Supercapacitor and Electrode Having Cellulose Nanofiber-Spaced Graphene Sheets and Production Process

Patent metadata

Field	Value
Publication number	US-2019206632-A1
Application number	US-201815861324-A
Country	US
Kind code	A1
Filing date	Jan 3, 2018
Priority date	Jan 3, 2018
Publication date	Jul 4, 2019
Grant date	—

Abstract

Provided is a supercapacitor comprising an anode, a cathode, an ion-permeable separator disposed between the anode and the cathode, and an electrolyte in ionic contact with the anode and the cathode, wherein at least one of the anode and the cathode contains multiple graphene sheets spaced by cellulosic nanofibers and has a specific surface area from 50 to 3,300 m2/g. Also provided is a process for producing an electrode for such a supercapacitor having a large electrode thickness, high active mass loading, high tap density, and exceptional energy density.

First claim

1 . A supercapacitor comprising an anode, a cathode, an ion-permeable separator disposed between said anode and said cathode, and an electrolyte in ionic contact with said anode and said cathode, wherein at least one of the anode and the cathode contains multiple graphene sheets spaced by cellulosic nanofibers and has a specific surface area from 50 to 3,300 m 2 /g.

2 . The supercapacitor of claim 1 , wherein said graphene sheets are selected from a pristine graphene or a non-pristine graphene material, having a content of non-carbon elements from 2% to 50% by weight, selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, chemically functionalized graphene, doped graphene, or a combination thereof.

3 . The supercapacitor of claim 1 , wherein said cellulosic nanofibers have a diameter from 1 nm to 100 nm.

4 . The supercapacitor of claim 1 , wherein said cellulosic nanofibers have a diameter from 2 nm to 10 nm.

5 . The supercapacitor of claim 1 , wherein said multiple graphene sheets are substantially aligned along a desired direction, and wherein said at least one of the anode and the cathode has a physical density from 0.5 to 1.7 g/cm 3 .

6 . The supercapacitor of claim 1 , wherein said at least one of the anode and the cathode has a physical density from 0.7 to 1.3 g/cm 3 .

7 . The supercapacitor of claim 1 , wherein said graphene sheets are deposited with a nanoscaled coating or particles of a redox pair partner selected from an intrinsically conductive polymer, a transition metal oxide, and/or an organic molecule, wherein said redox pair partner and said graphene sheets form a redox pair for pseudo-capacitance.

8 . The supercapacitor of claim 5 , wherein said intrinsically conducting polymer is selected from polyaniline, polypyrrole, polythiophene, polyfuran, sulfonated polyaniline, sulfonated polypyrrole, sulfonated polythiophene, sulfonated polyfuran, sulfonated polyacetylene, or a combination thereof.

9 . The supercapacitor of claim 1 , wherein said electrolyte contains an aqueous electrolyte, an organic electrolyte, an inorganic electrolyte, an ionic liquid electrolyte, or a mixture of an organic and an ionic electrolyte.

10 . The supercapacitor of claim 1 , further comprising an anode current collector in electronic contact with said anode or a cathode current collector in electronic contact with said cathode.

11 . The supercapacitor of claim 1 , wherein both the anode and the cathode contain graphene sheets spaced by cellulosic nanofibers and have a specific surface area from 50 to 3,300 m 2 /g.

12 . The supercapacitor of claim 1 , which is a lithium-ion capacitor or sodium-ion capacitor, wherein said cathode contains said cellulosic nanofiber-spaced graphene sheets and said anode contains a prelithiated anode active material or a pre-sodiated anode active material.

13 . A supercapacitor electrode containing multiple graphene sheets that are spaced by cellulosic nanofibers and having a specific surface area from 50 to 3,300 m 2 /g.

14 . The supercapacitor electrode of claim 13 , further containing a liquid or gel electrolyte residing in a space between graphene sheets.

15 . The supercapacitor electrode of claim 13 , wherein said graphene sheets are selected from a pristine graphene or a non-pristine graphene material, having a content of non-carbon elements from 2% to 50% by weight, selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, chemically functionalized graphene, doped graphene, or a combination thereof.

16 . The supercapacitor electrode of claim 13 , wherein said cellulosic nanofibers have a diameter from 1 nm to 100 nm.

17 . The supercapacitor electrode of claim 13 , wherein said cellulosic nanofibers have a diameter from 2 nm to 10 nm.

18 . The supercapacitor electrode of claim 13 , wherein said graphene sheets are deposited with a nanoscaled coating or particles of a redox pair partner selected from an intrinsically conductive polymer, a transition metal oxide, and/or an organic molecule, wherein said redox pair partner and said graphene sheets form a redox pair for pseudo-capacitance.

19 . The supercapacitor electrode of claim 18 , wherein said intrinsically conducting polymer is selected from polyaniline, polypyrrole, polythiophene, polyfuran, sulfonated polyaniline, sulfonated polypyrrole, sulfonated polythiophene, sulfonated polyfuran, sulfonated polyacetylene, or a combination thereof.

20 . The supercapacitor electrode of claim 13 , wherein said multiple graphene sheets are substantially aligned along a desired direction, and wherein said electrode has a physical density from 0.5 to 1.7 g/cm 3 .

21 . The supercapacitor of claim 13 , wherein said electrode has a physical density from 0.7 to 1.3 g/cm 3 .

22 . A process of producing the supercapacitor electrode of claim 13 , said process comprising a) dispersing said multiple graphene sheets, said cellulosic nanofibers, an optional conductive additive, and an optional resin binder in a liquid medium to form a graphene slurry; b) dispensing and depositing said graphene slurry onto a surface of a solid substrate or a current collector and forming a wet graphene layer thereon which is optionally subjected to a compression treatment to align graphene sheets along a desired direction; c) at least partially removing said liquid medium from said wet graphene layer to form a dry graphene layer wherein multiple graphene sheets are spaced by said cellulosic nanofibers to form said supercapacitor electrode, and d) an optional compression treatment to increase a density of said supercapacitor electrode.

23 . The process of claim 22 , further comprising combining said supercapacitor electrode and a second electrode to form a supercapacitor cell.

24 . A process of producing the supercapacitor electrode of claim 14 , said process comprising (a) preparing a graphene dispersion having multiple isolated graphene sheets and cellulosic nanofibers dispersed in a liquid or gel electrolyte; and (b) subjecting said graphene dispersion to a forced assembly procedure, forcing said multiple graphene sheets and cellulosic nanofibers to assemble into an electrolyte-impregnated laminar graphene structure, wherein said multiple graphene sheets are alternately spaced by thin electrolyte layers having a thickness from 0.4 nm to 10 nm and having cellulosic nanofibers dispersed in said thin electrolyte layers and said multiple graphene sheets are substantially aligned along a desired direction, and wherein said laminar graphene structure has a physical density from 0.5 to 1.7 g/cm 3 and a specific surface area from 50 to 3,300 m 2 /g, when measured in a dried state of said laminar structure with said electrolyte removed.

25 . The process of claim 24 , wherein said forced assembly procedure is conducted in the presence of a current collector, which current collector is embedded in said electrolyte-impregnated laminar graphene structure or bonded to said electrolyte-impregnated laminar graphene structure to form said supercapacitor electrode.

26 . The process of claim 24 , wherein said forced assembly procedure includes introducing said graphene dispersion, having an initial volume V 1 , in a mold cavity cell and dr

Assignees

• Nanotek Instruments Inc

Inventors

• Zhamu Aruna
• Jang Bor Z

Classifications

• H01G11/66

  Current collectors · CPC title

• H01G11/46

  Metal oxides · CPC title

• H01G11/48

  Conductive polymers · CPC title

• H01G11/86

  specially adapted for electrodes (carbonisation or activation of carbon for the manufacture of electrodes H01G11/34) · CPC title

• H01G11/28

  arranged or disposed on a current collector; Layers or phases between electrodes and current collectors, e.g. adhesives · CPC title