Battery

A battery comprising:

• a positive electrode;
• a negative electrode;
• a separator;
• and
• an electrolyte solution,
• the positive electrode is solid,
• the negative electrode is solid,
• the negative electrode forming a honeycomb core,
• the honeycomb core including a first face, a second face, a partition, and a circumferential wall,
• the second face facing away from the first face,
• the partition being formed between the first face and the second face,
• in a cross section parallel to the first face, the partition extending in a grid pattern to separate a plurality of hollow cells,
• in the cross section parallel to the first face, the circumferential wall surrounding a circumference of the partition,
• each of the hollow cells penetrating the honeycomb core in a direction from the first face toward the second face,
• the separator spatially separating the positive electrode from the negative electrode,
• the separator including a first layer and a second layer,
• the first layer covering at least part of the partition,
• the second layer covering at least part of the first face and at least part of the second face,
• the positive electrode including a first region and a second region,
• the first region being inserted in the hollow cells,
• in a cross section perpendicular to the first face, the second region extending outwardly beyond the second layer of the separator,
• the cross section parallel to the first face including a central part and an inner circumferential part,
• the inner circumferential part being formed adjacent to the circumferential wall and being formed along the circumferential wall,
• the central part being surrounded by the inner circumferential part,
• in the central part, the hollow cells having a first average filling factor,
• the first average filling factor being an average proportion of a cross-sectional area of the first layer in a cross-sectional area of the hollow cells in the central part,
• in the inner circumferential part, the hollow cells having a second average filling factor,
• the second average filling factor being an average proportion of a cross-sectional area of the first layer in a cross-sectional area of the hollow cells in the inner circumferential part,
• the second average filling factor being 2.1 times or more the first average filling factor.