Methanol is a likely alternative to petroleum-derived fuels and a number of electrochemical investigation have been reported on Pt electrode. However, results, appear rather scattered, depending highly on experimental conditions. The aims of the present paper are to understand general features of the electrooxidation of the 0-containirig C₁ compounds such as CO, HCOOH and CH₃OH on the identical experimental conditions.
The experiments were carried out by the usual electrochemical method but the special attention was paid to standardization of the surface state of the Pt electrode, the concentration of the reactants and the experimental procedures.
The steady state polarization measure ments show that the CH3OH oxidation, is slower by 1 to 2 orders of magnitude than those of HCOOH (acid) and CO. HC00^- does not oxidize in alkaline solution. The competitive oxidation of the reactants indicates that the slow CH₃OH oxidation is due to the weak interaction of CH₃OH with the Pt surface. The weak interaction can be explained by a high geometrical requirement for the adsorption sites but not by any special, poisoning effects of the adsorbed species since the latter is found to be a common species and present to an almost equal amount at the CH₃OH, HCOOH(Na), CO oxidations.
The surface oxida tion process of CH₃OH and HCOOH(Na) and CO will proceed by a common mechanism since their voltammograms undergo a sharp and drastic change in a common way at a solution pH of about 11. The CH₃OH oxidation mechanism was further discussed in detail.

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The degradation phenomena of β′′-Al₂O₃ ceramics (Na₂O⋅5Al₂O₃) used as the separator and the solid electrolyte of sociium-sulfur battery were studied with Na/Na cell. A darkened layer in Fig.6 was observed after the test. The culculated resistance of the darkened layer was found to be nearly zero, then the darkened layer became a degradated layer. The growth of this degradated layer was promoted by increasing temperature, current density and operating time. When the degradated layer thickness was proceeded into the second stage, the degradation rate was accelerated because of the cracks in β′′-Al₂O₃ ceramics and increase in the concentration of the sodium ion current.
The degradation process at 350°C is shown in Fig.13. The estimation of anperage life was possible. The first stage life (before the induction of cracks) was 7.4×10³ Ah/cm² and the breakage life was 7.8×10⁴ Ah/cm² at the O.1 A/cm² current density and 1 mm ceramics thickness.

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A new rechargeable cell, liquid podium/sodium β′′-alumina tube/tetravalent selenium in basic AlCl₃-NaCl melts, has been investigated to develop a high performance battery for the load-leveling application. The cells with carbon felt positive current collectors were able to charge and discharge efficiently even in basic chloroaluminate melts saturated with sodium chloride, as shown in Fig.2. The melt composition at the discharging limit is about 30/70 of AlCl₃-NaCl molar ratio, which depends on the deposition of sodium chloride, a poor electronic conductor, on the positive current collector.
Lower polarization, especially at charging, was ob served in the cells No. CS-54 in Fig.2and CS-62 in Fig.4; their current collectors were totally dipped in the positive melts. The energy density of Na/Se(IV) cells usually exceeds 300 Wh/kg with low current densities at 225°C, as shown in Fig.3. One cell, No. CS-61, showed a high energy density of 415 Wh/kg as well as high turn-around efficiency.; it had been prepared to work theoretically within the melt composition range between 65/35 and 30/70, as shown in Table 1. The resistance of this cell is about 7.0 ohm/cm²-β′′-alumina at 225°C.
Some degradation of the percent utilization of tetravalent selenium and of energy efficiency with continuous charge discharge cycles was observed for the Na/Se(IV) cells with the carbon felt current collectors, as shown in Fig.6.

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The charge-discharge characteristics of Al/FeS₂ secondary cells with various ternary melts were investigated for the operating temperature of 100-450°C. The Al/FeS₂ cells with 47 mol% AlCl₃-38 mol% NaCl-15 mol% MCl melts (M-=--Li, K) had a larger discharge capacity and a longer cycle life (450 cycles) than those with 47 mol% AlCl₃-53 mol% NaCl binary melts at 150°C. Using 50 mol% AlCl₃-25 mol% NaCl-25 mol% LiCl melt as the electrolyte, good charge-discharge cycling behavior could be demonstrated at 120°C. Such improvement of the cell performance was due to a decrease in the melting point of the electrolyte. AlCl₃-NaCl-1-butylpyridinium chloride (BPC) and AlCl₃-LiCl-BPC melts were found to be superior to the AlCl₃-BPC. melt as the electrolyte at 90-140°C. The cell with a basic A1C13NaClBPC melt (below 50 m ot% AlCl₃) had a larger discharge capacity and a higher cell voltage than those with the acidic melts. The BPC concentration affected the chargedischarge performance. The cell with AlCl₃-LiCl-BPC melt had a slightly tower cell voltage and a larger discharge capacity than those with the AlCl₃-LiCl-BPC melt. Both the basic AlCl₃-LiCl-BPC melts containing 9-17 mol% BPC and the basic AlCl₃-LiCl-BPC melts containing 7-17 mol% BPC were the most promising electrolytes around 100°C.

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Charge-discharge characteristics of a lithium (Li) electrode have been investigated in organic electrolyte systems containing high permittivity (dielectric constant) solvents such as propylene carbonate (PC), 3-methyl-1, 3-oxazolidin-2-one (MO), dimethyl sulfoxide (DMSO)and sulfolane, mixed with such a low viscosity ether as 1, 2-dimethoxyethane (DME). The electrolytic conductivity and the viscosity of the solutions were measured as the parameters that reflect the ionic behavior in the mixed solvent systems. The conductivity of an Li salt was generally improved by mixing the solvents. The anion of the electrolyte also influenced the conductivity to a great extent. Higher coulombic efficiencies of the Li electrode were observed for the charge-discharge cycles in the electrolytes consisting of the mixed solvents, PC+DME and DMSO+DME, especially with a mixing ratio of about 1 : 1. These solvent blending effects are related to the ionic mobility and the specific solvation of Li⁺ in the solution. The Li⁺ ion is preferentially coordinated by the solvent with higher donicity, whose chemical and electrochemical properties much influenced the coulombic efficiency of the Li cycling. The specific solvation of DME improved the Li cycling efficiency in LiPF₆/PC+DME, whereas the solvation of MO caused lowering of the efficiency in LiPF₆/MO+DME.

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Among the members of a series of vanadium oxides between V₂O₄ and V₂O₅, which have promising properties as an active material for secondary lithium batteries, hexavanadium tridecaoxide V₆O₁₃ is known to exhibit an excellent cycling performance.
In this study, Fe_yV_6-yO₁₃ (0<y<1.0) samples, in which Fe³⁺ substitutes for V⁴⁺, forming V⁵⁺ in proportional to the y value, have been synthesized as a modification of V₆O₁₃ by heating mixtures of Fe₂O₃, V₂O₅ and V with appropriate ratios in evacuated quartz ampoules. The chemical lithium insertion reaction into these oxides has been investigated using n-BuLi/hexane solutions.
The interplanar spacings of Li_xFe_yV_(6-y)O₁₃ expand along either the b or c axis in a discontinuous manner with increasing x values. The upper limit of lithium insertion, x_max, increases linearly with the iron contenty. These results suggest that V⁵⁺ is responsible for the reduction through lithium insertion. The electrode potential vs. x relation indicates that insertion of lithium up to x_max proceeds stepwise; in the first step up to [Li_(1+y)Fe³⁺_yV⁴⁺_(5-y)V⁵⁺O₁₃], and further to [Li_xmaxFe³⁺_yV³⁺_(2+y)V⁴⁺_(4-2y)O₁₃] in the second step where V⁵⁺ ions in the oxides are reduced to V³⁺ completely.
It was shown that x_max can be extended by forming extra V⁵⁺ ions through the substitution of iron and structural changes accompanied by valence change of vanadium in the host lattice is responsible for determining x_max.

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The composition, structure and discharge characteristics of graphite fluoride prepared from residual carbon have been investigated using natural graphites and petroleum cokes as raw carbon materials. The residual carbons show much lower crystallinity than raw carbons, still containing oxygen by 12-25 wt% after treatment at 400°C for 2 h under vacuum. Among them, the residual carbon obtained from flaky natural graphite has relatively well-ordered structure with a smaller amount of oxygen, compared with the others prepared from powdery natural graphite and petroleum cokes. The reaction of residual carbon with fluorine gas gives (CF)_n graphite fluoride with high reaction rate. The graphite fluoride thus prepared shows excellent cathode characteristics compared with those of usual (CF)_n. Flaky natural graphite is the most suitable raw material for preparing graphite fluoride with this process.

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A diaphragm-type Fe/Cr redox flow cell equipped with a rebalance cell and state of charge monitors has been developed. The electrolyte used was 1 M FeCl₂-1 M CrCl₃-2 M HCl solution for both Fe- and Cr-compartments. A 100 cycle-life test using the single cell without catalyst loading was carried out at 30°C. The system was evaluated in terms of working voltage, discharge capacity, charge/discharge coulombic efficiency, hydrogen gas evolution rate and cross-mixing rate. The average charge/discharge coulombic efficiency during 100 cycles was 96.7%. The losses of electricity due to hydrogen gas evolution and cross mixing were calculated to be 1.5% and 1.8%, respectively, based on the electricity used for charging. The possibility of application to an electrical energy storage system is discussed in terms of the reliability and the cycle life of the system.

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Electrochemical characteristics of LaNi₅ and related alloys were investigated as negative electrode materials for nickel-hydrogen batteiries and were discussed in terms of the equilibrium hydrogen pressure. The equilibrium potential (open-circuit potential) of the alloy negative electrodes shifted to the less negative side when the equilibrium hydrogen pressure was reduced by the partial substitution of Cu, Cr, Mn or Al for Ni in LaNi₅. A linear relationship was found to exist between the measured equilibrium potential and logarithmic equilibrium hydrogen pressure, in agreement with the theoretically deduced equation. The discharge capacity was greatly influenced by temperature and cell inner pressure in such a manner that it sharply decreased when the equilibrium hydrogen pressure exceeded cell inner pressure as a result of the increase in temperature or the decrease in cell inner pressure. These observations were also explained on the basis of the pressure-composition isotherms of alloy-hydrogen systems.

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It has been found that the porosity of the sintered nickel plaque for nickel-cadmium batteries made by the slurry technique can be controlled by adjusting the “slurry porosity”defined by the volume ratio of the liquid carrier to the slurry, besides sintering temperature and sintering time. The sintered porosity increased with an increase of slurry porosity, but only slight increment of the former was observed beyond a value of the latter (O.94).
The pore-size distribution of the plaque made by using methyl cellulose was scar e cely affected by the slurry porosity and showed almost uniform pore-size in the vicinity of 10 μm, while carboxymethylcellulose had a greater distribution of the pore-size ranging from 10 to 60 μm and the fraction of large pores increased as the slurry porosity increased. This beneficial effect of methylcellulose seems to arise from its surfactant activity, which probably yields more homogeneous dispersion of nickel powder.

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The use of cytochrome c as a redox couple of redox type temperature-differential galvanic (TDG) cell is based on the fact that the formal potential of cytochrome c is highly dependent on temperature under some conditions. Performance of the thin-layer TDG cell containing cytochrome c and sodium chloride in aqueous solution (Fig.1) was measured in a temperature range of 7-60°C under steady state conditions. The lower temperature was kept at 7°C. Two gold-plate electrodes modified with di(4-pyridyl) disulfide were separated by 1 mm. The emf of the TDG cell changed biphasically (Fig.3) in the same way as the temperature variation of the formal potential of cytchrome c (Fig.2). The measured thermoelectric powers are -0.4--O.5 mV⋅K^-1 at temperatures lower than the inflection points of the emf vs. T curves and -0.7--1.3 mV⋅K^-1 at temperatures higher than those points. The absolute values of these thermoelectric powers are smaller than those of the temperature variation in the formal potential by 0.1-0.5 mV⋅K^-1. Because the diffusion coefficient of cytochrome cis small due to the large size of the molecule, a small output power was obtained with no convection in the electrolyte solution in the cell (Fig.5) a perpendicular gradient in temperature was applied to the cell placed horizontally. When the horizontal temperature gradient was applied to the cell which was placed perpendicularly, natural convection took place in the electrolyte solution. This resulted in greater output power (ca.4 times, Fig.5) with little change in heat flux (Fig.6). The maximum output power, 0.4 m⋅m^-2, was obtained by the cell with 11 mmol⋅dm^-3 cytochrome c and 1 mol⋅dm^-3 NaCl. The results obtained confirmed that the convection played the important role to make high output power and high thermal conversion efficiency for the temperaturedifferential galvanic cell with large molecules.

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LaMnO₃ with a large surface area (45 m²/g) prepared by an amorphous citrate complex precursor (ACP) method was found to be much more active for the direct four-electron reduction of oxygen than a conventional LaMnO₃ sample (4.6 m²/g) prepared by the acetate decomposition (AD) method (Figs.1 and 2, Table 1). This high activity was effectively utilized for fabricating a high performance oxygen cathode. It was revealed that a gasdiffusion type PTFE-bonded carbon electrode loaded with the large surface area LaMnO₃ catalyst of 60 wt% gave a current density as high as 2.0 A/cm² at -125 mV vs. Hg/HgO (0.8 V vs. RHE) in 9 mol/dm³ NaOH at 80°C, which was 2.5 times as large as that of the electrode loaded with the conventinal LaMnO₃ (Fig.3).

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Iridium oxide-coated platinum was prepared on the idea that coating of a tetravalent iridium cation will increase the amount of adsorbed oxygen on a Pt electrode because Ir⁴⁺ has large electron accepting property. The reversible potential of oxygen electrode reaction has been established on the iridium oxide-coated platinum in dilute aqueous boric acid solutions and observed about one year. The value of the exchange current density is ten times as much as the most active values reported in the literature. XPS observation confirmed that the surface Jr species was IrO₂.

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In order to evaluate the appropriateness of the intercalation mechanisms of lithium ions into the porous thin films of the copper Chevrel-phase compound (Cu₃Mo₆S_7.9) proposed in a previous paper, the OCV measurements for the cathode material were carried out using the same test cell (Li/2 M LiCl0₄ (M=mol⋅dm^-3) in PC-THF(4:6)/Cu₃Mo₆S_7.9) as that used previously. After the OCV measurements, the lattice parameters of the thin films were evaluated from X-ray diffraction patterns. The OCV and the lattice parameter changes due to the lithium incorporation agreed well with the proposed mechanisms. Some relaxation times may be necessary to reach an equilibrium volume after incorporation of lithium.

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The electrolyte volume change at the Cr-compartment of a diaphragm-type Fe/Cr redox flow cell during constant-current cycles was measured at room temperature. The electrolyte volume at the Cr-compartment increased for the charging process and decreased for the discharging process. The observed volume change was ca.0.5 cm³⋅A^-1⋅h^-1 based on the electricity passed both against and toward the Cr-compartment, which indicated that ca. O.75mol of water was reversibly transferred for each 1 F of the electricity passed. From the observed values, the maximum fluctuations of Cr- and Fe-concentrations in the electrolytes during cycles were estimated to be ca.1.3%.

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