Graphene and power storage device, and manufacturing method thereof
The formation method of graphene includes the steps of forming a layer including graphene oxide over a first conductive layer; and supplying a potential at which the reduction reaction of the graphene oxide occurs to the first conductive layer in an electrolyte where the first conductive layer as a working electrode and a second conductive layer with a as a counter electrode are immersed. A manufacturing method of a power storage device including at least a positive electrode, a negative electrode, an electrolyte, and a separator includes a step of forming graphene for an active material layer of one of or both the positive electrode and the negative electrode by the formation method.
1. A method for forming an electrode material, comprising:
forming a layer including graphene oxide on a first conductive layer;
immersing the first conductive layer and a second conductive layer that is different from the first conductive layer in an electrolyte after forming the layer; and
electrochemically reducing at least part of the graphene oxide in the layer on the first conductive layer,
wherein the electrolyte includes lithium,
wherein a potential is swept in a potential range including a potential at which the reduction is performed, and
wherein a sweep rate of the sweeping is set to higher than or equal to 0.005 mV/s and lower than or equal to 1 mV/s.
2. The method for forming the electrode material, according to claim 1 ,
wherein the electrolyte is an aprotic organic solvent.
3. The method for forming the electrode material, according to claim 1 ,
wherein the first conductive layer on which the layer is formed is a working electrode, and
wherein the second conductive layer is a counter electrode.
4. The method for forming the electrode material, according to claim 1 ,
wherein the sweeping is periodically performed.
5. The method for forming the electrode material, according to claim 1 ,
wherein the potential range is set to higher than or equal to 1.6 V and lower than or equal to 2.4 V with reference to a redox potential of lithium.
6. The method for forming the electrode material, according to claim 1 ,
wherein the graphene oxide includes a substituent formed in such a manner that at least one of a carbonyl group and a hydroxyl group reacts with ammonia, amine, or an alkali metal.
7. The method for forming the electrode material, according to claim 1 ,
wherein the reduced graphene oxide comprising:
carbon atoms whose proportion measured by X-ray photoelectron spectroscopy is higher than or equal to 80% and lower than or equal to 90%; and
oxygen atoms whose proportion measured by X-ray photoelectron spectroscopy is higher than or equal to 10% and lower than or equal to 20%, and
wherein a proportion of sp 2 -bonded carbon atoms of the carbon atoms is higher than or equal to 50% and lower than or equal to 80%.
8. A method for manufacturing an electrode, comprising:
forming an active layer including at least an active material and graphene oxide over a current collector; and
electrochemically reducing at least part of the graphene oxide in the active material layer over the current collector,
wherein the reduction is performed in an electrolyte including lithium,
wherein a potential is swept in a potential range including a potential at which the reduction is performed, and
wherein a sweep rate of the sweeping is set to higher than or equal to 0.005 mV/s and lower than or equal to 1 mV/s.
9. The method for manufacturing the electrode, according to claim 8 ,
wherein the reduction is performed in an aprotic organic solvent.
10. The method for manufacturing the electrode, according to claim 8 ,
wherein the sweeping is periodically performed.
11. The method for manufacturing the electrode, according to claim 8 ,
wherein the potential range is set to higher than or equal to 1.6 V and lower than or equal to 2.4 V with reference to a redox potential of lithium.
12. The method for manufacturing the electrode, according to claim 8 ,
wherein the graphene oxide includes a substituent formed in such a manner that at least one of a carbonyl group and a hydroxyl group reacts with ammonia, amine, or an alkali metal.
13. The method for manufacturing the electrode, according to claim 8 ,
wherein the reduced graphene oxide comprising:
carbon atoms whose proportion measured by X-ray photoelectron spectroscopy is higher than or equal to 80% and lower than or equal to 90%; and
oxygen atoms whose proportion measured by X-ray photoelectron spectroscopy is higher than or equal to 10% and lower than or equal to 20%, and
wherein a proportion of sp 2 -bonded carbon atoms of the carbon atoms is higher than or equal to 50% and lower than or equal to 80%.
14. A method for manufacturing a power storage device, comprising:
forming the electrode according to claim 8 as at least one of a positive electrode and a negative electrode.