Production technology of high-porosity lithium battery membrane by adopting ceramic coating

The invention discloses a production technology of a high-porosity lithium battery membrane by adopting ceramic coating. The production technology comprises the steps of performing material mixing, extrusion, filtration metering, die head extrusion, cast sheet cooling forming, bidirectional stretching, extraction drying, transverse pulling and amplitude expansion, thermal sizing, ceramic coating, water removal through a drying oven and on-line winding on polyethylene serving as raw material resin, white oil serving as a solvent, dichloromethane serving as an extracting agent and aluminum oxide serving as a ceramic base material, so that the high-porosity lithium battery membrane is prepared. Due to a technology for controlling the thermal sizing, the closing degree in the technical process is reduced so as to increase the porosity of the membrane base material; furthermore, the ceramic coating is directly executed after the thermal sizing technology is performed; due to the ceramic coating, the thermal contraction rate of the membrane is reduced, and the changes of the thickness and the performance of the membrane, which are caused by release of thermal stress in a high-porosity membrane storage process, in the conventional step-by-step preparation technology are avoided; meanwhile, the production cost is also lowered.