Porphyrin Integration Enhances Bipolar Redox Accessibility for High-Rate Sodium-Based Dual-Ion Storage.

Abstract

Closing the gap between theoretical multielectron capacity and practical accessibility remains the central bottleneck for high-energy organic batteries. Herein, we report a molecular design strategy that integrates a porphyrin motif into a sulfur-rich conjugated polymer (BTTP) to align electronic structure, state-dependent ion interactions, and electrochemical kinetics across the bipolar window. Despite possessing a lower theoretical capacity than its reference counterpart (BTB), BTTP achieves an exceptional theoretical capacity utilization of 94.2% (delivering 477 mAh g-1 at 0.5 A g-1, compared to only 53.5% and 351 mAh g-1 for BTB). Electrokinetic analyses, including GITT and DRT, confirm accelerated apparent ion diffusion and reduced polarization limitations, enabling BTTP to retain 166 mAh g-1 at an ultrahigh current density of 20 A g-1 over 25 000 cycles. Operando/ex situ spectroscopy and theoretical calculations elucidate that the dual pyrrolic/imino nitrogen sites in porphyrin and the sulfur-rich backbone cooperatively provide potential-dependent coordination environments for PF6 - anions and Na+ cations. This work suggests that molecular regulation of complementary ion-interaction environments within multi-active-unit frameworks, rather than simply increasing the number of redox units, is important for enhancing rate capability and capacity utilization.