In-situ synthesis of mixed-phase carbon material using simple pyrolysis method for high-performance supercapacitor

We report a novel mixed phase carbon material that contains both amorphous as well as crystalline phases for supercapacitor application. The amorphous carbon and crystalline carbon nanotubes are present in this mixed phase material which is prepared using an in-situ process in a simple and cost-effective method. In supercapacitor devices, better performance is achievable when there is good surface accessibility in electrode material and decent ion mobility. Amorphous material provides good surface accessibility whereas crystalline offer better electrons and ions mobility. Hence, the prepared mixed-phase carbon material has advantages for the supercapacitor. The material is tested for supercapacitor application where the electrochemical performances are obtained using Cyclic voltammetry (CV), Galvanostatic charge-discharge (GCD) and Electrochemical impedance spectroscopy (EIS) measurements. The mixed-phase electrode results in a specific capacitance of 37.54 F g −1 at 1 A g −1 and 36.80 F g −1 at 5 mV/s. The storage performance of this material is further increased by integrating it with a few layers of graphene. The prepared composite with a 30 wt. percentage of few-layer graphene gives the better supercapacitive properties and the maximum capacitance achieved by the composite is 282.52 F g −1 at 1 A g −1 and 281.84 F g −1 at 5 mV/s. The fabricated mixed-phase composite (30 wt% of few-layer graphene) offers excellent cyclic stability and 93 % capacitance is retained even after 10,000 cycles at 1 A g −1 . These outcomes suggest the mixed-phase composite electrode could be the best choice for high performance supercapacitor applications. • A novel material is prepared using a simple pyrolysis and cost-effective method • The prepared material contains both amorphous and crystalline phase • The storage performance of mixed phase material is enhanced by few layer graphene • A very low equivalent series resistance is achieved in the composite electrode • An excellent cyclic stability is observed in composite electrode over 10,000 cycles