Three‐dimensional Quantitative Evaluation of Interfacial Mass Transfer for Performance Enhanced and Durable Large‐scale Reversible Protonic Ceramic Cells

Abstract Reversible protonic ceramic cells (R‐PCCs) hold significant promise for energy storage and conversion. However, achieving high‐performance, large‐scale cells remains challenging, primarily due to issues with compatibility and adhesion at the electrode‐electrolyte interface. Here, a scalable strategy is presented for regulating an active interface structure (AIS) via tape casting to develop high‐performance, durable R‐PCCs. The AIS, located between BaZr₀.₁Ce₀.₇Y₀.₁Yb₀.₁O₃‐δ (BZCYYb) electrolyte and Ni‐BZCYYb anode, is systematically analyzed for its impact on electrochemical performance. Cells with a 20 µm AIS (20AIS) achieve peak power densities of 1.50 W cm⁻ 2 and current densities of − 1.66 A cm − 2 at 650 °C, outperforming conventional cells without AIS (0AIS) by ≈50%. The stable reversible operation is maintained for over 200 h. FIB‐SEM and 3D reconstruction reveal that the 20AIS sample exhibits a 65.7% increase in triple‐phase boundary length, despite reduced pore counts affecting gas transport, optimizing the balance between TPB length and transport resistance. Furthermore, the scalability of this approach is demonstrated by fabricating 10 × 10 cm 2 cells, meeting industry standards and reinforcing the method's commercial viability. These findings highlight a practical pathway for advancing R ‐ PCC technology toward industrial applications.