Facile synthesis of helical Co-based coordination supramolecular network micro-nano rods as a durable cathode for high-performance asymmetric supercapacitors and aqueous Co-Zn batteries

Abstract

Developing and exploring new-type electrode materials with powerful components and suitable morphologies for well-pleasing energy storage and conversion is an important task. Herein, a novel cobalt-based coordination supramolecular network (Co-CSN) material with a helical rod-like morphology is in-situ synthesized by employing Co foam as Co ions source and substrate through a facile solvothermal approach. The helical micro-nano structured Co-CSN possesses three-dimensional (3D) networks that formed via hydrogen bonds, which endows it structural flexibility and abundant open redox reaction sites. Based on these advantages, the as-fabricated self-supporting Co-CSN helical micro-nano rods deliver a high areal capacitance of 10.19F/cm2, a good rate capability of 76.4% when increasing the current density to 30 mA/cm2. Furthermore, the assembled asymmetric supercapacitor (ASC) yields a volumetric capacitance of 7.45F/cm3 at 3 mA/cm2 and a high energy density of 2.65 mW h cm−3. Meanwhile, the fabricated aqueous Co-CSN//Zn battery presents a high capacity of 1.37 mAh/cm2 and a remarkable energy density of 19.0 mW h cm−3. Impressively, these two devices exhibit superior cycling performance (84.8% of its initial capacitance retained for Co-CSN//AC ASC and 81.1% for Co-CSN//Zn battery after 10,000 cycles). This work demonstrates supper promising of coordination supramolecular network materials for electrochemical energy storage.