Alkaline earth gel electrolyte supercapacitor

1 . A gel electrode supercapacitor, comprising:

two nanocomposite electrodes, and

a gel electrolyte comprising an alkaline earth salt selected from the group consisting of barium hydroxide, calcium hydroxide and magnesium chloride, and propylene glycol;

wherein each nanocomposite electrode comprises:

a substrate;

polyvinylidene fluoride as a binding compound;

at least one conductive additive; and

at least one molybdenum doped carbon material selected from the group consisting of molybdenum doped graphene and molybdenum doped carbon nanotubes (CNTs);

wherein a mixture of 5-10 wt % of the polyvinylidene fluoride, 65-92 wt % of the at least one conductive additive, and 3-25 wt % of the at least one molybdenum doped carbon material based on the total weight of the at least one binding compound, the at least one conductive additive, and the at least one molybdenum doped carbon material, at least partially coats a surface of the substrate;

wherein the nanocomposite electrodes face one another, wherein the substrate of each nanocomposite electrode is at least partially coated with the mixture on an inside facing surface and the outer surfaces of each of the nanocomposite electrodes are not coated with the mixture; and

wherein the inside facing surfaces are separated by the gel electrolyte.

2 . The supercapacitor of claim 1 , wherein:

the at least one conductive additive is at least one selected from the group consisting of graphite, activated carbon, reduced graphene oxide, carbon nanotubes, carbon nanofibers, and carbon black; and

the substrate is a formed from at least one material selected from the group consisting of copper, aluminum, nickel, iron, and steel.

3 . The supercapacitor of claim 1 , wherein the molybdenum in the at least one molybdenum doped carbon material is at least one selected from the group consisting of α-MoO 3 , β-MoO 3 , and γ-MoO 3 .

4 . The supercapacitor of claim 1 , wherein molybdenum is homogeneously distributed throughout the at least one molybdenum doped carbon material.

5 . The supercapacitor of claim 1 , wherein the at least one molybdenum doped carbon material is molybdenum doped graphene;

the graphene of the at least one molybdenum doped carbon graphene has a sheet structure;

molybdenum is on a surface of sheets of the sheet structure; and

the at least one molybdenum doped graphene comprises 70-80 wt % C, 15-20 wt % O, 4-8 wt % H, and 3-10 wt % Mo, based on the total weight of the C, O, H, and Mo.

6 . The supercapacitor of claim 1 , wherein the at least one molybdenum doped carbon material is molybdenum doped CNTs;

the molybdenum doped CNTs have a diameter of 10-100 nm;

molybdenum is on walls of the CNTs; and

the molybdenum doped CNTs comprise 60-70 wt % C, 20-25 wt % O, 4-8 wt % H, and 10-20 wt % Mo, based on the total weight of the C, O, H, and Mo.

7 . The supercapacitor of claim 1 , wherein the thickness of the coating of the mixture on the substate is 500 nm-60 μm.

8 . The supercapacitor of claim 1 , having:

an energy density of 40-60 Wh/kg at a specific power of 250-300 W/kg; and

wherein the mixture has 15-25 wt % of the at least one molybdenum doped carbon material; and

the at least one molybdenum doped carbon material is molybdenum doped graphene.

9 . The supercapacitor of claim 8 , having a specific capacitance of 450-500 F/g at 0.5-5 A/g.

10 . The supercapacitor of claim 9 , wherein at least 90% of an initial specific capacitance is maintained after 10,000 charge-discharge cycles.

11 . The supercapacitor of claim 9 , wherein at least 88% of the initial specific capacitance is maintained after 10,000 charge-discharge cycles.

12 . The supercapacitor of claim 1 , having an energy density of 30-50 Wh/kg at a specific power of 250-300 W/kg;

wherein the mixture has 15-25 wt % of the at least one molybdenum doped carbon material; and

the at least one molybdenum doped carbon material is molybdenum doped carbon nanotubes.