The present application provides a rolled core and a battery, where the rolled core includes a positive electrode piece having a paste-removal portion of positive electrode piece, and a negative electrode piece including a negative current collector (10), a negative active material layer (20), and a gap filling body (30); the paste-removal portion of positive electrode piece is a missing part of the positive electrode piece relative to the negative electrode piece at a winding-start end of the rolled core; the negative current collector (10) includes a first side and a second side which are opposite to each other, and at least one of the first side and the second side is provided with a negative active material layer (20); the gap filling body (30) is arranged on one of the first side and the second side at a position corresponding to the winding-start end of the rolled core. The present application improves the flatness of the inner ring of the rolled core of the battery, reduces expansion deformation of the battery caused by uneven stress during cyclic expansion process, and reduces capacity degradation and battery failure caused by the edge precipitation of lithium, thereby improving battery usage effect.