Abstract: An apparatus and method for coating a functional layer on a current collector with an active material layer thereon, the apparatus including a first roll and a second roll, the first roll and second roll being for advancing the current collector; a gravure roll, the gravure roll being configured to coat the functional layer on the active material layer; a thickness measurer, the thickness measurer being configured to measure at least one of a thickness of the active material layer and a sum thickness of the active material layer and the functional layer; and a controller, the controller being in communication with the thickness measurer and being configured to control a rotation speed of the gravure roll.