Enhanced Oxygen Reduction Reaction Kinetics of Li-Containing Oxide as a High-Performance Cathode for Solid Oxide Fuel Cells Through Synergistic Li Volatilization and Anion Doping

Abstract

LiCoO₂ is widely used in lithium-ion batteries. Innovatively, this study reveals that by employing a synergistic strategy of Li volatilization and anion doping, LiCoO₂-based materials demonstrate exceptional performance as solid oxide fuel cell (SOFC) cathodes. At high temperatures, Li volatilization forms a Co₃O₄ phase. Concurrently, anionic doping is achieved by substituting F ions for O ions. The synergy of these two strategies increases the concentration of oxygen vacancies and the formation of heterogeneous interfaces, effectively enhancing the adsorption, dissociation, and diffusion rates of oxygen, thereby significantly improving the oxygen reduction reaction (ORR) of LiCoO₂ (LCO). LCOF1 (LiCoO_1.9F_0.1+Co₃O₄) exhibits an oxygen diffusion coefficient (D_chem) and surface exchange coefficient (K_chem) of 8.85 × 10^–5 cm² s^–1 and 7.61 × 10^–3 cm s^–1, respectively, which are 45% and 26% higher than those of undoped LCO. Furthermore, at 800 °C, LCOF1 achieves a PPD of 0.86 W cm^–2 and an Rp as low as 0.012 Ω cm², representing improvements of 110% in PPD and a reduction of 78.6% in Rp compared to LCO. These findings indicate that the synergistic effect of Li volatilization and F doping is an effective strategy for enhancing the performance of Li-containing cathodes, offering valuable perspectives for the development of high-performance SOFC cathodes.