ELECTRODE ACTIVE MATERIAL HAVING HIGH CAPACITANCE, METHOD FOR PRODUCING THE SAME, AND ELECTRODE AND ENERGY STORAGE DEVICE COMPRISING THE SAME

Abstract

An active material of the present invention has fine pores formed in the interlayer of a carbon material capable of exhibiting electrochemical double layer capacitance. The fine pores are formed by forming an oxidized graphite structure combined with oxygen in the interlayer of a part or whole of the carbon material containing soft carbon and then removing a part or whole of oxygen in the interlayer. A method for producing an energy storage active material for use in an electrochemical double layer capacitor comprises pre-treating a carbon material through heat treatment and oxidizing the pre-treated carbon material using an oxidant. The method further comprises reducing the oxidized carbon material through heat treatment. The interlayer distances of an active material for respective steps, measured by a powder X-ray diffraction method, are 0.33˜0.36 nm in the pre-treatment step, 0.5˜2.1 nm in the oxidation step, and 0.34˜0.5 nm in the reduction step.

Description

Claims

1. A method for producing an electrode active material for an energy storage device, the method comprising the steps of: pre-treating a carbon material through heat treatment; andoxidizing the pre-treated carbon material using an oxidant.

2. The method as claimed in claim 1, further comprising the step of cleansing the oxidized carbon material.

3. The method as claimed in claim 1, further comprising the step of reducing the oxidized carbon material through heat treatment.

4. The method as claimed in claim 1, wherein the carbon material is or comprises soft carbon.

5. The method as claimed in claim 4, wherein the soft carbon is formed of one or more materials selected from a group consisting of aliphatic polymer compound such as vinyl chloride resin and polyacrylonitrile, aromatic polymer compound such as mesophase pitch and polyimide, coal tar pitch, petroleum coke, coal tar coke, mesocarbon microbeads, and mesophase pitch spinning fiber.

6. The method as claimed in claim 1, wherein the pre-treating step comprises the step of heat treating a carbon material for 2˜24 hours at a temperature range of 300˜2000° C. under an inert atmosphere.

7. The method as claimed in claim 1, wherein the oxidation step comprises the step of oxidizing a carbon material in a solution containing an oxidant.

8. The method as claimed in claim 1, wherein the oxidant includes one or more selected from a group consisting of HNO3, H2SO4, H3PO4, H4P2O7, H3AsO4, HF, H2SeO4, HClO4, CF3COOH, BF3(CH3COOH)2, HSO3F, H5IO6, KMnO4, NaNO3, KClO3, NaClO3, NH4ClO3, AgClO3, HClO3, NaClO4, NH4ClO4, CrO3, (NH4)2S2O8, PbO2, MnO2, As2O5, Na2O2, H2O2, N2O5, C2H5OH and CH3OH.

9. The method as claimed in claim 1, wherein the oxidation step comprises the step of adding 0.5˜10 parts by weight of the oxidant to 1 part by weight of the carbon material.

10. The method as claimed in claim 1, wherein the oxidation step is performed at a temperature range of 0˜100° C.

11. The method as claimed in claim 3, wherein the step of reducing the oxidized carbon material through heat treatment comprises the step of heat treating an oxidized carbon material for 0.1˜100 hours at a temperature range of 100˜1000° C. and at a high vacuum pressure of no more than 10−1 torr under an inert or reductive gas atmosphere.

12. An electrode active material for an energy storage device produced by heat treating and oxidizing a carbon material, wherein an interlayer distance of a part or whole of graphite-like fine grains is within a range of 0.5˜2.1 nm.

13. An electrode active material for an energy storage device produced by heat treating a carbon material, oxidizing the carbon material with an oxidant and then reducing the oxidized carbon material through heat treatment, wherein an interlayer distance of graphite-like fine grain is within a range of 0.34˜0.5 nm.

14. An electrode for an energy storage device, comprising an active material according to claim 12, a conductive material, a binder and a current collector, wherein the electrode has an electrode density of 0.7˜1.1 g/ml.

15. The electrode as claimed in claim 14, wherein the electrode has an electrode expansion rate of no more than 25% due to application of voltage of 3.0 V and a capacitance per electrode volume of no less than 25 F/ml.

16. The electrode as claimed in claim 14, wherein 80˜95 parts by weight of the active material is included with respect to total 100 parts by weight of the active material, the conductive material and the binder.

17. An energy storage device, comprising a negative electrode, a positive electrode and an electrolytic solution, wherein at least one of the negative and positive electrodes comprises an active material produced by a method according claim 1.

18. The energy storage device as claimed in claim 17, wherein at least one of the negative and positive electrodes has an electrode density of 0.7˜1.1 g/ml.

19. The energy storage device as claimed in claim 17, wherein the electrolytic solution contains at least one selected from the group consisting of quaternary ammonium salt, quaternary imidazolium salt, quaternary pyridinium salt, quaternary hoshonium salt and lithium salt.

20. The energy storage device as claimed in claim 17, wherein at least one of the negative and positive electrodes has an electrode expansion rate of no more than 25% due to application of voltage of 3.0 V and a capacitance per electrode volume of no less than 25 F/ml.