N 12 as a Zero-Carbon Energy Carrier: A CL5D Framework Analysis of Polynitrogen High-Energy-Density Materials

Polynitrogen compounds represent the frontier of zero-carbon high-energy-density materials (HEDMs), releasing energy exclusively as molecular nitrogen (N 2) with no carbon emissions. Building on our prior computational study of the N 12 cage [1] and the CL5D spectroscopic hysteresis framework [2-4], we analyse N 12 as a candidate zero-carbon energy carrier in the context of computationally predicted neon-nitrogen compounds (NeN 10 , NeN 22 , t-N 20) reported by Lin et al. [5]. The N 12 cage, with a computed thermodynamic energy density of 67.3 kJ/g (16.1× TNT, 5.6× Lin et al.'s best compound), sits at the apex of the polynitrogen energy ladder. The CL5D convergence score C n (P) is applied to identify the pressure window most favourable for N 12 synthesis and storage, and the hysteresis coefficient η N12 = 8.28 × 10 −6 is proposed as a regulatory parameter for fuel cell energy conversion. A conceptual N 12-based fuel cell cycle is outlined, yielding an estimated useful energy output of 40.4 kJ/g at 60% conversion efficiency-approximately 2× the output of a hydrogen fuel cell per gram of fuel. All results are computational; experimental synthesis of N 12 remains the critical enabling step.