Bioactive small-molecule-based aqueous zinc-organic battery enables long-life and fast-charge performance

Abstract

Aqueous zinc-ion batteries (AZIBs) have become a current research hotspot owing to their high security and cost-effectiveness. However, the dissolution of electrode materials, low intrinsic conductivity, and slow reaction kinetics seriously hinder their practical application. Herein, a sulfur-containing organic small molecule (seriniquinone, SQ), which plays a significant role in melanoma treatment, was synthesized and used as electrodes for AZIBs. To address the dissolution problem as well as enhance the electrical conductivity, SQ was further optimized by conductive carbon modification to prepare SQ/CMK-3 composite electrodes. In Zn‖SQ/CMK-3 half-battery, SQ/CMK-3 cathode delivered an initial discharge capacity of 234.4 mA h g−1 at 100 mA g−1 and maintained 100.2 mA h g−1 after ultra-long cycles (5000) at the high current density of 1 A g−1. Moreover, a zinc storage mechanism with four Zn2+ between two SQ molecules was proposed based on the density functional theory calculation and confirmed by various ex-situ measurements. Assembled with SQ/CMK-3 composite as both the anode and cathode, the all-organic symmetric battery not only displayed a high reversible capacity of 110.9 mA h g−1 at 100 mA g−1 but also possessed a stable capacity retention rate of 82.4% after 2500 cycles with an average coulombic efficiency of 99.5%.