Novel high-temperature-resisting diaphragm of lithium battery and preparation process of diaphragm

The invention discloses a novel high-temperature-resisting diaphragm of a lithium battery and a preparation process of the diaphragm, which belong to the field of a battery diaphragm, and solve the problem in the prior art that the lithium battery diaphragm which is prepared by adopting a wet-method process is low in fuse temperature. The high-temperature-resisting diaphragm of the lithium battery is prepared by adopting a wet-method process. The diaphragm comprises an inner layer, an intermediate layer and an outer layer, wherein both the inner layer and the outer layer are prepared by adopting polyethylene and white oil as raw materials; the intermediate layer is prepared by adopting polyethylene, white oil and nanometer inorganic oxide as raw materials. The preparation process comprises the following steps of mixing, extrusion, compounding through a die head, casting, cooling and molding, bidirectional synchronous stretching, extraction, drying, transversely stretching and expanding and thermal setting. The fuse temperature of the diaphragm prepared through the process is detected to be 50 to 70 DEG C higher than that of the diaphragm with a single PE (polyethylene) component.