Abstract: An electrochemical device includes a positive electrode, a negative electrode, and a separator. The negative electrode includes a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector. A cross-section porosity at a depth of less than 10 ?m from a surface of the negative electrode active material layer in a direction toward and perpendicular to the negative electrode current collector is X10, satisfying 5%?X10?25%, where the surface faces away from the negative electrode current collector. In some embodiments of this application, the effect of the electrolytic solution infiltrating the negative electrode active material layer is improved, and an ion transmission channel is provided, thereby helping to reduce impedance and suppress lithium plating.