A simple route to electrophoretic deposition of transition metal-coated nickel oxide films for electrochemical capacitors

Nickel hydroxide films coated with transition metals such as nickel and cobalt were fabricated directly by a one-step electrophoretic deposition (EPD) in the presence of charging additives (transition metal salts). A nickel hydroxide particle with a weakly charged surface in an isopropanol solution was found to be detrimental to EPD and dispersion. When a small amount of charging additive was added to the suspension, the adsorption of dissolved metal ions on the nickel hydroxide resulted in a more positively charged particle surface, facilitating EPD and dispersion. When nickel hydroxide particles migrated to the negative electrode during the EPD process, the metal ions adsorbed on the particle were reduced electrochemically to form a metal layer. The as-deposited nickel hydroxide film converted to nickel oxide following heat treatment at 300 °C. Our results revealed that nickel oxide films coated with nickel and cobalt showed better capacitive behavior than the bare film. The improved capacitive behavior was attributed to the co-deposition of transition metals, which provided additional active sites on the nickel oxide surface for the electrochemical reaction to occur.     

A Computerized Test System for Communications Equipment Subassemblies

This paper describes an automatic test system for factory testing of telephone carrier equipment channel units. The system is intended for high volume subassemblies such as those found in pulse-code-modulation carrier systems where, typically, there are 24 units in each terminal. With the greater availability of minicomputers and digitally programmable instruments, a system is feasible at moderate cost. The system described uses a low-cost self-contained eight-bit minicomputer as the test sequence controller. Control information is transmitted to and from the various instruments by way of a data input-output buffer. A reed contact switching matrix is used to interconnect commercial equipment that is used to generate inputs and measure results. The resulting system is capable of making up to 100 functional tests on a channel unit in less than one minute. Significant savings have been possible in testing time and labor cost. Also, equipment reliability is improved because of uniform testing methods.     

Microporous poly(acrylonitrile-methyl methacrylate) membrane as a separator of rechargeable lithium battery

We studied microporous poly(acrylonitrile-methyl methacrylate), AMMA, membrane as the separator of Li/LiMn₂O₄ cell. The porous AMMA membrane was prepared by the phase inversion method with N,N-dimethylformamide (DMF) as the solvent and water as the non-solvent. We observed that morphology of the resulting membrane was strongly affected by the concentration of polymer solution: low concentration produced finger-like pores with dense skin on two surfaces of the membrane, while high concentration yielded open voids with dense layer on the other surface of the membrane. Regardless of their morphology, both membranes could be rapidly wetted by the liquid electrolyte (1.0 m LiBF₄ dissolved in 1:3 wt.% mixture of ethylene carbonate (EC) and γ-butyrolactone (GBL)), and could be swollen at elevated temperatures, which resulted in the formation of a microporous gel electrolyte (MGE). It was shown that the resulting MGE not only had high ionic conductivity and but also had good compatibility with metal lithium even at 60 °C. Cyclic voltammetric test showed that the MGE had an electrochemical window of 4.9 V versus Li⁺/Li. At room temperature, the Li/MGE/LiMn₂O₄ cell showed excellent cycliability with a specific capacity of 121-125 mA h g⁻¹ LiMn₂O₄. It was shown that even at 60 °C good mechanical strength of the MGE remained. Therefore, the MGE is suitable for the application of battery separator at elevated temperatures.     

An inorganic composite membrane as the separator of Li-ion batteries

We studied an inorganic composite membrane as the separator for Li-ion batteries. Being made of mainly CaCO₃ powder and a small amount of polymer binder, the composite membrane has excellent wettability with liquid electrolytes due to its high porosity and good capillarity. Ionic conductivity of the membrane can be easily achieved by absorbing a liquid electrolyte. Additional benefit of such a membrane is that the alkali CaCO₃ can scavenge acidic HF, which is inevitably present in the LiPF₆-based electrolytes used currently in the Li-ion batteries. In this work, we typically evaluated a membrane with the composition of 92:8 (wt.) CaCO₃/Telfon by using a 1.0 m LiPF₆ dissolved in a 3:7 (wt.) mixture of ethylene carbonate (EC) and ethylmethyl carbonate (EMC) as the liquid electrolyte. Ionic conductivity of the electrolyte-wetted membrane was measured to be 2.4 mS cm⁻¹ at 20 °C versus 8.0 mS cm⁻¹ of the liquid electrolyte. With the said membrane as a separator, both Li/graphite and Li/cathode half-cells exhibited good capacity retention. We also found that the Li-ion cell fabricated in this manner not only had stable capacity retention, but also showed good high-rate performance.     

Growth of GaAs by vacuum atomic layer epitaxy using tertiarybutylarsine

We report the results of GaAs grown by vacuum atomic layer epitaxy using trimethylgallium (TMGa) and tertiarybutylarsine (TBAs) as the group III and V sources. The growth rate saturates at one monolayer per cycle for a wide range of growth parameters. The temperature window for monolayer growth is as wide as 70°C. All the films are p-type with the carrier concentration depending on the exposure conditions of TMGa and TBAs.     

Investigation of dielectric properties of polymer laminates withpolyvinylidene fluoride

The breakdown field strength of polymer laminates consisting of polymer base films coated with a thin layer of polyvinylidene fluoride (PVDF) was investigated. The spin coating technique was used to make a layer of PVDF film. It was found that the dc breakdown field strength could be increased by as much as 18% by applying a very thin coating. The breakdown field strength was insensitive to the thickness of the polymer base films and the thickness of the PVDF coating within the thickness range used in the experiment. The effect of the coating on the permittivity and dissipation factor of polymer films over a wide frequency range was determined. Possible mechanisms for the enhancement of breakdown field strength have been discussed     

Catalytic effects of the silver ion on the indirect electrochemical oxidation of toluene to benzaldehyde using Ce3+/Ce4+ as mediator

The catalytic effects of the silver ion on toluene oxidation by Ce⁴⁺ as well as the anodic generation of Ce⁴⁺ were investigated. The rates of toluene oxidation were first order with respect to both Ag⁺ and Ce⁴⁺. Argentic oxides formed on the surface of the platinum anode when Ag⁺ was present in the anolyte, which increased the activity of the electrode. About 3×10^–3M of Ag⁺ was needed to obtain maximum current efficiency.     

The NUREG-1150 probabilistic risk assessment for the Grand Gulf Nuclear Station

This paper summarizes the findings of the probabilistic risk assessment (PRA) for Unit 1 of the Grand Gulf Nuclear Station performed in support of NUREG-1150. The emphasis is on the “back-end” analyses, that is, the accident progression, source term, consequence analyses, and risk results obtained when the results of these analyses are combined with the accident frequency analysis. The offsite risk from internal initiating events was found to be quite low, both with respect to the safety goals and to the other plants analyzed in NUREG-1150. The offsite risk is dominated by short-term station blackout plant damage states. The long-term station blackout group and the anticipated transients without scram (ATWS) group contribute considerably less to risk. Transients in which the power conversion system is unavailable are very minor contributors to risk. The low values for risk can be attributed to low core damage frequency, good emergency response, and plant features that reduce the potential source term.