SEPARATOR, ELECTROCHEMICAL DEVICE, AND ELECTRONIC DEVICE

A separator includes a separator substrate, a first coating layer, and a second coating layer. The separator substrate includes a first surface and a second surface disposed opposite to each other. The first surface faces a positive electrode, and the second surface faces a negative electrode. The first coating layer is disposed on the first surface, and the second coating layer is disposed on the second surface. The first coating layer is a dense solid filler coating. A porosity of the first coating layer is denoted as D, satisfying: 10%≤D