High-power, long-cycle and high-safety lithium battery composite diaphragm as well as preparation method and application thereof

The invention relates to the field of lithium battery diaphragms, and particularly discloses a high-power, long-cycle and high-safety lithium battery composite diaphragm as well as a preparation method and application thereof. The lithium battery composite diaphragm comprises a base membrane and a functional layer coated on at least one side surface of the base membrane. The functional layer comprises a mixed component of a first functional component and a second functional component, the first functional component comprises one or more of LiM12 (PO4) 3, Li < 1 + x > Al < x > M < 12-x > (PO4) 3 and Li < 16-4y > M < 1 > y > O8, and the second functional component comprises one or more of M < 1 > O2, M < 1 > P2O7, M < 2 > PO4, M < 2 > SiO5, M < 3 > (PO4) 2 and M < 2 > SiO4. The functional layer is formed by coating slurry, the slurry comprises, by weight, 5%-45% of a functional layer material and 55%-95% of a solvent, and the functional layer material comprises, by weight, 100 parts of mixed components, 0.3-0.8