Polylactam coated separator membranes for lithium ion secondary batteries and related coating formulations

Patent metadata

Field	Value
Publication number	US-2016204409-A1
Application number	US-201514982466-A
Country	US
Kind code	A1
Filing date	Dec 29, 2015
Priority date	Dec 29, 2014
Publication date	Jul 14, 2016
Grant date	—

Abstract

The present invention is preferably directed to a polylactam ceramic coating for a microporous battery separator for a lithium ion secondary battery and a method of making this formulation and application of this formulation to make a coated microporous battery separator. The preferred inventive coating has excellent thermal and chemical stability, excellent adhesion to microporous base substrate, membrane, and/or electrode, improved binding properties to ceramic particles and/or has improved or excellent resistance to thermal shrinkage, dimensional integrity, and/or oxidation stability when used in a rechargeable lithium ion battery.

First claim

We claim:

1 . A microporous battery separator membrane coated on one or both sides with a polylactam ceramic coating where the polylactam is defined by the chemical structure:

where R 1 , R 2 , R 3 , and R 4 can be an alkyl or aromatic substituents and R 5 can be an alkyl, aromatic, or fused ring and;
where the preferred polylactam can be a homopolymer or a copolymer where co-polymeric ‘X’ group can be a derived from vinyl, alkyl vinyl, substituted alkyl vinyl, vinyl alcohol, vinyl acetate, acrylic acid, alkyl acrylate, acrylonitrile, maleic anhydride, maleic imide, styrene, polyvinylpyrrolidone (PVP), polyvinylvalerolactam, polyvinylcaprolactam (PVCap), polyamide, or polyimide and;
where ‘m’ can have values between 1 and 10, and preferably is between a value of 2 and 4.

2 . The microporous battery separator membrane coated with a polylactam ceramic coating of claim 1 where the ‘m’ in the polylactam can have values between 1 and 10, preferably between a value of 2 and 4, for example;
when m=2, the polylactam is polyvinylpyrrolidone (PVP) with the chemical structure:

and when m=4, the polylactam is polyvinyl caprolactam (PVCap) with the chemical structure:

3 . The microporous battery separator membrane of claim 1 coated with a polylactam ceramic coating where the optimal range of molecular weight of the polylactam is in the range of 200,000 to 3,500,000, more preferably in the molecular weight range of 300,000 to 2,500,000 and most preferably in the molecular weight range of 300,000 to 2,000,000 g/mol.

4 . The microporous battery separator membrane of claim 1 coated with a polylactam ceramic coating where additive is added in a preferred range of 0.1 to 90 weight percent compared to polylactam, more preferably in the range of 0.1 to 50 weight percent compared to polylactam and most preferably in the range of 0.1 to 20 weight percent compared to polylactam.

5 . The microporous battery separator membrane coated with a polylactam ceramic coating of claim 1 where solvent in the ceramic coating slurry is water or water in an aqueous mixture containing a primary or secondary or tertiary alcohol.

6 . The microporous battery separator membrane of claim 1 coated with a polylactam ceramic coating where the preferred ceramic coating formulation is polylactam where an additive polyvinyl alcohol is added in a preferred range of 0.1 to 90 weight percent compared to polylactam, more preferably in the range of 0.1 to 50 weight percent compared to polylactam and most preferably in the range of 0.1 to 20 weight percent compared to polylactam.

7 . The microporous battery separator membrane of claim 1 coated with a polylactam ceramic coating where the preferred coating formulation has a ceramic to polylactam is added in a preferred range of 0.1 to 50 weight percent compared to ceramic, more preferably in the range of 0.1 to 20 weight percent compared to ceramic and most preferably in the range of 0.1 to 10 weight percent compared to ceramic.

8 . The microporous battery separator membrane coated with a polylactam ceramic coating of claim 1 where solid in water in the ceramic coating slurry ranges preferably in a preferred range of 1 to 90 weight percent, more preferably in the range of 1 to 70 weight percent and most preferably in the range of 1 to 50 weight percent.

9 . The microporous battery separator membrane coated with a polylactam ceramic coating of claim 1 where the base microporous separator membrane is a polyolefin, where the preferred polyolefin is polypropylene, polyethylene, polymethylpentene, polybutylene, and/or blends, mixtures thereof and their copolymers and combinations thereof.

10 . The microporous battery separator membrane coated with a polylactam ceramic coating of claim 1 where the base microporous separator membrane can be made using a dry stretch process or a wet process or can be a non-woven membrane.

11 . The microporous battery separator membrane coated with a polylactam ceramic coating in claim 1 further comprising ceramic particles where said ceramic particles may be organic or inorganic where non-limiting examples are silicon oxide (SiO 2 ), aluminum oxide (Al 2 O 3 ), boehmite (Al(O)OH), zirconium oxide, titanium dioxide (TiO 2 ), barium sulfate (BaSO 4 ), and oxides of transition metals and the like or mixtures thereof.

12 . The microporous battery separator membrane of claim 11 coated with a polylactam ceramic coating where the average particle size of the ceramic particles ranges from 0.05 to 4 μm in diameter, more preferably from 0.02 to 3 μm in diameter, and most preferably from 0.01 to 2 μm in diameter.

13 . The microporous battery separator membrane of claim 1 coated with a polylactam ceramic coating where the thickness of the coating layer is ≦10 μm, more preferably is ≦7 μm and most preferably ≦5 μm.

14 . The microporous battery separator membrane of claim 1 coated with a polylactam ceramic coating where the machine direction thermal shrinkage at 150° C. for 1 hour is ≦9%, more preferably ≦7% and most preferably ≦5%.

15 . The microporous battery separator membrane of claim 1 coated with a polylactam ceramic coating where the machine direction thermal shrinkage at 150° C. for 10 minutes is ≦9%, more preferably ≦7% and most preferably ≦5%.

16 . The microporous battery separator membrane of claim 1 coated with a polylactam ceramic coating where the transverse direction thermal shrinkage at 150° C. for 1 hour is ≦9%, more preferably ≦7% and most preferably ≦5%.

17 . The microporous battery separator membrane of claim 1 coated with a polylactam ceramic coating where the transverse direction thermal shrinkage at 150° C. for 10 minutes is ≦9%, more preferably ≦7% and most preferably ≦5%.

18 . The microporous battery separator membrane of claim 1 coated with a polyvinylpyrrolidone ceramic coating where the optimal range of molecular weight of the polylactam is in the range of 200,000 to 3,500,000, more preferably in the molecular weight range of 300,000 to 2,500,000 and most preferably in the molecular weight range of 300,000 to 2,000,000 g/mol.

19 . The microporous battery separator membrane of claim 1 coated with a polyvinylpyrrolidone ceramic coating where the additive is added in a preferred range of 0.1 to 90 weight percent compared to polyvinylpyrrolidone, more preferably in the range of 0.1 to 50 weight percent compared to polyvinylpyrrolidone and most preferably in the range of 0.1 to 20 weight percent compared to polyvinylpyrrolidone.

20 . The microporous battery separator membrane coated with a polyvinylpyrrolidone ceramic coating of claim 1 where solvent in the ceramic coating slurry is water or water in an aqueous mixture containing a primary or secondary or tertiary alcohol.

21 . The microporous battery separator membrane of claim 1 coated with a polyvinylpyrrolidone ceramic coating where the preferred ceramic coating formulation is polyvinylpyrrolidone where an additive polyvinyl alcohol is added in a preferred range of 0.1 to 90 weight percent compared to polyvinylpyrrolidone, more preferably in the range of 0.1 to 50 weight percent compared to polyvinylpyrrolidone and most preferably

Assignees

• Celgard Llc

Inventors

• Jeon Insik

Classifications

• H01M50/417 Primary

  Polyolefins · CPC title

• H01M50/449

  having a layered structure · CPC title

• H01M50/489

  Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties · CPC title

• H01M2/1653

  Electricity · mapped topic

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title