Negative pole piece and secondary battery

The invention belongs to the technical field of secondary batteries, and particularly relates to a negative pole piece and a secondary battery, the negative pole piece comprises a negative current collector, a first active layer and a second active layer, the single-side coating surface density of the negative pole piece is A, the percentage of the first section constant-current constant-voltage charging capacity to the total capacity is a, and the percentage of the second section constant-current constant-voltage charging capacity to the total capacity is b. The single-side coating surface density of the first active layer is B, the single-side coating surface density of the second active layer is C, and the single-side coating surface density of the first active layer and the single-side coating surface density of the second active layer meet the following relations: B = A * a%, and C = A-B. The negative pole piece is provided with the two coating layers, and the surface density of the two coating layers is