Battery and assembled battery

1. A battery, comprising:

a substantially cylindrically shaped winding electrode having a hollow portion in the center; and

a sheath material having flexibility which sheathes the winding electrode,

wherein a width of the hollow portion is 2.5 mm or less,

wherein the sheath material includes a first sheath material and a second sheath material,

wherein the first sheath material includes a first space portion having a substantially semicylindrical shape and a first peripheral portion extending from four sides of the first space portion,

wherein the second sheath material includes a second space portion having the substantially semicylindrical shape and a second peripheral portion extending from four sides of the second space portion, and

wherein the first sheath material has a substantially same shape as the second sheath material.

2. The battery according to claim 1 , wherein the hollow portion is substantially cylindrically shaped with a diameter of 2.5 mm or less that extends along a central axis of the winding electrode.

3. The battery according to claim 1 , further comprising:

a positive electrode lead and a negative electrode lead both provided at an outer peripheral portion of the winding electrode.

4. The battery according to claim 3 ,

wherein the positive electrode lead is led out to the outside of the sheath material from an end portion of one side of the winding electrode, and

the negative electrode lead is led out to the outside of the sheath material from an end portion of the other side of the winding electrode.

5. The battery according to claim 4 ,

wherein the sheath material is joined by sandwiching the positive electrode lead at an end portion side of one side of the winding electrode, and is joined by sandwiching the negative electrode lead at an end portion side of the other side of the winding electrode.

6. The battery according to claim 3 ,

wherein both of the positive electrode lead and the negative electrode lead are led out to the outside of the sheath material from the end portion of one side of the winding electrode.

7. The battery according to claim 6 ,

wherein the sheath material is joined by sandwiching the positive electrode lead and the negative electrode lead at the end portion side of one side of the winding electrode.

8. The battery according to claim 3 ,

wherein the sheath material is equipped with a first joining portion and a second joining portion provided at a peripheral surface side of the winding electrode,

the positive electrode lead and the negative electrode lead are provided on a first half peripheral surface side of a peripheral surface of the winding electrode, and

the first joining portion and the second joining portion are bent so as to follow a second half peripheral surface of the peripheral surface of the winding electrode.

9. The battery according to claim 3 ,

wherein the positive electrode lead and the negative electrode lead are bent substantially perpendicularly to an end surface at the center of the end surface of the winding electrode, and are led out to the outside of the sheath material.

10. The battery according to claim 1 ,

wherein the winding electrode is equipped with a positive electrode, a negative electrode, and a separator, and

the separator is folded at an inner peripheral side of the winding electrode.

11. The battery according to claim 1 ,

wherein the winding electrode is equipped with a positive electrode, a negative electrode, and a separator, and

wherein ends of the separator are provided at an outer peripheral side of the winding electrode.

12. The battery according to claim 1 ,

wherein the sheath material is a laminated film.

13. The battery according to claim 1 ,

wherein the sheath material has a film shape.

14. The battery according to claim 1 ,

wherein a thickness of the sheath material at an end surface side of the winding electrode and a thickness of the sheath material at the peripheral surface side of the winding electrode are different from each other.

15. The battery according to claim 5 ,

wherein each of the positive electrode lead and the negative electrode lead is provided at a position facing a bottom portion of the first space portion or the second space portion in the outer peripheral portion of the winding electrode.

16. The battery according to claim 1 ,

wherein the winding electrode is equipped with the positive electrode, the negative electrode, and the separator, and

both ends in a width direction of the separator are positioned closer to the outside than both ends in a width direction of the positive electrode and the negative electrode.

17. The battery according to claim 16 ,

wherein the separator is fused at an end portion of the winding electrode.

18. The battery according to claim 1 ,

wherein the winding electrode is equipped with the positive electrode and the negative electrode, and

thicknesses of the positive electrode and the negative electrode are 150 micrometers or less.

19. The battery according to claim 1 ,

wherein the winding electrode is equipped with an electrolyte including an electrolytic solution and a polymer compound.

20. The battery according to claim 1 , further comprising:

a winding stop portion covering one turn or more of the peripheral surface of the winding electrode,

wherein the winding stop portion covers at least both end portions of the peripheral surface of the winding electrode.

21. An assembled battery, comprising:

a plurality of batteries electrically connected in at least one of parallel and series,

wherein the batteries are equipped with a substantially cylindrically shaped winding electrode having a hollow portion in the center and a sheath material having flexibility which sheathes the winding electrode, and a width of the hollow portion is 2.5 mm or less,

wherein the sheath material includes a first sheath material and a second sheath material,

wherein the first sheath material includes a first space portion having a substantially semicylindrical shape and a first peripheral portion extending from four sides of the first space portion,

wherein the second sheath material includes a second space portion having the substantially semicylindrical shape and a second peripheral portion extending from four sides of the second space portion, and

wherein the first sheath material has a substantially same shape as the second sheath material.

22. The assembled battery according to claim 21 , wherein the hollow portion is substantially cylindrically shaped with a diameter of 2.5 mm or less that extends along a central axis of the winding electrode.