Abstract: The slitting assembly includes a grinding wheel with a wide flat grinding face for first cutting a multilayer sheet of soft and compressible, electronic device material, such as lithium-ion polymer material for a uni-cell battery, to a first depth and includes a cutting wheel with a blade-like edge for completing the slit by cutting through uncut layers of the multilayer sheet. The grinding face has a width of at least the thickness of the multilayer sheet, and in practice, the depth of the cut is preferably one half the sheet thickness, which in a uni-cell battery sheet is midway through a separator layer. The grinding wheel is positioned to apply cutting forces to the multilayer sheet in a direction that is substantially parallel to the feed direction to control the application of compressive forces that may compress the soft sheet material and if uncontrolled, may create short circuits between electrically conductive layers.