Avoiding undesirable cathode/electrolyte interfacial reactions for proton-conducting solid oxide fuel cells by Joule heating

The co-firing stage is an unavoidable step in the fabrication process of solid oxide fuel cells (SOFCs), and avoiding unwanted interfacial reactions is crucial for cathode construction during the co-firing process. In this study, LiMn₂O₄ (LiMO), a traditional electrode material for Li-ion batteries, was discovered to have protonation and proton diffusion properties, showing significant promise as a cathode for proton-conducting SOFCs (H-SOFCs). However, obvious interactions between the LiMO cathode and BaCe_0.7Zr_0.1Y_0.2O_3−δ (BCZY) electrolyte can be identified during the co-firing process using the conventional sintering method, resulting in poor performance and making the use of LiMO in H-SOFCs challenging. To address this issue, the Joule heating process is used to produce the LiMO cathode for H-SOFCs. In contrast to the traditional co-firing process, which takes a few hours, the Joule heating method, which completes the co-sintering procedure in a few seconds, can successfully bind the LiMO to the BCZY electrolyte with no visible interlayer reactions or elemental diffusions. As a result, the full potential of LiMO for H-SOFCs is realized, resulting in a high fuel cell output of 1426 mW·cm⁻² at 700 °C, approximately double that of the cell utilizing the normally sintered LiMO cathode. To the best of our knowledge, this is the first study to use Joule heating to prevent the cathode/electrolyte interfacial reaction in H-SOFCs, which presents an interesting approach for manufacturing and may also breathe new life into some materials that are previously incompatible with H-SOFCs.