Surfactant tuned morphology of mesoporous β-Co(OH)2/CMC nanoflakes: a prospective candidate for supercapacitors

Abstract

Innovative electrode materials are the need of the hour towards the fabrication of electrochemical energy storage systems with superior performance. In the objective of designing flexible high power supercapacitors, herein, we have synthesized β-cobalt hydroxide/carboxymethyl cellulose nanoflakes via a facile route using anionic, cationic, and non-ionic structure directing agents. When tested as a supercapacitor electrode, β-cobalt hydroxide/carboxymethyl cellulose nanoflakes prepared using cationic surfactant (cetyltrimethylammonium chloride) exhibit better electrochemical behaviour including specific capacitance (306 C g−1 at a scan rate of 2 mV s−1), excellent cycle life (89% capacitance retention even after 5000 repeated charge/discharge cycles) in an aqueous alkaline solution. Furthermore, we have designed an asymmetric supercapacitor utilizing β-cobalt hydroxide/carboxymethyl cellulose and activated carbon as electrodes which is capable of delivering an energy density of 29.7 W h kg−1 with the power density of 695 W kg−1. The notable features of this device open pathways for the new electrode materials in supercapacitors.