Misfit-Layered Cobaltite Ca(3)Co(4)O(9+Delta)As A New Electrode For Supercapacitor With Excellent Cycling Stability

One of the major challenges for transition metal used as supercapacitor electrode is their poor electrical conductivity. In this study, misfit-layered cobaltite Ca3Co4O9+delta (CCO) oxide is successfully synthesized using sol-gel method. The structure, morphology and surface composition of the obtained CCO powder are characterized by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy measurement. Herein the CCO exhibits a high electrical conductivity of 62.0 S cm(-1) at room temperature. The prepared CCO electrode was characterized by cyclic voltammetry and galvanostatic charge-discharge method to evaluate its electrochemical performances. The CCO electrode displays good capacitance features with a mass specific capacitance of 229.3 F g(-1) at a scanning rate of 2 mV s(-1), which are mainly due to its high electrical conductivity and unique layered structure. Furthermore, the CCO electrode shows outstanding cycling performance with 107% capacitance retention after 44 000 cycles. More importantly, the bulk CCO can be directly used as free-standing electrode for electrochemical supercapacitors with an area specific capacitance (340 mF cm(-2)) and excellent cycling stability. (C) 2019 Elsevier B.V. All rights reserved.