EVE Energy Co., Ltd. v. VARTA Microbattery GmbH

1. Case Identification

• Case #: IPR2023-00160
• Patent #: 11,024,869
• Filed: November 8, 2022
• Petitioner(s): EVE ENERGY CO., LTD.
• Patent Owner(s): VARTA MICROBATTERY GMBH
• Challenged Claims: 1-30

2. Patent Overview

• Title: Button Cell Battery with Wound Electrode Assembly
• Brief Description: The ’869 patent discloses a lithium-ion button cell battery comprising a housing (cell cup and cell top) and an internal electrode-separator assembly. The assembly is a multi-layer structure of positive and negative electrodes with a separator, wound into a spiral. The invention’s focus is on the configuration of the electrode leads, where uncoated portions of the metallic electrode films are bent to extend from the winding and are welded to the flat interior surfaces of the housing to serve as terminals.

3. Grounds for Unpatentability

Ground 1: Obviousness over Higuchi, Kobayashi, and Okochi - Claims 1-8, 10, 18-19, 22-27, and 30

• Prior Art Relied Upon: Higuchi (Chinese Patent Publication No. CN101286572A), Kobayashi (Japanese Patent Publication No. JP2007294111A), and Okochi (European Patent No. EP0829105B1).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner asserted that the primary reference, Higuchi, discloses the fundamental structure of a button cell with a spirally wound electrode-separator assembly (claim 1D) and uncoated electrode leads. However, Petitioner argued Higuchi’s design, where both terminals are on the top surface, poses a significant risk of short-circuiting. To resolve this, a person of ordinary skill in the art (POSITA) would replace Higuchi’s housing with the housing from Kobayashi. Kobayashi teaches a more stable and space-efficient housing with a cell cup and cell top that serve as opposing terminals, physically separating them to prevent short-circuits (claims 1A-1C). To connect Higuchi’s electrode leads to Kobayashi’s housing, a POSITA would look to Okochi, which explicitly teaches bending electrode leads to lie flat between the winding face and the housing surface and then welding them (claims 1F, 1G, 1I). The combination of these three references allegedly renders the limitations of independent claim 1 and numerous dependent claims obvious.
  • Motivation to Combine: A POSITA would combine these references to solve a known problem. They would replace Higuchi's risky housing with Kobayashi's safer, more robust housing design, which was a known alternative for button cells. The motivation to then incorporate Okochi was to use a known, reliable method for connecting the electrode leads to the flat surfaces of the newly adopted housing, which was a simple and predictable design modification.
  • Expectation of Success: A POSITA would have had a reasonable expectation of success because the combination involves substituting known components (housings) and applying a standard manufacturing technique (lead welding per Okochi) to analogous battery structures. The result was a predictable improvement in safety and space efficiency without altering the fundamental operating principle of the wound battery cell.

Ground 2: Obviousness over Higuchi, Kobayashi, and Okochi in view of Bennett - Claim 9

• 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 Higuchi-Kobayashi-Okochi combination from Ground 1, which establishes the overlapping housing structure of claim 8. Claim 9 adds a specific dimensional limitation, requiring the height of the overlap area to be between 20% and 99% of the cell top casing's height. Petitioner argued that while the primary combination teaches the structure, Bennett explicitly discloses these specific dimensional ratios for a nearly identical button cell housing.
  • Motivation to Combine: A POSITA, having constructed the battery of Ground 1, would consult a reference like Bennett for conventional and proven dimensional relationships for such housings. The motivation was simply to implement a known, functional geometric ratio to ensure proper sealing and structural integrity, which is a routine design choice.

Ground 3: Obviousness over Higuchi, Kobayashi, and Okochi in view of Brenner - Claims 11-17, 20, and 29

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

• Core Argument for this Ground:

  • Prior Art Mapping: This ground addresses claims related to the insulating seal, including its compression, thickness, and the formation of an interference fit. Petitioner asserted that the core combination provides a basic gasket seal (from Kobayashi). Brenner was introduced because it teaches specific enhancements to such seals in button cells, including using a film seal of a particular thickness (claims 12-14, 20), compressing it to a specific percentage of its initial thickness (claim 11), and drawing a portion of the cell cup casing inward to create an interference fit that improves sealing (claims 15-17).
  • Motivation to Combine: A POSITA would be motivated to incorporate Brenner’s teachings to improve the sealing characteristics and capacity of the battery from Ground 1. Using a thinner, compressible film seal and creating an indent for an interference fit were known techniques taught by Brenner to achieve better sealing and a more compact design.

• Additional Grounds: Petitioner asserted additional obviousness challenges, arguing claim 21 is obvious over the primary combination in view of Kubota (Patent 5,654,114) for teaching the addition of a winding core, and claim 28 is obvious over the primary combination in view of Kaun (Application # 2007/0160901) for teaching a non-beaded sealing mechanism that increases internal volume.

4. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under 35 U.S.C. §314(a) pursuant to the Fintiv factors would be inappropriate. The petition asserted that the parallel district court litigation was in a nascent stage, with minimal investment by the parties and the court, and a trial date set for well after the statutory deadline for a Final Written Decision (FWD). Petitioner further contended that the strong and compelling merits of the unpatentability grounds weigh heavily in favor of institution. Finally, 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 an inter partes review and cancellation of claims 1-30 of Patent 11,024,869 as unpatentable.