The invention discloses a preparation process of a 
lithium battery diaphragm. The preparation process comprises the following steps of: 1, preparing a membrane 
casting solution; 2, carrying out electrostatic 
spinning on the membrane 
casting solution to obtain a prefabricated 
fiber membrane; 3, performing baking at high temperature; and 4, 
coating the upper surface and the lower surface of the 
fiber membrane with a 
ceramic material. According to the invention, 
polyimide is modified, a soft 
chain segment can be introduced into a 
polyimide molecular chain, the flexibility of the 
polyimide molecular chain is improved, the flexibility of the 
fiber membrane is improved, also 
polyethylene glycol is combined with a 
membrane matrix in a chemical bonding mode, the 
binding force is high, the solventresistance and the high 
temperature resistance of 
polyethylene glycol are improved, and the diaphragm has efficient and lasting 
ionic conductivity; besides, the surface of the polyimide fiber membraneis coated with the 
ceramic material, so that the 
pore diameter of the diaphragm can be effectively reduced, the average 
pore diameter of the diaphragm is about 0.1microm, the 
pore diameter distribution is uniform, and the use performance of the 
lithium battery diaphragm is improved.