Method for manufacturing battery, battery, and winding device

A battery comprising an electrode body wound in a cylindrical shape with a hollow in a center,

• wherein
• the electrode body has an outside diameter of 10 mm or less,
• the electrode body has an inside diameter of 2 mm or less, and
• a ratio of a minimum value of the outside diameter of the electrode body to a maximum value of the outside diameter of the electrode body is 0.99 or more and 1.00 or less.

A winding device comprising:

• a winding shaft including a winding core;
• and
• a support configured to support the winding shaft movably in an axial direction of the winding shaft,
• wherein
• the winding core has an outside diameter of 2 mm or less, and has a plurality of holes in a peripheral surface of the winding core, and
• the winding core and the winding shaft have a hollow connected to the plurality of holes.