Nickel Doping Manipulation towards Developing High-Performance Cathode for Proton Ceramic Fuel Cells

An ideal cathode for proton ceramic fuel cell (PCFC) should have superior oxygen reduction reaction activity, high proton conductivity, good chemical compatibility with electrolyte and sufficient stability, thus rational design of the electrode material is needed. Here, by taking advantage of the limited solubility of nickel in perovskite lattice, we propose a new dual phase cathode developed based on nickel doping manipulation strategy. We rationally design a perovskite precursor with the nominal composition of Ba(Co_0.4Fe_0.4Zr_0.1Y_0.1)_0.8Ni_0.2O_3−δ (BCFZYN0.2). During high temperature calcination, a nanocomposite, composed of a B-site cation deficient and nickel-doped BCFZY perovskite main phase and nanosized NiO minor phase, is formed. The NiO nanoparticles effectively improve the surface oxygen exchange kinetics and the B-site cation deficiency structure enhances proton conductivity, thus leading to superior ORR activity of BCFZYN0.2. Furthermore, a low thermal expansion coefficient (15.3 × 10^–6 K⁻¹) is achieved, ensuring good thermomechanical compatibility the electrolyte. A peak power density of 860 mW cm⁻² at 600 °C is obtained from the corresponding PCFC, and the cell operates stably for 200 h without any significant degradation. The proposing strategy, by providing a new opportunity for the development of highly active and durable PCFC cathodes, may accelerate the practical use of this technology.