A binder composition for a secondary battery comprising: a copolymer having a functional group; and an alkali metal ion bound to the functional group of the copolymer, wherein the alkali metal ion is included in an amount of 0.2 parts by weight to 5 parts by weight with respect to 100 parts by weight of the copolymer, and the copolymer comprises three or more selected from the group consisting of: (a) a repeating unit derived from a conjugated diene-based monomer or a unit derived from a conjugated diene-based polymer; (b) a repeating unit derived from a (meth)acrylic acid ester-based monomer; (c) one or more repeating units selected from the group consisting of a repeating unit derived from a vinyl-based monomer, a repeating unit derived from a (meth)acrylamide-based monomer, and a repeating unit derived from a nitrile-based monomer; and (d) a repeating unit derived from an unsaturated carboxylic acid-based monomer, wherein the vinyl-based monomer is one or more selected from the group consisting of styrene, α-methylstyrene, β-methylstyrene, p-t-butylstyrene, and divinylbenzene, the unsaturated carboxylic acid-based monomer is one or more selected from the group consisting of maleic acid, fumaric acid, methacrylic acid, acrylic acid, glutaric acid, itaconic acid, tetrahydrophthalic acid, crotonic acid, isocrotonic acid, and nadic acid, the (meth)acrylic acid ester-based monomer is one or more selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-ethyl hexyl acrylate, 2-ethyl hexyl acrylate, 2-hydroxy ethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, n-ethyl hexyl methacrylate, 2-ethyl hexyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, methacryloxyethyl ethylene urea, β-carboxy ethyl acrylate, aliphatic monoacrylate, dipropylene diacrylate, ditrimethylolpropane tetraacrylate,, dipentaerythritol hexaacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, lauryl acrylate, seryl acrylate, stearyl acrylate, lauryl methacrylate, cetyl methacrylate, and stearyl methacrylate. a copolymer having a functional group; and an alkali metal ion bound to the functional group of the copolymer, wherein the alkali metal ion is included in an amount of 0.2 parts by weight to 5 parts by weight with respect to 100 parts by weight of the copolymer, and the copolymer comprises three or more selected from the group consisting of: (a) a repeating unit derived from a conjugated diene-based monomer or a unit derived from a conjugated diene-based polymer; (b) a repeating unit derived from a (meth)acrylic acid ester-based monomer; (c) one or more repeating units selected from the group consisting of a repeating unit derived from a vinyl-based monomer, a repeating unit derived from a (meth)acrylamide-based monomer, and a repeating unit derived from a nitrile-based monomer; and (d) a repeating unit derived from an unsaturated carboxylic acid-based monomer, (a) a repeating unit derived from a conjugated diene-based monomer or a unit derived from a conjugated diene-based polymer; (b) a repeating unit derived from a (meth)acrylic acid ester-based monomer; (c) one or more repeating units selected from the group consisting of a repeating unit derived from a vinyl-based monomer, a repeating unit derived from a (meth)acrylamide-based monomer, and a repeating unit derived from a nitrile-based monomer; and (d) a repeating unit derived from an unsaturated carboxylic acid-based monomer, wherein the vinyl-based monomer is one or more selected from the group consisting of styrene, α-methylstyrene, β-methylstyrene, p-t-butylstyrene, and divinylbenzene, the unsaturated carboxylic acid-based monomer is one or more selected from the group consisting of maleic acid, fumaric acid, methacrylic acid, acrylic acid, glutaric acid, itaconic acid, tetrahydrophthalic acid, crotonic acid, isocrotonic acid, and nadic acid, the (meth)acrylic acid ester-based monomer is one or more selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-ethyl hexyl acrylate, 2-ethyl hexyl acrylate, 2-hydroxy ethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, n-ethyl hexyl methacrylate, 2-ethyl hexyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, methacryloxyethyl ethylene urea, β-carboxy ethyl acrylate, aliphatic monoacrylate, dipropylene diacrylate, ditrimethylolpropane tetraacrylate,, dipentaerythritol hexaacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, lauryl acrylate, seryl acrylate, stearyl acrylate, lauryl methacrylate, cetyl methacrylate, and stearyl methacrylate.