Non-aqueous electrolyte additive for improving safety and lithium ion secondary battery comprising the same
View Patent ↗The present invention relates to a non-aqueous electrolyte additive for improving safety and a lithium secondary battery comprising the same, and more particularly to a non-aqueous electrolyte additive that can improve cycle life and safety properties of a lithium ion secondary battery. According to the present invention, an organometallic compound represented by the Chemical Formula 1 is added to a non-aqueous electrolyte of a battery as an additive, and thus if a battery voltage is out of normal operation voltage range due to a short circuit and overcharge of a battery, etc., the non-aqueous electrolyte additive decomposes and a part of the decomposed additive polymerizes to form an insulating film on a cathode surface, and a part of the metal reacts with an insulating film formed on a cathode surface to improve thermal stability of the battery, thereby improving safety of the battery.
1. A non-aqueous electrolyte lithium ion secondary battery comprising:
a) an anode capable of adsorbing and releasing lithium;
b) a cathode capable of adsorbing and releasing lithium; and
c) a non-aqueous electrolyte solution comprising a lithium salt, an aprotic solvent, and an organometallic compound represented by the following Chemical Formula 1a:
Si(R 1 ) y (OR) x-y-z (OH) z [Chemical Formula 1a]
wherein R 1 is a phenyl group or a halogen-substituted phenyl group coordinated with a central metal atom;
R is an alkyl group coordinated with a central metal atom;
x is a valence of a central metal atom;
y is a value satisfying 0<y<x; and
z is a value satisfying 0<z<x.
2. The lithium ion secondary battery according to claim 1 , wherein the a) anode comprises carbon material selected from a group consisting of graphite, carbon fiber, and active carbon as active material.
3. The lithium ion secondary battery according to claim 1 , wherein the b) cathode comprises a lithium transition metal complex oxide represented by the following Chemical Formula 2 as active material:
Li x MO 2 [Chemical Formula 2]
wherein M is Ni, Co, or Mn; and x is a value satisfying 0.05≦x≦1.10.
4. The lithium ion secondary battery according to claim 1 , wherein the c) organometallic compound is contained in an amount of 0.01 to 20 wt % of electrolyte.
5. The lithium ion secondary battery according to claim 1 , wherein the c) organometallic compound is phenylalkoxysilanol.
6. The lithium ion secondary battery according to claim 1 , wherein the R in the c) organometallic compound is methyl or ethyl.