In the present paper we report on high rate electrodes made from a conventional battery cathode material, vanadium pentoxide. The electrodes were obtained through a sol-gel process by which the active materials were coated in the form of thin, highly porous, layers on appropriate conducting substrates. The composite electrodes are characterized by very short ionic and electronic paths throughout the intercalation compound. Aerogel films deposited on a Hastelloy felt substrate had specific surface areas of 40 m2/g with pores of 20-200 nm diameter and wall thicknesses of 10-20 nm. Electrochemical impedance analysis revealed the expected response for intercalation, except that there was no Warburg (diffusion) component. The latter demonstrates that we successfully eliminated one of the primary limitations of intercalation materials, i.e. diffusion in the solid phase, by the design of the composite electrodes.
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We would like to thank MEMTEC America Co. (FL, USA) for kindly providing the Hastelloy felt substrate. This work was supported by ARPA/URI N/N00014-92-J-1875 and by DOE/DE-FG02-93ER14384.