## 1 Introduction  
A supercapacitor is a new storage device positioned between traditional capacitors and batteries. Electrochemically activated materials or porous materials are used for storage in a supercapacitor. The advantages of a supercapacitor are its high power density, high energy density, excellent cycle life, and fast charge and discharge times [1, 2]. Supercapacitors have attracted considerable attention in recent years because they do not have the disadvantages that traditional batteries and capacitors have.  
It has been discovered that charges can be separated using Coulomb electrostatic force and form double layers across the surface of electrodes and electrolytes [3]. The concept of an electrical double-layer capacitor (EDLC) involves applying DC voltage to electrodes, which are typically porous carbon, to establish an electrical double-layer for charges storage. A pseudocapacitor stores electrical energy through rapid and continuous redox reactions between the electrodes and the electrolyte. Metal oxides and conducting polymers are commonly used as the electrode materials in pseudocapacitors. Porous carbon is usually chosen as the electrode material in commercial products because of the high cost of metal oxides and the poor stability of the conducting polymers. Therefore, composite electrodes exhibit such advantages as double-layer capacitance and pseudo-capacitance [4, 5].  
[PERSON] et al. prepared an asymmetrical composite electrode by using NiO and carbon in 1999, and the results showed more favorable energy density than carbon-carbon electrodes [6]. However, [PERSON] et al. in 1999 proposed a oxide composite consisting of Ti, V, and W oxides for the application of ECs [7]; meanwhile [PERSON] and [PERSON] reported that RuO\({}_{2}\) coated with WO\({}_{3}\) showed good capacitive performances in both acidic and alkaline media in 2001 [8,9]. In 2005, [PERSON] et al. showed a hybrid-type electrochemical capacitor, in which the activated-carbon (AC) load with nickel oxide was used as cathode material and the activated-carbon was used as anode material. Although the BET surface area of the activated-carbon decreased after nickel oxide loading compared with that of the starting material, its specific capacitance increased 10.84%, from 175.40 to 194.01 F-g\({}^{-1}\)[10,11]. Recently, amorphous tungsten oxide with microwave radiation was reported to be a promising electrode material for electrochemical capacitors (ECs) [12]. Accordingly, tungsten oxides and NiO of certain microstructures should be of pseudocapacitive behavior.  
In this study, the carbon electrode using mesocarbon microbeads (MCMBs) was adopted for the fabrication of a supercapacitor. To fabricate the composite electrodes of the supercapacitor, NiO and WO\({}_{3}\) layers were deposited onto carbon electrodes using electron beam evaporation. This technique, one of the physical vapor deposition methods, was chosen largely for the growth of device quality films [13]. The influences of various scan rates of the cyclic voltammograms (CVs) on the characteristics of capacitance were studied. The charge/discharge efficiency and lifetime of the composite electrodes were also discussed.