Enhancement of low-temperature solid oxide fuel cell performance and durability via surface chemistry modification

Abstract

The development of active cathodes is one of the most critical challenges to lowering the operating temperature for solid oxide fuel cells (SOFCs). Here we demonstrated that by modifying the cathode surface chemistry at a relatively low temperature, the cathode activity and durability can be simultaneously enhanced on high-performing, low-temperature cathodes such as (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ (LSCF) and Sr0.5Sm0.5CoO3-δ (SSC). This low-temperature modification using multi-valent cations activates the highly defected surface and maintains the nanoscale electrocatalysts by bypassing the high-temperature sintering procedure for SOFC fabrication. The modified cathode at 600°C shows an order of magnitude reduction in impedance to only 0.05 Ωcm2 with a peak power density of 1.1 W/cm2 and increases stability over 2000 h. The combination of in situ characterization, distribution of relaxation time analysis on impedance spectroscopy, and surface chemistry analysis reveals the importance of surface chemistry control on the gas-solid reaction activity and durability and provides the design principle for numerous future solid oxide cells.