PTAB

IPR2023-00160

Eve Energy Co Ltd v. VARTA Microbattery GmbH

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Button Cell
  • Brief Description: The ’869 patent discloses a button cell battery containing an electrode-separator assembly wound in a spiral shape. The design features a metallic film from an electrode that is bent to extend out from the winding, serving as an output conductor that is welded to the cell housing.

3. Grounds for Unpatentability

Ground 1: Claims 1-4, 6-10, 18-19, 22-27, and 30 are obvious over Higuchi, Kobayashi, and Okochi.

  • Prior Art Relied Upon: Higuchi (Chinese Patent Pub. No. CN101286572A), Kobayashi (Japanese Patent Pub. No. JP2007294111A), and Okochi (European Patent No. EP0829105B1).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Higuchi discloses the core wound electrode-separator assembly for a button cell. The combination replaces Higuchi’s housing with Kobayashi’s housing, which provides a cell cup and cell top that form the battery’s terminals on opposite ends. The combination then applies Okochi’s teachings to bend Higuchi’s uncoated electrode leads (output conductors) to lie flat between the winding end faces and the internal surfaces of Kobayashi's housing, where they are welded.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine the references to solve known problems. First, a POSITA would replace Higuchi’s housing with Kobayashi’s more stable design to mitigate a clear risk of short-circuiting, as Higuchi’s design places insulated positive and negative terminals in close proximity on the same side of the cell. Kobayashi’s design physically separates the terminals on opposite ends of the battery, improving safety and enabling more efficient use of internal space. Second, a POSITA would incorporate Okochi’s technique of routing electrode leads from opposite faces of the winding and welding them to the housing. This was a known method to create stable electrical connections in a compact design, which would have been a natural way to connect Higuchi’s leads to Kobayashi’s housing.
    • Expectation of Success: Petitioner asserted that combining these elements would have been a predictable implementation of known design principles. Replacing a battery housing and modifying electrode lead routing are standard modifications in battery design, and a POSITA would expect the resulting combination to function as intended without altering the fundamental operating principle of the wound cell.

Ground 2: Claim 9 is obvious over Higuchi, Kobayashi, and Okochi, in further view of Bennett.

  • Prior Art Relied Upon: Higuchi, Kobayashi, Okochi, and Bennett (European Patent No. EP1266413B1).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground builds on the combination in Ground 1. Claim 9 adds a limitation that the height of the overlapping area between the cell cup casing and cell top casing is from 20% to 99% of the cell top casing’s height. While Kobayashi illustrates such an overlap, Bennett explicitly discloses dimensions for a similar button cell housing where the overlap height is approximately 92% of the total height, falling squarely within the claimed range.
    • Motivation to Combine: A POSITA, having created the primary combination, would look to analogous art like Bennett for specific, optimized dimensional relationships. Since Bennett describes a similar housing geometry, applying its proven dimensions to the combined design would be an obvious and predictable design choice to ensure a robust seal and structure.

Ground 3: Claims 11-17, 20, and 29 are obvious over Higuchi, Kobayashi, and Okochi, in further view of Brenner.

  • Prior Art Relied Upon: Higuchi, Kobayashi, Okochi, and Brenner (German Patent Pub. No. DE102005058132A1).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground challenges claims related to the insulating seal. The primary combination discloses a gasket (from Kobayashi). Brenner teaches a button cell with a film seal and provides specific details recited in the dependent claims, including seal compression ratios (10% to 90%), initial thickness ranges (e.g., 50-250 µm), and forming an interference fit by drawing a portion of the cell cup casing radially inward.
    • Motivation to Combine: A POSITA would have been motivated to incorporate Brenner’s seal characteristics into the primary combination to achieve "significant capacity improvement" and "better sealing characteristics," as taught by Brenner. The seals in all references perform the same function, making Brenner’s specific teachings an obvious improvement to apply to the analogous structure from Kobayashi.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including:

    • Claim 21 over the primary combination in view of Kubota (Patent 5,654,114), which teaches adding a winding core to prevent the winding from expanding.
    • Claim 28 over the primary combination in view of Kaun (Application # 2007/0160901), which teaches using an insert-molded gasket for a non-beaded, gas-tight seal that improves energy density.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under Fintiv is inappropriate. The parallel district court litigation is in its early stages, with the trial date scheduled well after the statutory deadline for a Final Written Decision in the IPR. Petitioner contended that party and judicial investment in the litigation has been minimal. Furthermore, Petitioner stipulated that if the IPR is instituted, it will not pursue the same invalidity grounds in the parallel proceeding, mitigating any overlap.

5. Relief Requested

  • Petitioner requests institution of inter partes review and cancellation of claims 1-30 of the ’869 patent as unpatentable.