Nanocubic Co
Co 3 O 4 nanocubes as can be homogeneously assembled on a few-layer graphene sheet, such a composite as can be used in conjunction with an anode and incorporated into a high energy lithium-ion battery.
1. A composite comprising a graphene sheet component comprising a plurality of graphene layers; and particles comprising Co 3 O 4 coupled thereto, each said particle nanodimensioned, said particles dispersed substantially uniformly on said graphene sheet component, wherein said graphene component is a mechanical exfoliation product of an expandable graphite source material which has not been subjected to an oxidation step so that said graphene sheet component is substantially unoxidized, and wherein Co +3 cations at a surface of said Co 3 O 4 particles are bound to organic counter ions in the form of an anionic cage surrounding the Co 3 O 4 particles, wherein said particles have a cubic morphology and said cubic particles have an average edge dimension of about 4 nm.
2. The composite of claim 1 wherein said organic counter ions are carboxylate anions.
3. The composite of claim 1 wherein adjacent said cubic particles have a nanodimensioned distance therebetween.
4. The composite of claim 1 wherein said graphene sheet component comprises about 10- about 20 graphene layers.
5. The composite of claim 1 wherein each said graphene layer has two opposed sides, and said particles are coupled to each side of a said graphene layer.
6. A composite comprising a graphene sheet component comprising 2- about 30 graphene layers, said graphene sheet component substantially unoxidized; and particles comprising crystalline Co 3 O 4 coupled thereto, each said particle nanodimensioned and having a cubic morphology, each said graphene layer having two opposed sides and said particles dispersed substantially uniformly on each said side of a said graphene layer, wherein said graphene component is a mechanical exfoliation product of an expandable graphite source material which has not been subjected to an oxidation step to provide said substantially unoxidized graphene sheet component, and wherein Co +3 cations at a surface of said Co 3 O 4 particles are bound to organic counter ions in the form of an anionic cage surrounding the Co 3 O 4 particles, wherein said cubic particles have an average edge dimension of about 4 nm.
7. A composite of claim 6 wherein said organic counter ions are carboxylate anions.
8. The composite of claim 6 wherein adjacent said cubic particles have a nanodimensioned distance therebetween.
9. The composite of claim 6 wherein said graphene sheet component comprises about 10- about 20 graphene layers.
10. The composite of claim 6 incorporated into an anode component of a lithium-ion electrical power cell.
11. A lithium-ion electrical power cell, said cell comprising an anode comprising a composite comprising a graphene sheet component comprising a plurality of graphene layers, said graphene sheet component substantially unoxidized; and particles comprising Co 3 O 4 coupled thereto, each said particle nanodimensioned and having a cubic morphology, said particles dispersed substantially uniformly on said graphene sheet component, wherein said graphene component is a mechanical exfoliation product of an expandable graphite source material which has not been subjected to an oxidation step to provide said substantially unoxidized graphene sheet component, and wherein Co +3 cations at a surface of said Co 3 O 4 particles are bound to organic counter ions in the form of an anionic cage surrounding the Co 3 O 4 particles, wherein said cubic particles have an average edge dimension of about 4 nm.
12. The power cell of claim 11 wherein each said graphene layer has two opposed sides, and said particles are coupled to each side of a said graphene layer.
13. The power cell of claim 11 arranged in a battery of said power cells.
14. A hydrothermal method of preparing the composite of claim 1 , said method comprising:
providing a medium comprising the substantially unoxidized graphene sheet component, aqueous dimethylformamide, and cobalt(II) acetate, said graphene sheet component comprising 2- to about 30 graphene layers;
introducing said medium to an autoclave reaction vessel; and
reacting said medium under seal and at least one of a temperature and a pressure for a time sufficient to hydrothermally provide the composite of claim 1 .
15. The method of claim 14 wherein said temperature is about 120°- about 130° C.
16. The method of claim 14 wherein said aqueous dimethylformamide is about 8:2 (v/v) dimethylformamide:water.
17. The method of claim 14 wherein said reaction is in one vessel without transfer of reaction intermediate compounds.
18. The composite of claim 1 wherein the substantially unoxidized graphene sheet component is characterized by the absence of a peak at about 1204 cm −1 as measured using Fourier transform infrared spectroscopy.
19. The power cell of claim 11 wherein said graphene sheet component comprises about 10- about 20 graphene layers.
20. The composite of claim 1 , wherein the organic counter ions are acetate anions.
21. The composite of claim 6 , wherein the organic counter ions are acetate anions.
22. The power cell of claim 11 , wherein the organic counter ions are acetate anions.
23. A composite comprising a graphene sheet component comprising a plurality of graphene layers; and particles comprising Co 3 O 4 coupled thereto, each said particle nanodimensioned, said particles dispersed substantially uniformly on said graphene sheet component, wherein said graphene component is a mechanical exfoliation product of an expandable graphite source material which has not been subjected to an oxidation step so that said graphene sheet component is substantially unoxidized, and wherein Co +3 cations at a surface of said Co 3 O 4 particles are bound to acetate anions, wherein said Co 3 O 4 particles have a cubic morphology and an average edge dimension of about 4 nm.