Impact of Carbon Structure over the Pseudocapacitive K-Ion Storage in New Cobalt-Manganese Oxides Derived from Coordination Compounds

Abstract

The rapidly growing use of intermittent energy sources such as solar and wind power to generate electricity requires the development of reliable, affordable, and efficient electric energy storage systems [1]. Electrochemical capacitors are excellent devices that have a high power (>10 kW kg-1), high rate capability and long cycle life (>1 000 000 cycles) [2]. A great diversity of materials has been widely investigated as supercapacitor electrodes, such as carbon materials, graphene-based composites metal hydroxides and metal oxides. In this work, a new pseudocapacitive materials were obtained by thermal descomposition of cyanometalates formed by precipitation over different carbon structures (graphene oxide, carbon nanotubes and mesoporous carbon). The materials were thoroughly characterized using XRD, FRX, Raman, ATR-FTIR, SEM, TEM and XPS. Furthermore, the electrochemical performance of the materials was tested by cyclic voltammetry, step potential electrochemical spectroscopy, electrochemical impedance spectroscopy and charge-discharge curves at different current rates in 1 M NaOH. The material formed in presence of graphene oxide exhibited the best electrochemical behavior, maintaining 98% of its initial capacitance after 500 cycles at 1 Ag-1. References Yang, J. Zhang, M. C.W. Kintner-Meyer, X. Lu, D. Choi, J. P. Lemmon, J. Liu, Chem. Rev. Electrochemical Energy Storage for Green Grid. 2011, 111, 3577 – 3613.S. Aric, P. Bruce, B. Scrosati, J.-M. Tarascon, W. V. Schalkwijk, Nanostructured materials for advanced energy conversion and storage devices. Nat. Mater. 2005, 4, 366 – 377