Electricity-to-ammonia interconversion in protonic ceramic cells: advances, challenges and perspectives

Abstract

NH3 is an attractive alternative fuel to hydrogen and methane, offering advantages such as easy compression at room temperature, straightforward storage and transportation, high volumetric energy density, and carbon-free nature. However, conventional NH3 synthesis operates at high temperatures and pressures, resulting in substantial energy demands and elevated equipment and maintenance costs. Protonic ceramic cells (PCCs), as a cutting-edge energy conversion technology, can realize NH3 synthesis at moderate pressures and low-to-intermediate temperatures by utilizing surplus renewable electricity generated by wind and solar power. Additionally, PCCs can be employed to convert NH3 into electricity to meet instantaneous demand, providing a means to address the seasonal and intermittent nature of renewable energy sources. Despite their potential, the commercial application of electricity-to-NH3 interconversion in PCCs faces several challenges, primarily related to insufficient performance and durability. This review systematically explores the mechanisms and challenges of electricity-to-NH3 interconversion in PCCs, highlights recent advancements in NH3 synthesis using PCCs and direct NH3-fueled proton ceramic fuel cells (DA-PCFCs), and discusses perspectives for realizing high-efficiency electricity-to-NH3 interconversion. This review aims to establish a scientific foundation for efficient electricity-to-NH3 interconversion via PCCs and provides critical insights for designing high-performance and durable PCC components.