The solid electrolyte membrane according to the present disclosure interrupts migration of lithium ions by the formation of an ion conduction-interrupting layer in the electrolyte membrane through the phase separation of polymers under a high-temperature condition, including an increase in the internal temperature of a battery. Since a battery is prevented from thermal runaway and explosion through the formation of the ‘ion conduction-interrupting layer’ (also referred to as ‘interrupting layer’), it is possible to improve the heat resistance and safety of the battery.