TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The metal fluoride is lithium fluoride, sodium fluoride, potassium fluoride, magnesium difluoride, calcium difluoride, copper difluoride, cadmium difluoride, iron difluoride, manganese difluoride, nickel difluoride, lead difluoride, tin difluoride, strontium difluoride, zinc difluoride, aluminum trifluoride, boron trifluoride, bismuth trifluoride, cerium trifluoride, chromium trifluoride, iron trifluoride, indium trifluoride, lanthanum trifluoride, manganese trifluoride, neodymium trifluoride, yttrium fluoride, cerium tetrafluoride, germanium tetrafluoride, hafnium tetrafluoride, silicon tetrafluoride, tin tetrafluoride, titanium tetrafluoride, vanadium tetrafluoride, zirconium tetrafluoride, vanadium pentafluoride, niobium pentafluoride, antimony pentafluoride, tantalum pentafluoride, bismuth pentafluoride, molybdenum pentafluoride, rhenium pentafluoride, sulfur pentafluoride, and/or tungsten pentafluoride. The heat-resistant layer comprises particles comprising a metal fluoride. The particles have an average diameter of 0.01-50 mu m, preferably 0.5-10 mu m. The heat-resistant layer: comprises 20-90 wt.% of the particles; further comprises a matrix material, where the matrix material is a polymer comprising polyvinylidene fluoride, polyurethane, polyethylene oxide, polyacrylonitrile, polymethylacrylate, polyacrylamide, polyvinyl acetate, polyvinylpyrrolidone, polyvinyl alcohol, PTFE, glycol diacrylate, hexafluoropropylene, and/or chlorotetrafluoroethylene; comprises 5-80 wt.% of the matrix material; and has a thickness of 0.5-50 mu m. The lithium secondary battery further comprises a shutdown layer (2), where the shutdown layer comprises a material comprising polyethylene and/or polypropylene. The heat-resistant battery layer has a thickness of 1-25 mu m, preferably 2.5-5 mu m. The surface is a surface of an electrode comprising a positive electrode or a negative electrode. The solvent comprises a first solvent and a second solvent having a boiling point higher than a boiling point of the first solvent.