Optimizing Solid Oxide Fuel Cell Performance with LiCoO₂–LiAlO₂ Composite Electrolytes: Tackling Short Circuit Challenges

This research addresses the short-circuit issue linked to high electronic conductivity in LiCoO 2 (LCO) when used alone as an electrolyte in solid oxide fuel cells (SOFCs). A composite electrolyte system combining LCO and LiAlO 2 (LAO) was developed. Various mass ratios of LCO-LAO composites (3:7, 5:5, 7:3) were created through mechanical mixing and analyzed for structure, energy band characteristics, and electrochemical performance. Structural characterization revealed that LCO and LAO in the composite exhibit good chemical compatibility, with LAO uniformly distributed on the surface of LCO, creating a stable heterogeneous interface. UV–Vis spectroscopy demonstrated that the wide bandgap characteristics of LAO (4.52 eV) effectively suppressed electron leakage, and the bandgap width of the composite material significantly increased with the rising LAO ratio (e.g., 2.72 eV for 5LCO-5LAO). Electrochemical testing showed that the 5LCO-5LAO electrolyte exhibited optimal performance at 550 °C, achieving an open-circuit voltage (OCV) of 1.05 V and a maximum power density (MPD) of 487.5 mW/cm 2 . This ratio effectively balances the electron-blocking effect of LAO with the ionic transport capability of LCO, successfully addressing the short-circuit defect of the single LCO electrolyte and providing insights into the design of low-temperature SOFC electrolytes.