Abstract: An integrated sheet structure for a secondary battery, including a first mixture layer containing a first active material and a first binder, a second mixture layer containing a second active material and a second binder, and a third mixture layer located between the first mixture layer and the second mixture layer and containing solid particles and a third binder, in which the first mixture layer and the third mixture layer are bonded each other, and the second mixture layer and the third mixture layer are bonded each other.

Abstract: Provided is a secondary battery including a negative electrode, a positive electrode, a separation layer in contact with an active material-containing layer of the negative electrode, and an aqueous electrolyte. A first concentration corresponding to a first metal concentration represented by Equation 1 (first metal concentration=atomic concentration of Hg, Pb, Zn, and/or Bi/sum of atomic concentrations of elements B to U in periodic table, excluding carbon and oxygen) in a boundary region between the active material-containing layer and the separation layer is 2% or more and 8.2% or less. A ratio of the first concentration to a second concentration corresponding to the first metal concentration represented by Equation 1 in the active material-containing layer excluding the boundary region is 2.5 or more and less than 4.

Abstract: A steel strip having an excellent phosphate-coating property is produced by subjecting at least one surface of the steel strip to electrolytic treatment in which the steel strip serves as an anode and the steel strip surface is brought into contact with an aqueous solution containing at least one phosphate selected from the group consisting of alkali metal phosphates and ammonium phosphate and having a concentration of phosphoric anions of 0.05 mole/l or more and a pH of from 4 to 7, at an anode current density of 2 A/dm.sup.2 or more, to an extent that a phosphate surface layer is formed in an amount of 0.0001 to 0.05 g/m.sup.2 on the metal strip surface.