentration of I3− in the electrolyte. In addition, the ionic-liquid gel electrolyte possesses thixotropic behavior, which allows it to easily penetrate into the inner part of the TiO2 mesoporous film. As a result, large improvements of the photovoltage from 695 mV to 785 mV and of the photocurrent from 13.3 mA cm−2 to 14.9 mA cm−2 are achieved. This leads to significant enhancement of the power conversion efficiency, from 6.2% to 8.1%, for the cell with A-SiO2 compared to that of the pristine ionic-liquid electrolyte.

In this work, a unique approach is developed to generate photoswitchable and water-soluble fluorescent nano-aggregates. Initially, a new light-controlled diarylethene-dansyl dyad DAE 1 is formed by linking two dansyl fluorophores covalently to a symmetrical dithienylethene backbone, whose photophysical properties can be reversibly switched by optical stimuli. Subsequently, the water insolubility of the molecular switch 1 is overcome by incorporating it into the bilayer of liposome DPPC (1,2-dihexadecanoyl-sn-glycero-3-phosphocholine) in water. This strategy creates stable fluorescent nano-aggregates OF-1@DPPC (≈25 nm diameter) that are soluble in an aqueous medium. The nano-aggregates OF-1@DPPC retain and even improve the photoswitchable fluorescence properties of DAE 1. More importantly, OF-1@DPPC exhibits a remarkable photostability and fatigue resistance after 5 cycles of irradiation with UV and visible light, which is crucial for its practical application.

As one of the main components, inorganic nanofillers have important effect on the performance of “soggy sand” electrolytes. In this study, we first incorporate AlOOH nanofibers into ionic liquid electrolytes to enhance the mechanical property and ionic conductivity of the electrolytes. The AlOOH nanofiber has high aspect ratio coupled with favorable surface properties such as rich hydroxyl groups, which facilitate to interact with cations of ionic liquids, promote salt dissociation, and form stable gels by self-assembly. In addition, the nanofiber fillers with high aspect ratio can form ion-conducting network channels and longer-range continuous ion transport pathways. The enhancing ionic conductivity of “soggy sand” electrolytes and performance of DSSCs due to addition of AlOOH nanofibers are systematically investigated by various techniques. The highest ionic conductivity of “soggy sand” electrolyte reaches 3.69 mS cm−1 at room temperature, which is 4 times than that of the pristine ionic liquid electrolyte. The effective solidification by AlOOH nanofibers provides substantial improvements in stability. The “soggy sand” electrolytes with AlOOH nanofibers can significantly improve the performance of devices by accelerating charge transport, reducing electron recombination and increasing charge collection efficiency. The DSSC with AlOOH nanofibers in electrolyte yields a high efficiency up to 7.89%, which is 29% higher than that of the reference device.

Introducing oligo-organosiloxane grafting oligo(ethylene oxide-co-propylene oxide) dimethylamine (OEA) into PEO polymer electrolyte, at low degree loading (OEA:PEO = 0.05:0.95, w/w), improved remarkably the performance of solid state dye sensitized solar cell (SDSCs), resulting in an overall conversion efficiency of 3.06% under AM 1.5 illumination of 100 mW cm −2 . The addition of OEA into PEO electrolyte not only significantly increased ionic conductivity and apparent diffusion coefficients of I 3 − in the electrolyte, but also promoted interfacial contacts of electrolyte/TiO 2 and interfacial property of electrolyte/counter electrode. The quaternized OEA (OEI) was also introduced to the PEO electrolyte. XRD patterns revealed that the addition of small amount of OEA or OEI did not reduce the crystallinity of PEO much while its crystal orientation was preferentially directed. Besides, IR measurements illustrated the existence of hydrogen bond between the dimethylamine groups on OEA and the hydroxyl groups on PEO. The crystal orientation and also the hydrogen bond were deduced benefited the electrolytic properties and further the device photovoltaic performances.

Ionic liquid polymers, poly(1-alkyl-3-(acryloyloxy)hexylimidazolium iodide), are synthesized and used as mono-ion transport electrolytes for all-solid-state dye-sensitized solar cells. For these ionic liquid polymers, imidazolium cations are tethered on polymer main chain and only iodide species is mobile. Such a mono-ion transport feature is favorable as solid-state electrolyte in dye-sensitized solar cells. High thermal stability up to 200 °C for these ionic liquid polymers is confirmed by thermogravimetric analysis. Among these ionic liquid polymers, poly(1-ethyl-3-(acryloyloxy)hexylimidazolium iodide) (PEI) exhibits the highest ionic conductivity (3.63 × 10−4 S cm−1) at room temperature. The dye-sensitized solar cell based on PEI electrolyte without the addition of iodine exhibits the open-circuit voltage of 838 mV, the short-circuit current density of 9.75 mA cm−2 and the conversion efficiency of 5.29%, measured at AM 1.5 illumination (100 mW cm−2). Incorporating iodine into PEI electrolyte results in the decrease of both the open-circuit voltage and the photocurrent density due to the visible light adsorption by iodine and the enhancement of the recombination between conduction band electrons and the triiodide.

A novel thixotropic composite electrolyte was fabricated by using the amine group-functionalized silica nanoparticles as the gelator of an ionic liquid-based electrolyte for dye-sensitized solar cells. The SEM image of electrode deposited with electrolyte confirms that the high viscous gel electrolyte has a good contact with TiO 2 electrode ascribed to the thixotropic property of the electrolyte. Based on the thixotropic and ionic liquid based-electrolyte containing the amine group-functionalized silica particles, the cells show better performance owing to the increased open-circuit voltage than that of the liquid device, yield a high energy conversion efficiency of 6.69% under AM 1.5 illumination at 100 mV cm −2 when the content of the amine group-functionalized silica is 15 wt.% and exhibit a long-term stability without sealing.

A new kind of carboxyl group-functionalized silica nanoparticles were synthesized and employed as framework to form “soggy sand” electrolyte for dye-sensitized solar cells. The property of this electrolyte has been evaluated by studying the effect of the carboxyl group-functionalized silica nanoparticles content on the performance of dye-sensitized solar cells. The cells based on electrolyte containing the carboxyl group-functionalized silica nanoparticles show better performance owing to the increased short-circuit photocurrent than that of the liquid device and yield the energy conversion efficiency of 7.1% under AM 1.5 illumination at 100 mV cm−2 when the content of the carboxyl group-functionalized silica is 15 wt.%. Keywords: Functionalized silica, Ionic liquid, Soggy sand electrolyte, Dye-sensitized solar cells

A kind of polymer–metal complex gel electrolyte is successfully prepared and is used in dye-sensitized solar cells. Raman and X-ray photoelectron spectroscopy confirm the structure of this complex and is found that the metal ion reacts with nitrogen in the polymer. This novel electrolyte shows apparent diffusion coefficient of iodide of 8.37 × 10−7 cm2 s−1 and the energy conversion efficiency of 6.10% when the amount of ZnI2 is 0.04 M. By studying the dissociation active energy of the inorganic salt in electrolytes, we find that the metal salts can dissociate more easily after reacting with polymer and as a result can provide extra free iodide ion. The cell maintains ca. 93% of its initial efficiency after 20 d without further sealing, which shows good long-time stability.

The acidic ionic liquid polymer P [((3-(4-vinylpyridine) propanesulfonic acid) iodide)-co-(acrylonitrile)], which is named as P-HI for short, has been employed in ionic liquid electrolyte for dye-sensitized solar cells. The novel acidic ionic liquid polymer/ionic liquid composite polymer electrolyte does not contain iodine, and the performance of this electrolyte has been evaluated by studying the content of P-HI and the iodine concentration on the performance of dye-sensitized solar cells. The cell based on electrolyte containing 20 wt.% P-HI yields an overall energy conversion efficiency of 6.95% under AM 1.5 illumination at 100 mW cm−2. Keywords: Acidic ionic liquid polymer, Ionic liquid, Electrolyte, Dye-sensitized solar cells

Poly(vinylpyridine- co -ethylene glycol methyl ether methacrylate) (P(VP- co -MEOMA)) and α,ω-diiodo poly(ethylene oxide- co -propylene oxide) (I[(EO) 0.8 - co -(PO) 0.2 ] y I) were synthesized and used as chemically cross-linked precursors of the electrolyte for dye-sensitized solar cells. Meanwhile, α-iodo poly(ethylene oxide- co -propylene oxide) methyl ether (CH 3 O[(EO) 0.8 - co -(PO) 0.2 ] x I) was synthesized and added into the electrolyte as an internal plasticizer. Novel polymer electrolyte resulting from chemically cross-linked precursors was obtained by the quaterisation at 90 °C for 30 min. The characteristics for this kind of electrolyte were investigated by means of ionic conductivity, thermogravimetric and photocurrent–voltage. The ambient ionic conductivity was significantly enhanced to 2.3 × 10 −4 S cm −1 after introducing plasticizer, modified-ionic liquid. The weight loss of the solid state electrolyte at 200 °C was 1.8%, and its decomposition temperature was 287 °C. Solid state dye-sensitized solar cell based on chemically cross-linked electrolyte presented an overall conversion efficiency of 2.35% under AM1.5 irradiation (100 mW cm −2 ). The as-fabricated device maintained 88% of its initial performance at room temperature even without sealing for 30 days, showing a good stability.

A poly(ether urethane) (PEUR)/poly(ethylene oxide) (PEO)/SiO 2 based nanocomposite polymer is prepared and employed in the construction of high efficiency all-solid-state dye-sensitized nanocrystalline solar cells. The introduction of low-molecular weight PEUR prepolymer into PEO electrolyte has greatly enhance the electrolyte performance by both improving the interfacial contact properties of electrode/electrolyte and decreasing the PEO crystallization, which were confirmed by XRD and SEM characteristics. The effects of polymer composition, nano SiO 2 content on the ionic conductivity and I 3 − ions diffusion of polymer-blend electrolyte are investigated. The optimized composition yields an energy conversion efficiency of 3.71% under irradiation by white light (100 mW cm −2 ).

Two latent chemical cross-linked precursors: (1) oligo-organophosphazene with propionitrile and iodo-(ethylene oxide- co -propylene oxide) and (2) oligo-organosiloxane grafting oligo-ethylene oxide and propylene oxide dimethylamine are synthesized to form all-solid-state polymer electrolyte for dye-sensitized solar cells employing in situ quaterization reaction. This novel electrolyte shows about 6.79 × 10 −7 cm 2 s −1 of the apparent diffusion coefficient of triiodide. The disintegrating temperature of 181 °C demonstrates good thermal stability of the solid-state electrolyte. Proper amount of 7 nm SiO 2 modified with 3-triethoxysilylpropyl oligo(oxyethylene- co -oxypropylene) monomethyl urethane is added to the electrolyte and the photocurrent conversion efficiency reaches 2.66% compared with that of 1.81% with no additive.

Polymer electrolyte through in situ quanternization reaction by oligo-siloxane containing quanternary ammonium groups was synthesized for all solid-state dye-sensitized solar cells (DSSCs). These two latent crosslinked precursors are oligo-organosiloxane grafting oligo-ethylene oxide and propylene oxide dimethylamine (OEA) and the oligo-organosiloxane grafting oligo-ethylene oxide and propylene oxide bromide (OEB). This chemically crosslinked electrolyte shows good ambient conductivity of 2.6 × 10−4 S/cm when incorporating appropriate amount of 1-iodide oligo-ethylene glycol monomethylether (IOEGMME) as an additive. Photoelectrochemical performances for different electrolytes were also analyzed. Copyright © 2009 John Wiley & Sons, Ltd.

A series of all-solid polymer electrolytes were prepared by cross-linking new designed poly(organophosphazene) macromonomers. The ionic conductivities of these all-solid, dimensional steady polymer electrolytes were reported. The temperature dependence of ionic conductivity of the all-solid polymer electrolytes suggested that the ionic transport is correlated with the segmental motion of the polymer. The relationship between lithium salts content and ionic conductivity was discussed and investigated by Infrared spectrum. Furthermore, the polarity of the host materials was thought to be a key to the ionic conductivity of polymer electrolyte. The all-solid polymer electrolytes based on these poly(organophosphazenes) showed ionic conductivity of 10−4 S cm−1 at room temperature.

Poly(vinylpyridine-co-acrylonitrile) (P(VP-co-AN)) was used to form polymer electrolytes for dye-sensitized solar cells (DSSCs). The effects of P(VP-co-AN) on the photovoltaic performances of DSSCs have been investigated with nonaqueous electrolytes containing alkali-iodide and iodine. It was found that the effect of P(VP-co-AN) on Voc closely related to its amount in the electrolyte. Lower amount of P(VP-co-AN) was benefit for the construction of a solar cell containing P(VP-co-AN) with higher energy conversion efficiency. Chemically crosslinking solidification with backbone polymer P(VP-co-AN) amount of 3% fabricated quasi–solid DSSCs with 10% increased conversion efficiencies with relative to that of the initial liquid DSSCs.

This work describes a series of novel Eucommia ulmoides gum (EUG)-based damping materials with excellent damping properties by using the interpenetrating polymer network (IPN) method for the first time; this is an innovative application of EUG. The novel core-shell structure of an EUG-based multicomponent latex interpenetrating polymer network (LIPN) can be controlled by selecting a suitable initiator system, emulsification method, and polymeric sequence and by regulating the miscibility among the components. The damping properties and morphology of multicomponent LIPNs were investigated by dynamic mechanical analysis (DMA) and transmission electron microscope (TEM) in order to reveal the relationship between structure and performance. The results show that some LIPNs that use EUG as the seed in the multicomponent core-shell structure have a high damping factor (tanδ) at a broader temperature range. For example, the EUG/PS/PBA LIPN (1/1/1 by weight) possesses excellent damping properties; its temperature range for tanδ>0.3 extends to almost 130°C. EUG-based LIPNs, particularly the trinary EUG-based LIPNs are novel damping materials with good potential for development.

All solid-state comb-like network polymer electrolytes (CNPE) based on poly(methylsiloxane) with pendant PEO chains as internal plasticizing chains (IPC) have been designed and synthesized. Ultraviolet (UV) polymerization method was applied for the curing of CNPEs. Effects of the network structure on the conductive properties and mechanical properties were discussed in details. Ionic conductivity of the prepared CNPE is one order of magnitude larger than those without IPCs, which suggests that the expected drop of conductivity caused by crosslinking has been well compensated by the introduction of IPCs. Maximum conductivity of 1.01 × 10−4 S cm−1 and maximum tensile strength of 0.66 MPa were obtained at 30 °C. Electrochemical stability and electrolyte/electrodes interfacial stability properties were evaluated by cyclic voltammetry and ac impedance, respectively.

Composite polymer electrolytes based on room temperature ionic liquids and polyether have been designed and synthesized. All room temperature ionic liquids which contain short poly(ethylene oxide) chains have good compatibility with the prepolymer, polyether based on polysiloxane. An ultraviolet polymerization method was utilized for the curing of the composite polymer electrolytes. The composite polymer electrolytes which are composed of the room temperature ionic liquids and polyether based on polysiloxane showed high ionic conductivity and high thermal stability. The ionic conductivity of the composite polymer electrolytes is nearly two magnitudes higher than those electrolytes with pure polyether based on polysiloxane. A maximum conductivity of 1.05 × 10−3 S/cm−1 is achieved at 30°C. Thermogravimetic analysis revealed scarcely any thermal weight loss at 80°C and thermal decomposition of the composite polymer electrolytes had not been observed up to 250°C. It retains electrochemical stable till 4.2 V which is acceptable. Copyright © 2006 John Wiley & Sons, Ltd.

The ionic conductivities of all-solid polymer electrolytes prepared by UV irradiation crosslinkable oligo(oxyethylene) branched low molecular weight poly(organophosphazenes) macromonomers are reported. The dimensional stability of the poly(organophosphazes) electrolytes was improved by crosslinking. The temperature dependence of ionic conductivity of the all-solid polymer electrolytes followed the Vogel–Tamman–Fulcher equation. Furthermore, the effects of the length of the oligo(oxyethylene) chain and the degree of crosslinking on the ionic conductivity of the polymer electrolytes are discussed. The stability of the lithium electrode and the all-solid polymer electrolytes interface were evaluated by measuring the alternating current impedance on symmetric cells. The maximum ionic conductivity of the all-solid polymer electrolyte was obtained as high as 2.92 × 10−4 sec/cm at 25°C. Copyright © 2006 John Wiley & Sons, Ltd.

Novel polymer electrolytes based on ionic liquid with no volatile solvents containing chemically crosslinked gelators were prepared for quasi-solid dye-sensitized solar cells (DSCs). The polymer electrolytes can keep over 90% of the ionic liquid electrolyte performance. The two constituents of the chemically crosslinked gelators, polypyridyl-pendant dendritic derivatives and multifunctional halogen derivatives, respectively, are suitable for solidification of ionic liquid electrolytes in DSCs by in situ polymerization. The ionic conductivity and photoelectrochemical performances of different polymer electrolytes were evaluated and discussed. Copyright © 2006 John Wiley & Sons, Ltd.

Gel polymer electrolytes were prepared by incorporating polyacrylonitrile (PAN) in a mixture of polysiloxane with quaternary ammonium side groups (PSQAS), ethylene carbonate (EC), propylene carbonate (PC) and iodine. The influence of PAN content on the ionic conductivity of gel polymer electrolytes and the charge-transfer kinetic performance in counterelectrode–electrolyte interface was investigated. The dye-sensitized solar cell with the gel polymer electrolyte containing 5 wt.% PAN showed the best photovoltaic performance; a maximum incident photon conversion efficiency of 63% at 520 nm was obtained, the short-circuit photocurrent density ( J sc ), the open-circuit voltage ( V oc ) and the fill factor (FF) were 7 mA cm −2 , 0.565 V and 0.65, respectively. The corresponding overall conversion efficiency ( η ) is 4.3%.

A novel quaternary ammonium salt, polysiloxane containing quaternary ammonium groups, was designed and synthesized. Thermogravimetric results showed that the polymer maintained stable below 250°C. Ambient conductivities higher than 10−4 S cm−1 could be observed when appropriate amounts of suitable plasticizers were incorporated into the present quaternary ammonium salt. A dye-sensitized solar cell fabricated using a plasticized electrolyte showed a fill factor of 0.50 and an energy conversion efficiency of 7.7%. Copyright © 2004 John Wiley & Sons, Ltd.

Four novel liquid cycloaliphatic diepoxides, with two epoxycyclohexyl moieties linked via –O– (EpoI), –OCH2CH2O– (EpoII), –OCH (CH3)CH2O– (EpoIII), –OCH(CH3)CH2CH(CH3)O– (EpoIV), respectively, and their diene precursors were synthesized and characterized. These diepoxides could be readily cured with hexahydro-4-methylphthalic anhydride (HMPA) using Iron (III) acetylacetonate as curing accelerator. The thermal and mechanical properties of cured products were examined by differential scanning calorimetry (DSC), thermal mechanical analysis (TMA) and dynamic mechanical analysis (DMA). The thermogravimetric analysis (TGA) data revealed that, the cured EpoI and EpoII had similar thermal decomposition onset temperature to the commercial ERL-4221™ (>300 °C), whereas the cured EopIII and EpoIV, having secondary or tertiary carbon–ether linkages, started to decompose at obviously lower temperature (around 220 °C), which just lay in the desired reworkability temperature range (200–300 °C). The higher glass transition temperature (>120 °C) and moderately low thermal decomposition temperature made EpoIII and EpolV suitable candidates for future reworkable flip chip electronic packaging application.

A novel surface modification approach involving the application of radiation technology to the development of graphite anode of lithium ion batteries. Ionic conductive poly(stylene sulfonic acid) lithium salt (PSSALi) was microencapsulated on the surface of graphite particles by means of radiation-initiated polymerization. Results showed that the cointercalation of solvated Li+ in a propylene carbonate (PC) based electrolyte was depressed successfully and the initial coulombic efficiency was enhanced after encapsulation. The high stability of the surface structure of encapsulated graphite during the initial intercalation process was observed by in situ Raman spectroscopy. Copyright © 2003 John Wiley & Sons, Ltd.

A series of novel comb-like polysiloxanes with oligo(oxyethy1ene) side chains and quaternary ammonium groups, has been synthesized by hydrosilylation of poly(methylhydrosi1oxane) with poly(ethy1ene glycol) allyl methyl ether and N,N-dimethylallylamine, followed by quaternization with methyl iodide. The glass transition temperature of these solvent-free electrolytes was measured and found to be dependent on the content of quaternary ammonium side groups anchored to the polysiloxane backbone. The influence of quaternary ammonium group content and temperature on the ionic conductivity has been investigated. A maximum conductivity of 1.57 × 10−5 S cm−1 at 25 °C was achieved for a poiysiloxane containing 30 % quaternary ammonium side groups. The temperature dependence of the ionic conductivity shows the “Vogel-Tammann-Fulcher” (VTF) behavior. The values of the VTF Parameters were calculated.

Novel surface modification approach for graphite anode of lithium ion batteries was developed in this study. Poly(acrylonitrile) was in situ encapsulated on the surface of natural graphite (N-graphite) particles via radiation-initiated polymerization. The graphite obtained shows a large improvement in electrochemical performance such as initial Coulombic efficiency and cycleability compared with the original N-graphite. The structural stability of graphite surface is enhanced due to the fact that encapsulated poly(acrylonitrile) can depress the co-intercalation of solvated lithium ion.

An amorphous carbon doped with sulfur to be used as anode material for lithium ion batteries is prepared by heat-treatment of a mixture of polyacrylonitrile (PAN) and sulfuric acid. With X-ray photoelectron spectroscopy (XPS), elemental analysis, X-ray powder diffraction (XRD), scanning electron microscopy, and electrochemical capacity measurements effects of sulfur on properties of the carbon anode are investigated. The added sulfur favorably increases the charge capacity in close correlation with an increase of the size of graphite crystallites, L c , the interlayer distance, d 0 0 2 , and the number of micropores, and the doping of sulfur in the state of CSC. On the other hand, it also causes detrimental changes, for example the formation of amine-group nitrogen, sulfate/sulfonate deposits, and macropores. Nevertheless, as a result, both reversible and irreversible capacities are enhanced. This clearly shows, that added heteroatoms may have opposite influences, good and bad, on electrochemical performance of carbonaceous anode materials. Approaches towards suppressing the unfavorable ones in the application in lithium ion batteries are discussed.

Electrochemical lithium insertion behavior of boron-containing carbons was studied by constant-current potentiometry. The boron-containing carbons were prepared by pyrolyzing a phenolic resin chemically bonded with boron atoms, which was synthesized via an esterification reaction of the phenol hydroxyl groups by boric acid. It was found that the as-prepared boron-containing carbons at pyrolysis temperatures higher than 700 °C could accommodate more lithium species than the corresponding boron-free carbon, yet those prepared at pyrolysis temperatures lower than 700 °C accommodated less lithium than the boron-free control sample. In particular, the boron-containing carbon prepared at 900 °C exhibited a capacity higher than the theoretical value of graphite and reasonable charge/discharge voltage curves. The elemental, X-ray diffractometric and X-ray photoelectron spectroscopic analysis results indicated that at the pyrolysis temperature of 500 °C, the lithium accommodation capacity of the pyrolytic carbon was mainly dependent on its residual hydrogen content, rather than the boron content. However, when pyrolyzed at 900 °C, more boron atoms were bonded with carbon atoms and introduced to the graphene microcrystallite structure. Therefore, boron atoms exerted a considerable effect on the lithium insertion behavior and more lithium species were reversibly inserted into the carbon matrix due to the electron-deficient nature of boron atoms.

A novel graphite material for lithium ion batteries was prepared by encapsulation of an ionic conductive polymer on the surface of natural graphite particles via radiation-initiated polymerization. The graphite obtained shows great improvement in electrochemical performance such as initial coulombic efficiency and cycleability compared with the original natural graphite. Raman spectroscopy indicates that the structural stability of the graphite surface is enhanced due to the fact that encapsulated polymers can depress the exfoliation of graphite layers caused by co-intercalation of solvent molecules. The solid electrolyte interface (SEI) film formed on the encapsulated graphite electrode retains a stable morphology during repeated cycling, and thus avoids an increase in the electrode's impedance.

Poly(ethyleneoxide) (PEO) based gel network polymer electrolytes prepared from crosslinking reaction were applied in fabricating quasi-solid-state dye-sensitized TiO 2 photoelectrochemical cells. Incident photon-to-current conversion efficiencies up to 48% and 40%, overall energy conversion efficiencies up to 3.6% and 2.9% have been achieved respectively for the resulting cells containing PEO 2000 and PEO 1500 segments.

Urea–formaldehyde resin and polymethacrylate, as two typical polymers for heterochain and carbon chain polymers, respectively, were synthesized and pyrolyzed to prepare carbonaceous materials for the anode of lithium ion batteries. The effect of cross-linking structure of both polymeric precursors on the physical and electrochemical properties of as-prepared carbons was investigated by thermal analysis, X-ray diffraction and cyclic charge/discharge method and compared with each other. It was found that, even though two typical types of polymers were used, the two types of resultant carbons showed the same trend with the change of cross-linking density of polymers in the size of graphene layers and in the lithium accommodation capacity. The same positive influence of the cross-link structure of both representative polymers on the ability of lithium insertion in resultant carbons was confirmed.

Phosphorus-containing carbon has been prepared by the pyrolysis of phenolic resin containing chemically bonded phosphorus atoms, which is synthesized through the esterification of phenolic hydroxyl group by phosphoric acid. The electrochemical insertion of lithium in as-prepared carbon is also investigated. It is found that, at a pyrolysis temperature of 500°C, the addition of phosphoric acid in the precursor lowers the reversible capacity of the resultant carbon, but at 900°C, the addition of phosphoric acid in the precursor resin increases the reversible capacity of resultant carbon. Especially, the phosphorus-containing carbon prepared by the above method at 900°C gives a capacity beyond the theoretical value of graphite and reasonable discharge/charge curves. The phosphorus-containing carbon prepared by the pyrolysis at 500°C shows a similar electrochemical behavior to that of pure carbon and the effect of phosphorus atoms is little. Its reversible capacity is mainly determined by the content of hydrogen atoms rather than phosphorus atoms. However, at a relatively high pyrolysis temperature, 900°C, more phosphorus atoms are bonded with carbon atoms and are introduced to the microcrystallite structure of carbon. Hence, phosphorus element exerts a strike effect on the electrochemical behavior of carbon and, because of its different electronic effect from carbon element, more lithium species are inserted into carbon matrix.

A novel network polymer electrolyte based on the polymethylsiloxane system has been designed and synthesized. In the network polymers, different numbers of PEO chains with various molecular weights were introduced onto the networks as immobile internal plasticizer through a hydrosilylation reaction. The presence of internal plasticizers pendant on the network backbones can lower the glass transition temperatures (Tg) of the electrolytes, make the lithium salt easily dissolved and accelerate the migration of free lithium ions migration. The ambient ionic conductivity (σRT) was significantly enhanced compared with that of network polymer electrolytes without internal plasticizers. The optimum ionic conductivity was 10−4.1 S cm−1 at room temperature and 10−3.0 S cm−1 at 80°C.

Nitrogen-containing polymeric carbon as anode materials for the lithium ion secondary battery is prepared from polyacrylonitrile (PAN) and melamine–formaldehyde resin (MF) at 600 and 800°C. Its physicochemical properties were investigated through elemental analysis, X-ray powder diffraction, X-ray photoelectron spectroscopy, and measurement of specific surface area. Results show that this kind of carbon is amorphous. Nitrogen atoms exist in the prepared polymeric carbon mainly as two states, that is, graphene nitrogen and conjugated nitrogen, and favor the enhancement of reversible lithium capacity. All the prepared polymeric carbon has a reversible capacity higher than that of the theoretic value of graphite, 372 mAh/g, and the highest reversible capacity can be up to 536 mAh/g. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1735–1741, 2000

Gel polymer electrolytes (GPE) were prepared by a crosslinking reaction between poly(ethylene glycol) and a crosslinking agent with three isocyanate groups in the presence of propylene carbonate (PC) and ethylene carbonate (EC) or their mixture, and their ionic conducting behavior was carefully investigated. When the plasticizer amount was fixed, the ionic conductivity was greatly influenced by the nature of plasticizers. It was found that the conductivity data followed the Arrhenius equation in the GPE. Whatever plasticizer was used, a maximum ambient conductivity was found at a salt concentration near [Li+]/[EO] equal to 0.20. The physical stability of GPE was studied qualitatively by weight loss of GPE under pressure. It was shown that the stability was greatly affected by the network structure of the GPE and the most stable one in our research was the GPE containing the PEO1000 segment, which has a strong interaction between network and plasticizers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2957–2962, 2000

Poly[methoxy oligo (oxyethylene) propylene] was synthesized by means of the Et(Ind) 2 ZrCl 2 -MAO catalyst. The ionic conductivity of poly[methoxy oligo (oxyethylene) propylene] with the lithium salt depends on the content of the lithium salt. The temperature dependence of conductivity was determined and the Vogel-Tammann/ Hesser-Fulcher (VTF) plot agreed well with theoretical values, confirming the influence of the polymer segmental motion on conductivity. The ionic conductivity as high as 10 -4.7 s/cm can be obtained at room temperature, and this can be increased one or two orders of magnitude by blending the polyelectrolyte with hydroxyl-containing additives such as tetraethylene glycol.

Nitrogen-containing carbons have been made from different polymer precursors at 600°C. Their composition and structure have been studied by chemical analysis, X-ray powder diffraction and X-ray photoelectron spectroscopy. These results show that this kind of carbon is disordered, and nitrogen exists as two kinds of forms in the polymeric carbons: graphene nitrogen (N1s binding energy 398.5 eV) and conjugated nitrogen (N1s binding energy 400.2 eV). The discharge and charge process suggests that these two kinds of nitrogen are bonded satisfactorily and could not result in irreversible reaction with Li. The increase of reversible capacity mainly results from the graphene nitrogen, and the higher the content of nitrogen, the higher the charge capacity. Part of the irreversible capacity is derived from the formed lithium carbide and lithium atoms which are intercalated and could not be deintercalated.

A class of ambient temperature solid electrolyte based on an `inorganic salt–organic salt' hybrid system is reported. The hybrid system was investigated by the measurement of ionic conductivities and the interaction between the ions of the hybrid system was studied by Raman spectroscopy. The organic salt in the hybrid system not only promoted the dissociation of the lithium salt, but also provided the hybrid system with an improved rubbery property.

The electrochemical hydrating/dehydrating behavior of MmNi5-type alloy electrodes in an alkaline solution was investigated with cyclic voltammetry, scanning electron microscopy and X-ray photoelectron spectroscopy analysis. At an Mm(Ni3.8Co0.5Al0.4Mn0.3)5 powder microelectrode, a hydrogen absorption peak was observed at more negative potential than that of the water electroreduction and hydrogen adsorption peak in its cyclic voltammograms. In addition, the electrochemical mechanism of the hydrogen absorption and desorption at the hydride electrodes in the alkaline solution is discussed.

Carbons pyrolyzed at temperature ranging from 500°C to 1 000°C are promising materials for high-energy density lithium batteries. These carbons not only possess a capacity higher than the theoretical value of graphite, but also display a different electrochemical behavior from that of graphite. Mechanisms now available for this phenomenon are reviewed after the presentation of mechanism of lithiun intercalation in graphite. Based on the recent research, a new model for lithium insertion in carbons pyrolyzed at low temperature and sane ideas for further study are proposed.

Disordered polyacenes were prepared from poly(styrene-co-divinylbenzene). The structures and electrochemical properties of these samples were studied. The result shows that the crosslinking unit of divinylbenzene in copolymer is beneficial to the charge capacity of the resultant polyacene. The change capacity of polyacene increases with the increase of the content of divinylbenzene (DVB), and finally surpasses the theoretical capacity of graphite (372 mA hr/g) when the content of DVB goes up to 5 wt%. Moreover, the charge curves have a potential plateau at approximately 1 V v. Li/Li+, and the increase of charge capacity mainly results from the lengthening of this plateau. Copyright © 1999 John Wiley & Sons, Ltd.

Through the measurement of electrochemical properties of carbon anodes based on copolymers of 4-VP and AN with crosslinker DVB, it is found that the introduction of crosslinker DVB can favor the enhancement of reversible capacity, and the highest can be up to 600 mAh g− 1. Measurements of Thermal gravity analysis, elemental analysis, X-ray powder diffraction, scanning electron microscopy and specific surface area indicate that the incorporation of DVB into polymer PAN can not only affect the contents of nitrogen and hydrogen, but also favor the carbonization process. In addition, it can result in improvement of the regularity of the obtained carbon structure, i.e. the formation of graphite structure, and the number of micropores is increased. By virtue of all these factors, charge capacity below and above 0.9 V enhances and charging voltages decrease with the addition amount of DVB.

Through measurement of the intensity of the EPR signal of carbon anodes at different discharge and charge potentials, a micropore mechanism is suggested for the storage of lithium in low temperature carbons (LTCs), and it is further confirmed by results from the addition of pore-genic agent and introduction of crosslinker DVB into addition polymers PAN and P(4-VP). The size of micropores acting effectively as ‘reservoirs’ for lithium storage is suggested to be below 100 nm. The phenomena, which are characteristic in LTCs such as voltage hysteresis and capacity fading, are explained through the suggested mechanism.