Boosting Zinc-Ion Storage via In Situ Electrochemical Balancing of Active Sites and Conjugation in Truxene-Based Cathodes

Abstract

As promising cathodes for aqueous zinc-ion batteries (AZIBs), organic carbonyl compounds are often designed with an emphasis on either high active-site density or extended conjugation, while the balance between these two key aspects is often neglected. This work explores an in situ electrochemical balance for modulating active sites and π-conjugation in truxene-based cathodes. Unlike the highly conjugated truxene and the highly carbonylated truxene, the hydroxyl-rich truxene (TX-OH) achieves an optimal, self-regulated balance between redox-active sites and conjugation via in situ electrochemical oxidation, which is difficult to attain through conventional synthesis. The TX-OH cathode delivers a reversible specific capacity of ∼107 mAh g–1, with discharge plateaus at 1.3 and 1.1 V vs Zn/Zn2+. At a high current density of 5 A g–1 (∼50 C), it sustains a good capacity of 66.9 mAh g–1 after 3000 cycles with 96.0% retention. The proposed in situ electrochemical balancing strategy offers a novel and facile pathway for designing high-power, long-life organic electrode materials in AZIBs.