Composite lithium battery separator and preparation method therefor

A composite lithium battery separator comprising:

• a base film or a ceramic film;
• and
• a coating layer covering a single side or two sides of the base film or the ceramic film, wherein the coating layer is formed by coating a slurry, wherein the slurry comprises, in percentage by weight, 5%-45% of a coating polymer and 55%-95% of an organic solvent, and wherein the coating polymer comprises, in parts by weight, 10-100 parts of a fluorine resin polymer or acrylic resin polymer, 0.5-10 parts of a polymer adhesive and 0-90 parts of inorganic nanoparticles,
• wherein the inorganic nanoparticles are a mixture of conventional inorganic particles and inorganic particles having lithium ion conducting capability, and a weight ratio of the conventional inorganic particles to the inorganic particles having lithium ion conducting capability is 80-95:20-5, and wherein a particle size of the conventional inorganic particles ranges 0.01-10 μm;
• and
• the conventional inorganic particles are composed of inorganic particles with a big particle size and inorganic particles with a small particle size in a weight ratio of 80-90:20-10, a particle size of the inorganic particles with a small particle size ranges 0.01-0.2 μm, and a particle size of the inorganic particles with a big particle size ranges 0.2-10 μm.