Preparation method of lithium battery diaphragm

The invention discloses a preparation method of a lithium battery diaphragm. The preparation method comprises the following steps of preparing ceramic slurry; soaking a diaphragm base material in a slurry pool for coating; elevating the diaphragm base material into a baking oven for drying; symmetrically arranging a plurality of air inlet pipes at two sides of the diaphragm in the baking oven, wherein an arrangement mode of the air inlet pipes is an m*n array form, m is the number of the air inlet pipes in the longitudinal direction and is greater than or equal to 2, n is the number of the air inlet pipes in the transverse direction and is greater than or equal to 1, the air volumes of the air inlet pipes positioned in the same row are identical, and the air volumes of the air inlet pipes in the longitudinal direction from bottom to top is gradually weakened. According to the method, the heat shrinkable property of the diaphragm can be improved, and the adhesive property of the diaphragm and a pole piece in t