Secondary battery, battery pack, electronic apparatus, electric tool, electric vehicle, and power storage system

1. A secondary battery comprising:

an electrode body in which a positive electrode and a negative electrode are laminated via a separator and wound with a coil opening portion of the electrode body as a center,

wherein the positive electrode includes a first positive electrode active material layer formed on a first side of a positive electrode collector and a second positive electrode active material layer formed on a second side of the positive electrode collector, and

wherein a ratio A/(A+B) of an area density A (mg/cm 2 ) of the first positive electrode active material layer and an area density B (mg/cm 2 ) of the second positive electrode active material layer, an inner diameter C (mm) of the coil opening portion, and a ratio D/E of a thickness D (μm) of the positive electrode and a thickness E (μm) of the positive electrode collector satisfy a relationship expressed below:

0.380≦ A /( A+B )≦[0.593−0.007×( D/E )]×(0.03× C+ 0.87)

wherein C is 2.5≦C≦4 and D/E is 13.333≦D/E≦20; and

wherein the positive electrode includes a single side active material layer formation region in which the second positive electrode active material layer is formed on a single side of an end portion of the positive electrode collector, and

wherein a length F (mm) of the single side active material layer formation region satisfies a relationship expressed below:

[0.3×( D/E ) 2 −7×( D/E )+45]≦ F≦ 50.

2. The secondary battery according to claim 1 , wherein the first positive electrode active material layer is formed on an inner circumference side of the positive electrode collector, and the second positive electrode active material layer is formed on an outer circumference side of the positive electrode collector.

3. The secondary battery according to claim 1 , which further satisfies a relationship expressed below:

0.428≦ A /( A+B )≦[0.593−0.007×( D/E )]×(0.03× C+ 0.87).

4. The secondary battery according to claim 1 , wherein the negative electrode includes a negative electrode active material comprising at least one of silicon and tin.

5. The secondary battery according to claim 1 ,

wherein the negative electrode includes a negative electrode active material comprising tin, cobalt, and carbon, and

wherein an amount of carbon in the negative electrode active material is equal to or greater than 9.9 mass % and equal to or less than 29.7 mass %, an amount of cobalt to a total amount of tin and the cobalt in the negative electrode active material is equal to or greater than 20 mass % and equal to or less than 70 mass %, and a half-value width of a diffraction peak that is obtained by X-ray diffraction of the negative electrode active material is equal to or greater than 1°, and wherein a diffraction angle 2 θis equal to or greater than 20° and equal to or less than 50°.

6. The secondary battery according to claim 1 , which is a lithium ion secondary battery.

7. A battery pack comprising:

the secondary battery according to claim 1 ;

a control section that controls the secondary battery; and

an outer packaging that contains the secondary battery.

8. An electronic apparatus comprising the secondary battery according to claim 1 as a power source.

9. An electric tool comprising the secondary battery according to claim 1 as a power source.

10. An electric vehicle comprising the secondary battery according to claim 1 as a power source.

11. A power storage system comprising the secondary battery according to claim 1 as a power storage source.

12. A secondary battery comprising:

an electrode body in which a positive electrode and a negative electrode are laminated via a separator and wound with a coil opening portion of the electrode body as a center,

wherein the positive electrode includes a first positive electrode active material layer formed on a first side of a positive electrode collector and a second positive electrode active material layer formed on a second side of the positive electrode collector,

wherein the positive electrode includes a single side active material layer formation region in which the second positive electrode active material layer is formed on a single side of an end portion of the positive electrode collector, and

wherein a ratio D/E of a thickness D (μm) of the positive electrode and a thickness E (μm) of the positive electrode collector and a length F (mm) of the single side active material layer formation region satisfy a relationship expressed below:

[0.3×( D/E ) 2 −7×( D/E )+45]≦ F≦ 50.

13. The secondary battery according to claim 12 , wherein the first positive electrode active material layer is formed on an inner circumference side of the positive electrode collector, and the second positive electrode active material layer is formed on an outer circumference side of the positive electrode collector.

14. The secondary battery according to claim 12 , wherein the negative electrode includes a negative electrode active material comprising at least one of silicon and tin.

15. A battery pack comprising:

the secondary battery according to claim 12 ;

a control section that controls the secondary battery; and

an outer packaging that contains the secondary battery.

16. An electronic apparatus comprising the secondary battery according to claim 12 as a power source.

17. An electric tool comprising the secondary battery according to claim 12 as a power source.

18. An electric vehicle comprising the secondary battery according to claim 12 as a power source.

19. A power storage system comprising the secondary battery according to claim 12 as a power storage source.