DCT

2:26-cv-00598

LG Energy Solution Ltd v. Eve Energy Co Ltd

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:26-cv-00598, E.D. Tex., 07/21/2026
  • Venue Allegations: Venue is alleged to be proper on the basis that all defendants are not residents of the United States and therefore may be sued in any judicial district.
  • Core Dispute: Plaintiff alleges that Defendants' secondary cylindrical battery cells, and downstream products incorporating them, infringe five U.S. patents related to battery safety features, internal structure, and manufacturing methods.
  • Technical Context: The technology pertains to the design and construction of rechargeable cylindrical lithium-ion batteries, a foundational component for a wide range of products from power tools to electric vehicles.
  • Key Procedural History: The complaint notes that U.S. Patent No. 8,420,257 was originally assigned to LG Chem, Ltd. and subsequently assigned to Plaintiff LG Energy Solution Ltd v. Eve Energy Co Ltd. No other significant procedural events, such as prior litigation or administrative proceedings, are mentioned in the complaint.

Case Timeline

Date Event
2009-10-13 '257 Patent Priority Date
2013-04-16 '257 Patent Issue Date
2017-04-14 '735 Patent Priority Date
2017-10-13 '924 Patent Priority Date
2018-11-28 '866 Patent Priority Date
2022-07-19 '965 Patent Priority Date
2023-09-05 '866 Patent Issue Date
2025-09-09 '924 Patent Issue Date
2025-09-09 '965 Patent Issue Date
2026-06-02 '735 Patent Issue Date
2026-07-21 Complaint Filing Date

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 8,420,257 - "Cap Assembly Comprising Gasket Prevented from Sagging," issued April 16, 2013

The Invention Explained

  • Problem Addressed: In conventional cylindrical batteries, the main gasket that seals the top cap assembly can sag due to gravity or loss of elasticity, creating a space between the gasket and the safety vent through which the battery's electrolyte can leak Compl. ¶47 '257 Patent, col. 1:17-48
  • The Patented Solution: The invention introduces a cap assembly with a two-part gasket system. A "main gasket" provides the primary seal, while a separate "auxiliary gasket" is positioned to physically support the main gasket from below, preventing it from sagging and thereby maintaining the seal's integrity Compl. ¶47 '257 Patent, abstract '257 Patent, Fig. 2a
  • Technical Importance: This design enhances battery safety and reliability by creating a more robust seal that mitigates the risk of hazardous electrolyte leakage.

Key Claims at a Glance

  • The complaint asserts at least independent Claim 1 and dependent Claim 4 Compl. ¶71
  • The essential elements of independent Claim 1 include Compl. ¶72:
    • A cap assembly comprising a main gasket surrounding a safety vent and an auxiliary gasket surrounding a current interrupt device (CID).
    • A portion of the main gasket is seated on the CID.
    • The main gasket is "supported upwardly by the auxiliary gasket to minimize the amount the main gasket sags away from the safety vent."

U.S. Patent No. 11,749,866 - "Secondary Battery," issued September 5, 2023

The Invention Explained

  • Problem Addressed: Conventional safety vents in battery caps may not reliably rupture at a pre-designed pressure, or they may interfere with the top cap during activation, potentially delaying the venting of gas during an over-pressure event '866 Patent, col. 1:59-62 '866 Patent, col. 2:1-4
  • The Patented Solution: The invention discloses a safety vent with a dual-notch design. It includes a "rupture notch portion" intended to break and vent gas at a predetermined pressure, and a separate "bending notch portion" located inward from the rupture notch. This bending notch is designed to deform (bend) as pressure rises, allowing part of the vent to move while maintaining clearance from the top cap, ensuring the rupture function is not impeded Compl. ¶51 '866 Patent, abstract The patent's Figure 11 illustrates the resulting improvement in venting pressure distribution compared to the prior art '866 Patent, Fig. 11
  • Technical Importance: This innovation aims to improve the consistency and reliability of the battery's primary safety mechanism for over-pressure events.

Key Claims at a Glance

  • The complaint asserts at least independent Claim 1 Compl. ¶82
  • The essential elements of independent Claim 1 include Compl. ¶83:
    • A secondary battery with an electrode assembly, a can member, and a top cap assembly.
    • The top cap assembly includes a top cap and a safety vent part below it.
    • The safety vent part comprises a "rupture portion," a "rupture notch portion" defining the rupture portion's boundary, and a "bending notch portion."
    • The bending notch portion is located on a bottom surface of the rupture portion and is spaced apart from the rupture notch portion.
    • The bending notch portion is configured to be "bent when the internal pressure within the can member increases."

U.S. Patent No. 12,412,924 - "Multilayer Nanoporous Separator," issued September 9, 2025

  • Technology Synopsis: The patent describes a multilayer separator for a lithium battery. It claims a porous polymeric layer coated with a composite layer of inorganic oxide and polymer, which provides heat stability and maintains porosity at elevated temperatures Compl. ¶55
  • Asserted Claims: At least Claim 1 Compl. ¶92
  • Accused Features: The EVE 50E and EVE 40PL secondary cylindrical battery cells are alleged to infringe Compl. ¶92

U.S. Patent No. 12,412,965 - "Cylindrical Battery, Battery Pack and Vehicle," issued September 9, 2025

  • Technology Synopsis: The patent claims a specific geometric arrangement for the winding end positions of the electrodes within a cylindrical battery. This arrangement is designed to counteract rotational stress from charge/discharge cycles, thereby preventing the battery's core from collapsing and reducing internal short circuits Compl. ¶59
  • Asserted Claims: At least Claim 1 Compl. ¶102
  • Accused Features: The EVE 40PL secondary cylindrical battery cells are alleged to infringe Compl. ¶102

U.S. Patent No. 12,646,735 - "Secondary Battery and Method for Manufacturing the Same," issued June 2, 2026

  • Technology Synopsis: The patent discloses a secondary battery with a "multi-tab current collection structure." This is achieved by creating a "notching tab part" on the electrode collector that is wound into overlapping layers, cut to form multiple tabs, and then bent and welded to the battery, a design intended to reduce resistance and improve safety Compl. ¶63
  • Asserted Claims: At least Claim 1 Compl. ¶112
  • Accused Features: The EVE 40PL secondary cylindrical battery cells are alleged to infringe Compl. ¶112

III. The Accused Instrumentality

Product Identification

  • The complaint identifies the "Accused Products" as secondary cylindrical battery cells manufactured by Defendant EVE, including specifically the EVE 20P, 29V, 40PL, 50PL, and 50E models Compl. ¶67 The definition also includes downstream products, such as power tools made by Defendants Bosch, Koki, and Chervon, that incorporate these EVE cells Compl. ¶68 Compl. ¶69

Functionality and Market Context

  • The Accused Products are cylindrical rechargeable battery cells, including those in 18650, 21700, and "next-generation tabless formats" Compl. ¶66 The complaint alleges that EVE markets its 40PL and 50PL cells as having a "tabless structure" that reduces impedance and increases power, positioning them as replacements for traditional multi-tab battery packs in professional and industrial tool applications Compl. ¶67

IV. Analysis of Infringement Allegations

The complaint references claim chart exhibits (Exhibits 6-13) that were not provided with the complaint document Compl. ¶74 Compl. ¶84 Compl. ¶94 Compl. ¶104 Compl. ¶114 The infringement theory for each patent is summarized below based on the complaint's narrative allegations. No probative visual evidence provided in complaint.

  • '257 Patent Infringement Allegations: Plaintiff alleges that the Accused Products, including the EVE 20P, 29V, and 50E cells, infringe at least Claims 1 and 4 of the '257 patent Compl. ¶71 The infringement theory is that these cells contain a cap assembly with a main gasket and an auxiliary gasket, where the auxiliary gasket structurally supports the main gasket to prevent it from sagging away from the safety vent, thereby meeting the limitations of Claim 1 Compl. ¶72 Claim 4 adds limitations requiring the CID to be press-fitted to the main gasket and in direct contact with the auxiliary gasket Compl. ¶73

  • '866 Patent Infringement Allegations: Plaintiff alleges that the Accused Products, including the EVE 50E cells, infringe at least Claim 1 of the '866 patent Compl. ¶82 The infringement theory centers on the safety vent structure within the battery cap. The complaint alleges the accused cells contain a safety vent with both a rupture portion configured to break at a set pressure and a distinct bending notch portion that is configured to bend as pressure increases, thereby maintaining clearance between the vent and the top cap Compl. ¶83

V. Key Claim Terms for Construction

'257 Patent

  • The Term: "supported upwardly by the auxiliary gasket to minimize the amount the main gasket sags"
  • Context and Importance: This functional language is central to the invention's purpose of preventing electrolyte leakage. The infringement analysis will depend on whether the accused structure performs this specific anti-sagging support function, as opposed to merely providing a secondary seal. Practitioners may focus on this term to determine if a specific structural arrangement (e.g., direct contact) is required to satisfy the functional language.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The language of Claim 1 itself is functional and does not specify a particular mechanism of support, which may support a construction covering various forms of structural interaction that result in minimizing sag Compl. ¶72 '257 Patent, cl. 1
    • Evidence for a Narrower Interpretation: The patent's detailed description and Figure 2a show the auxiliary gasket (510a) directly under and in contact with a portion of the main gasket (500a) that is seated on the CID (440) '257 Patent, Fig. 2a '257 Patent, col. 4:21-25 This embodiment may be used to argue for a narrower construction requiring direct physical contact and the application of an upward force.

'866 Patent

  • The Term: "bending notch portion"
  • Context and Importance: The novelty of the '866 patent appears to reside in its dual-notch safety vent design. The distinction between the "rupture notch portion" and the "bending notch portion" is critical. The case will likely hinge on whether the accused products contain a structure that meets the definition of this term, both structurally and functionally.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The claim language describes it as a "portion," which could be argued to encompass any area of the vent designed or predisposed to bend, not necessarily a discrete, machined "notch" '866 Patent, cl. 1
    • Evidence for a Narrower Interpretation: The patent specification explicitly describes the bending notch portion as being "concavely indented (or grooved)" and having a recessed depth less than the rupture notch portion '866 Patent, col. 5:30-33 '866 Patent, cl. 2 Figures such as Figure 6 show the bending notch (115) as a distinct physical groove separate from the rupture notch (113) '866 Patent, Fig. 6 This may support a narrower construction requiring a physically distinct, indented feature.

VI. Other Allegations

  • Indirect Infringement: For each asserted patent, the complaint alleges both induced and contributory infringement. The inducement allegations are based on Defendants' "sales, engineering, and technical marketing efforts" that allegedly encourage customers to use the infringing products Compl. ¶75 Compl. ¶85 Compl. ¶95 Compl. ¶105 Compl. ¶115 The contributory infringement allegations state that the accused battery cells are a material part of the invention, are not staple articles of commerce, and are especially adapted for infringement Compl. ¶78 Compl. ¶88 Compl. ¶98 Compl. ¶108 Compl. ¶118
  • Willful Infringement: For all asserted patents, the complaint alleges that infringement is intentional, deliberate, and willful. The basis for this allegation is knowledge of the patents and infringement "since at least as of the filing of this Complaint," suggesting a theory of post-suit willfulness Compl. ¶79 Compl. ¶89 Compl. ¶99 Compl. ¶109 Compl. ¶119

VII. Analyst's Conclusion: Key Questions for the Case

  • A primary issue will be one of structural and functional correspondence: Do the internal components of the accused EVE battery cells, upon inspection and testing, contain the specific two-part gasket support system of the '257 patent or the dual-notch (rupture and bending) safety vent structure of the '866 patent? This will require detailed evidentiary analysis comparing the physical products to the claim language.
  • A second core issue will be one of claim scope: Can the functional term "supported upwardly...to minimize...sags" in the '257 patent be met by any two-gasket arrangement, or does it require the specific direct contact shown in the patent's embodiment? Similarly, for the '866 patent, does the term "bending notch portion" require a distinct physical groove, as shown in the patent's figures, or can it read on a more generally weakened or thinned area designed to bend?
  • A central question for the '965 and '735 patents will be one of manufacturing and design intent: Do the accused "tabless" cells achieve their structure through the specific electrode winding arrangements claimed in the '965 patent to manage stress, or the specific "notching tab part" manufacturing process claimed in the '735 patent? This moves the dispute beyond simple product features to the underlying design and manufacturing choices.
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