<p>Polymeric nitrogen has long been pursued as a high-energy density material but is very challenging to synthesize at ambient pressure conditions especially with light element precursors. Using a developed one pot method, we successfully synthesized the atomic polymeric nitrogen employing lithium azide as a precursor. Raman spectrum measurements detected the emerging vibrational peak at 635 cm⁻¹ for the polymerized lithium azide sample, indicating the formation of atomic cubic gauche nitrogen (cg-N) with N–N single bonds. Through systematic investigations, the preparation conditions are optimized to be 180°C with a reaction time of 3 h for obtaining atomic cubic gauche polymeric nitrogen. The one pot method achieves the quantitative synthesis of cg-N at ambient pressure using alkali metal azide as the precursors. It offers a simple way for further scalable synthesis of polymeric atomic nitrogen high energy density materials.</p>