N-Methylaniline was electropolymerized at a constant anodic potential in several aqueous acid solutions containing different anions: ClO4-, Cl- NO3- and SO42-. After the initial stage of the electropolymerization, the anodic current linearly increased for the Cl-, NO3- and SO42- solutions, while it decreased for the ClO4- solution. The linear increasing current in the i-t curves implied ID nucleation growth of poly (N-methylaniline) (PNMA) on the electrode surface. The polymerization rate estimated from the slope values of the i-t curves was in the order of SO42- > NO3- > Cl-. The conductivity of the obtained PNMAs was the same order and the highest conductivity of 2.2 × 10-3 S cm-1 was seen for the SO42- doped PNMA. The order was explained by the Hofmeister series of the anions which represents the lyophilicity. To reduce the relative lyophilicity, organic solvents such as dimethylsulfoxide were added to the SO42- polymerizing solution and the electropolymerization was performed. The conductivity of the obtained PNMAs was further enhanced. The most conductive PNMA was obtained when dimethylsulfoxide was added (σ = 1.0 × 10-2 S cm-1).
The oxygen reduction reaction (ORR) on Pt in proton conductive room temperature molten salts (RTMSs) at 140℃ has been investigated for application in intermediate temperature (from 100 to 200℃) fuel cells. The ORR current was observed on Pt in neutralized RTMSs and acid-added RTMSs under an oxygen atmosphere. The order of the potential at the ORR current of -10-2 mA cm-2 was a mixture of trifluoromethanesulfonic acid and 1-ethyl-3-methylimidazolium triflate > a mixture of trifluoromethanesulfonic acid and 2-ethylimidazolium triflate > 85% phosphoric acid > 2-ethylimidazolium triflate > 2-ethylimidazolium tetrafluoroborate. The 1-ethyl-3-methylimidazolium cation would be more effective for the ORR on Pt than the 2-ethylimidazolium cation. The acid-added RTMSs will be better than the neutral one, concerning the ORR.
Array of macropores filled with electrodeposited Ni was formed on Si substrate applying the novel process, which consists of Si electrochemical etching and Ni electrodeposition using single electrolyte. This electrolyte contained HF as Si dissolution agent and Ni(OSO2NH2)2 4H2O as Ni2+ source for Ni electrodeposition. First, array of macropores was formed on Si (100) substrate by applying anodic current. The formation was carried out area-selectively by applying Au/Cr micropatterns formed at the back side surface of the substrate as the shade mask, which enables to control the illumination condition for hole generation condition. Subsequently, the applied bias was switched to cathodic current, and Ni was filled into c.a. 200 µm depth Si macropores without void-like defects. Array of Ni needles with smooth surface was formed area-selectively by removal of the Si region of the Ni filled specimen with 25 wt% tetramethylammonium hydroxide (TMAH) aqueous solution at 90℃.
The Al film prepared by the electroplating method was applied to the negative electrode for lithium secondary batteries. The electroplated Al film obtained from a 66.7 mol% AlCl3-33.3 mol% EMIC ambient-temperature molten salt melt was used. The discharge potential of the electroplated Al negative electrode showed the flat potential profile at 0.4 V vs. Li+/Li. The discharge capacity of 2nd to 5th cycle was 224-400 mAh g-1 and the charge-discharge efficiency maintained ca. 90%. It was found that the electroplated Al electrode as the negative electrode for lithium secondary batteries operates quite effectively.
The Sodium Sulfur battery (NAS battery) was proposed based on the idea of Ford Motor Company adopting beta alumina as the solid electrolyte in 1967. In Japan because of its theoretical high energy density and high efficiency, the “Moonlight Project” led by Agency of Industrial Science and Technology picked up the NAS battery as battery energy storage system from 1980, but a practical model with satisfactory capabilities was not realized. Since 1984 Tokyo Electric Power Company (TEPCO) has cooperated with NGK Insulators, Ltd. to develop the NAS battery independently and succeeded in realizing battery energy storage system for the first time in the world. One of the technical issues solved in this development is the bonding technology of ceramic and metal that provides long-term durability and ensure the safety in case of battery troubles. This paper shows the relation between condition of thermal compression bonding for ceramic and metal and durability on the NAS battery.
The thermal property of the K-birnessite-type MnO2 doped with cobalt was examined in the temperature range up to 600℃ by means of TG-DTA, XRD and TEM measurements. The Co doped birnessite phase, KxMn1-yCoyC2・zH2O (x = 0〜0.37, y = 0~0.22, z = 0.19〜0.28), was gradually transformed to the hollandite MnO2 phase having a (2×2) tunnel structure on heat treating in the temperature range between 350 and 450℃, though undoped birnessite was transformed at 300℃. A single phase of high crystalline hollandite was formed at 550℃. The XRD measurement showed that the nano-composite manganese oxide consisting of the birnessite phase and the hollandite phase was formed at 350 - 450℃ in the course of annealing the birnessite oxide. The electrochemical properties of the birnessite and its calcined products were examined as cathodes for rechargeable lithium batteries. The birnessite / hollandite composite formed at around 350℃ exhibited a S-shaped smooth discharge curve with an average potential of 2.8 V vs. Li/Li+ and better performances with the initial discharge capacity of 238 mAh/g and the cycling capacity of about 170 - 205 mAh/g during 10 cyclings.
Fluorination is known to prohibit CO adsorption at LaNi5 group metal hydride. This characteristic was applied to fabricate a CO tolerant catalyst of fluorinated Pt black by exposing it in diluted F2 gas. To test the tolerance to CO poisoning, H2 oxidation current in H2 gas with fixed amount of CO was measured by using a half cell simulating the anode of a polymer electrolyte fuel cell (PEFC). The results show that fluorinated Pt black, especially those treated in low F2 concentration (1%), improved CO tolerance. On the other hand, treating in high F2 concentration (10%) decreased the active surface area of Pt catalyst for H2 oxidation. These electrochemical characteristics together with the results in XPS spectra indicated that chemisorption of F improved the CO tolerance on Pt surface, but not the Pt fluoride formation.