In this work published in the Journal of the Electrochemical Society, we studied the effect of cold-pressing and spark-plasma sintering (SPS) processing on the Na3OBr sodium-rich anti-perovskite solid electrolytes was studied. SPS was found to reduce the interfacial impedance by 3 orders of magnitude. The much lower conductivity of Na3OBr compared to the lithium analogue is attributed to the significantly higher defect formation energies. This work is led by the Laboratory of Energy Storage and Conversion of Prof Shirley Meng. Zhi Deng and Prof Ong are co-authors.