The utility model belongs to the technical field of lithium ion secondary batteries and particularly a lithium ion secondary battery comprising a packaging bag, a bare battery cell contained in the packaging bag and electrolyte filled into the packaging bag and the bare battery cell, wherein the outer surface of the bare battery cell is fixedly connected with the inner surface of the packaging bag through an adhesive layer with the porosity of 30-80%, and the thickness of the adhesive layer is 0.1-1000mu m. Compared with the prior art, the lithium ion secondary battery has the advantage that the packaging bag and the bare battery cell are fixed by using the adhesive layer with a porous structure and a certain thickness, so that the safety problem caused by abuse can be solved under the condition that other performances of the battery are not affected.