Nickel‐Free Synthesis of Poly(pyrene‐4,5,9,10‐tetraone) for Sodium‐based Batteries: Insights into Electrode Architecture and Reversible Na‐ion Insertion

Organic electrode-active materials offer a sustainable pathway toward sodium-based batteries, yet their application is hindered by electrolyte dissolution, limited conductivity, and synthetic challenges. Herein, we present an efficient nickel-free synthesis of poly(pyrene-4,5,9,10-tetraone) (PPTO), a high-capacity organic carbonyl-based polymer, via oxidative Pd-catalyzed homopolymerization of propylene glycol-protected PTO boronic esters. Among different conductive carbon-based electrodes, a PPTO@CNTs@Ketjen Black composite electrode achieves a reversible capacity of 286 mAh g$^{−1}$ at 1 A g$^{−1}$, 72% capacity retention over 500 cycles, and delivers 201 mAh g$^{−1}$ even at 10 A g$^{−1}$. An energy density of 549 Wh kg$^{−1}$ (at low rates) and 346 Wh kg$^{−1}$ (at high rates) is achieved based on active-material mass under half-cell conditions (275 Wh kg$^{−1}$ based on total electrode mass). Ex situ spectroscopy, combined with theoretical calculations, reveals a two-electron redox process of each PTO unit with possible intermolecular interactions stabilizing the reduced state. Kinetic studies demonstrate rapid Na$^+$ transport (D$_{Na}$$^+$ ≈ 10$^{−10}$ cm$^2$ s$^{−1}$) and capacitive-dominated storage. ... mehrTomographic 3D image data reconstruction highlights the favorable microstructure of the CNT/Ketjen Black composite in hindering PPTO dissolution. This work provides insights into the interplay between polymer chemistry, electrode architecture, and ion transport, offering design principles for organic electrode materials for sodium-based batteries.