PTAB

IPR2014-00680

SK Innovation Co Ltd v. Celgard LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Separator for High Energy Lithium Battery
  • Brief Description: The ’586 patent discloses a multi-layer separator for use in high-energy rechargeable lithium batteries. The separator is designed to enhance safety by comprising at least one ceramic composite layer to block dendrite growth and prevent electronic shorting, and at least one polyolefinic microporous layer to provide a thermal shut-down function.

3. Grounds for Unpatentability

Ground 1: Obviousness over JP '674 and the '730 patent - Claims 1-6 and 11(1-6) are obvious over JP '674 in view of the '730 patent.

  • Prior Art Relied Upon: JP ’674 (Japanese Patent Application Publication No. 11-283674) and the ’730 patent (Patent 4,650,730).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that JP ’674 disclosed a separator for lithium batteries comprising a gel-like electrolyte membrane that meets the limitations of the claimed "ceramic composite layer." This membrane is a composite of a polymer (matrix material) and solid microparticles (inorganic particles) and is disclosed as a solution for preventing electronic shorting. While JP ’674 disclosed a polyolefin separator, Petitioner asserted that the ’730 patent supplied the explicit teaching of a "microporous" polyolefinic layer. The ’730 patent described a microporous polyethylene separator that provides a "shut-down" function by drastically reducing porosity at elevated temperatures, thereby blocking ionic flow to prevent thermal runaway.
    • Motivation to Combine: Petitioner contended that a person of ordinary skill in the art (POSITA) would combine these references because both addressed the same known problem of improving the high-temperature reliability and safety of lithium batteries. A POSITA would have been motivated to substitute the basic separator in JP ’674 with the well-known microporous polyolefinic separator from the ’730 patent to incorporate its superior thermal shut-down safety feature.
    • Expectation of Success: The combination involved substituting one known separator type for another to achieve a predictable improvement in safety. Because the ’730 patent explicitly taught the desired shut-down functionality, a POSITA would have had a reasonable expectation of success.

Ground 2: Obviousness over JP '674, the '730 patent, and the '114 patent - Claims 7-10, 11(7-10), and 12 are obvious over JP '674 in view of the '730 patent and the '114 patent.

  • Prior Art Relied Upon: JP ’674, the ’730 patent, and the ’114 patent (Patent 5,654,114).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the combination of JP ’674 and the ’730 patent to establish the basic two-layer separator structure. The ’114 patent was added to teach the specific physical properties of the polyolefinic microporous layer recited in claims 7 and 12, namely a porosity of 20-80%, an average pore size of 0.02 to 2 microns, and a Gurley Number of 15 to 150 seconds. Petitioner asserted the ’114 patent disclosed a microporous polyolefin sheet with a porosity (35-40%), maximum pore size (0.05 to 0.15 µm), and air permeability (25 to 60 sec/10 cc) that fall squarely within the claimed ranges.
    • Motivation to Combine: A POSITA, seeking to optimize the separator taught by the primary combination, would have been motivated to use a microporous layer with the properties described in the ’114 patent. The ’114 patent taught that these properties provided desirable advantages such as high ion permeability and prescribed mechanical strength. The ’586 patent itself acknowledged that such properties were found in commercially available membranes, suggesting their selection was a matter of routine optimization.
    • Expectation of Success: The combination represented a predictable result of selecting a known microporous membrane with well-understood properties to optimize separator performance. The claimed property ranges were not associated with any unexpected benefits, and success in achieving them was reasonably expected.

Ground 3: Obviousness over JP '674, the '730 patent, and JP '395 - Claims 7-10, 11(7-10), and 12 are obvious over JP '674 in view of the '730 patent and JP '395.

  • Prior Art Relied Upon: JP ’674, the ’730 patent, and JP ’395 (Japanese Patent Application Publication No. 11-80395).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground presented an alternative to Ground 2, using JP ’395 instead of the ’114 patent to teach the specific physical properties of the microporous layer. Petitioner argued that JP ’395 disclosed a polyolefin microporous membrane with a porosity of 10-90% (typically 40-50%), a pore diameter of 0.1 to 1.0 µm, and a permeability corresponding to a Gurley Number up to 400 sec/10 cc. These disclosed ranges encompass or overlap with the ranges recited in claims 7 and 12.
    • Motivation to Combine: A POSITA would combine the teachings because JP ’395 explicitly promoted its microporous layer for providing advantages directly relevant to the problems addressed by JP ’674 and the ’730 patent. These advantages included low electrical resistance, excellent shut-down function, and high thermal conductivity, which would improve the overall safety and performance of the separator.
    • Expectation of Success: The motivation to combine was strong, as a POSITA would be implementing a known solution taught by JP ’395 to solve a known problem. The outcome was predictable, and there was a high expectation of success in achieving a separator with the combined characteristics.

4. Key Claim Construction Positions

  • Preambles: Petitioner argued that the preambles of the independent claims (e.g., "A separator for a high energy rechargeable lithium battery") were not claim limitations. The argument was that the preambles merely stated a purpose or intended use for a structurally complete invention defined in the body of the claims and provided no antecedent basis for any claim terms.
  • "Matrix material": Petitioner asserted that the term "matrix material" required no special construction and should be given its plain and ordinary meaning: "a material in which something is enclosed or embedded." This interpretation was argued to be consistent with the specification and dictionary definitions.

5. Relief Requested

  • Petitioner requested the institution of an inter partes review (IPR) and the cancellation of claims 1-12 of the ’586 patent as unpatentable under 35 U.S.C. §103.