High-temperature-resistant long-service-life cylindrical lithium ion battery

The invention relates to the field of lithium ion batteries, in particular to a high-temperature-resistant lithium ion battery. The technical scheme adopted by the invention is as follows: the composite electrolyte comprises an aramid nanofiber-based diaphragm and a composite electrolyte, wherein an aluminum oxide coating is arranged on the aramid nanofiber-based diaphragm; an additive of the composite electrolyte is a film-forming additive, an organic solvent of the electrolyte is a non-aqueous organic solvent, and the non-aqueous organic solvent is a mixture of cyclic carbonate and chain carbonate; and the electrolyte is lithium hexafluorophosphate. In the aspect of the diaphragm, starting from the raw materials of the battery diaphragm, the characteristics of temperature difference resistance and the like of the traditional polyolefin diaphragm are improved, and the aramid nanofiber-based diaphragm with more excellent performance and better film forming effect is selected as the battery diaphragm, so that