Lithium ion battery diaphragm, preparation method thereof and lithium ion battery

The invention relates to the technical field of lithium ion batteries, in particular to a preparation method of a lithium ion battery diaphragm, the lithium ion battery diaphragm and a lithium ion battery. The preparation method of the lithium ion battery diaphragm comprises the following steps of: carrying out melt blending on polypropylene resin, a stabilizer, a nucleating agent, silane coupling agent modified conductive carbon black and silane coupling agent modified carbon nanotubes to obtain polypropylene particles; putting polypropylene particles, a dispersion medium, a dispersing agent and a surfactant into a reaction kettle together, then continuously introducing a foaming agent, heating and pressurizing, and starting foaming after a preset temperature and a preset pressure are reached, so as to obtain conductive polypropylene beads; and preparing a conductive polypropylene film layer from the conductive polypropylene beads, and compounding the conductive polypropylene film layer with a polyethylene f