2:21-cv-00399
VARTA Microbattery GmbH v. Eve Energy Co Ltd
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: VARTA Microbattery GmbH (Germany)
- Defendant: EVE Energy Co., Ltd. (China)
- Plaintiff’s Counsel: Leydig, Voit & Mayer, Ltd.; Ramey & Flock, PC
- Case Identification: 2:21-cv-00399, E.D. Tex., 10/25/2021
- Venue Allegations: Plaintiff alleges venue is proper in any judicial district because Defendant is a foreign corporation.
- Core Dispute: Plaintiff alleges that Defendant’s rechargeable lithium-ion coin cell batteries infringe six U.S. patents related to the internal construction and manufacturing of microbatteries.
- Technical Context: The technology concerns the internal architecture of small, high-density rechargeable batteries, a critical component market for compact consumer electronics such as wireless earbuds and other wearable devices.
- Key Procedural History: The complaint alleges that Defendant had pre-suit knowledge of certain patents-in-suit due to prior litigation Plaintiff filed against one of Defendant’s customers in February 2020. It also notes that Defendant filed a petition for inter partes review of the ’581 Patent in February 2021 and sought to invalidate a Chinese counterpart to the asserted family in June 2020, suggesting a history of engagement with Plaintiff's patent portfolio.
Case Timeline
| Date | Event |
|---|---|
| 2009-02-09 | Priority Date for ’835, ’581, ’913, ’869 Patents |
| 2009-06-18 | Priority Date for ’904, ’905 Patents |
| 2015-10-06 | U.S. Patent No. 9,153,835 Issues |
| 2016-11-15 | U.S. Patent No. 9,496,581 Issues |
| 2017-10-24 | U.S. Patent No. 9,799,913 Issues |
| 2020-02-05 | Alleged date of Defendant's knowledge of ’835, ’581, ’913 Patents via suit against its customer |
| 2020-06-09 | Defendant allegedly files invalidation petition for Chinese counterpart patent |
| 2021-02-02 | Defendant files petition for inter partes review of the ’581 Patent |
| 2021-06-01 | U.S. Patent Nos. 11,024,869, 11,024,904, and 11,024,905 Issue |
| 2021-10-25 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 9,153,835 - Button Cells and Method for Producing Same
The Invention Explained
- Problem Addressed: Traditional button cells with flat, stacked electrodes are susceptible to leaking. This is particularly true for rechargeable lithium-ion systems where electrodes physically swell and shrink during charging and discharging, creating axial mechanical stress on the battery's seals (’869 Patent, col. 1:43-col. 2:14).
- The Patented Solution: The invention reorients the internal components. Instead of stacking flat electrode discs, it uses a spirally wound electrode-separator assembly where the flat layers are aligned "essentially at right angles" to the flat top and bottom of the housing (’835 Patent, Abstract). As shown in patent Figures 3b and 4, this structure converts the problematic axial forces from electrode swelling into radial forces, which the cylindrical housing can better withstand, thereby improving sealing and reliability (’869 Patent, col. 4:1-9).
- Technical Importance: This design allows for the creation of more robust, higher-density rechargeable coin cells suitable for demanding applications where space is limited and mechanical integrity is critical (Compl. ¶15).
Key Claims at a Glance
- The complaint asserts independent claims 1 and 10.
- Essential elements of independent claim 1 include:
- A housing cup and a housing top separated by an insulating seal, forming a housing with a flat bottom and top area.
- An electrode-separator assembly within the housing with positive and negative electrodes as flat layers.
- The electrode layers are "aligned essentially at right angles to the flat bottom area and the flat top area."
- The button cell is "closed without being beaded over."
- An insulator is arranged between the end faces of the spiral winding and the housing.
- The complaint reserves the right to assert dependent claims (Compl. ¶41).
U.S. Patent No. 9,496,581 - Button Cells and Method of Producing Same
The Invention Explained
- Problem Addressed: Within a wound-electrode battery, establishing a reliable, space-efficient electrical connection between the spirally wound internal electrodes and the external flat housing terminals can be complex, often requiring additional components that consume valuable internal volume (’869 Patent, col. 2:1-4).
- The Patented Solution: The patent describes a specific connection method for a battery with a wound-electrode structure. The invention claims an "output conductor," such as a thin foil, that rests flat between an end face of the spiral winding and the corresponding flat housing surface (e.g., the top or bottom) to which it connects (’581 Patent, Abstract; ’835 Patent, col. 6:3-13). This creates a direct, large-surface-area electrical contact without requiring complex or bulky connectors.
- Technical Importance: This approach simplifies manufacturing and maximizes the internal volume available for active electrode material, contributing to higher power density (Compl. ¶15).
Key Claims at a Glance
- The complaint asserts independent claims 1 and 10.
- Essential elements of independent claim 1 include:
- A housing with a flat bottom and top area.
- A spiral winding electrode-separator assembly inside.
- The electrode layers are aligned "essentially at right angles" to the flat bottom and top areas.
- One of the electrodes connects to the housing via an "output conductor comprising a foil resting flat between an end face of the spiral winding and the flat top or the flat bottom area to which it is connected."
- The complaint reserves the right to assert dependent claims (Compl. ¶56).
U.S. Patent No. 9,799,913 - Button Cells and Method of Producing Same
Technology Synopsis
This patent, part of the same family as the ’835 and ’581 Patents, also covers a button cell with a spirally wound electrode assembly oriented orthogonally to the housing surfaces. The claims focus on the combination of this structure with an output conductor foil and an insulator that prevents direct mechanical and electrical contact between the winding and the housing, addressing potential short circuits (Compl. ¶¶78-79).
Asserted Claims
Independent claims 1, 4, and 6 are asserted (Compl. ¶72).
Accused Features
The complaint alleges the EVE batteries contain a spirally wound electrode assembly where at least one electrode connects to the housing via a foil resting between the winding and the housing, and an insulator prevents direct contact (Compl. ¶¶78-79).
U.S. Patent No. 11,024,869 - Button Cells and Method of Producing Same
Technology Synopsis
This patent further details the structure of the output conductor. It claims a metallic film or mesh that is part of the electrode itself being bent to extend out from the electrode winding. This bent portion then lies flat between the winding and the housing and is welded to the housing to form the electrical connection (’869 Patent, Abstract).
Asserted Claims
Independent claim 1 is asserted (Compl. ¶85).
Accused Features
The complaint alleges the EVE batteries use a metallic film from an electrode that is bent to extend out of the winding, lies flat against the housing, and is welded to it, serving as an output conductor (Compl. ¶¶89, 91).
U.S. Patent No. 11,024,904 - Button Cell Having Winding Electrode and Method For the Production Thereof
Technology Synopsis
This patent focuses on the specific method of electrical connection. It claims a current collector (a metal foil or mesh) that has an uncoated section directly connected to a housing component via "one or more spot welded connections and/or linear welded connections." It further specifies that these welded connections are located in a subregion adjacent to the central open cavity of the winding (’904 Patent, col. 11:45-col. 12:17).
Asserted Claims
Independent claims 1, 11, and 17 are asserted (Compl. ¶97).
Accused Features
The complaint alleges that the EVE batteries use current collectors with uncoated sections that are directly connected to the housing via spot or linear welds (Compl. ¶102).
U.S. Patent No. 11,024,905 - Button Cell Having Winding Electrode and Method For the Production Thereof
Technology Synopsis
This patent claims a structure with two distinct current collectors for the positive and negative electrodes. Each collector has an end section that is bent to extend out of the electrode winding, forming an uncoated flat layer. These flat layers are adjacent to opposite end sides of the winding and are each welded to a corresponding housing surface (’905 Patent, Abstract).
Asserted Claims
Independent claim 1 is asserted (Compl. ¶111).
Accused Features
The complaint alleges that the EVE batteries include first and second current collectors with bent end sections that form uncoated flat layers, which are in turn welded to the housing surfaces (Compl. ¶¶116-119).
III. The Accused Instrumentality
Product Identification
The accused products are rechargeable lithium-ion button or coin cell batteries sold by Defendant, including at least part numbers ICR 1254, ICR 1240, and ICR 1454 (collectively "the EVE batteries") (Compl. ¶28, ¶32).
Functionality and Market Context
The complaint alleges the EVE batteries contain a housing cup and a housing top enclosing an "electrode-separator assembly" (Compl. ¶29-¶30). An image provided in the complaint shows this internal assembly as a spirally wound structure. (Compl. ¶29). A second image depicts the external cylindrical housing of the accused battery. (Compl. ¶29). These batteries are allegedly incorporated into electronic devices such as wireless earphones sold in the U.S. market, positioning them as components for the high-volume consumer electronics industry (Compl. ¶36).
IV. Analysis of Infringement Allegations
9,153,835 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A button cell comprising: a housing cup and a housing top separated from one another by an electrically insulating seal and which form a housing with a flat bottom area and a flat top area parallel to it... | The EVE batteries have a housing cup and housing top separated by an insulating seal, forming a housing with a flat bottom and top area. | ¶44 | col. 3:25-33 |
| an electrode-separator assembly within the housing comprising at least one positive and at least one negative electrode in the form of flat layers and connected to one another by at least one flat separator... | The EVE batteries have an electrode-separator assembly with a positive and negative electrode in the form of flat layers connected by a flat separator. | ¶45 | col. 3:41-48 |
| wherein the electrode layers are aligned essentially at right angles to the flat bottom area and the flat top area and the button cell is closed without being beaded over... | The EVE batteries' electrode layers are allegedly aligned at right angles to the flat bottom and top areas, and the housing is closed without being beaded over. | ¶46 | col. 3:50-54 |
| and the electrode-separator assembly is in the form of a spiral winding having end faces...facing in an axial direction relative to the flat bottom area and the flat top area... | The EVE batteries have an electrode-separator assembly in the form of a spiral winding with end faces facing axially relative to the flat bottom and top areas. | ¶47 | col. 4:16-24 |
| and an insulating means...arranged between the end faces of the spiral winding and the housing cup and the housing top. | The EVE batteries are alleged to have an insulator arranged between the end faces of the spiral winding and the housing cup/top. | ¶48 | col. 6:35-39 |
9,496,581 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A button cell comprising: a housing cup and a housing top separated from one another by an insulating seal and which form a housing with a flat bottom area and a flat top area parallel to it... | The EVE batteries have a housing cup and a housing top separated by an insulating seal to form a housing with a flat bottom and top area. | ¶59 | col. 3:25-33 |
| and an electrode-separator assembly within the housing including flat layer positive and negative electrodes and connected to one another by a flat separator... | The EVE batteries have an electrode-separator assembly with positive and negative electrodes in the form of flat layers connected by a flat separator. | ¶60 | col. 3:41-48 |
| wherein the layers are aligned essentially at right angles to the flat bottom and the flat top... | The electrode layers in the EVE batteries are allegedly aligned essentially at right angles to the flat bottom and top areas. | ¶61 | col. 3:50-54 |
| and the electrode-separator assembly is a spiral winding having end faces defining side surfaces of the spiral winding facing in an axial direction relative to the flat bottom and the flat top... | The EVE batteries allegedly have a spiral winding with end faces facing in the axial direction relative to the flat bottom and top areas. | ¶62 | col. 4:16-24 |
| and one of the electrodes connects to the flat bottom or the flat top via an output conductor including a thin film resting flat between an end face of the spiral winding and the flat top or the flat bottom. | The EVE batteries allegedly have an electrode that connects to the housing via an output conductor comprising a foil resting flat between an end face of the spiral winding and the housing. | ¶63 | col. 6:3-13 |
Identified Points of Contention
- Scope Questions: The infringement analysis for all asserted patents may turn on the construction of "aligned essentially at right angles to the flat bottom area and the flat top area." The dispute will likely center on the degree of perpendicularity required by the term "essentially" and whether the accused products' wound structures meet that standard.
- Structural Questions: For the ’835 Patent, a key issue may be whether the sealing mechanism of the accused EVE batteries constitutes being "closed without being beaded over," a specific manufacturing method distinguished from traditional crimping. For the remaining patents, the dispute may focus on whether the precise structures used in the EVE batteries for electrical connection—such as bent electrode foils, specific weld locations, and insulating layers—map onto the detailed claim limitations describing the output conductors.
- Technical Questions: A factual question will be what evidence demonstrates that the accused batteries' internal components function as claimed. For instance, regarding the ’581 Patent, the analysis will question whether the accused "foil" performs the specific function of an "output conductor" that is distinct from the electrode's current collector, and whether it is "resting flat" in the manner required by the claim.
V. Key Claim Terms for Construction
The Term: "aligned essentially at right angles to the flat bottom area and the flat top area"
- Context and Importance: This term appears in the independent claims of multiple asserted patents and captures the core inventive concept of reorienting the electrode layers to manage mechanical stress. The definition of "essentially" will be critical; a narrow construction requiring near-perfect 90-degree angles might allow Defendant to argue non-infringement, while a broader, more functional definition could favor the Plaintiff's position.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification explains the functional purpose is to convert axial forces into radial forces, which can be better absorbed by the housing (’869 Patent, col. 4:1-9). This functional description may support an interpretation where any alignment that achieves this force-conversion benefit qualifies as "essentially at right angles," even if not perfectly perpendicular.
- Evidence for a Narrower Interpretation: The patent figures, such as Figure 4 of the ’835 Patent, depict the electrode layers as being parallel to the side casing of the housing and perpendicular to the flat top and bottom surfaces. This visual depiction of a geometrically orthogonal arrangement could support a narrower construction limited to structures that are physically close to a 90-degree angle.
The Term: "closed without being beaded over"
- Context and Importance: This term from claim 1 of the ’835 Patent distinguishes the invention from a common prior art method of sealing button cells by crimping or "beading" the edge of the housing cup over the top. The infringement analysis for this claim will depend on whether the accused batteries use this specific alternative closure method.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The term could be construed functionally to cover any non-crimping closure method that relies on a force-fit or interference fit between the housing components to create a seal. The patent contrasts the invention with traditional beading, suggesting the key distinction is the absence of that specific, known technique (’869 Patent, col. 2:10-17).
- Evidence for a Narrower Interpretation: The specification describes a specific alternative method involving a "force-fitting connection" where a cylindrical cell top is pressed into a conical cell cup (’869 Patent, col. 7:1-8). This detailed description of a particular embodiment could be used to argue that "without being beaded over" is limited to this specific force-fit technique and does not cover other potential non-beaded closure methods.
VI. Other Allegations
Indirect Infringement
The complaint alleges that Defendant induces infringement by knowingly encouraging and aiding its OEM customers and their resellers to import and sell products in the United States (such as wireless earphones) that incorporate the accused EVE batteries. Alleged acts of inducement include advertising, distributing datasheets and instructions, and providing technical support for the batteries (Compl. ¶36, ¶38).
Willful Infringement
The complaint alleges willful infringement based on both pre-suit and post-suit knowledge. For the ’835, ’581, and ’913 Patents, pre-suit knowledge is alleged to date back to at least February 5, 2020, when Plaintiff sued one of Defendant’s customers, and June 9, 2020, when Defendant allegedly sought to invalidate a Chinese counterpart patent (Compl. ¶33-34, ¶55, ¶70, ¶83). For the more recently issued ’869, ’904, and ’905 Patents, willfulness is alleged based on knowledge since their issue date of June 1, 2021 (Compl. ¶95, ¶109, ¶124).
VII. Analyst’s Conclusion: Key Questions for the Case
- A central issue will be one of definitional scope: how will the court construe the term "aligned essentially at right angles"? The case may turn on whether this phrase requires a strict geometric perpendicularity, as depicted in patent figures, or a broader functional orientation that successfully converts axial stress to radial stress, regardless of the precise angle.
- A key technical and evidentiary question will be one of structural correspondence: does the specific construction of the accused batteries' electrical contacts—including the use of bent foils, welds, and insulators—fall within the detailed limitations of the asserted claims across the six patents? This will require a granular, patent-by-patent comparison of the accused product's architecture against the claimed elements.
- A third core issue will relate to willfulness and damages: given the alleged history of prior litigation against Defendant's customer and administrative challenges to the patent family, the court will have to determine when Defendant knew or should have known of its alleged infringement for each patent, a finding that could significantly impact potential damages.