Surface-doped perovskite electrolyte for low-temperature ceramic electrochemical cells

Protonic ceramic electrochemical cells (PCECs) can be employed for power generation and sustainable hydrogen production. Lowering the PCEC operating temperature to >500 °C can facilitate its scale-up and commercialization. However, achieving high energy efficiency and long-term durability at low operating temperatures is a long-standing challenge. Here, we report a simple and scalable approach for fabricating metal ion doping into perovskite (Li-doped SrTiO₃ (STO)) using the sol-gel approach and presented as a proton conducting electrolyte with lower ohmic and polarization resistance for low-temperature ceramic fuel cells. The prepared electrolyte with symmetrical electrodes attains high power densities in fuel-cell mode (∼0.65 W cm⁻² at 520 °C and ∼0.20 W cm⁻² at 420 °C) and exceptional current densities in steam electrolysis mode (−0.94 A cm⁻² at 1.4 V and 520 °C). Additionally, five-layer devices (Ni-NCAL/BCZYYb/Li-STO/BCZYYb/NCAL-Ni) demonstrate the proton fuel cell performance of 0.55 W cm⁻² at 520 °C.