Sustainable Synthesis of Edge‐Dominant Pyridinic Nitrogen‐Doped Carbon from Tannic Acid for High‐Performance Vanadium Redox Flow Batteries

A novel carbon material with edge‐dominant pyridinic nitrogen doping is synthesized from tannic acid (TA), an agricultural byproduct, using a quick and straightforward two‐step microwave irradiation technique. Tris(2‐aminoethyl)amine (TAEA) plays a dual role in this process, acting as a condensing agent for TA in the initial step and providing nitrogen for the pyridinic structure in the second step. This approach results in a distinctive carbon structure (C–TA/TAEA) characterized by enhanced graphitic features, fewer imperfections, and similar hydrophilicity. The edge pyridinic configuration lowers the desorption energy of V 3+ complexes and the deprotonation energy of VO 2+ complexes, thereby boosting the catalytic activity for vanadium ion redox reactions (VIRR) by influencing the rate‐limiting steps of both positive and negative side VIRRs. When applied to commercial thermal‐treated graphite felt (T‐GF/[C‐TA/TAEA]), the material demonstrates stable performance during vanadium redox flow battery (VRFB) single cell testing, even at 500 mA cm −2 , showing improved energy efficiency (EE) and discharge capacity compared to T‐GF. Furthermore, when applied to pristine graphite felt (GF/[C–TA/TAEA]), the material maintains a 94.12% discharge capacity retention rate over 1000 cycles at 400 mA cm −2 , underscoring its potential as an eco‐friendly, energy‐efficient treatment method for producing VRFB electrodes.