Low-temperature composite heat insulation layer, preparation method thereof and application of low-temperature composite heat insulation layer in vehicle-mounted low-temperature hydrogen storage tank

The invention provides a low-temperature composite heat insulation layer, a preparation method thereof and application of the low-temperature composite heat insulation layer in a vehicle-mounted low-temperature hydrogen storage tank. The composite heat insulation layer comprises a hollow microsphere layer and a multi-layer heat insulation layer; the hollow microsphere layer comprises a support body and hollow microsphere powder; the support body is filled with the hollow microsphere powder to form the hollow microsphere layer; and the multi-layer heat insulation layer comprises at least one of a uniform-density multi-layer heat insulation material layer, a variable-density multi-layer heat insulation material layer, a uniform-density integrated heat insulation film and a variable-density integrated heat insulation film. According to the composite heat insulation layer, the hollow microsphere layer and the multi-layer heat insulation layer are used in a composite mode, and the advantages of the two heat insula