Cell and Secondary Battery

Disclosed are a cell and a secondary battery. The cell includes a cell body; a length of the cell body is L, and a thickness of the cell body is H; and the L and the H satisfy the following relational expression: L/H>7. According to the cell and the secondary battery provided in the disclosure, by reasonably designing a relationship between the length L and the thickness H of the cell body, that is, a ratio between the length L and the thickness H of the cell body is defined within a specific relational expression of L/H>7, the heat dissipation performance of the cell is improved, and the heat inside the cell is discharged to the outside timely, such that the service life and safety performance of the secondary battery are improved, thereby having a higher potential for market promotion.