Ion In Electrolyte Solutions Research Articles

Surface Analysis of Magnesium Metal Anode

Introduction Rechargeable magnesium battery is expected as a candidate of post lithium-ion battery1. One of the biggest challenges in the rechargeable magnesium battery is reversible deposition/dissolution process of the magnesium metal anode, because the magnesium deposition process does not occur in the most of the conventional ionic electrolyte solution, while organohaloalminate-based electrolytes show highly reversible magnesium deposition/dissolution2. Recently several research group reported that Mg(TFSI)2 in ether-based solvents show reversible magnesium deposition/dissolution3, 4. However since the electrochemical behaviors of the Mg(TFSI)2-based ionic electrolyte solutions are very different from the organohaloalminate-based electrolytes; the ionic electrolytes show high overpotential and low coulombic efficiency, we think the electrodeposition process of the magnesium metal is not that simple as lithium, sodium or any other metal. Here we conducted in situFTIR spectroscopy and Lab-HAXPES to confirm the formation process of so-called SEI layer and passivation layer on magnesium metal in various electrolyte solutions. Experimental A three-electrode in situ FTIR cell with internal reflection geometry was build upon a diamond ATR disc of DuraSamplIR (Smiths Detection). Platinum thin film electrode was fabricated on the diamond-window as the working electrode. A magnesium quasi-reference electrode and a magnesium counter electrode were employed for the electrochemical measurement. The FTIR spectra were taken by single beam mode and subtractively normalized interfacial FTIR spectra (SNIFTIRS) were calculated. The SNIFTIRS have positive peaks and negative peaks corresponding to the decreased species and the increased species during the electrochemical measurement respectively. The Lab-HAXPES measurement was performed using Cr-Ka radiation. Results Figure 1 shows a comparison of in situ FTIR spectra for an organohaloalminate-based electrolyte (0.25M EtMgCl : EtAlCl2 = 1 : 2 by mol in THF) and an ionic electrolyte solution(0.5 M Mg(TFSI)2 in BuMe-triglyme) during a two-cycles of CV measurement. The cathodic scan was terminated at the electrode potential slightly above the magnesium deposition. In the case of the organohaloalminate-based electrolyte, reversible spectra changes corresponding to the adsorption state changes of THF were observed for two cycles, as shown in Figure 1 (a). It suggests that no irreversible electrochemical reaction takes place at the surface of the electrode. In other words, no SEI layer was formed in the organohaloalminate-based electrolyte. On the other hand, irreversible spectra changes were observed in the case of Mg(TFSI)2 in BuMe-triglyme. The irreversible reaction should be corresponding to the cathodic decomposition of the TFSI anion. The XPS analysis proved that a surface layer containing some fluorinated organic species were formed at the surface of the Mg negative electrode in the case of Mg(TFSI)2-based electrolyte. The high overpotential and poor reversibility of the Mg(TFSI)2 system could be due to the formation of the surface layer.

Enhanced Electrochemiluminescence on Indium Tin Oxide Modified with Dendrimer-Encapsulated Nanoparticles

Here, we report enhanced electrochemiluminescence (ECL) on indium tin oxide (ITO) electrodes modified with amine-terminated dendrimers encapsulating catalytic nanoparticles, which can be applied for sensitive electrochemiluminescence(ECL)-based assay. Specifically, we prepared Pt and Au dendrimer-encapsulated nanoparticles (DENs) using amine-terminated polyamidoamine (PAMAM) dendrimers, and subsequently immobilized the DENs onto ITO surfaces via electrooxidative grafting of the terminal amines of dendrimers to the surfaces.[1] The resulting DEN-modified ITOs preserved good optical transparency of ITO and exhibited highly catalyzed electrochemical oxidation of Ru(bpy)3 2+ (bpy, 2,2’-bipyridine)/ tri-n-propylamine (TPrA), leading to significantly increased ECL emission.[2] Especially, the Pt DEN-modified ITO electrode provides negligible transmittance drop, i.e. only ~1.99% over the entire visible region, and exhibited not only much enhanced (i.e., ~213-fold increase compared to ECL obtained from bare ITO), but also stable ECL emission under consecutive potential scans from 0.00 to 1.10 V for 10 cycles, which allowed ~329 times more sensitive ECL-based analysis of nicotine using the Pt DEN-modified ITO compared with the use of bare ITO. However, we observed relatively poor stability of Au DENs on the ITO surfaces.[2] We found that the poor stability of Au DENs is closely related with the presence of chloride ions in electrolyte solutions.[3] In the absence of chloride ions, we demonstrated that the Au DEN-modified ITOs could be used as a versatile ECL based platform for sensitive electroanalysis of reactive oxygen species (ROS), such as hydrogen peroxide. [1] S. B. Lee, Y. Ju, Y. Kim, C. M. Koo, and J. Kim, Chem . Com un . 2013, 49, 8913. [2] Y. Kim and J. Kim, Anal . C hem . 2014, 86, 1654. [3] Lee, S. B.; Kwon, J.; Kim, J. Electroanalysis 2015 , 27, 2180-2186.

The Effect of Preparation Temperature of Electrolytes on Undoped and Ag-Doped TiO<sub>2</sub> Nanotube Structures

In this work, we present the effect of preparation temperature of electrolytes for fabricating undoped and silver (Ag) doped titanium dioxide (TiO2) nanotubes by the electrochemical anodic oxidation of pure titanium sheets in electrolytes, mixtures of ethylene glycol (EG), ammonium fluoride (NH4F) and deionized water, that contain with different of silver ions. Heat treatment of electrolytes was carried out at 100 °C during preparation process. The morphology and structure of prepared nanotubes were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The structures of TiO2 nanotubes obtained from heat treatment and non-heat treatment of electrolyte solutions and adding silver ions in electrolyte solution are similar. The nanotubes appear in arrays and the diameters of nanotubes were about 92 nm for non-heat treatment electrolyte solution and undoped TiO2 and about 102 nm for heat treatment electrolyte solution and all Ag-doped TiO2 nanotube arrays. When the concentration of silver nitrate (AgNO3) increases, the TiO2 nanotube arrays cracked and are not well arranged.

Correlation Between Free Volume and Ionic Conductivity of Non-Aqueous Lithium Battery Electrolyte Solutions over a Wide Concentration Range

There is little known about the transport behavior of ions in electrolyte solutions at very high concentration and there is currently no satisfactory theory/equation to describe it [1,2]. In this work electrolyte solutions of lithium salts of various anions: [(CF3SO2)2N]°¥, (TFSI), [PF6]°¥ and [BF4]°¥ dissolved in polar solvents and solvent mixtures up to saturation have been prepared. The solvents are propylene carbonate (PC), acetonitrile (ACN), adiponitrile (ADN) and ethylene carbonate:dimethyl carbonate (1:1 v/v) (EC:DMC). The Ionic conductivity and density of the electrolyte solutions have been measured over a wide concentration range (up to 5.4 M). The specific ionic conductivity (κ) vs. C plots show a non-ideal behavior with very strong dependence on concentration (a typical Gaussian-like function) while the molar conductivity (Λ) vs. C plots show an exponential decrease similar to the behavior of weak electrolyte solutions. The conductivity vs. concentration data were fitted to various equations of known models (Debye-Hückel-Onsager’s square-rate law: Λ vs. C^1/2, Cubic-root law: Λ vs. C^3, Casteel-Amis equation: κ/κmax vs. C/Cmax , or the corresponding state-law equation based on the pseudo-lattice theory: κ/κmax vs. C/Cmax .The models show good fit only in the low concentration, with the last two models fail to show universal behavior beyond the concentration of maximum conductivity, Cmax. However, we have derived a new, semi-empirical equation that shows a very good fit over the whole concentration range and can correlate molar ionic conductivity to changes in free volume within the liquid solution: Λ = A' exp [-B C], B =-γ Vo/Vf, and Vf = V-Vo Where Vƒ is the free volume which can be calculated from the difference between the measured volume, V, of the liquid (from density measurements) and the Van der Waal “molecular “volume, Vo, which can be obtained from XRD data at low temperatures or calculated using chemical models. C is concentration, A’ is a pre-exponential factor that can be related to limiting molar conductivity and square root of temerature. γ is a correction factor for overlapping holes with a value between 0.5 and 1. These preliminary results are encouraging in bringing us closer to a free volume-based approach to explain the behavior of ionic conductivity of electrolyte solutions at very high concentrations. However, more work is underway to study more solutions with different chemical and physical properties, including aqueous solutions, to test the validity of this approach. [1] S. I. Smedley, The Interpretation of Ionic Conductivity in Liquids, Springer, 1980 [2] C.A. Angell, J. Phys. Chem., 70, 1966, 3988

Surface Analysis of Magnesium Metal Anode for Rechargeable Magnesium Batteries

1. Introduction Magnesium metal is an ideal anode active material because of its high theoretical capacity > 3500 mAh·cm-3and dendrite-free morphology. However the surface of the magnesium metal anode is easily passivated in most of the ionic electrolyte solution, as a consequence, very limited choices of the electrolyte solutions are available for the reversible magnesium deposition/dissolution. Magnesium organohaloalminates, typically synthesized by mixing Grignard reagents and alminate-based Lewis acids, are well known as magnesium electrolytes having excellent reversibility and forming highly crystalline magnesium. Despite of its good electrochemical properties, the Mg organohaloaluminate has a lot of difficulties to be an electrolyte solution of a practical battery system. Recently ionic electrolyte solutions containing ionic magnesium salt: Mg(TFSI)2 were proposed as the alternative to the Mg organohaloalminates [2, 3]. Compered with the Mg organohaloalminate-based system, the Mg(TFSI)2based electrolyte solutions show poor reversibility and high overpotential. In the present study, we conducted surface analyses of the electrodeposited magnesium electrodes in various electrolyte solutions: Mg organohaloalminates, Mg(TFSI)2in triglyme and other solvents, to understand the key property of the magnesium deposition/dissolution process. 2. Experimental In this study, we used two electrolyte solutions. An Mg organohaloalminate solution was prepared by mixing with EtMgCl in THF and Et2AlCl resulting to form the electrolyte containing 0.25 mol dm-3 of magnesium. A 0.5 M of Mg(TFSI)2in triethylene glycol dimethyl ether (G3) was also prepared as the comparison. The electrodeposition test was carried out using a three-electrode cell. The working electrode was platinum sheet, and the magnesium metal was employed as the quasi-reference electrode and the counter electrode. The electrodes deposited Mg were rinsed with THF or DME, and observed the surface morphology by SEM. The surface analysis was performed for Mg metal electrodes immersed in the electrolyte solutions for 24 hours. The Mg metal electrodes were rinsed with solvents and the surface analyses were performed using XPS. 3. Results and Discussion Fig. 1 shows the SEM images of electrodeposited Mg on the Pt electrodes. At a glance the surface morphologies of the electrodeposited Mg were significantly dependent upon the electrolyte solution. In the case of the Mg organohaloalminate solution, the surface morphology is very smooth, and the formation of hexagonal-particles is clearly observed in the high magnification SEM images, whereas the magnesium metal deposited in the Mg(TFSI)2solution showed spherical particles . Moreover, the XRD pattern detected low crystalline of electrodeposited Mg from the TFSI system. Fig. 2 shows the XPS C 1s spectra of immersed Mg in the electrolyte solutions. The XPS spectra of the Mg metal immersed in the Mg organohaloalminate solution had a peak assigned the C-C bonds from the surface to bulk. However, the case of the Mg metal immersed in the Mg(TFSI)2system, a peak corresponding to the C-O-C bonds and a peak assigned C-F bonds were detected. It clearly suggests that the TFSI anion is easily reduced at the surface of the Mg metal resulting in the formation of the surface film. Hence we assume that the surface film hinders the smooth deposition and dissolution of the Mg. Also we think that the reduction stability of the anion is crucial for Mg deposition/dissolution process. 4. Reference [1] D. Aurbach. Z. Lu, A. Schechter, Y. Gofer, R. Turgeman, Y. Cohen, M. Moshkovich, and E. Levi, Nature, 407, 724-727 (2000) [2] T. Fukutsuka, K. Asaka, A. Inoo, R. Yasui, K. Miyazaki, T. Abe, K. Nishio, and Y. Uchimoto, Chem. Lett., 43, 1788-1790 (2014) [3] H. Senoh, H. Sakaebe, H. Sano, M. Yao, K. Kuratani, N. Takeuchi, and T. Kiyobayashi, J. Electrochem. Soc., 161, A1315 (2014) Figure 1

Effect of ionic contaminants on dielectric dispersion and relaxation processes over static permittivity frequency region in neat liquid poly(ethylene glycol)

Complex dielectric permittivity, ac electrical conductivity, electric modulus and impedance spectra of poly(ethylene glycol) (PEG200) were investigated in the frequency range from 20Hz to 1MHz and temperatures from 5 to 55°C. Temperature dependent relaxation processes caused by charging and discharging of electric double layers (EDLs) in the 1kHz–10kHz range and by the ions dynamics above 100kHz were explored from the comparative analysis of the spectra of complex quantities. The values of static permittivity, Kirkwood correlation factor, dc ionic conductivity, EDLs and conductivity relaxation times, and the activation energies of PEG200 were determined. It has been observed that the ionic contaminants influence the electric conduction behaviour of neat PEG200 which is found exactly similar to that of the diluted ionic electrolyte solution of lithium perchlorate dissolved in PEG200. The temperature dependent conductivity and viscosity data related to the ions movement in viscous media were analyzed which revealed that the Stokes-Einstein-Nernst model was not fulfilled for PEG200.

周波数変調原子間力顕微鏡を用いた溶液環境下のナノスケール電位・電荷密度計測

Surface charges on nanometer-scale structures in liquids play an essentially important role in various physical, chemical and biochemical phenomena such as ionic adsorptions, microscopic electrode reactions and specific ligand bindings. These molecular-scale interactions are mediated through local electric double layers (EDLs) formed by the counter ions in electrolyte solution. Although static-mode atomic force microscopy (AFM) including colloidal probe AFM is a powerful technique for surface charge density measurements and EDL analysis on a submicron scale in liquids, precise surface charge density analysis with molecular resolution has not been realized because of its limitation of the resolution and the electrical force detection sensitivity. Here recent molecular-scale surface charge measurements of self-assembled micellar structures and biomolecules by three-dimensional (3D) force mapping based on frequency modulation AFM are presented.

Electrochemical performance of activated carbons prepared from rice husk in different types of non-aqueous electrolytes

Activated carbons (ACs) prepared from rice husk (RH), an agricultural byproduct, have mesoporosity that is obtainable from leaching of the mineral component of silica. To verify the suitability of RH-derived ACs for the use of electrode materials of electrical double-layer capacitors, we evaluated the electrochemical performance of three RH-derived ACs (two micro- and mesoporous ACs and one mesoporous AC). Evaluation was done by using the non-aqueous ionic electrolyte solutions 1 mol dm−3 triethylmethyl ammonium tetrafluoroborate/propylene carbonate (PC) solution, 1.5 mol dm−3 spiro-(1,1′)-bipyrrolidinium tetrafluoroborate/PC (SBP·BF4/PC) solution, and the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIm·BF4). Under low voltage scan rate (1 mV s−1) and low current density (<1 mA cm−2), mesoporous AC, which had the highest specific surface area, showed the highest specific capacitance (120 F g−1) in EMIm·BF4. However, its specific capacitance considerably decreased because of the increase in scan rate and current density. Under high scan rate (10 and 100 mV s−1) and high current density (>10 mA cm−2), micro- and mesoporous AC in 1.5 mol dm−3 SBP·BF4/PC showed the highest specific capacitance and highest retention of specific capacitance, even though its specific surface area was not the highest. Mesoporous AC showed voltage-dependent specific capacitance, indicating that ionic transport in the mesoporous structure was sensitive to electric field. It was finally shown that micro- and mesoporosity developed by utilizing natural structure and composition of RH was useful for the electrode materials of advanced electrical double-layer capacitors requiring more viscous non-aqueous electrolytes.

Enhanced Electrochemiluminescence of Luminol on Indium Tin Oxide Modified with Dendrimer‐Encapsulated Au Nanoparticles

AbstractEnhanced electrochemiluminescence (ECL) of luminol was reported with the use of dendrimer‐encapsulated Au nanoparticle (Au DEN)‐modified ITOs in the presence of hydrogen peroxide, which was applied for sensitive ECL‐based electroanalysis of hydrogen peroxide. The enhanced ECL of luminol in the presence of hydrogen peroxide was attributed to facile electrochemical oxidation of luminol/hydrogen peroxide on the Au DEN‐modified ITOs at potentials as low as ∼0.4 V (vs. Ag/AgCl). Spooling ECL spectroscopy measurements indicated that the enhanced ECL emission of luminol/hydrogen peroxide system on the Au DEN‐modified ITOs originated from excited 3‐aminophthalate as same as that obtained on bare ITOs. Stability of Au DENs on ITO surfaces was also addressed and found to be closely related with the presence of chloride ions in electrolyte solutions.

細胞刺激用マイクロデバイスに関する研究 (第1報)

This present paper describes some test results about micro-patterning and actuation of conductive polymer (polypyrrole, PPy) for a development of mechanical stimulation device for cultured cells. Pyrrole molecules are selectively electrochemically polymerized with NaDBS to be patterned in dot array using an OFPR template. The fabricated PPy dot has circular truncated cone shape, in which the bottom diameter changed from approximately 10 to 30μm with electric charge. An applied voltage makes the PPy dots expanded or contracted by adsorption or desorption of ions in electrolyte solution. A cyclic change of PPy dot diameter is in-situ observed by a CCD microscope. It is confirmed that the increase of PPy dot diameter corresponds to lateral strain in contraction state. It is found that the maximum change of PPy dot diameter also reaches to 10% at +1V. It is confirmed that the surface of PPy dot has cell adhesiveness after protein coating.

Characterization of ion separation in electrodialysis membranes using , a dimensionless number

In electrodialysis membranes (EDMEMs), electric potential gradient serves primarily as driving force to separate ions in electrolyte solutions using anion and cation exchange membranes. Nevertheless, the mere increase in electric potential gradient would not straightforwardly correspond to higher efficiency. Instead, the orientation of electric field lines, in combination with those of the main fluid flow stream, plays a prevailing role. In the present study, a new dimensionless number is proposed, which characterizes the orientation of electric field lines and their effect on the separation process. The dimensionless number would also serve as an engineering design tool which describes the effectiveness of different EDMEM stacks under different operating conditions i.e. velocity or geometrical aspects i.e. dimension of electrodes and membranes.

Molecular-scale investigations of structures and surface charge distribution of surfactant aggregates by three-dimensional force mapping

Surface charges on nanoscale structures in liquids, such as biomolecules and nano-micelles, play an essentially important role in their structural stability as well as their chemical activities. These structures interact with each other through electric double layers (EDLs) formed by the counter ions in electrolyte solution. Although static-mode atomic force microscopy (AFM) including colloidal-probe AFM is a powerful technique for surface charge density measurements and EDL analysis on a submicron scale in liquids, precise surface charge density analysis with single-nanometer resolution has not been made because of its limitation of the resolution and the detection sensitivity. Here we demonstrate molecular-scale surface charge measurements of self-assembled micellar structures, molecular hemicylinders of sodium dodecyl sulfate (SDS), by three-dimensional (3D) force mapping based on frequency modulation AFM. The SDS hemicylindrical structures with a diameter of 4.8 nm on a graphite surface were clearly imaged. We have succeeded in visualizing 3D EDL forces on the SDS hemicylinder surfaces and obtaining the molecular-scale charge density for the first time. The results showed that the surface charge on the trench regions between the hemicylinders was much smaller than that on the hemicylinder tops. The method can be applied to a wide variety of local charge distribution studies, such as spatial charge variation on a single protein molecule.

Extreme pH-induced lateral reorganization of supported lipid bilayer by fluorescence microscope

The extreme pH-induced lateral reorganization of supported lipid bilayer membranes are studied by fluorescence microscopy. The results show that the fluid dioleoyl-phosphatidylcholine bilayers in extreme acidic or basic solution presents a similar phenomenon to endocytosis and exocytosis, such as rupture, detachment, budding, formation of microtubules etc. In the view of the interaction of polar molecules with H+/H3O+ or OH ions, we conclude that the zwitterionic phospholipid headgroup as core adsorbs the H+/H3O+ or OH ions in electrolyte solution. The asymmetric charge adsorption quantity of the lipid headgroups leads to the effective area discrepancy between the outer and inner leaflets of lipid bilayers. The asymmetric membrane curvatures induce a variety of structures and dynamic responses. The present study helps explain lipid membranes reorganization under extreme pH conditions and provides some guidelines for deformation process of lipid membranes.

Effect of electrolyte constituents on the motion of ionic species and recombination kinetics in dye-sensitized solar cells

The dynamic motion of ions in electrolyte solutions and its effect on recombination was investigated by the heterodyne transient grating method in addition to transient absorption and transient photocurrent methods in dye sensitized solar cells. Realignment of ionic species at the electrode/electrolyte interface was observed after the electron injection in TiO2 on the order of μs. The process was affected by the total quantity of ionic species as well as cation species in the electrolyte. The recombination processes of the electrons were also affected by the constituents; the probability of the electron-electrolyte recombination decreased with decrease in I2 concentration; the dominant recombination process changed from the electron-electrolyte to the electron-dye recombination by decreasing I(-) concentration. It is concluded that sufficient I(-) is necessary for the suppression of the electron-dye recombination and that sufficient I2 is necessary for an efficient redox cycle, while low concentration of I3(-) ions at the electrolyte/TiO2 interface is preferable to suppress the electron-electrolyte recombination. The effect of the cation size in an electrolyte solution on the charge dynamics was also investigated, and it was revealed that the steric hindrance of cations changed the penetration of ionic species into the nanoporous dye/TiO2 electrode, causing a change in the electrostatic properties at the interface. The cation dependence indicated that the presence of large-sized cations suppressed the electron-electrolyte recombination by disturbing the approach of I3(-) paired with the cations.

Electrochemical reductive dechlorination of trichloroacetic acid on porous Ag-Pd thin foam

Porous Ag-Pd thin foam (PAPTF) possesses high electrocatalytic activities towards reductive dechlorination of trichloroacetic acid in alkaline media and is expected to be promising electro catalyst for the dechlorination of chlorinated organic wastes. The electrocatalytic activities of PAPTF depend mainly on the Ag components and the morphology. However, the content of Pd(II) in the system can strongly affect the electrocatalytic performance. In this work, PAPTF was fabricated through a rapid one-step electrodeposition method within the hydrogen bubble dynamic template and characterized by SEM, EDS, and cyclic voltammetry. Morphology and composition of as-fabricated PAPTF can be modified significantly by applying different deposition conditions, such as concentration ratio of Ag(I) to Pd(II) ions in electrolytic solution and deposition time.

Catalytic Activity of Porous Pd-Ni Thin Foam towards Electrooxidation of Methanol

Porous Pd-Ni thin foam was fabricated by a rapid one-step electrodeposition process within hydrogen bubble dynamic template and characterized by SEM, EDS, and cyclic voltammetry. Morphology and composition of the foam can be modified significantly by applying different deposition conditions, such as concentration ratio of Pd (II) ions to Ni (II) ions in electrolytic solution and deposition time. Electrocatalytic activities of the foam towards methanol oxidation in alkaline media were investigated, which depend mainly on Pd components and its morphology. Low nickel content can assist Pd further enhance the electrocatalytic performance, particularly the tolerance to intermediates of methanol oxidation, while high nickel content brings adverse effect. The high catalytic activity and the low cost of the Pd-Ni foams enable them to be promising electrocatalysts for the oxidation of methanol in alkaline media.

Fabrication of a novel porous Ni–P thin-film using electroless-plating: Application to embedded thin-film resistor

A novel porous Ni–P alloy thin-film was developed to fabricate embedded resistor through the electroless deposition by introducing manganese ion in electrolyte solutions. SEM images demonstrated high density of pores or holes with diameters ranging from 0.1μm to 3.0μm was formed in Ni–P thin-film when the concentrations of MnSO4·H2O changed from 0 to 50g/dm3. Resistance testing results revealed a significant increasing of resistance as the concentration of MnSO4·H2O increases and thereby a quadratical relationship between them was primly fitted with low deviation of 5.75%. Moreover, to explore the application practice of this porous thin-film in embedded resistor, distribution experiment was designed to investigate resistance tolerance using maximum deviation method. Tolerances under 15% indicated this porous Ni–P thin-film is a very practical candidate to fabricate embedded resistors.

Effects of Electrolyte Additives on the Suppression of Mn Deposition on Edge Plane Graphite for Lithium-Ion Batteries

To suppress the degradation of graphite negative-electrodes that is caused by the dissolution of Mn-containing positive-electrode materials, the effects of additives that should strongly interact with Mn ion in electrolyte solution were examined. The edge plane of highly oriented pyrolytic graphite (HOPG) was used as a model graphite electrode, and its electrochemical properties were investigated by cyclic voltammetry and electrochemical impedance spectroscopy in Mn-ion-containing electrolyte solution. 100 ppm Mn ion dissolved in the electrolyte solution caused a significant decrease in redox currents due to the intercalation and de-intercalation reactions of Li+ at an edge plane HOPG electrode, and a remarkable increase in interfacial resistance consisting of surface film resistance and charge transfer resistance due to Li+ transfer at an interface between the electrode and electrolyte solution. This performance deterioration could be effectively suppressed by the addition of a certain type of cyclic ether to the electrolyte solution. The influence of the additive concentration on interfacial resistance was also investigated.

Effect of Polymeric p-Type Semiconductor on Photovoltaic Properties in Dye-Sensitized Solar Cell

A hole formed in photo-excited dye molecule under illumination is transferred to cathode with iodine ion in electrolyte solution in the dye-sensitized solar cell developed by M. Grätzel and the conductivity of the iodine ion affects conversion efficiency of the cell. In this work, effect of the polymeric p-type semiconductor on the hole transferability is investigated. PEDOT:PSS and P3HT were used as the p-type semiconductors. Dye-sensitized solar cells were composed of aluminium plate, Nb-doped TiO2 layer adsorbed with TCNQ, the electrolyte solution containing iodine ions, and ITO glass plate. In a solid-type cell substituted the electrolyte solution with the p-type semiconductor, photocurrent was not generated. The photocurrent was generated in the solar cell by introducing the electrolyte solution containing iodine ions between the ITO glass and the p-type semiconductor formed on the dye-adsorbed Nb-doped-TiO2 layer or between the dye-adsorbed Nb-doped-TiO2 layer and the p-type semiconductor formed on the ITO glass. The conversion efficiency increased with the introduction of the p-type semiconductor such as PEDOT:PSS, compared only with the electrolyte solution. The p-type semiconductor containing iodine ions promote the hole transfer of iodine ion, compared with that in the electrolyte solution.

ChemInform Abstract: Lithium‐Ion Conducting Electrolyte Salts for Lithium Batteries

AbstractReview: 166 refs.