▎ 摘　　要

NOVELTY - An ion secondary battery comprises a positive electrode, a negative electrode, an electrolyte solution and a separator connected to the positive electrode and the negative electrode. The positive electrode is graphene-nickel composite material, where nickel nanoparticles are embedded in graphene. The nickel nanoparticles have size of 0.5-10 microns. The negative electrode is aluminum-silicon alloy containing 5-8 %mass silicon. The electrolytic solution comprises aluminum(III) ion, chloride ion and/or 1-ethyl-3-methylimidazolium ion. USE - Ion secondary battery (claimed). ADVANTAGE - The safe ion secondary battery has excellent thermal stability, charge and discharge voltage of 3.5 V or more, cycle durability of more than 5000 times, and energy density of 90 W.hour/Kg or more, and does not cause explosion. DETAILED DESCRIPTION - An ion secondary battery comprises a positive electrode, a negative electrode, an electrolyte solution and a separator connected to the positive electrode and the negative electrode. The positive electrode is graphene-nickel composite material, where nickel nanoparticles are embedded in graphene. The nickel nanoparticles have size of 0.5-10 microns. The negative electrode is aluminum-silicon alloy containing 5-8 %mass silicon. The electrolytic solution comprises aluminum(III) ion, chloride ion and/or 1-ethyl-3-methylimidazolium ion. The molar ratio of 1-ethyl-3-methylimidazolium ion and aluminum(III) ion is more than 3:2 and less than 4:1. An INDEPENDENT CLAIM is included for preparation of ion secondary battery.