ELECTRODE AND SOLID-ELECTROLYTE THIN-FILMS FOR SECONDARY LITHIUM-ION BATTERIES

Electrostatic spray deposition (ESD) was employed to prepare thin laye rs of Li1.2Mn2O4 (nominal composition) and BPO4:0.035Li(2)O for all-so lid-state thin film lithium-ion batteries. The relationships between l ayer morphologies and deposition conditions such as solvent compositio n of the precursor solutions and substrate temperature were investigat ed. It was found that a low substrate temperature and/or high boiling point of the solvent may lead to a relatively dense structure. Reticul ar porous structures are formed, if films were deposited at 250 degree s C and a mixture of 85 vol.% butyl carbitol and 15 vol.% ethanol was used as the solvent. The Li1.2Mn2O4 layers, formed in the 250-400 degr ees C temperature range, were amorphous or micro-crystalline. After an nealing beyond 600 degrees C, they could be crystallized into a spinel -structured material. Glassy BPO4:0.035Li(2)O layers could fill the po res of porous Li1.2Mn2O4 layers to form a dense intermediate electroly te layer. Thin-film rocking-chair batteries, Li1.2Mn2O4\BPO4:0.035Li(2 )O\Li1.2Mn2O4/Al, were prepared and revealed an open-circuit voltage o f about 1.2 V after charging. (C) 1997 Elsevier Science S.A.