Under ideally polarizable conditions, TiO2 film electrode/solution electrolyte interface exhibited frequency dispersion, The effects of external factors such as the concentration of KNO3, various electrolytes and applied potentials near the flat band potential on the CPE behavior of TiO2 film electrode were studied in electrolyte solution by using A.C. impedance spectra. It was found that concentration of KNO3 had a significant effect on the CPE exponent n only when the concentration is smaller than 0.1 mol· L－ 1. In this concentration range, the CPE exponent n went up with increase of KNO3 concentration, once the concentration was larger than this value, however, the CPE exponent n approached to a constant, irrelevant of the concentration. Near the flat band potential, the influence of applied potential on the exponent n depended on the selected frequency range. When the frequency was in lower range, that is smaller than 0.1 Hz, this influence was obvious,on the other hand, it bore no relation to applied potential in higher frequency. Types of electrolytes only affected the CPE constant Q, having nothing to do with the CPE exponent n.
CoSn alloy and Cu-Sn samples were syn thesized by H 2 -reduction following solid-state r eaction between Co ?,Cu?,Sn?and NaOH at ambient temperature.The samples were characterized by XRD,S EM.The results showed that CoSn alloy(80～200nm)is globe-shaped,ultrafine hexagon al material,and Cu-Sn alloy powder consists of two phases,i.e.Cu 6 Sn 5 and Cu 3 Sn.Cu-Sn powder has spherical morphology and the particle size is estimated to be 60～70nm.The electro chemical performances of CoSn alloy and Cu-Sn powder were studied using lithium-ions model cell Li /LiPF 6 (EC +DMC)/CoSn(or Cu-Sn).It was demonstrated the reversible discharge capacities for 10cycles keep above 280mAh ·g -1 for nanophase Cu-Sn,and 60mAh ·g -1 for CoSn alloy.Differ-ential capacity plots showed that th e reaction mechanisms of Cu-Sn with l ithium were reversible.
