High Li+-ion storage capacity and double-electrochromic behavior of sol-gel-derived iron oxide thin films with sulfate residues
2001 (English)In: Chemistry of Materials, ISSN 0897-4756, Vol. 13, no 6, 1976-1983 p.Article in journal (Refereed) Published
FeSO4. 7H(2)O was precipitated with ammonia solution in the presence of H2O2 as an oxidant. The precipitate was washed slightly with deionized water and then peptized with acetic acid (ca. 60 mol %) to attain a homogeneous sol. Iron oxide films were fabricated by spin-coating the sol onto ITO-coated glass substrates and annealing at 350 degreesC or above. Structural and compositional analyses were done by TG-DTA, FTIR, XRD, TEM, and XPS. The results showed that sulfate residues were adsorbed on the surface of the Fe2O8 nanoparticles constituting the films by monodentate coordination with Fe(III) surface sites when heat treatment was carried out at less than or equal to 450 degreesC, while a conversion to bidentate occurred at 500 degreesC, As shown by the cyclic voltammograms results, the films annealed at 350 degreesC exhibited Li+-ion storage capacity as high as ca. 0.50 mC(.)cm(-2) per nanometer of the film thickness and showed double-electrochromic behavior depending on the extent of intercalation during the electrochemical lithium insertion/extraction processes. It is proposed that the adsorbed sulfate residues lead to the enhanced electroactivity of the iron oxide films by retarding crystallization and dehydration of the films. The high charge capacity and nearly optical passiveness of the iron oxide films suggest their promising applications as counter-electrodes in electrochromic devices.
Place, publisher, year, edition, pages
2001. Vol. 13, no 6, 1976-1983 p.
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-47925DOI: 10.1021/cm000657jOAI: oai:DiVA.org:liu-47925DiVA: diva2:268821