The present invention provides a battery small in time variation of the battery properties from the initial battery properties over a long term storage period of the battery. The battery is a lithium secondary battery in which a positive electrode including a positive electrode active material capable of intercalating and deintercalating lithium ions and a negative electrode including a negative electrode active material capable of intercalating and deintercalating lithium ions are formed through the intermediary of an electrolyte, wherein: the negative electrode active material is a carbon material having a crystallinity of the surface thereof lower than the crystallinity of the carbon material; and the electrolyte contains an organic compound having a carboxylic anhydride group.
Description
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a longitudinal sectional view of a lithium secondary battery.
Claims
1. A lithium secondary battery in which a positive electrode comprising a positive electrode active material capable of intercalating and deintercalating lithium ions and a negative electrode comprising a negative electrode active material capable of intercalating and deintercalating lithium ions are formed through the intermediary of an electrolyte, wherein:
the negative electrode active material is a carbon material having a crystallinity of the surface thereof lower than the crystallinity of the carbon material; andthe electrolyte comprises therein an organic compound having a carboxylic anhydride group.
2. A lithium secondary battery in which a positive electrode comprising a positive electrode active material capable of intercalating and deintercalating lithium ions and a negative electrode comprising a negative electrode active material capable of intercalating and deintercalating lithium ions are formed through the intermediary of an electrolyte, wherein:
the negative electrode active material is a carbon material having a crystallinity of the surface thereof lower than the crystallinity of the carbon material; andthe electrolyte comprises therein an organic compound satisfying the following chemical formula (1) in which R1 and R2 each are a group having 1 to 20 carbon atoms and comprising at least one element selected from the group consisting of hydrogen, sulfur, oxygen, nitrogen, fluorine, chlorine, bromine and iodine.
3. The lithium secondary battery according to claim 1, wherein the organic compound comprises at least one ring.
4. The lithium secondary battery according to claim 1, wherein the organic compound is comprised in a content of 0.01 to 10% by weight.
5. A lithium secondary battery in which a positive electrode comprising a positive electrode active material capable of intercalating and deintercalating lithium ions and a negative electrode comprising a negative electrode active material capable of intercalating and deintercalating lithium ions are formed through the intermediary of an electrolyte, wherein:
the electrolyte comprises therein methyltetrahydrophthalic anhydride.
6. The lithium secondary battery according to claim 1, wherein the electrolyte is prepared by dissolving a lithium salt in a solvent comprising at least one selected from the group consisting of ethylene carbonate, propylene carbonate, gamma-butyrolactone, dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate.
7. A lithium secondary battery in which a positive electrode comprising a positive electrode active material capable of intercalating and deintercalating lithium ions and a negative electrode comprising a negative electrode active material capable of intercalating and deintercalating lithium ions are formed through the intermediary of an electrolyte, wherein:
the negative electrode active material is a carbon material having a crystallinity of the surface thereof lower than the crystallinity of the carbon material; anda coating comprising a carboxylic anhydride group is formed on the negative electrode surface in contact with the electrolyte.
8. A lithium secondary battery in which a positive electrode comprising a positive electrode active material capable of intercalating and deintercalating lithium ions and a negative electrode comprising a negative electrode active material capable of intercalating and deintercalating lithium ions are formed through the intermediary of an electrolyte, wherein:
the negative electrode comprises therein an organic compound having a carboxylic anhydride group.
9. The lithium secondary battery according to claim 8, wherein the organic compound satisfies the chemical formula (2) in which R1 and R2 each are a group having 1 to 20 carbon atoms and comprising at least one element selected from the group consisting of hydrogen, sulfur, oxygen, nitrogen, fluorine, chlorine, bromine and iodine.
10. The lithium secondary battery according to claim 8, wherein the organic compound is a solid at 25° C. or a liquid having a boiling point higher than 240° C. under an atmospheric pressure of 1 atm.
11. The lithium secondary battery according to claim 8, wherein the organic compound is a carboxylic anhydride which is a solid at 25° C. or a liquid higher in boiling point than a dispersant comprised in the negative electrode.
12. A lithium secondary battery in which a positive electrode comprising a positive electrode active material capable of intercalating and deintercalating lithium ions and a negative electrode comprising a negative electrode active material capable of intercalating and deintercalating lithium ions are formed through the intermediary of an electrolyte, wherein:
the negative electrode active material is a carbon material having a crystallinity of the surface thereof lower than the crystallinity of the carbon material;the electrolyte comprises therein an organic compound having a carboxylic anhydride group; andthe detected intensity of the C—O bond is stronger than the detected intensity of the C═O bond in the analysis of the surface of the negative electrode obtained by disassembling the lithium secondary battery after a 60-day storage.
Patent Application
20070196740
