Lithium ion secondary battery and charging method therefor, and charge or charge/discharge control system for lithium ion secondary battery

1. A lithium ion secondary battery comprising a positive electrode containing a composite lithium oxide, a negative electrode capable of absorbing and desorbing lithium ions, a sheet-like separator interposed between said positive electrode and said negative electrode, a non-aqueous electrolyte and a porous electron-insulating film attached to the surface of said negative electrode,

wherein said separator is a monolayer film comprising a polypropylene resin or a multilayer film whose layer to be in contact with the positive electrode comprises a polypropylene resin,

said porous electron-insulating film comprises an inorganic oxide filler and a binder,

said inorganic oxide filler comprises aluminum oxide or magnesium oxide, and

said separator has a thickness not less than 1.5 times the thickness of said porous electron-insulating film.

2. The lithium ion secondary battery in accordance with claim 1 , wherein said porous electron-insulating film has a thickness of not less than 1 μm.

3. The lithium ion secondary battery in accordance with claim 1 , wherein the total thickness of said separator and said porous electron-insulating film is not less than 15 μm and not greater than 30 μm.

4. The lithium ion secondary battery in accordance with claim 1 , wherein the separator comprises a three-layered separator comprising a layer made of polyethylene and two layers made of polypropylene sandwiching the polyethylene layer.

5. The lithium ion secondary battery in accordance with claim 1 , wherein the separator has a thickness of about 3 to about 5.5 times the thickness of the porous electron-insulating film.

6. The lithium ion secondary battery in accordance with claim 1 , wherein the inorganic oxide comprises magnesium oxide having an average particle size of about 0.3 μm.

7. The lithium ion secondary battery in accordance with claim 1 , wherein the binder comprises a polymer having an acrylate skeleton.

8. A method for charging the lithium ion secondary battery in accordance with claim 1 , wherein the battery is charged to a voltage of not less than 4.3 V.

9. The method in accordance with claim 8 , wherein the lithium ion secondary battery is charged to a voltage of not less than 4.4 V.

10. The method in accordance with claim 9 , wherein the lithium ion secondary battery is charged to a voltage of not less than 4.5 V.

11. The method in accordance with claim 10 , wherein the lithium ion secondary battery is charged to a voltage of not less than 4.6 V.

12. A method for charging the lithium ion secondary battery in accordance with claim 1 , wherein the battery is charged by a charger whose end-of-charge voltage is set to not less than 4.3 V.

13. The method in accordance with claim 12 , wherein the battery is charged by a charger whose end-of-charge voltage is set to not less than 4.4 V.

14. The method in accordance with claim 13 , wherein the battery is charged by a charger whose end-of-charge voltage is set to not less than 4.5 V.

15. The method in accordance with claim 14 , wherein the battery is charged by a charger whose end-of-charge voltage is set to not less than 4.6 V.

16. A charge control system of a lithium ion secondary battery comprising the lithium ion secondary battery in accordance with claim 1 and a charger whose end-of-charge voltage is set to not less than 4.3 V.

17. A charge/discharge control system for controlling the lithium ion secondary battery in accordance with claim 1 to be within a predetermined voltage range, wherein the upper limit of said predetermined voltage range is set to not less than 4.3 V.

18. The charge/discharge control system in accordance with claim 17 , wherein the upper limit of said predetermined voltage range is set to not less than 4.4 V.

19. The charge/discharge control system in accordance with claim 18 , wherein the upper limit of said predetermined voltage range is set to not less than 4.5 V.

20. The charge/discharge control system in accordance with claim 19 , wherein the upper limit of said predetermined voltage range is set to not less than 4.6 V.

21. The lithium ion secondary battery in accordance with claim 1 , having an end-of-charge voltage set to not less than 4.3 V.

22. The lithium ion secondary battery in accordance with claim 21 , having an end-of-charge voltage set to not less than 4.4 V.

23. The lithium ion secondary battery in accordance with claim 22 , having an end-of-charge voltage set to not less than 4.5 V.

24. The lithium ion secondary battery in accordance with claim 23 , having an end-of-charge voltage set to not less than 4.6 V.