A lithium secondary battery comprising: a cathode; a lithium thin film anode having a thickness of less than 100 μm; and an electrolyte disposed between the cathode and the anode, the electrolyte comprising: a block copolymer comprising a structural domain and a rubbery domain, wherein the structural domain comprises a structural block selected from polystyrene, hydrogenated polystyrene, poly(C1 to C8 alkyl)methacrylate, poly(methyl methacrylate), polyvinylpyridine, polyvinyl cyclohexane, polyimide, polyamide, polyethylene, polybutylene, polypropylene, poly(4-methylpentene-1), poly(butylene terephthalate), poly(isobutyl methacrylate), poly(ethylene terephthalate), polydimethylsiloxane, polyacrylonitrile, polymaleic acid, poly(maleic anhydride), poly(methacrylic acid), poly(tert-butyl vinyl ether), poly(cyclohexyl methacrylate), poly(cyclohexyl vinyl ether), polyvinylidenefluoride, polydivinylbenzene, a combination thereof, or a copolymer comprising at least two different structural units of the foregoing polymers, and wherein the rubbery domain comprises a rubbery block selected from polyisoprene, polybutadiene, polychloroprene, polyisobutylene, polyurethane, a copolymer comprising units thereof, or a combination thereof, wherein: the amount of the rubbery block of the block copolymer is from 50 to 80 parts by weight based on 100 parts by weight of a total weight of the block copolymer; the amount of the structural block of the block copolymer is from 20 to 50 parts by weight based on 100 parts by weight of a total weight of the block copolymer; the block copolymer of the electrolyte does not comprise an alkylene oxide repeating unit; and the anode is a lithium metal or lithium metal alloy electrode. a cathode; a lithium thin film anode having a thickness of less than 100 μm; and an electrolyte disposed between the cathode and the anode, the electrolyte comprising: a block copolymer comprising a structural domain and a rubbery domain, wherein the structural domain comprises a structural block selected from polystyrene, hydrogenated polystyrene, poly(C1 to C8 alkyl)methacrylate, poly(methyl methacrylate), polyvinylpyridine, polyvinyl cyclohexane, polyimide, polyamide, polyethylene, polybutylene, polypropylene, poly(4-methylpentene-1), poly(butylene terephthalate), poly(isobutyl methacrylate), poly(ethylene terephthalate), polydimethylsiloxane, polyacrylonitrile, polymaleic acid, poly(maleic anhydride), poly(methacrylic acid), poly(tert-butyl vinyl ether), poly(cyclohexyl methacrylate), poly(cyclohexyl vinyl ether), polyvinylidenefluoride, polydivinylbenzene, a combination thereof, or a copolymer comprising at least two different structural units of the foregoing polymers, and wherein the rubbery domain comprises a rubbery block selected from polyisoprene, polybutadiene, polychloroprene, polyisobutylene, polyurethane, a copolymer comprising units thereof, or a combination thereof, wherein: a block copolymer comprising a structural domain and a rubbery domain, wherein the structural domain comprises a structural block selected from polystyrene, hydrogenated polystyrene, poly(C1 to C8 alkyl)methacrylate, poly(methyl methacrylate), polyvinylpyridine, polyvinyl cyclohexane, polyimide, polyamide, polyethylene, polybutylene, polypropylene, poly(4-methylpentene-1), poly(butylene terephthalate), poly(isobutyl methacrylate), poly(ethylene terephthalate), polydimethylsiloxane, polyacrylonitrile, polymaleic acid, poly(maleic anhydride), poly(methacrylic acid), poly(tert-butyl vinyl ether), poly(cyclohexyl methacrylate), poly(cyclohexyl vinyl ether), polyvinylidenefluoride, polydivinylbenzene, a combination thereof, or a copolymer comprising at least two different structural units of the foregoing polymers, and wherein the rubbery domain comprises a rubbery block selected from polyisoprene, polybutadiene, polychloroprene, polyisobutylene, polyurethane, a copolymer comprising units thereof, or a combination thereof, wherein: the amount of the rubbery block of the block copolymer is from 50 to 80 parts by weight based on 100 parts by weight of a total weight of the block copolymer; the amount of the structural block of the block copolymer is from 20 to 50 parts by weight based on 100 parts by weight of a total weight of the block copolymer; the block copolymer of the electrolyte does not comprise an alkylene oxide repeating unit; and the anode is a lithium metal or lithium metal alloy electrode.