(Pr0.9La0.1)1.9(Ni0.7Cu0.3)0.9Mn0.1O4+δ nanofiber cathode with Pr site cation defect prepared by electrospinning and its application in reversible fuel cells

Abstract

In this contribution, the Pr-site cation-deficient (Pr0.9La0.1)1.9(Ni0.7Cu0.3)0.9Mn0.1O4+δ nanofiber electrode material is successfully prepared by electrospinning and microwave sintering, and the effect of defects on the crystal structure and electrochemical performance are systematically studied. The resulted cations deficiency within material can form a certain amount of oxygen vacancies, which improves its hydration performance and accelerates the surface exchange coefficient of oxygen. Based on the thermogravimetric analysis (TGA) and electrical conductivity relaxation (ECR) technology, it is concluded that the enhanced proton conductivity of the material benefits from the oxygen vacancies caused by internal crystal defects. The doping of Mn element weakens the binding energy of the Ni–O bond, which avails the release of lattice oxygen. In addition, the distribution of relaxation time (DRT) analysis demonstrates that the main electrode reaction is the dissociation reaction process of the adsorbed oxygen. As a result, the polarization resistance (Rp) of the symmetrical cells at 700 °C is only 0.101 Ω cm2. In the single-cell fuel mode, the power density reaches 894 mW cm−2, and the excited current density in the electrolysis mode is 1563 mA cm−2 at 700 °C.