Composite diaphragm and preparation method thereof, secondary battery and electric device

The invention belongs to the technical field of diaphragms, and particularly relates to a composite diaphragm and a lithium metal battery, the composite diaphragm comprises a base membrane and a modified coating arranged on at least one surface of the base membrane, and the modified coating is used for guiding lithium ions to be uniformly distributed. The composite diaphragm disclosed by the invention is provided with the modified coating for capturing and guiding lithium ions to be uniformly distributed on the base membrane, so that the condition that the lithium ions are deposited and gathered near pores of the base membrane to generate lithium dendrites is avoided. 本发明属于隔膜技术领域，尤其涉及一种复合隔膜及锂金属电池，包括基膜以及设置于基膜至少一表面的改性涂层，所述改性涂层用于引导锂离子均匀分布。本发明的一种复合隔膜，具有捕获并引导锂离子在基膜均匀分布的改性涂层，避免了锂离子在基膜孔隙附近沉积聚集出现锂枝晶的情况。