NOVELTY - The autonomous battery shutdown system comprises a battery comprising an anode (110), a cathode (120) and an electrolyte composition (130) between the anode and the cathode, where: the electrolyte composition comprises an ionically conductive liquid (132) comprising lithium ions, temperature-sensitive particles (134) and thermally stable particles; the temperature-sensitive particles comprise a polymer having a melting temperature of 60-120 degrees C and a hydrophilic surface; and when the temperature of the battery exceeds 110 degrees C, the polymer melts and forms an ion barrier.    USE - Used as an autonomous battery shutdown system.    ADVANTAGE - The system safely shut downs the battery without catastrophic failure of the battery thus extending lifespan of the battery and reducing over all cost of the battery, and does not inhibit the charging and discharging of the battery during normal use.    DETAILED DESCRIPTION - The autonomous battery shutdown system comprises a battery comprising an anode (110), a cathode (120) and an electrolyte composition (130) between the anode and the cathode, where: the electrolyte composition comprises an ionically conductive liquid (132) comprising lithium ions, temperature-sensitive particles (134) and thermally stable particles; the temperature-sensitive particles comprise a polymer having a melting temperature of 60-120 degrees C and a hydrophilic surface; and when the temperature of the battery exceeds 110 degrees C, the polymer melts and forms an ion barrier that traverses the battery. The temperature-sensitive particles are present in contact with the anode and/or the cathode. The ion barrier comprises a polymer film. The temperature-sensitive particles comprise solid particles, capsules comprising a capsule wall having a melting temperature of 60-120 degrees C, and a barrier-forming agent enclosed by the capsule wall. When the temperature of the battery exceeds 120 degrees C, the capsule wall melts, a barrier-forming substance is released and the released barrier-forming substance forms the ion barrier that traverses the battery. The barrier-forming substance comprises a polymerizer that forms the polymer film. The electrolyte composition comprises the polymerizer. The barrier-forming substance comprises an activator for the polymerizer. The battery further comprises a separator that traverses the battery. A polymer of the thermally stable particles has a glass transition temperature of greater than 120 degrees C.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of an autonomous battery shutdown system.    Anode (110)    Cathode (120)    Electrolyte composition (130)    Ionically conductive liquid (132)    Temperature sensitive particles. (134)