Determination of Li+ Diffusion Coefficients in the LixV2O5 (x=0-1) Nanocrystals of Composite Film Cathodes

Abstract

The Li+ ion diffusion coefficients (DLi+) in V2O5 (2.12 x 10(-12) cm(2) s(-1)) and in the intermediate alpha-, epsilon-, and delta-LixV2O5 phases (1.6 x 10(-14), 8.0 x 10(-15), and 8.5 x 10(-15) cm(2) s(-1), respectively), reversibly formed during charging/discharging processes of the crystalline-V2O5 and PEDOT (poly-3,4-ethylenedioxythiophene) composite-film electrode, are precisely determined by the galvanostatic intermittent titration technique. The specific surface area of the composite film is estimated to be 13.600 m(2) g(-1), where the external surface area and the nanopore area are 10.704 and 2.896 m(2) g(-1), respectively. The V2O5 crystals are coated and interconnected by a conductive polymer network in the composite film, thereby improving the electrode characteristics. V2O5 and PEDOT composite-film cathodes showed high specific capacities (290 mA h g(-1) at a 1 C rate), excellent rate capabilities (178 mA h g(-1) at a 10 C rate), and superior cycling stabilities (ca. 15% degradation after 500 consecutive cycles).