The invention discloses a preparation method of a
porous film. The preparation method comprises the following steps: (1) acquiring a porous support body; (2) preparing a thick size containing
raw material powder, a binder, a dispersant and a pore forming agent; (3) loading the size onto the porous support body, and
drying to make a film billet; (4)
sintering the film billet to make a
porous film precursor; (5) removing the pore forming agent from the precursor to obtain a
porous film with the thickness of 5-3,000 [mu]m, the average aperture of 0.05-100 [mu]m and the
porosity of 40-90%. The preparation method has the following advantages: firstly, no
chemical reaction occurs between the pore forming agent and the
raw material powder, so that the ingredients of the porous film cannot be damaged; secondly, the pore forming agent is excellent in
thermal stability and always occupies a certain space (place) in the
sintering process; after
sintering, the pore forming agent is removed, holes or pores are generated in situ; therefore, the whole technological process is simple, the hole structure of the porous film is easy to control, and the
porosity is remarkably improved.