Discharge–charge characteristics and performance of Li/FeOOH(an) battery with PAN-based polymer electrolyte

The discharge–charge characteristics and performance of a Li/FeOOH(an) solid polymer battery are investigated. The cell uses a cathode of amorphous FeOOH with aniline derivatives (FeOOH(an)) and a polyacrylonitrile-based solid polymer electrolyte. The ionic conductivity of the electrolyte sample used for electrochemical measurements is 1.6×10−3 Ω−1 cm−1 at room temperature. Its anodic stability is above 4.5 V. The diffusion coefficient of Li+ ions into the cathode is found to be 2.97×10−11 cm2 s−1 by a.c. impedance spectroscopy. Variations of impedance parameters and the diffusion coefficient are investigated during the first discharge–charge. From the results of these measurements, it is concluded that the structure of FeOOH(an) is deformed by Li+ ion insertion/extraction. The electrochemical redox reaction of FeOOH(an) is investigated by cyclic voltammetry. In the potential range 2.0 to ∼4.0 V, the first discharge–charge is irreversible. Thereafter, reversible cycling processes take place. The initial discharge capacity is ∼130 mA h g−1 at a current density of 0.1 mA cm−2.