Electrochemical device comprising aliphatic nitrile compound
View Patent ↗The present invention provides a cathode having a protection layer formed by a complex between the surface of a cathode active material and an aliphatic nitrile compound, as well as an electrochemical device comprising the cathode. Also, the present invention provides an electrochemical device comprising: (1) a cathode having a protection layer formed by a complex between the surface of a cathode active material and an aliphatic nitrile compound; (2) an anode having a passivation layer formed by a compound selected from the group consisting of vinylene carbonate, its derivative and an ether compound; and (3) an electrolyte solution containing a lithium salt and a solvent.
1. A method for preparing a cathode, which comprises:
immersing a cathode comprising a cathode active material applied on a collector in an electrolyte solution comprising an aliphatic nitrile compound; and
treating the immersed cathode at a temperature of 60-90° C. to form a protection layer formed by a complex between the surface of the cathode active material and the aliphatic nitrile compound.
2. The method of claim 1 , wherein the aliphatic nitrile compound is represented by the following Formula 1:
wherein R represents an alkylene group having 1 to 15 carbon atoms.
3. The method of claim 1 , wherein the aliphatic nitrile compound is succinonitrile.
4. The method of claim 1 , wherein the cathode active material is at least one selected from the group consisting of LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , LiMnO 2 and LiNi 1-x Co x O 2 (0<x<1).