Physical and electrochemical characterization of thin films of iron phosphate and nitrided iron phosphate for all-solid-state batteries

An attempt was made to fabricate all-solid-state lithium-ion rechargeable batteries with amorphous iron phosphate (FePO4) and iron phosphorous oxynitride (FePON) thin-film electrodes, which have been successfully fabricated by radio-frequency sputtering at oxygen and nitrogen ambient, respectively. The all-solid-state thin-film battery of Li/LiPON/FePON had a higher capacity of 63 mu Ah/cm(2)-mu m than Li/LiPON/FePO4 by discharge/charge measurement. For novel FePON thin-film electrode, the insertion of nitrogen into FePO4 has been examined by X-ray photoelectron spectra and Raman spectroscopy. Our results demonstrated that FePO4 and FePON thin film electrodes with the features of amorphous structure, good-matched interface with LiPON electrolyte, and low-temperature preparation conditions may make them attractive as cathodes for the all-solid-state thin-film lithium-ion batteries. (c) 2006 The Electrochemical Society.