PTAB

IPR2017-02115

Samsung SDI Co., Ltd. v. UBE Industries, Ltd

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1. Case Identification

2. Patent Overview

  • Title: LITHIUM SECONDARY BATTERY AND ELECTROLYTE THEREOF
  • Brief Description: The ’809 patent is directed to a non-aqueous electrolyte for a lithium secondary battery. The purported invention involves adding 0.1% to 4% by weight of a sultone derivative to a non-aqueous solvent, which contains a cyclic carbonate and a linear carbonate as main components, to suppress the decomposition of the electrolyte.

3. Grounds for Unpatentability

Ground 1: Obviousness over Simon-161 and Simon-93 - Claims 2-8, 10-12, 14-15, and 17-24 are obvious over Simon-161 in view of Simon-93.

  • Prior Art Relied Upon: Simon-161 (French Patent Application Publication No. 2719161) and Simon-93 (B. Simon et al., “Electrochemical study of the passivating layer on lithium intercalated carbon electrodes in nonaqueous solvents,” J. Power Sources (1993)).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Simon-161 discloses all elements of the base claims except for the specific concentration range of the sultone additive. Simon-161 teaches a lithium-ion battery with a graphite anode, a lithium complex oxide cathode, and a non-aqueous electrolyte containing a mixture of cyclic and linear carbonates. It further teaches adding a sultone (e.g., propane sultone) to this electrolyte to form a passivation layer and prevent exfoliation of the graphite anode, disclosing a general additive range of 0.01% to 10% by weight. Simon-93, authored by the same inventors as Simon-161, discloses using 0.1M propane sultone (calculated by Petitioner to be 1.1% by weight) as an additive in a similar electrolyte system, which improved the stability of the passivation layer. Petitioner asserted that this 1.1% concentration falls squarely within the ’809 patent’s claimed range of 0.1% to 4%.
    • Motivation to Combine: A POSITA would combine the teachings of Simon-161 and Simon-93 because they were written by the same authors, are directed to solving the identical problem of graphite anode exfoliation in lithium-ion batteries, and propose the same solution of using sultone additives to form a stable passivation layer. As Simon-161 provides a general disclosure of sultone additives, a POSITA would have looked to the more specific teachings in the related Simon-93 publication to determine an effective and optimal concentration, finding the explicit disclosure of 1.1% by weight propane sultone.
    • Expectation of Success: Because Simon-93 demonstrated that adding 1.1% propane sultone resulted in improved stability (i.e., a lower self-discharge rate), a POSITA would have had a reasonable expectation of success in applying this specific concentration to the battery system of Simon-161 to improve the stability of its passivation layer.

Ground 2: Obviousness over Simon-161 and Shishikura - Claims 2-8, 10-12, 14-15, and 17-24 are obvious over Simon-161 in view of Shishikura.

  • Prior Art Relied Upon: Simon-161 (French Patent Application Publication No. 2719161) and Shishikura (Japanese Patent Publication No. 62-100948).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted again that Simon-161 teaches the fundamental battery structure and electrolyte composition. The missing limitation—the specific concentration of the sultone additive—is supplied by Shishikura. Shishikura teaches adding butane sultone or propane sultone to a non-aqueous electrolyte to form a protective layer on the anode and prevent electrolyte decomposition. Shishikura discloses a desirable concentration range of 0.1 to 2 vol.%, which Petitioner calculated to correspond to 0.13 to 2.7% by weight. This disclosed range overlaps with and is taught within the ’809 patent’s claimed range of 0.1% to 4% by weight.
    • Motivation to Combine: A POSITA would combine these references as both are in the field of lithium secondary battery electrolytes and address the common problem of solvent decomposition at the anode. Shishikura expressly teaches that adding a sultone in the preferred 0.1 to 2 vol.% range yields significant benefits, including improved charging/discharging efficiency and lower self-discharge. A POSITA seeking to optimize the sultone additive generally disclosed in Simon-161 would have been motivated to use the specific, beneficial concentration ranges taught by Shishikura.
    • Expectation of Success: Although Shishikura uses an alkali metal anode instead of graphite, Petitioner argued both references teach that sultones form a protective passivation layer to prevent reductive decomposition of the solvent. Because both references teach the same mechanism and Shishikura demonstrates the beneficial effects of using a specific, overlapping concentration range of sultone, a POSITA would have had a reasonable expectation of success in modifying the electrolyte of Simon-161 with the concentration taught in Shishikura.

4. Key Claim Construction Positions

  • "...wherein R¹, R², R³, R⁴, R⁵ and R⁶ independently represent...": Petitioner argued this term should be construed to mean that the R groups may be each independently selected. This construction is supported by examples in the ’809 patent specification where the R groups on the sultone molecule are different (e.g., 2,4-pentane sultone). A narrower construction would be inconsistent with the patent's own disclosures.
  • "graphite": Petitioner argued this term should be construed as "natural or artificial graphite." This construction is supported by the specification's explicit mention of both types of graphite for use in the anode and by the language of amended claims from a prior reexamination.

5. Relief Requested

  • Petitioner requested that the Board institute an inter partes review (IPR) and cancel claims 2-8, 10-12, 14-15, and 17-24 of the ’809 patent as unpatentable.