A secondary battery includes an electrode assembly. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. The separator is disposed between the positive electrode plate and the negative electrode plate. The negative electrode plate includes a negative electrode current collector and a negative electrode active material layer. A surface of the negative electrode active material layer facing towards the positive electrode plate has grooves, a width of the groove is W mm, and a spacing of the grooves is S mm. A thickness of the electrode assembly is T.sub.1 mm, satisfying: WST.sub.1/1000.

An embodiment of the present invention relates to a bonded object or a method for manufacturing a bonded object, the bonded object having bases bonded therein while placing an adhesive layer in between, the adhesive layer being obtained from a fluororubber composition that contains at least one fluororubber selected from fluoroelastomer (FKM) and perfluoroelastomer (FFKM), and has a Mooney viscosity (ML 1+10) at 121 C., measured in accordance with ASTM D1646, of 80 to 115.

An embodiment of the present invention relates to a bonded object or a method for manufacturing a bonded object, the bonded object having bases bonded therein while placing an adhesive layer in between, the adhesive layer being obtained from a fluororubber composition that contains at least one fluororubber selected from fluoroelastomer (FKM) and perfluoroelastomer (FFKM), and has a Mooney viscosity (ML 1+10) at 121 C., measured in accordance with ASTM D1646, of 80 to 115.