Effect of back diffusion on energy efficiency of electrochemical ammonia compressor

Conventional ammonia compression technologies consume significant energy, leading to substantial greenhouse gas emissions. We analyzed the back-diffusion of ammonia in an electrochemical ammonia compressor (EAC) and evaluated its performance and efficiency based on temperature and relative humidity (RH). We evaluated EAC performance under various conditions and developed a model to analyze voltage and pressure changes. Ammonia's permeability is about 890 times higher than hydrogen, increasing compression time due to back diffusion. As temperature rises, the overpotential increases, with a 0.035 V rise at 100 degrees C compared to 60 degrees C, and back-diffusion extends compression time by 130 s. Lower humidity increases overpotential, with a 0.099 V rise at 10% RH compared to 50% RH, but reduces back diffusion by 165 s. This study improves our understanding of EACs and guides future performance enhancements. We aim to develop a new membrane to enhance ammonium ion movement and minimize ammonia back-diffusion.