EQCM studies of composition and electrochemical performance of film prepared by electrochemical reduction of sodium ferrate

A solid film was prepared by electrodepositing on a gold-film-coated quartz crystal electrode in Na₂FeO₄ solution, and characterized in 1?M LiClO₄/propylene carbonate (PC) + 1, 2-dimethoxyethane (DME; 1:1 by volume) electrolyte using electrochemical quartz crystal microbalance (EQCM). The EQCM experimental and X-ray photoelectron spectroscopy results indicate that the composition of the electrodeposited solid film prepared in the potential range of 0.18 to ?0.57?V vs. Ag/AgCl is FeOOH; and almost 1?mol lithium ions can be intercalated into and then extracted from 1?mol FeOOH film during discharge/charge process in 1?M LiClO₄/PC + DME electrolyte. The discharge/charge experiment indicates that the specific capacity of FeOOH film stabilizes at a value close to its theoretical specific capacity after 20 cycles, and FeOOH film maintains a specific capacity of about 300?mAh?g^?1 at the end of 170 cycles. It is therefore concluded that the FeOOH film has a good electrochemical cycle ability in 1?M LiClO₄/PC + DME electrolyte.