Functional layer engineering to improve performance of protonic ceramic fuel cells

Protonic ceramic fuel cells (PCFCs) have been attracting increasing attention because of their advances in high-efficiency power generation in an intermediate-temperature range, as compared to the high-temperature solid oxide fuel cells (SOFCs). The greatest difference between PCFCs and SOFCs is the specific requirement of protonic (H (+)) conductivity at the PCFC cathode, in addition to the electronic (e-) and oxide-ion (O2-) conductivity. The development of a triple H+/ e(-)/ O2- conductor for PCFC cathode is still challenging. Thus, the most-widely used cathode material is based on the mature e(-)/ O2- conductor. However, this leads to insufficient triple phase boundary (TPB), i.e., reaction area. Herein, an efficient strategy that uses a * 100 nm-thick proton conductive functional layer (La(0.5)Sr(0.)5CoO(3-)d, LSC55) in-between the typical La(0.8)Sr(0.)2CoO(3-) d cathode (a mature e(-)/O2- conductor, LSC82) and BaZr0.4Ce0.4Y0.1Yb0.1O3- d electrolyte (11 mm in diameter, 20 lm in thickness) is proposed to significantly enhance the reaction area. Reasonably, the ohmic resistance and polarization resistance are both decreased by 47% and 62%, respectively, compared with that of PCFCs without the functional layer. The power density of the PCFC with such a functional layer can be raised by up to 2.24 times, superior to those described in previous reports. The enhanced PCFC performances are attributed to the well-built TPB and enhanced reaction area via the functional layer engineering strategy.