Multilayer hybrid battery separators for lithium ion secondary batteries and methods of making same
View Patent ↗A multi-layered battery separator for a lithium secondary battery includes a first layer of a dry processed membrane bonded to a second layer of a wet processed membrane. The first layer may be made of a polypropylene based resin. The second layer may be made of a polyethylene based resin. The separator may have more than two layers. The separator may have a ratio of MD/TD tensile strength in the range of about 1.5-3.0. The separator may have a thickness of about 35.0 microns or less. The separator may have a puncture strength of greater than about 630 gf. The separator may have a dielectric breakdown of at least about 2000V.
1. A multi-layered battery separator for a lithium secondary battery comprises at least a first polypropylene based resin layer of a dry processed microporous membrane with slit-like pores bonded to a second polyethylene based resin layer of a wet processed microporous membrane with rounded pores, the separator having a ratio of MD/TD tensile strength in the range of about 1.5-3.0, a thickness of about 35.0 microns or less, a puncture strength of greater than about 630 gf, and a dielectric breakdown of at least about 2000V.
2. The separator of claim 1 has at least three layers.
3. The separator of claim 1 has only two layers.
4. The separator of claim 1 wherein said polypropylene based resin is polypropylene or a blend containing polypropylene.
5. The separator of claim 1 wherein said polyethylene based resin is polyethylene or a blend containing polyethylene.
6. The separator of claim 2 has a configuration of a polypropylene layer/a polyethylene layer/a polypropylene layer.
7. The separator of claim 2 has a configuration of a dry processed membrane/a wet processed membrane/a dry processed membrane.
8. The separator of claim 1 has a ratio of MD/TD tensile strength in the range of about 1.6-2.5.
9. The separator of claim 1 has a ratio of MD/TD tensile strength in the range of about 1.8-2.2.
10. The separator of claim 1 has a thickness in the range of about 5.0-30.0 microns.
11. The separator of claim 1 has a thickness in the range of about 5.0-26.0 microns.
12. The separator of claim 1 has a puncture strength in the range of about 630-1500 gf.
13. The separator of claim 1 has a dielectric breakdown in the range of about 2000-5000V.
14. A battery comprising the separator of claim 1 .
15. A battery comprising the separator of claim 2 .
16. A battery comprising the separator of claim 3 .
17. A battery comprising the separator of claim 7 .