TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Composition: The positive electrode contains active material including nickel and/or manganese atom. The negative electrode is chosen from carbon negative electrode, silicon-containing negative electrode and titanium-containing negative electrode. The battery further has an overcharge prevention apparatus which blocks electric current when pressure inside a battery becomes more than specified pressure. Preferred Property: The battery has charge positive electrode electric potential of 4.25 V or more.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The aromatic compound (A) is of formulae (A1)-(A3). At least 1 ring among three or more fused or linked ring structure contained in the specific aromatic compound is aliphatic ring. The aromatic compound (A1) is preferably of formulae (A11)-(A13). The aromatic compound (A2) is preferably of formula (A21) or (A22). The aromatic compound (A3) is preferably of formula (A31) or (A32). The aromatic compound (B) is preferably of formula (B1). The content of propylene carbonate in organic solvent is 5 vol.% or more with respect to all solvent. The electrolyte solution further contains halogen-containing compound, polymeric compound, phosphorus-containing compound, sulfur-containing compound, silicon-containing compound, nitrile compound, metal complex compound and/or imide compound. The content of specific aromatic compound with respect to whole quantity of electrolyte is 0.1-10 %mass. The specific aromatic compound is compound which generates gas during overcharging.Ra1-Ra5=H, W' or another substituents, where at least one of Ra1-Ra5 is cycloalkyl or aryl, or at least 2 among Ra1-Ra5 bond or condense to form aryl or aliphatic ring;W'=electron-attractive group;Wa=electron-withdrawing coupling group;Ar11,Ar12=aryl;Ar13,Ar14=aromatic coupling group;Ya=non-electron-withdrawing coupling group;n,s=1-3;Cy=cycloalkyl or aryl;u,r=1 or 2;Ya=non-electron-withdrawing coupling group;p=0-3;andRb1-Rb10=H or substituent, in which at least one of Rb1-Rb5 and at least one of Rb6-Rb10 are branched alkyl group in which tertiary carbon or quaternary carbon is bonded with aromatic ring.