Micro-concave roller and method for manufacturing lithium ion battery diaphragms

The invention provides a micro-concave roller for manufacturing lithium-ion battery diaphragms. The roller comprises a main shaft and coaxial bearing shafts fixedly connected to both ends of the mainshaft, wherein the main shaft and the bearing shafts are in a hollow structure containing a cavity for a circulating heat exchange medium to enter, and the surface of the main shaft is plated with a chromium layer; the main shaft comprises two identical straight parts and a micro-concave part located between the two straight parts, the straight parts are of an equal-diameter cylinder shape, the micro-concave part is cylindrical with smooth arc-shaped walls whose diameters gradually decrease from both ends to the middle, the micro-concave part is symmetrical about the plane of the vertical spindle axis in the middle, and the diameters of both ends are the same as the diameters of the straight parts. The invention also provides a method for manufacturing lithium-ion battery diaphragms, and the method uses the above-