Eve Energy Co Ltd v. VARTA Microbattery GmbH

1. Case Identification

• Case #: IPR2021-00474
• Patent #: 9,496,581
• Filed: February 2, 2021
• Petitioner(s): Eve Energy Co., Ltd.
• Patent Owner(s): VARTA Microbattery GmbH
• Challenged Claims: 1-13

2. Patent Overview

• Title: Button Cells and Method of Producing Same
• Brief Description: The ’581 patent discloses button cell batteries with a spirally wound electrode-separator assembly. The patent’s asserted novelty is orienting the electrode layers at a right angle to the flat top and bottom of the cell housing to improve resistance to axial mechanical loads that occur during charging and discharging cycles.

3. Grounds for Unpatentability

Ground 1: Obviousness of Claims 1-12 over Brown, Higuchi, Arai, and Okochi

• Prior Art Relied Upon: Brown (Patent 3,748,182), Higuchi (Chinese Publication # CN 101286572), Arai (Application # 2006/0124973), and Okochi (EP 0829105).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Brown taught the core invention: a button cell with a spirally wound electrode assembly where the electrode layers are aligned at right angles to the flat top and bottom of the housing. To the extent Brown was ambiguous, Higuchi was argued to explicitly disclose using strip-shaped electrodes in a spiral winding to maximize battery capacity and prevent deformation. Petitioner further argued that Arai and Okochi taught the claimed output conductor, disclosing metal foil tabs that are welded to an electrode and folded to rest flat between an end face of the spiral winding and the housing. The dependent claims were argued to be obvious as they recited well-known battery features, such as specific layer sequences (disclosed by Brown and Higuchi) and the use of plastic insulators (disclosed by Brown and Arai).
  • Motivation to Combine: A POSITA would combine these references to solve two known problems in the art. First, a POSITA would use the right-angled winding orientation taught by Brown and Higuchi to address battery deformation from electrode expansion during charging cycles. Second, a POSITA would use strip-shaped electrodes (Higuchi) and flat foil conductors (Arai, Okochi) to maximize the active volume within the battery housing, a well-established goal in battery design.
  • Expectation of Success: A POSITA would have a reasonable expectation of success because all references are in the same field of battery design and involve combining known elements to achieve predictable results, such as improved durability and capacity.

Ground 2: Obviousness of Claim 13 over Brown, Higuchi, Arai, Okochi, and Kageyama

• Prior Art Relied Upon: Brown (Patent 3,748,182), Higuchi (Chinese Publication # CN 101286572), Arai (Application # 2006/0124973), Okochi (EP 0829105), and Kageyama (Japanese Publication # H07-153488).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground adds Kageyama to the combination from Ground 1 to address method claim 13, which recites heat-treating the winding on its end faces before installation. Petitioner argued that Okochi disclosed heat-treating the electrode group with hot air to shrink protruding portions of the separator. Kageyama was argued to supplement this by explicitly teaching heat molding of separator layers at a temperature that softens but does not melt the material, making it thermoplastically deformable as required by the claim.
  • Motivation to Combine: A POSITA would be motivated to add the heat-treatment step from Okochi and Kageyama to the manufacturing process of the button cell from Ground 1. This was presented as the application of a known technique (thermoforming separator layers) to a known device (a spirally wound electrode assembly) to achieve the predictable result of molding the separator for a better fit within the housing.
  • Expectation of Success: Success would be expected, as applying heat to thermoformable plastic separators was a well-known technique to manipulate their shape in battery manufacturing.

Ground 3: Anticipation of Claims 1-2, 4-5, and 8-11 by Kano

• Prior Art Relied Upon: Kano (Japanese Publication # P2003-31266A).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Kano, by itself, disclosed every limitation of the challenged claims. Kano was asserted to teach a "flat non-aqueous secondary battery" (a button cell) containing a spirally wound electrode group. Petitioner contended that Kano's figures clearly show the electrode layers aligned at right angles to the flat housing top and bottom. Furthermore, Kano was argued to disclose an output conductor comprising a foil (current collectors 6 and 7) bent at 90 degrees to rest flat between the end face of the winding and the inner surface of the housing can, thus meeting all limitations of independent claim 1 and the challenged dependent claims.

4. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §325(d) would be improper because the primary reference, Brown, and three other references were never before the Examiner during prosecution or in any other proceeding.
• Petitioner argued against denial under §314(a) (General Plastic factors), stating it has no involvement or control over a separate, instituted IPR on the ’581 patent (IPR2020-01211). Therefore, it cannot control whether those parties settle, which could adversely affect Petitioner. The asserted prior art was also argued to be non-cumulative.

5. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-13 of the ’581 patent as unpatentable.