NOVELTY - An electrolyte solution comprises nitrogen compound (I)-(VI), metal ion of group I elements or group II elements and organic solvent.    USE - Electrolyte solution for non-aqueous secondary battery (claimed) e.g. lithium ion secondary battery. Uses include but are not limited to video tape recorder, mobile telephone, notebook personal computer, mobile personal computer, cordless phone, hand-held terminal, portable copying machine, portable printer, minidisc, electric shaver, etc.    ADVANTAGE - The non-aqueous secondary battery provided using electrolyte has high density and overcharge prevention property, excellent durability and charging and discharging property, suppressed deterioration and reduced size.    DETAILED DESCRIPTION - An electrolyte solution comprises nitrogen compound of formulae (I)-(VI), metal ion of I group elements or II group elements or its salt, and organic solvent.    X1=electron-attractive group;    L11=coupling group;    L12=-C(=O)-, C-C multiple bond, N-N single bond or multiple bond, C-N multiple bond or N-L11-(X1)n1;    or L12+N=ring;    n1=1-3;    R21=alkyl, aryl, alkoxy, aryloxy, aralkyl, alkenyl or N-containing group;    L12=L11 or N-C(=O)-R21;    L31=-S(=O)- or -S(=o)2-;    R31,R32=alkyl, aryl, heteroaryl, aralkyl, alkylsulfonyl, arylsulfonyl, acyl, alkoxycarbonyl or -L31-R33;    R31+R32=bond or ring Cy;    R33=alkyl, aryl, aralkyl or nitrogen-containing group;    R41,R42=alkyl, aryl, heteroaryl, aralkyl, alkylsulfonyl, arylsulfonyl, acyl, alkoxycarbonyl or phosphorus-containing group;    R43, R44=alkyl, aryl, aralkyl, alkoxy, aryloxy, aralkyloxy, halo or nitrogen-containing group;    R51, R52=alkyl, aryl, heteroaryl, aralkyl, alkylsulfonyl, arylsulfonyl, alkoxycarbonyl or acyl;    R53-R55=H, alkyl, aryl, aralkyl or nitrogen-containing group;    R61, R62=alkyl, aryl, heteroaryl, aralkyl, alkylsulfonyl, arylsulfonyl or alkoxycarbonyl;    or R31+R32, R41+R42, R51+R52, R61+R62, R43+R44=bond or ring with N;and    n6=2-4.    INDEPENDENT CLAIMS are included for the following:    (1) non-aqueous secondary battery, which comprises positive electrode, negative electrode and electrolyte solution; and    (2) additive for electrolyte, which is nitrogen-containing compound of formula: Z-N(R101)-(R102) having oxidation onset potential higher than oxidation onset potential of amine compound of formula: H-N(R101)(R102).    R101,R102=organic group.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic view of lithium ion secondary battery.    Positive electrode electrical power collector (1)    Positive electrode active material layer (2)    Anode collector (3)    Negative electrode active material layer (4)    Electrolyte solution (5)