At moderate temperatures and H 2 pressures, e.g., 423 K and 5 bar, an fcc solid solution Pd 0.81 Au 0.19 alloy is shown to form a hydrogen-stabilized, ordered phase. The dissolved hydrogen plays two roles during hydrogen heat treatment (HHT): (i) a kinetic role in enhancing the metal atom rearrangement leading to ordering and (ii) an equilibrium role in shifting the equilibrium from a disordered to an H-stabilized ordered alloy. The H-induced changes are followed by diagnostic H 2 isotherms, usually measured at 348 K.The hydrogen solubilities found in the diagnostic isotherms (348 K) are greatest for alloys which have been treated with hydrogen at the highest p H 2 for the longest times at moderate temperatures, e.g., 473 K, where the H solubilities and H-assisted metal atom diffusivities are both appreciable. Thermodynamic parameters for hydrogen solution in the alloy before and after HHT have been determined from equilibrium pressure-composition-temperature data and calorimetry.Dissolved H is shown to stabilize the ordered state because, at the same temperature where ordering occurs, but in the absence of dissolved H, the alloy returns to its disordered form. Dissolved H is shown to assist metal atom diffusion because the return of the ordered form to a nearly disordered state characteristic of 1 MPa is faster in the presence of H 2 than in vacuo.

We report on the preparation of an all solid-state thin film micro-supercapacitor using RuO 2 electrode film and LiPON electrolyte film on a Pt/Ti/Si substrate with dual target dc and rf reactive sputtering. Room temperature charge-discharge measurements based on a symmetrical RuO 2 /LiPON/RuO 2 structure clearly demonstrated the cyclibility dependence of the RuO 2 electrode on the microstructure. Using both glancing angle X-ray diffraction (GXRD) and transmission electron microscopy (TEM) analysis, it was found that the characteristics of the thin film supercapacitor are dependent on the microstructure of the RuO 2 film. In addition, high-resolution electron transmission microscopy (HREM) analysis after cycling demonstrates that the interface layer formed by interfacial reaction between the LiPON and RuO 2 acts as the main factor in the degradation of the performance of the thin film micro-supercapacitor.

Amorphous vanadium oxide (V 2 O 5 ) is a very good candidate as material for cathode thin film since it has a relatively high capacity. In addition, the room temperature deposition process is valuable in V 2 O 5 thin film fabrication. Due to these advantages, much effort to grow amorphous V 2 O 5 thin film has been made. In this research, we successfully grew amorphous V 2 O 5 thin film using room temperature sputtering. Based on a Li/LiPON/V 2 O 5 full cell structure, charge-discharge performances were measured according to cycling number. Even though the full cell structure showed an average capacity of 15 μAh/cm 2 over more than 500 cycles, a capacity fade was shown after a few cycles. Many reports revealed that the phase change of V 2 O 5 from amorphous to crystalline made this kind of capacity fade. In order to investigate this phenomenon, high-resolution transmission electron microscopy (HRTEM) was employed. The as-deposited V 2 O 5 thin film consisted of a homogeneous amorphous without any grain-boundary and/or polycrystalline island. However, the microcrystalline V 2 O 5 phase was randomly distributed in the amorphous V 2 O 5 thin film matrix after 450 cycles by cross sectional TEM (XTEM). That is, some amorphous phase in the V 2 O 5 matrix changed to the crystalline phase. This crystalline phase strongly prevented the extraction of Li ions during the charge process, which induced the irreversible diffusion of Li ions from cathode to anode. From this result, a high efficiency thin film battery based on amorphous V 2 O 5 can be fabricated by preventing amorphous-crystal phase transformation during cycling.

The effect of Pt co-sputtering on the characteristics of amorphous V 2 O 5 films, grown by dc reactive sputtering, was investigated using glancing angle x-ray diffraction (GXRD), transmission electron microscopy (TEM), transmission electron diffraction (TED) and charge-discharge measurement. It was found that the Pt co-sputtering processes influence the growth mechanism as well as the characteristics of V 2 O 5 films. In addition, it was found that the Pt co-sputtered V 2 O 5 cathode film exhibits cyclibility better than the undoped V 2 O 5 cathode film, due to the absence of short range order, which is generally shown in undoped V 2 O 5 cathode films. Possible explanations for the cycling behavior of the Pt doped V 2 O 5 cathode film and Pt co-sputtering effect on the electrochemical properties of thin film batteries are suggested.

The multilayer films of LiCoO 2 / M / LiCoO 2 / M / LiCoO 2 structure were prepared by a magnetron sputtering without post-annealing 1 . The as-deposited multilayer films exhibited a nanocrystalline structure, which is similar to that of LiCoO 2 single layer films. Electrochemical performances of the LiCoO 2 /M multilayer films and a LiCoO 2 single layer film were investigated at a current density ranging from 30 to 1000 uA/cm 2 , in which for those samples, the total thickness of LiCoO 2 layer is about 4.2um. The enhanced rate capability in the LiCoO 2 /Ag, Pt multilayer films is mainly ascribed to the increase of the electronic conductivity 2 . We have fabricated the all solid state thin film batteries for polymer substrate. As a result, we confirmed high initial irreversible capacity and low cycle ability because of interface and structure instability.