Superbat: battery-like supercapacitor utilized by graphene foam and zinc oxide (ZnO) electrodes induced by structural defects

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Official URL: http://dx.doi.org/10.1039/C9NA00199A

The current work presents a hybrid type of energy storage device composed of both graphene foam and zinc oxide electrodes which exhibit both electrochemical performances of supercapacitor with relatively higher powder density and battery with relatively higher energy density as compared to each individual component as single devices. And, they correlate the hybrid performance to the defective structure of the electrodes. To enhance the electrochemical performance of supercapacitors it is necessary to have well-defined mass, shape and surface area of electrode materials. Here we present original design mounting device that enable to determine precisely the all critical parameters of electrode materials in particular mass and surface area. By the aid of the original setup we produced supercapacitor device which act as battery due to its high energy density values, hence we named it as superbat. In this work, 3D graphene foam was used as first electrode due to its large surface. As second electrode ZnO nanocrystals were used as second electrode for its defective structure. Paramagnetic resonance Raman and impedance spectroscopy have been undertaken in order to understand the origin of the performance of hybrid capacitor in more depth. In particular, we obtained high specific capacitance value (C = 448 F/g) which is exceptionally related not only the quality of synthesis but also the choice of electrode and electrolyte materials. Moreover, each component used in the construction of the hybrid supercapacitor is also played a key role to achieve high capacitance value. The results demonstrated the remarkable performance and stability of the superbat.