INFLUENCE OF NICKEL OXIDE AMOUNT ON ELECTRICAL PARAMETERS AND STABILITY OF SUPERCAPACITORS

A carbon/nickel oxide composite capacitors were made using arc plasma jet and magnetron sputtering deposition techniques. Carbon coatings were deposited on stainless steel substrates at atmospheric pressure from argon-acetylene gases mixture by plasma jet chemical vapor deposition. Nickel oxide (NiO2) layer was formed on the carbon coating employing magnetron sputtering deposition. The thickness of the deposited nickel oxide film was verified in the range from 18 to 360 nm. In order to characterize differences between produced capacitors, the specific capacitance (C) and maximum working voltage (U) were measured. It was obtained that the increase of NiO2 film thickness from 18 nm up to 72 nm, increases capacitance from 9 F g−1 up to 15 F g−1. Further increase of the metal oxide thickness decreases the specific capacitance value. Experimental results showed that the supercapacitors with thinner nickel oxide layers work much stable. The stability voltages were 0.58 V and 0.35 V, for the capacitors with NiO2 layer thickness of 18 nmand 360 nm, respectively.