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The has shown outstanding electrochemical properties. The microstructure of cathode was investigated by using TEM (transmission electron microscopy) and X-ray diffraction techniques. The was produced by sol-gel method to synthesize fine particles less than in the average diameter. In this study, emphasis was given to the examination and interpretation of the microstructural change during charge-discharge cycling experiments, which appeared to be one of the main causes of early degradation of rechargeable batteries. Results showed that the cathode produced by sol-gel method had high reversible capacity and excellent cycling stability due to its homogeneous distribution of Ni and Co cations on u atomic scale. In particular, the cathode did not show severe strain induced structural defects or cubic spinel disordering during cycling experiments, which had been observed in the conventional cathode. The $LiNi_{0.8}Co_{0.2-x}M_x[M

We prepared a polymer electrolyte by blending PEGDA with PVdF and PMMA. PVdF was added to improve mechanical properties and PMMA was to impede the outflow of organic solvent by increasing an affinity for it. To study electrochemical properties of the blend polymer electrolyte, we investigated ionic conductivity, electrochemical stability window and battery performance as a function of blend ratio and amount of initiator. Also we studied the mechanical properties of the blend polymer electrolyte.

Copper-doped vanadium oxide (CuxV2O5) thin film cathode materials for a thin film microbattery have been prepared by DC reactive magnetron co-sputtering with O2/Ar ratio of 10/90 and compared with pure V2O5 thin film. The film structures have been characterized by x-ray diffraction analysis, transmission electron microscopy, Auger electron spectroscopy and X-ray photoelectron spectroscopy. X-ray diffraction and TEM studies show that the CuxV2O5 film was amorphous and phenomenal behavior of copper present in thin film with substrate has been explained by thermodynamical model. Copper doping helps to increase the thickness of the film more than 1 micrometer resulting increase of total capacity. Cycling behavior of the CuxV2O5/Lipon/Li configuration cell system was beyond 500 cycles with average capacity of 50 μAh/cm2-μm, which is higher than the pure V2O5 thin film system.

AB2-type alloy, a kind of hydrogen storage alloys used as an anode of Ni-MH batteries, has a large discharge capacity but still has several problems such as initial activation, cycle life and self-discharge. In this study, we have investigated the effects of Cr addition and fluorination after La addition on AB2-type alloy with Zr0.7Ti0.3V0.4Mn0.4Ni1.2 composition. The EPMA and SEM surface analysis techniques were used and the crystal structure was characterized by XRD analysis. Metal hydride negative was characterized by galvanostatic cycling test, electrochemical impedance spectroscopy and potentiodynamic polarization. Cr-addition is found to be effective to improve cycle life and self-discharge characteristics but ineffective to promote initial activation due to the formation of stable oxide film on alloy surface. Highly reactive particles have been formed by fluorination after La-addition to the alloys and those particles may remarkably improve the initial activation of MH-negative electrodes.

Thin films of pure SnO2, of the Sn/Li2O layered structure, and of Sn/Li2O were fabricated by sputtering method, while a `lithium-reacted tin oxide thin film' was assembled by the evaporation of lithium metal onto a SnO2 thin film. Film structure and charge/discharge characteristics were compared. The lithium-reacted tin oxide thin film, the Sn/Li2O layered structure, and the Sn/Li2O co-sputtered thin films did not show any irreversible side reactions of forming Li2O and metallic Sn near 0.8 V vs Li/Li+. The initial charge retention of the Sn/Li2O layered structure and Sn/Li2O co-sputtered thin films was about 50% and a similar value was found for the lithium-reacted tin oxide thin film (more than 60%). Sn/Li2O layered structure and Sn/Li2O co-sputtered thin films showed better cycling behavior over 500 cycles than the pure SnO2 and lithium-reacted tin oxide thin film in the cut-off range from 1.2 to 0 V vs Li/Li+. Keywords: Lithium batteries, Anode, Layered structure, Co-sputtering, Tin oxide, Lithium oxide

The effect of fluorination on the surface of an AB 2 -type hydrogen-storage alloy with the composition Zr 0.7 Ti 0.3 V 0.4 Mn 0.4 Ni 1.2 is investigated. Electron probe microanalysis (EPMA), scanning electron microscopy (SEM), Auger electron spectroscopy (AES), and X-ray diffraction (XRD) techniques show that the fluorinated AB 2 -type alloys have a unique surface morphology and high reactivity with a protective film. The treatment is found to be effective when lanthanum is incorporated in the alloy. The cycle-life of the metal hydride (MH) electrode increases significantly as a result of a decrease in the overpotential by electrode polarization. The degradation rate of the MH electrode is less than 3% after 100 cycles when lanthanum is added at 1–3 wt.%.

PPy/LiMn2O4 composites were prepared by chemical synthesis of pyrrole monomer onto LiMn2O4 powder in the presence of dodecyl bezenesufonic acid (DBSA) dopant. Thermogravimetric analysis showed that the content of LiMn2O4 in the composite increased with increasing the amount of manganese oxide powder. The battery performance of PPy/LiMn2O4 composite cathodes initially charged was compared with the physical mixture of both materials. Li/(PPy/LiMn2O4) ion cell with EC/DMC/1M LiPF6 electrolyte showed that cycle performance was enhanced by the redox reactivity of PPy as well as the enhanced conductivity of composite electrode. The reversibility of Li cation was proven by electrochemical voltage spectroscopy (EVS).

Tin oxide and tin-based composite electrodes are examined in both bulk and thin-film form for prospective use as negative electrodes for lithium rechargeable batteries. For bulk electrodes, tin oxides and Sn–Zn–P–O composite materials are compared by charge–discharge testings. Thin films of oxides and composite thin-film electrodes prepared by heat treatment (temperature and time) are characterized by X-ray diffraction analysis, Auger electron spectroscopy, and scanning electron microscopy. The characteristics of thin films are found to depend on the heat-treatment temperature, which influences the structure, the grain size, and adhesion to the substrate. Capacities higher than 350 mA h g −1 are found for bulk electrodes beyond 20 cycles, and beyond 100 cycles for thin-film electrodes.

An examination is made of the discharge and cycle life of Zr 0.5 Ti 0.5 V 0.6 Ni 1.4 alloys when a fraction (0.2 at.%) of the Ni-component is substituted by Cr or Mn. In addition, the Zr:Ti component ratios are varied to extend the cycle life of high capacity, Mn-substituted Zr 1− x Ti x V 0.6 Ni 1.2 Mn 0.2 ( x =0.0, 0.25, 0.5, 0.75) alloys. The metallurgical microstructure is observed by X-ray diffraction analysis, scanning electron microscopy, and energy dispersive X-ray analysis. Active–passive potentiodynamic behaviour, as well as charge–discharge cycle characteristics, is evaluated, and dissolved V-species in the electrolytic solution is analyzed by inductively coupled plasma spectroscopy. The corrosion behaviour of the V–Cr or the V–Mn phase in the alkaline electrolyte solution is found to determine the cycle life of an AB 2 alloy. Cr-substituted (Zr 0.5 Ti 0.5 Ni 1.2 Cr 0.2 ) alloy, containing a V–Cr phase, is estimated to involve a dissolution rate of 0.028 wt.% vanadium per cycle in an alkaline electrolytic solution, while Mn-substituted (Zr 0.5 Ti 0.5 V 0.6 Ni 1.2 Mn 0.2 ) alloy, containing a V–Mn phase, is estimated to have a dissolution rate of 0.138 wt.% vanadium per cycle. For Mn-substituted alloys, an optimum Zr:Ti ratio of 3:1, i.e., Zr 0.75 Ti 0.25 V 0.6 Ni 1.2 Mn 0.2 , is found to have the most stable cycle life. The improvement in cycle life caused by increasing the Zr content in the alloy is attributed to increase in the corrosion resistance of the alloy due to less formation of the corrosive V–Mn phase.

It has been demonstrated that LiCoO 2 is a very attractive cathode active material for lithium rechargeable cells. Poly(acrylonitrile) (PAN)-based polymer electrolyte is used for Li/LiCoO 2 cells. PAN-based polymer electrolyte shows ionic conductivity of the order 1 mS cm −1 at room temperature, irrespective of time evolution, and wide electrochemical stability up to 4.3 V (versus Li + /Li). An LiCoO 2 composite cathode containing 4 wt.% conductive material displays a good cycling performance. From a.c. impedance results, the interfacial resistance of Li/LiCoO 2 cells is dominated by the passive layer formed at the lithium/polymer electrolyte interface.

A MOSFET type sensor for O2 gas detection with a gate material of LaF3 film deposited on an ordinary n-channel MOSFET was fabricated. The LaF3 film of 800 A thickness and the Pt film of 500 A thickness were deposited, sequentially, by the e-beam evaporation method. The amount of drain current was decreased by about 130 μA with O2 gas and the response and regeneration times of this sensor were 1 and 17 min at 80 °C, respectively, when measured by the constant voltage method (VD = 3 V, VG = 0 V). In the constant voltage method, the higher the operating temperature, the shorter the response time. As oxygen gas was injected, the gate voltage of this sensor was shifted to 30 mV and its response time was 3.5 min with the constant current method (ID = 500 nA). When the oxygen concentration was 0.05% in nitrogen, the gate voltage ratio of the oxygen gas sensor approached 0.5.

A solid electrolyte oxygen sensor has been prepared by the implementation of r.f. magnetron sputtering and electron-beam evaporation methods. Thin films of LaF3 are applied as F− ion-conducting solid electrolytes and a sensing electrode made of platinum black or an electron-beam evaporated Pt film is coated on the surface of the solid electrolytes. Co-sputtered Sn-SnF2 films or electron-beam evaporated Sn/SnF2 multilayered films are used as a reference electrode. The potential of the sensing electrode relative to that of the reference electrode changes logarithmically with the dissolved oxygen concentration in distilled water, but small e.m.f. changes are observed in a gas environment. The structure of LaF3 is found to be microcrystalline when formed by electron-beam evaporation and the r.f. magnetron sputtering method. The capacitance of a thin-film type sensor has been examined with the aid of an impedance technique. When the sensor is exposed to oxygen, the capacitance value decreases because of the increase of F− ion migration flux due to the adsorption of oxygen atoms on the sensing electrode surface.

In this study, we have examined the phenomenon of excess heat generation during the D 2 O electrolysis in relation to electrode materials and the method of electrode preparation

The electrochemical properties of poly(acrylonitrile) (PAN)-based polymer electrolyte and the discharge characteristics of an Li/LiCoO 2 cell were investigated. The PAN-based polymer electrolyte maintained an ionic conductivity of 1 mS/cm at room temperature, irrespective of storage time. Also, this electrolyte showed high electrochemical stability up to 4.3 V (versus Li + /Li). An Li/LiCoO 2 cell battery with this electrolyte has been fabricated and tested. This battery showed good cycling performance.

Sputter deposited 3000 A tin oxide thin films into which metallic lithium (6000 A) was reacted were studied to develop a new negative electrode for thin film rechargeable lithium batteries. The crystal structure and chemical composition of the lithium reacted tin oxide films were characterized by X-ray diffraction (XRD) analysis and Auger electron spectroscopy, respectively. The charge/discharge performances of these films exhibited capacities >400 mAh/g for >75 cycles. There was no irreversible plateau near 0.8 V vs. Li/Li due to reduction of SnO 2 to Sn and Li 2 O during the first charge half-cycle. XRD and scanning transmission electron microscopy results suggest that the lithium-reacted tin oxide thin film consists of metallic tin, lithium oxide, and reduced tin oxide, and the reacted thin films show reduced microcracks created by density fluctuations.

Experimental results concerning the kinetics of electron-transfer reactions at metal electrodes covered by anodic oxide films are discussed and compared to predictions from the theory. The rate equations used in the comparison are presented assuming a n -type semiconducting film. Semi-quantitative agreement between experiment and theory is observed. At electrodes covered by very thin films, direct electron exchange between the metal and the electrolyte predominates. The exchange cd drops exponentially with film thickness. For thicknesses greater than a few nm, electron exchange preferentially occurs with the oxide film even for oxides having a large band gap. The transfer coefficients then depend on electrode potential in an often non-monotonous way, and the rate is independent of thickness. The examples of oxide covered niobium and titanium are discussed in detail considering the influences of donor density and structure of the oxide, of the potential distribution at the semiconductor—electrolyte interface, and of the reorganization energy of the redox system.