Lithium-ion secondary battery, separation membrane, and method for manufacturing these

A separation membrane for being disposed between a positive electrode mixture layer and a negative electrode mixture layer, in a lithium ion secondary battery comprising a positive electrode mixture layer that contains a positive electrode active material, a first lithium salt and a first solvent, and a negative electrode mixture layer that contains a negative electrode active material, a second lithium salt and a second solvent different from the first solvent,

• wherein the separation membrane contains a polymer having lithium ion conductivity, a third lithium salt, and a third solvent, and
• wherein the polymer is a polymer of polymerizable components that include a monomer and a thiol compound.

A method for manufacturing a separation membrane for being disposed between a positive electrode mixture layer and a negative electrode mixture layer, in a lithium ion secondary battery comprising a positive electrode mixture layer that contains a positive electrode active material, a first lithium salt and a first solvent, and a negative electrode mixture layer that contains a negative electrode active material, a second lithium salt and a second solvent different from the first solvent,

• wherein the method comprises forming a slurry containing polymerizable components including a monomer and a thiol compound, a tertiary lithium salt, and a tertiary solvent into a membrane, and then reacting the polymerizable components to obtain a separation membrane.