BINDER FOR SOLID-STATE SECONDARY BATTERY, SLURRY FOR SOLID-STATE SECONDARY BATTERY, METHOD FOR FORMING LAYER FOR SOLID-STATE SECONDARY BATTERY AND SOLID-STATE SECONDARY BATTERY

An oxide-based solid-state secondary battery and a binder for a solid-state secondary battery using an oxide-based solid electrolyte that contains a fluorine-containing polymer including a vinylidene fluoride unit and a fluorinated monomer unit other than the vinylidene fluoride unit. The fluorinated monomer unit is at least one copolymerization unit (A) selected from a monomer unit having a structure represented by formula (1) and a monomer unit having a structure represented by formula (2): wherein Rfand Rfare each a linear or branched fluorinated alkyl or fluorinated alkoxy group with 1 to 12 carbon atoms, which optionally contains an oxygen atom between carbon-carbon atoms when the number of carbon atoms is 2 or more.