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. An electrochemical device comprising:
a cathode having a protection layer formed by a complex between the surface of a cathode active material and an aliphatic nitrile compound;
an anode; and
an electrolyte solution containing a lithium salt and a solvent,
wherein the complex between the surface of the cathode active material and the aliphatic nitrile compound is formed by immersing the cathode having the cathode active material applied on a collector in an electrolyte solution containing the aliphatic nitrile compound and then treating the resultant cathode at a temperature of 60-90° C.,
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);
wherein the aliphatic nitrile compound is represented by the following formula 1:
wherein R represents an alkylene group having 1 to 15 carbon atoms; and
wherein the anode has a passivation layer formed by a compound selected from the group consisting of vinylene carbonate represented by the following formula 2, its derivative and an ether compound:
2. The electrochemical device of claim 1 , wherein the ether compound is benzyl methyl ether or tetraethylene glycol dimethyl ether.
3. The electrochemical device of claim 1 , wherein the solvent is at least one cyclic carbonate selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC) and gamma-butyrolactone (GBL); at least one linear carbonate selected from the group consisting of diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC) and methylpropyl carbonate (MPC); or a combination of the cyclic carbonate and the linear carbonate.
4. The electrochemical device of claim 1 , wherein the aliphatic nitrile compound is succinonitrile.
5. A cathode having a protection layer formed by a complex between the surface of a cathode active material and an aliphatic nitrile compound,
wherein the complex between the surface of the cathode active material and the aliphatic nitrile compound is formed by immersing the cathode having the cathode active material applied on a collector in an electrolyte solution containing the aliphatic nitrile compound and then treating the immersed cathode at a temperature of 60-90° C.;
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); and
wherein the aliphatic nitrile compound is represented by the following formula 1:
wherein R represents an alkylene group having 1 to 15 carbon atoms.
6. The cathode of claim 5 , wherein the aliphatic nitrile compound is succinonitrile.
7. The electrochemical device of claim 1 , wherein the cathode having the complex formed between the surface of the cathode active material and the aliphatic nitrile compound is prepared prior to assembly of the electrochemical device and used in assembly of the electrochemical device.