Binder having high adhesion for carbon-coated lithium iron phosphate electrode, electrode containing same, and lithium secondary battery containing same
View Patent ↗The present disclosure provides a polymer binder for a secondary battery electrode, which serves as a binder for a carbon-coated lithium iron phosphate (c-LiFePO 4 ) electrode and is a copolymer containing a hard segment capable of hydrogen bonding in the electrode and a soft segment having a polyol structure. Also, the present disclosure provides a secondary battery electrode and a lithium secondary battery containing the same, wherein a nonaqueous electrolyte solution is applied to an electrode mixture containing the binder for an electrode.
1. A polymer binder for a secondary battery electrode, wherein the polymer binder is a copolymer containing a hard segment capable of hydrogen bonding in the electrode and soft segment having a polyol structure,
wherein the hard segment comprises a urethane group bonded to a first aromatic group and a urea group bonded to a second aromatic group.
2. The polymer binder for a secondary battery electrode according to claim 1 , wherein the copolymer forms a polycarbonate-based electrode interface film by reacting with a compound of Chemical Formula 1 in an electrolyte solution:
3. The polymer binder for a secondary battery electrode according to claim 1 , wherein the copolymer has a number-average molecular weight of 210,000-1,000,000.
4. The polymer binder for a secondary battery electrode according to claim 1 , wherein the soft segment is an aliphatic polyol compound having a weight-average molecular weight of 1,000-3,000.
5. The polymer binder for a secondary battery electrode according to claim 4 , wherein the aliphatic polyol is at least one selected from a group consisting of polyethylene glycol, polytetramethylene ether glycol, polypropylene glycol, polycarbonate diol, polycaprolactone diol and an ethylene-propylene glycol copolymer.
6. The secondary battery electrode comprising the polymer binder for a secondary battery electrode according to claim 1 .
7. The secondary battery electrode according to claim 6 , wherein the secondary battery electrode comprises carbon-coated lithium iron phosphate (c-LiFePO 4 ).
8. A secondary battery comprising:
the secondary battery electrode according to claim 6 ; and
a nonaqueous electrolyte solution,
wherein the nonaqueous electrolyte solution comprises a compound of Chemical Formula 1:
9. The secondary battery according to claim 8 , wherein the copolymer of the binder forms a polycarbonate-based electrode interface film by reacting with the compound of Chemical Formula 1.
10. The secondary battery according to claim 8 , wherein the polymer binder is comprised in 1-15% by weight of the electrode.
11. The secondary battery according to claim 8 , wherein the content of the compound of Chemical Formula 1 in the nonaqueous electrolyte solution is 0.1-7.0% by volume.