Supercapacitors represent an attractive alternative for portable electronics and automotive applications due to their high capacitance, specific power and extended life. In fact, the growing demand of portable systems and hybrid electric vehicles, memory protection in CMOS, logic circuit, VCRs, CD players, PCs, UPS in security alarm systems, remote sensing, smoke detectors, etc. require high power in short-term pulses. So, in the last 20 years, supercapacitors have been required for the development of large and small devices driven by electrical power. In this paper, asymmetric supercapacitors with high energy density were successfully fabricated using graphene as negative electrode and polyaniline as positive electrode. The weight of active material was 5.6 mg. The surface topography was characterized by scanning electron microscopy (SEM). The electrochemical properties of the composite were evaluated by cyclic voltammetry (CV), charge-discharge measurements and electrical impedance spectroscopy (EIS). The separator was a filter paper soaked in aqueous potassium hydroxide (6M).This enhances both the specific capacitance to 620.76 F/g at scan rate of 1 mV/s and the energy density to 86.22Wh/kg. Another low leakage supercapacitor was fabricated using polyvinyl alcohol (PVA) separator and 6 mole potassium hydroxide salt with specific capacitance of 220.35 F/g at scan rate of 1 mV/s.