Abstract: The transition to sustainable energy system has driven the development of protonic ceramic fuel cells (PCFCs), which offer high efficiency, exceptional fuel flexibility and improved durability at low-intermediate temperatures (300-700℃). Ammonia, with its high hydrogen content, easy transportation and storage and carbon-free nature, serves as an ideal fuel for PCFCs. However, the poor catalytic activity and instability of existing Ni-based anodes under ammonia fuel conditions, combined with the inefficient proton conductivity of perovskite electrolytes, greatly limit the performance of direct-ammonia PCFCs, particularly at lower temperatures. Here, we constructed symmetrical PCFCs featuring a novel LaCePr oxide (LCP) electrolyte, which leverages a surface proton transport mechanism to achieve an ionic conductivity exceeding 0.1 Scm-1 at 550℃. Instead of conventional Ni-based anode, a layered lithium ternary transition metal oxide LiNi0.8Co0.15Al0.05O2-δ (NCAL) supported on nickel foam was adopted as both anode and cathode, and two modification strategies including heterostructure composite and bilayer electrodes with a perovskite oxide Ba0.875Fe0.95Zr0.05O3-δ (BFZ) were designed to improve the catalytic activity of NCAL symmetrical electrode. The heterostructure composite electrode design proved most effective, followed by the pure NCAL electrode design, with the bilayer electrode design being the least effective. The optimal symmetric electrode design is the NCAL-BFZ heterostructure composite in a weight ratio of 90:10. The corresponding symmetric fuel cell with a 308μm thick LCP electrolyte delivered peak power densities of 893 mWcm-2 and 696 mWcm-2 under H2 and NH3 fuels at 550℃, respectively. Specifically, at 450℃, peak power densities of 370 mWcm-2 and 279 mWcm-2 were achieved for both fuels. Such excellent low-temperature output performance surpasses that of the state-of-the-art direct-ammonia PCFCs, which can be attributed to the good catalytic activity of NCAL-BFZ composite electrode to ammonia decomposition and oxygen reduction reaction. The NCAL-BFZ (90:10) heterostructure composite electrode in direct-ammonia symmetrical PCFC showed the best catalytic performances, with a polarization resistance of 0.154 Ωcm-2 at 550℃. The introduction of BFZ to NCAL not only improve the catalytic activity but also improve the stability of NCAL electrode under ammonia fuel.