A Generalizable Active-Site Blocking Strategy Enables High Initial Coulombic Efficiency in Mononitrogen-Containing...

Mononitrogen-containing aromatic compounds, exemplified by carbazole (CZ) and triphenylamine, are emerging as promising high-potential candidates (3.6-4.3 V vs. Li⁺/Li) for p-type anion-storage electrode materials. However, the inherent reactivity of their para positions at elevated potentials (>4 V) induces undesirable electropolymerization, leading to severe low initial coulombic efficiency (ICE). Herein, we propose an active-site blocking strategy to fundamentally address this critical challenge through molecular engineering. Specifically, we develop a CZ-based organic polymer, poly[5-(9-ethyl-9H-carbazol-3-yl)-5,10-dihydrophenazine] (p-ECZDPZ), tailored as the model system to validate the efficacy of our proposed strategy. By strategically incorporating 5,10-dihydrophenazine and ethyl group into its structure, the active para positions of the CZ moieties are effectively blocked. This enables a superior ICE of 86% without requiring any pretreatment, surpassing other known CZ-based organic electrode materials to date. The constructed Li-based dual-ion full batteries (LDIBs) achieve a peak discharge capacity of 204 mAh g^-1, an ICE of 84%, and a stable operation over 20 000 cycles. At high cathode mass loading, the LDIBs demonstrate an energy density of 445 Wh kg^-1 while retaining no capacity decay for 8000 cycles. Pouch-type full cells achieve direct activation during the first charge process, realizing an energy density of 305 Wh kg^-1 _cathode.