Solid oxide fuel cell is one of the most promising energy conversion device due to its several advantages involving the high efficiency and high power density without any harmful byproducts. However, mechanically and chemically unstable state of SOFC system in high operating temperature in the range of 700-800 °C still remain challenge to solve for universal commercialization. In order to preserve the stability for long time operation, we applied thin protection layer on the surface of the unstable electrode scaffold. A novel infiltration method using biopolymer was adopted to coat the few nanometers deep protection layer. The porous scaffold made of Sm0.5Sr0.5CoO3-δ (SSC) was coated by thin film of Gd0.2Ce0.8O2-δ (GDC) to be used as electrode. Using the unique property of the biopolymer, uniform and thin GDC layer in a thickness of ~3 nm was successfully covered on the SSC cathode surface. With GDC/SSC hetero-interface, the performance enhancement can be achieved because of enlarged TPB on the cathode surface. Interestingly, as well as performance enhancement, it demonstrated the excellent stability at 650 °C for 100 h compared with non-GDC coated SSC cathode and discretely GDC coated SSC cathode. With surface analysis, it can be ascribed that the enhanced durability is from the suppression of Sr segregation with thin GDC layer.