Performance of Protonic Ceramic Fuel Cell with Thin Film Yttrium Doped Barium Zirconate Electrolyte

Perovskite protonic ceramics, or proton-conducting oxides, have attracted much attention in recent decades as alternative electrolytes for conventional solid oxide fuel cells (SOFCs). Protonic ceramics have higher ionic conductivity and lower activation energy in SOFCs’ low operating temperature region (under 600°C) than oxide-ion-conducting oxides. Recently, many attempts have been made to enhance fuel cell performance by adopting thin-film protonic ceramics as electrolytes. In this work, anode-supported thin-film protonic ceramic fuel cells (PCFCs) were fabricated with thin-film yttrium-doped barium zirconate (BZY, BaZr_0.85Y_0.15O_3-δ), which is one of the best-performing protonic ceramics with high bulk ion conductivity and good chemical stability. However, this material possesses poor sinterability, resulting in severe grain separation and a dramatic increase in ohmic overpotential from slow ion transport. In this work, we have applied novel multi-step annealing processes to achieve the densification of the BZY electrolytes, good adhesion between layers, and effective grain growth of the supporting composites. The NiO-BZY composite anode support was fabricated by tape casting and the BZY electrolyte was deposited by pulsed laser deposition (PLD) with a thickness of 2 μm. A perovskite cathode material of La_0.6Sr_0.4Co_3-δ (LSC) was formed porously by PLD with a thickness of 2 μm. The microstructures of the fabricated PCFCs were analyzed using scanning electron microscopy (SEM). The electrochemical performance in terms of current–voltage characteristics was obtained, and the maximum power output of 320‒530 mW/cm² was measured at 450‒600°C. The alternating current (AC) impedance data were collected under DC bias conditions at each operating temperature and analyzed to determine the resistive factors for the power outputs.