US 12,255,354 B2
Separator for lithium secondary battery with improved adhesiveness towards electrode and resistance characteristics and lithium secondary battery comprising the separator
So-Mi Jeong, Daejeon (KR); Dong-Wook Sung, Daejeon (KR); and Dae-Sung Jang, Daejeon (KR)
Assigned to LG ENERGY SOLUTION, LTD., Seoul (KR)
Filed by LG ENERGY SOLUTION, LTD., Seoul (KR)
Filed on Sep. 25, 2023, as Appl. No. 18/372,682.
Application 18/372,682 is a continuation of application No. 17/044,364, granted, now 11,811,093, previously published as PCT/KR2019/012770, filed on Sep. 30, 2019.
Claims priority of application No. 10-2018-0116543 (KR), filed on Sep. 28, 2018.
Prior Publication US 2024/0021960 A1, Jan. 18, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. H01M 50/489 (2021.01); H01M 10/052 (2010.01); H01M 50/426 (2021.01); H01M 50/449 (2021.01)
CPC H01M 50/489 (2021.01) [H01M 10/052 (2013.01); H01M 50/426 (2021.01); H01M 50/449 (2021.01)] 16 Claims
OG exemplary drawing
 
1. A separator for a lithium secondary battery, comprising:
a porous substrate; and
a porous coating layer disposed on at least one surface of the porous substrate and comprising inorganic particles and a binder polymer,
wherein the binder polymer comprises a terpolymer including a repeat unit derived from vinylidenefluoride (VDF), a repeat unit derived from hexafluoropropylene (HFP) and a repeat unit derived from chlorotrifluoroethylene (CTFE),
the terpolymer includes 65 to 90 weight % of the repeat unit derived from VDF, 1 to 28 weight % of the repeat unit derived from HFP and 5 to 28 weight % of the repeat unit derived from CTFE with respect to a total amount of the terpolymer, and
the separator for a lithium secondary battery has adhesiveness ranging from 30 gf/25 mm to 150 gf/25 mm and machine direction (MD) thermal shrinkage of 1 to 18% and transverse direction (TD) thermal shrinkage of 1 to 17%,
wherein
when a weight fraction of F (fluorine) and a weight fraction of CI (chlorine) are indicated such that a sum of the weight fraction of F and the weight fraction of Cl is 100,
the weight fraction (a) of CI (chlorine) in a surface region of the porous coating layer and the weight fraction (b) of CI (chlorine) in a bottom region of the porous coating layer satisfy the following formula:
0≤|(a−b)/a×100|≤100
wherein the surface region is a region extending downwards from a surface to a bottom by 10% of the total thickness of the porous coating layer, and
the bottom region is a region extending upwards from the bottom of the porous coating layer to the surface by 10% of the total thickness of the porous coating layer.