An experimental feasibility study of vanadium oxide films on metallic bipolar plates for the cold start enhancement of fuel cell vehicles

2011 ◽  
Vol 36 (24) ◽  
pp. 15826-15837 ◽  
Author(s):  
Hye-Mi Jung ◽  
Sukkee Um
Keyword(s):  
Fuel Cell ◽  
Vanadium Oxide ◽  
Feasibility Study ◽  
Oxide Films ◽  
Cold Start ◽  
Fuel Cell Vehicles ◽  
Bipolar Plates ◽  
Metallic Bipolar Plates ◽  
Vanadium Oxide Films

Experimental Study of Electrical Switching Characteristics of Vanadium Oxide Thin Films on Bipolar Plates for Improving Thaw-at-Start

2011 ◽  
Author(s):  
Hye-Mi Jung ◽  
Jung-Hun Noh ◽  
Sukkee Um
Keyword(s):  
Thin Films ◽  
Fuel Cell ◽  
Vanadium Oxide ◽  
Cold Start ◽  
Fuel Cell Vehicles ◽  
Bipolar Plates ◽  
Electrical Switching ◽  
X Ray ◽  
Switching Characteristics ◽  
Vanadium Oxide Thin Films

The ultimate goal of cold start of hydrogen-powered polymer electrolyte fuel cell vehicles is to minimize the significant system thaw energy requirement and to achieve the short time period desired for freeze start (e.g. less than 30 seconds) in a subfreezing environment. As part of an effort to improve cold start capability for fuel cell vehicles, this work presents a new thaw-at-start strategy using electrical characteristics of vanadium oxide thin films as self-heating source at sub-zero temperature. Vanadium-based thin film coated on the surface of flat bipolar plates (e.g. carbon-based graphite and metallic bipolar plates) have been synthesized by a dip-coating method via aqueous sol-gel chemistry. Subsequently, the detailed in-/ex-situ analyses of the thin films have been carried out using diverse diagnostic techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) to investigate the chemical composition, crystallinity, and microstructure. In addition, electrical switching characteristics of the thin films on bipolar plates was cautiously observed over a temperature range from −20°C to 80°C by means of 4-point probes installed in a thermo -hygrostat. By doing so, it has been possible to correctly infer the relationship between a tendency of the thermally-induced electrical switching hysteresis and bipolar plate materials. Also, comprehensive theoretical study on the basis of the experimental results have been performed to estimate the heat dissipation rate by Joule heating from the solid thin films on bipolar plates for the rapid cold-start operation of fuel cell vehicles.

Vanadium oxide films for optical modulation applications

2006 ◽  
Author(s):  
S. Paradis ◽  
P. Mérel ◽  
P. Laou ◽  
D. Alain
Keyword(s):  
Vanadium Oxide ◽  
Oxide Films ◽  
Optical Modulation ◽  
Vanadium Oxide Films

Structural transformation and functional properties of vanadium oxide films after low-temperature annealing

2014 ◽  
Vol 564 ◽  
pp. 179-185 ◽  
Author(s):  
Yu. Goltvyanskyi ◽  
I. Khatsevych ◽  
A. Kuchuk ◽  
V. Kladko ◽  
V. Melnik ◽  
...  
Keyword(s):  
Low Temperature ◽  
Vanadium Oxide ◽  
Functional Properties ◽  
Structural Transformation ◽  
Oxide Films ◽  
Low Temperature Annealing ◽  
Vanadium Oxide Films

Characterization and Electrochemical Performances of Vanadium Oxide Films Doped with Metal Ions

2013 ◽  
Vol 537 ◽  
pp. 174-178
Author(s):  
Ji Chao Wang ◽  
Guang Ming Wu ◽  
Guo Hua Gao ◽  
Xiao Wei Zhou
Keyword(s):  
Metal Ions ◽  
Vanadium Oxide ◽  
Volume Fraction ◽  
Electrochemical Impedance ◽  
Sol Gel ◽  
Electrochemical Techniques ◽  
Oxide Films ◽  
Dip Coating ◽  
Electrochemical Performances ◽  
Vanadium Oxide Films

Vanadium oxide films were prepared via the sol–gel process and dip coating method, using V2O5as raw materials and H2O2(volume fraction 30) as the solvent. Mn and Ni ions were added to vanadium oxide sol to prepare doping vanadium oxide films. The films were characterized by atomic force microscopy, FT-IR, X-ray diffraction and electrochemical techniques. The add-on of Metal ions will not affect the morphology of the vanadium oxide films, but change the valence of vanadium ion and vanadium oxide crystal phase. Furthermore, cyclic voltammetry curves show that metal ions doping vanadium oxide films exhibit reversible electrochemical reaction. But electrochemical impedance spectroscopy indicates pure vanadium oxide film has a better diffusion rate.

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