Micromachined fuel cells are among a class of microscale devices being explored for portable power generation In this paper, we report processing and geometric design criteria for the fabrication of free-standing electrolyte membranes for microscale solid-oxide fuel cells Submicron, dense, nanocrystalline yttria-stabilized zirconia (YSZ) and gadolinium-doped ceria (GDC) films were deposited onto silicon nitride membranes using electron-beam evaporation and sputter deposition Selective silicon nitride removal leads to free-standing, square, electrolyte membranes with side dimensions as large as 1025 μm for YSZ and 525 μm for GDC, with high processing yields for YSZ Residual stresses are tensile (+85 to +235 MPa) and compressive (–865 to -155 MPa) in as-deposited evaporated and sputtered films, respectively Tensile evaporated films faul via brittle fracture during annealing at temperatures below 773 K; thermal limitations are dependent on the film thickness to membrane size aspect ratio Sputtered films with compressive residual stresses show superior mechanical and thermal stability than evaporated films Sputtered 1025-μm membranes survive annealing at 773 K, which leads to the generation of tensile stresses and brittle fracture at elevated temperatures (923 K)

Fabrication and structural characterization of self-supporting electrolyte membranes for a micro solid-oxide fuel cell

In accordance with the present invention, deposition of LiCoO2 layers in a pulsed-dc physical vapor deposition process is presented. Such a deposition can provide a low-temperature, high deposition rate deposition of a crystalline layer of LiCoO2 with a desired or orientation. Some embodiments of the deposition addresses the need for high rate deposition of LiCoO2 films, which can be utilized as the cathode layer in a solid state rechargeable Li battery. Embodiments of the process according to the present invention can eliminate the high temperature (>700°C) anneal step that is conventionally needed to crystallize the LiCoO2 layer. Some embodiments of the process can improve a battery utilizing the LiCoO2 layer by utilizing a rapid thermal anneal process with short ramp rates.

Deposition of licoo2

The present invention relates to apparatus, compositions and methods of fabricating high performance thin-film batteries on metallic substrates, polymeric substrates, or doped or undoped silicon substrates by fabricating an appropriate barrier layer composed, for example, of barrier sublayers between the substrate and the battery part of the present invention thereby separating these two parts chemically during the entire battery fabrication process as well as during any operation and storage of the electrochemical apparatus during its entire lifetime. In a preferred embodiment of the present invention thin-film batteries fabricated onto a thin, flexible stainless steel foil substrate using an appropriate barrier layer that is composed of barrier sublayers have uncompromised electrochemical performance compared to thin-film batteries fabricated onto ceramic substrates when using a 700° C. post-deposition anneal process for a LiCoO 2 positive cathode.

Electrochemical Apparatus With Barrier Layer Protected Substrate

An electrochemical device is claimed and disclosed wherein certain embodiments have a cathode greater than about 4 μm and less than about 200 μm thick; a thin electrolyte less than about 10 μm thick; and an anode less than about 30 μm thick. Another claimed and disclosed electrochemical device includes a cathode greater than about 0.5 μm and less than about 200 μm thick; a thin electrolyte less than about 10 μm thick; and an anode less than about 30 μm thick, wherein the cathode is fabricated by a non-vapor phase deposition method. The electrochemical device may also include a substrate, a current collector, an anode current collector, encapsulation and a moderating layer.

Hybrid thin-film battery

The use of vapor deposition techniques enables synthesis of the basic components of a solid oxide fuel cell (SOFC); namely, the electrolyte layer, the two electrodes, and the electrolyte-electrode interfaces. Such vapor deposition techniques provide solutions to each of the three critical steps of material synthesis to produce a thin film solid oxide fuel cell (TFSOFC). The electrolyte is formed by reactive deposition of essentially any ion conducting oxide, such as defect free, yttria stabilized zirconia (YSZ) by planar magnetron sputtering. The electrodes are formed from ceramic powders sputter coated with an appropriate metal and sintered to a porous compact. The electrolyte-electrode interface is formed by chemical vapor deposition of zirconia compounds onto the porous electrodes to provide a dense, smooth surface on which to continue the growth of the defect-free electrolyte, whereby a single fuel cell or multiple cells may be fabricated.

Hybrid deposition of thin film solid oxide fuel cells and electrolyzers

The structural, compositional, and electrical properties of rf sputter‐deposited Y2O3‐doped ZrO2 films have been investigated as a function of sputtering conditions. The results show that the application of an rf substrate bias during deposition has a large effect on both the morphological and electrical properties of the films. Auger electron spectroscopy, electron diffraction, and scanning‐electron‐fractography results show that films deposited at P=20 mTorr (2.67 Pa), VT=−500 V, and VS=−40 V are nearly stoichiometric, have a cubic crystal structure, and a relatively equiaxed microstructure. The results of electrical measurements indicate that films grown under these sputtering conditions have an ionic transference number which is nearly zero below 100 °C and rises to approximately 0.4 at 200 °C.

Morphological and electrical properties of rf sputtered Y2O3‐doped ZrO2 thin films

Single‐crystal epitaxial In1−xGaxSb thin films have been grown at compositions ranging from x=0 to x=1 on a variety of substrates including BaF2, NaCl, and InSb using multitarget rf sputtering. The films were deposited on rotating substrates from two targets, InSb and GaSb, with separate discharges allowing independent control of relative sputtering rates. Alloy‐film composition was determined by Auger spectroscopy using bulk standards. The results agreed very well with predicted values calculated from a simple theory which is presented in this paper. Within experimental error, measured lattice constants were found to vary linearly with alloy‐film composition. The amorphous to polycrystalline to single‐crystal growth transition temperatures were found to increase with Ga concentration in the films. Single‐crystal InSb films were obtained at substrate temperatures as low as 150 °C. High dislocation densities were observed in In‐rich films due to large film‐substrate lattice mismatch. Thermoelectric measure...

J. L. Zilko

Papers

Morphological and electrical properties of rf sputtered Y2O3‐doped ZrO2 thin films

Epitaxial growth of In1−xGaxSb thin films by multitarget rf sputtering

Growth of In1−xGaxSb and In1−xAlxSb films by mulsti target R.F. sputtering