High-temperature Electrochemical Properties Of The Perovskite Structure Oxide Cathode Materials Research

The perovskites-like cathode materials show a relatively high oxygen diffusion and surface exchange coefficient, and such materials also exhibited mixed ionic and electronic conductivity, which are promising cathode materials for solid oxide fuel cell.Cathode materials La2Cu1-xCoxO4, LaSrC1-xFexO4 Ca2Fe2-xMnxO5 and Ca2-xSrxFe2O5 were prepared by solid reaction method. The characterizations of basic properties were completed by XRD, SEM and IR technique. The electrochemical properties of cathode were analysed completely. The results show that La2Cu0.8Co0.2O4 cathode gave the polarization resistance of 0.5Ω·cm2 at 700℃, but LaSrCu0.7Fe0.3O4 cathode gave the lowest polarization resistance of 0.38Ω·cm2 at 700℃. The rate-limiting steps of the electrode reactions were charge transfer process and oxygen ions transfer from the thriple phase boundary (TPB) to the electrolyte.While Sr and Mn doping in new material Ca2Fe2O5, the conductivity increased obviously. The Ca2Fe1.3Mn0.7O5 cathode gave the polarization resistance of 0.23Ω·cm2 at 750℃, and Ca1.95Sr0.05Fe2O5 cathode gave the polarization resistance of 0.3Ω·cm2 at 750℃. The rate-limiting step of the electrode reaction was charge transfer process.Preparation of the CFM-CGO and CFM-Ag composite electrode can improve the electrochemical properties of cathode materials. The addition of 40 wt.% CGO show the lowest polarization resistance of 0.2Ω·cm2 at 750℃. The rate-limiting step of the electrode reaction was charge transfer process on the thriple phase boundary.