Hydrogel electrolyte for a supercapacitor

Patent metadata

Field	Value
Publication number	US-12424394-B2
Application number	US-202217879457-A
Country	US
Kind code	B2
Filing date	Aug 2, 2022
Priority date	Aug 2, 2022
Publication date	Sep 23, 2025
Grant date	Sep 23, 2025

Abstract

A hydrogel electrolyte for a supercapacitor includes sodium carboxymethyl cellulose (C), water, citric acid (CA); and an aqueous extract of Hibiscus sabdariffa . The sodium carboxymethyl cellulose (C) and the citric acid (CA) form a citric acid cross-linked cellulose-based polymer hydrogel (C-CA-C). An organic acid from the aqueous extract of Hibiscus sabdariffa is intercalated to the citric acid cross-linked cellulose-based polymer hydrogel (C-CA-C) via hydrogen bonds. A method of preparation of the hydrogel electrolyte is also discussed.

First claim

The invention claimed is:

1. A hydrogel electrolyte for a supercapacitor, comprising:
sodium carboxymethyl cellulose (C);
water;
citric acid (CA); and
an aqueous extract of Hibiscus sabdariffa;
wherein the sodium carboxymethyl cellulose (C) and the citric acid (CA) form a citric acid crosslinked cellulose-based polymer hydrogel (C-CA-C); and
wherein an organic acid from the aqueous extract of Hibiscus sabdariffa is intercalated to the citric acid crosslinked cellulose-based polymer hydrogel (C-CA-C) via hydrogen bonds.

2. The hydrogel electrolyte of claim 1 , wherein the organic acid is at least one selected from a group consisting of a phenolic acid, hydroxycitric acid, a hibiscus acid, tartaric acid, malic acid, and ascorbic acid.

3. The hydrogel electrolyte of claim 1 , wherein the sodium carboxymethyl cellulose and citric acid have a weight ratio of 1:4 to 4:1.

4. The hydrogel electrolyte of claim 1 , wherein the hydrogel comprises 50 to 99 wt % of water relative to the total weight of the hydrogel.

5. The hydrogel electrolyte of claim 1 , wherein the hydrogel electrolyte has a weight loss of less than 10% when heated to a temperature of up to 200° C. for at least 15 minutes.

6. The hydrogel electrolyte of claim 1 , wherein the hydrogel electrolyte has an ion conductivity of 0.005 to 0.05 S cm −1 at 20 to 30° C.

7. The hydrogel electrolyte of claim 1 , wherein the aqueous extract of Hibiscus sabdariffa is made by contacting Hibiscus sabdariffa with water at a mass ratio of the Hibiscus sabdariffa to water of 1:25 to 1:5.

8. The hydrogel electrolyte of claim 7 , wherein the contacting is done for 12 to 96 h at 20 to 30° C.

9. The hydrogel electrolyte of claim 7 , wherein Hibiscus sabdariffa is ground, blended, or cut.

10. The hydrogel electrolyte of claim 7 , wherein the Hibiscus sabdariffa is a flower of Hibiscus sabdariffa.

11. A method of making the hydrogel electrolyte of claim 1 , comprising:
mixing sodium carboxymethyl cellulose powder and water to form a first mixture;
mixing citric acid with the first mixture to form a second mixture; and
mixing the aqueous extract of Hibiscus sabdariffa with the second mixture to form the hydrogel electrolyte.

12. A supercapacitor, comprising:
an anode;
a cathode; and
the hydrogel electrolyte of claim 1 ;
wherein the anode and the cathode have a surface of a conductive carbonaceous material in contact with the hydrogel electrolyte.

13. The supercapacitor of claim 12 , wherein:
the conductive carbonaceous material is at least one selected from a group consisting of graphite, activated carbon, reduced graphene oxide, carbon nanotubes, carbon nanofibers, and carbon black.

14. The supercapacitor of claim 12 , which has a power density of 200 to 500 W/kg.

15. The supercapacitor of claim 12 , which has an energy density of 50 to 120 W·h/kg.

16. The supercapacitor of claim 12 , wherein at least 90% of the initial specific capacitance is maintained after 90,000 to 12,000 charge-discharge cycles.

17. The supercapacitor of claim 12 , which has a specific capacitance of 380 to 500 F/g at 0.2 to 0.8 mA.

18. The supercapacitor of claim 12 , which has an equivalent series resistance of 3 to 11 Ohm.

19. A supercapacitor assembly, comprising:
2 to 10 of the supercapacitors of claim 12 connected in parallel and/or in series.

20. A light-emitting diode device comprising the supercapacitor of claim 12 , wherein:
the supercapacitor is electrically connected to a light-emitting diode; and
the supercapacitor functions as a battery.

Assignees

• Univ Imam Abdulrahman Bin Faisal

Inventors

• Cevik Emre
• Bozkurt Ayhan

Classifications

• H01G11/34

  characterised by carbonisation or activation of carbon · CPC title

• H01G11/42

  Powders or particles, e.g. composition thereof · CPC title

• H01G11/36

  Nanostructures, e.g. nanofibres, nanotubes or fullerenes · CPC title

• Y02E60/13

  Energy storage using capacitors · CPC title

• H01G11/38

  Carbon pastes or blends; Binders or additives therein · CPC title