TECHNOLOGY FOCUS - POLYMERS - Preferred Method: The perovskite structure is prepared by spinning precursor solution of ion-electron mixed conductor oxide component A and spinning precursor solution of oxygen ion conductive electrolyte composition B. The spinning process of precursor solution of ion-electron mixed conductor oxide component A involves magnetic stirring desired acetate or nitrate-containing reagents corresponding metal ions in deionized water, alcohol and N,N-dimethylformamide mixed solvent, and dissolving polyvinylpyrrolidone in mixed solution above or magnetic stirring polyvinylpyrrolidone and dissolving in deionized water, alcohol, N,N- dimethylformamide mixed solvent, adding desired acetate or nitrate containing reagent corresponding metal ion, dissolving completely, spinning ultrasound solution perovskite structure oxide precursor to bubble and standing at room temperature for 5-15 hours. The spinning process of precursor solution of ion-electron mixed conductor oxide component B involves magnetic stirring desired acetate or nitrate-containing reagents corresponding metal ions in deionized water, alcohol and N,N-dimethylformamide mixed solvent, and dissolving polyvinylpyrrolidone in mixed solution above or magnetic stirring polyvinylpyrrolidone and dissolving in deionized water, alcohol, N,N- dimethylformamide mixed solvent, adding desired acetate or nitrate containing reagent corresponding metal ion, dissolving completely, spinning ultrasound solution perovskite structure oxide precursor to bubble and standing at room temperature for 5-15 hours. The preparation of shell electrospinning nanofibers involves spinning precursor solution of prepared ion-electron mixed conductor oxide component A, spinning precursor solution of oxygen ion conductor electrolyte component B, injecting into electrostatic spinning head of inner and outer channel, carrying coaxial spinning at flow rate of 5-30 mu l per minute, spinning voltage of 10-25 kV, and spinning needle and acceptor distance is 5-15cm; oven drying at 40-80 degrees C and treating for 10-20 hours; and sintering core-shell nanofibers cathode phase involves heating to 400-600 degrees C in 3-6 degrees C per minute heating rate, incubating for 2-5 hours, heating again to 1000-1150 degrees C in 5-10 degrees C heating rate, incubating for 1-5 hours and lowering to room temperature in 5-12 degrees C heating rate. Preferred Component: The volume ratio of mixed solution of deionized water, alcohol and N,N- dimethylformamide is 0.1-0.5:0.5-1:5-10. The polyvinylpyrrolidone is 1.5-3 times the amount of mixed solution of acetate and nitrate containing reagent.