Split cell nanocomposite supercapacitor

1 . A split cell nanocomposite supercapacitor, comprising:

first and second nanocomposite electrodes, a membrane separator and an electrolyte,

wherein the first and second nanocomposite electrodes are circular flat electrodes,

wherein the first nanocomposite electrode comprises a first substrate and the second nanocomposite electrode comprises a second substrate,

wherein the electrolyte and the membrane separator are between and in direct contact with the first and second electrodes,

wherein both the first and the second substrates are made from at least one material selected from the group consisting of stainless steel, aluminum, nickel, copper and platinum;

wherein both the first and the second substrates are coated on a surface contacting the membrane separator with a nanocomposite mixture comprising:

polyvinylidene fluoride as a binding compound;

at least one carbonaceous compound; and

vanadium doped spinel ferrite nanoparticles (V-SFNPs);

wherein the V-SFNPs have a formula of Co x Ni 1-x V y Fe 2-y O z ;

wherein x=0.1-0.9, y=0.01-0.10, and z=3-5.

2 . The split cell nanocomposite supercapacitor of claim 1 , wherein the V-SFNPs have:

a substantially spherical shape;

an average size of 10-1000 nm.

3 . The split cell nanocomposite supercapacitor of claim 1 , wherein the V-SFNPs comprises:

20-30 wt % oxygen, 1-10 wt % vanadium, 40-50 wt % iron, 10-20 wt % cobalt, and 10-20 wt % nickel, based on the total weight of the oxygen, vanadium, iron, cobalt, and nickel.

4 . The split cell nanocomposite supercapacitor of claim 1 , wherein the nanocomposite mixture comprises:

1-20 wt. % of the V-SFNPs; and

80-99 wt. % of the binding compound, and the carbonaceous compound based on the total weight of the V-SFNPs, the binding compound, and the carbonaceous compound.

5 . The split cell nanocomposite supercapacitor of claim 1 , having:

85-92 wt % carbon, 5-10 wt % oxygen, 0.1-2 wt % vanadium, 0.5-2 wt % iron, 0.5-1 wt % cobalt, and 0.5-1 wt % nickel, based on the total weight of the carbon, oxygen, vanadium, iron, cobalt, and nickel.

6 . The split cell nanocomposite supercapacitor of claim 1 , wherein:

the carbonaceous compound is at least one selected from the group consisting of graphite, activated carbon, reduced graphene oxide, carbon nanotubes, carbon nanofibers, and carbon black.

7 . The split cell nanocomposite supercapacitor of claim 1 , wherein:

the electrolyte is at least one selected from a group consisting of an alkali metal salt and an alkaline earth metal salt;

wherein the electrolyte has a molarity of 1-10 in water.

8 . The split cell nanocomposite supercapacitor of claim 1 , wherein:

the membrane separator is selected from a group consisting of a polypropylene membrane, a glass fiber membrane, and a cellulose fiber membrane.

9 . The split cell nanocomposite supercapacitor of claim 1 , having:

an energy density of 50-80 Wh/kg at a power density of 500-8000 W/kg.

10 . The split cell nanocomposite supercapacitor of claim 1 , having:

a specific capacitance of 325-375 F/g at 1 mA.

11 . The split cell nanocomposite supercapacitor of claim 10 , wherein:

at least 90% of an initial specific capacitance is maintained after 10,000 charge discharge cycles.

12 . The split cell nanocomposite supercapacitor of claim 1 , wherein the V-SFNPs are made by a method comprising:

mixing a cobalt (II) salt, a nickel salt, an iron (III) salt, and a vanadium (III) salt in water to form a mixture;

adjusting the pH of the mixture to 10-12 with a base to form a basic mixture;

heating the basic mixture to 150-200° C. for 10-20 hours to form a powder; and

washing the powder with water and drying at a temperature of 60-80° C. to form the V-SFNPs.