LG Chem Ltd v. Amperex Technology Ltd

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: LG Chem, Ltd. (South Korea) and Toray Industries, Inc. (Japan)
  • Defendant: Amperex Technology Limited (China)
  • Plaintiff’s Counsel: Kerr, Russell and Weber, PLC
• Case Identification: 2:17-cv-13476, E.D. Mich., 10/25/2017
• Venue Allegations: Venue is alleged to be proper because the Defendant is a foreign entity subject to personal jurisdiction in the district and has committed acts of patent infringement there.
• Core Dispute: Plaintiffs allege that Defendant’s lithium-ion battery cells infringe three patents related to composite separators designed to enhance battery safety and performance.
• Technical Context: The technology concerns separators, a critical component in lithium-ion batteries that prevents direct contact between the cathode and anode while allowing ion flow, with innovations aimed at improving thermal stability and mechanical robustness.
• Key Procedural History: The complaint alleges that Plaintiffs provided Defendant with actual notice of infringement for all three patents-in-suit, including claim charts, on May 11, 2017, approximately five months before filing the lawsuit.

Case Timeline

Date	Event
2004-12-22	’517 Patent Priority Date
2005-12-06	’241 Patent Priority Date
2007-02-05	’152 Patent Priority Date
2009-12-29	’241 Patent Issue Date
2010-02-16	’517 Patent Issue Date
2010-05-04	’152 Patent Issue Date
2017-05-11	Plaintiffs allegedly provide notice and claim charts to Defendant
2017-10-25	Complaint Filing Date

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

U.S. Patent No. 7,662,517 - "Organic/Inorganic Composite Microporous Membrane and Electrochemical Device Prepared Thereby," issued February 16, 2010

The Invention Explained

• Problem Addressed: Conventional polyolefin separators used in lithium-ion batteries can suffer from significant heat shrinkage at high temperatures, which can lead to internal short circuits and safety issues like fire or explosion (’517 Patent, col. 1:10-22). Prior attempts to coat separators with inorganic materials often resulted in non-uniform pore structures or poor adhesion, degrading battery quality (’517 Patent, col. 2:1-21).
• The Patented Solution: The invention is a composite porous separator created by coating a standard polyolefin separator substrate with an "active layer." This active layer consists of inorganic particles (e.g., ceramics) that are interconnected and fixed in place by a binder polymer. This creates a defined pore structure within the coating itself, which, in conjunction with the pores in the substrate, allows for efficient ion transport while providing a thermally stable barrier (’517 Patent, Abstract; col. 4:1-15).
• Technical Importance: This design aims to simultaneously improve the thermal and electrochemical safety of lithium-ion batteries without significantly compromising their performance, addressing a critical challenge in battery technology (Compl. ¶15).

Key Claims at a Glance

• The complaint asserts independent claim 1 (Compl. ¶19).
• Essential elements of claim 1 include:
  • A polyolefin-based separator substrate.
  • An active layer coating the substrate, comprising a mixture of inorganic particles and a binder polymer.
  • The inorganic particles are interconnected and fixed by the binder polymer.
  • Interstitial volumes among the inorganic particles form a pore structure.
  • The inorganic particles have a size between 0.001 µm and 10 µm.
  • The inorganic particles are present in an amount of 50-99 wt % of the mixture.
  • The separator has uniform pore structures both in the active layer and the polyolefin-based separator substrate.
• The complaint alleges infringement of "at least claim 1," implicitly reserving the right to assert other claims (Compl. ¶19).

U.S. Patent No. 7,638,241 - "Organic/Inorganic Composite Separator Having Morphology Gradient, Manufacturing Method Thereof and Electrochemical Device Containing the Same," issued December 29, 2009

The Invention Explained

• Problem Addressed: In composite separators, if the binder polymer content is too low, the inorganic particles can detach from the active layer during the battery assembly process (e.g., winding). Conversely, if the binder content is too high, it can clog the pores, reducing porosity and harming battery performance (’241 Patent, col. 2:1-15).
• The Patented Solution: The invention creates an active layer with a "heterogeneity of composition morphology," or a structural gradient. Specifically, the concentration of the binder polymer relative to the inorganic particles is intentionally made higher at the surface of the active layer than it is inside the active layer. This structure provides a durable, binder-rich outer surface for good adhesion and scratch resistance, while maintaining high porosity in the interior of the layer for efficient ion flow (’241 Patent, Abstract; col. 2:35-51).
• Technical Importance: This gradient-based approach offers a way to improve the mechanical robustness and manufacturability of the separator without making a significant trade-off in electrochemical performance (’241 Patent, col. 2:52-60).

Key Claims at a Glance

• The complaint asserts independent claim 1 (Compl. ¶29).
• Essential elements of claim 1 include:
  • A porous substrate having pores.
  • A porous active layer containing a mixture of inorganic particles and a binder polymer, coating at least one surface of the substrate.
  • The porous active layer shows heterogeneity of composition morphology toward a thickness direction.
  • A content ratio of the binder polymer/inorganic particles in a surface region of the porous active layer is higher than that of the binder polymer/inorganic particles inside the porous active layer.
• The complaint alleges infringement of "at least claim 1" (Compl. ¶29).

U.S. Patent No. 7,709,152 - "Organic/Inorganic Composite Separator Having Porous Active Coating Layer and Electrochemical Device Containing the Same," issued May 4, 2010

• Technology Synopsis: This patent addresses the problem of ensuring the mechanical integrity and thermal stability of the composite separator’s active layer (’152 Patent, col. 2:21-32). The invention claims an organic/inorganic composite separator defined by specific, measurable physical performance characteristics: the porous active layer must have a peeling force of 5 gf/cm or greater, and the overall separator must exhibit thermal shrinkage of 50% or less after being held at 150°C for one hour (’152 Patent, Abstract; Claim 1).
• Asserted Claims: The complaint asserts independent claim 1 (Compl. ¶39).
• Accused Features: The separator in the accused ATL Cell 844297 is alleged to have a peeling force above 5 gf/cm and thermal shrinkage below 50%, meeting the quantitative limitations of the claim (Compl. ¶41).

III. The Accused Instrumentality

Product Identification

Defendant ATL’s rechargeable lithium ion/polymer battery cells, packs, and systems (Compl. ¶17). The complaint specifically identifies "ATL Cell 844297" as an exemplary infringing product for all three asserted patents, and also names cells 425882, 346176, 494397, and A1445 as infringing products (Compl. ¶¶ 19, 22, 29, 32, 39, 42).

Functionality and Market Context

• The accused products are battery cells used in a wide array of consumer electronics, including laptop computers and smart phones (Compl. ¶17). The complaint alleges that the separators within these cells are composed of a polyethylene substrate (a type of polyolefin) coated with an active layer made from a mixture of aluminum oxide (an inorganic particle) and PVDF-HFP (a binder polymer) (Compl. ¶¶ 21, 31, 41).
• Plaintiffs allege that the Defendant competes directly with them by "flooding the U.S. market with inexpensive, low-quality batteries" (Compl. ¶17).
  No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

’517 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
an organic/inorganic composite porous separator comprising: (a) a polyolefin-based separator substrate;	The ATL Cell 844297 includes a separator substrate made from polyethylene, which is a type of polyolefin.	¶21	col. 8:24-33
and (b) an active layer formed by coating at least one region...with a mixture of inorganic particles and a binder polymer,	The ATL cell includes an active layer made from a mixture of aluminum oxide (inorganic particle) and PVDF-HFP (binder polymer).	¶21	col. 4:10-15
wherein the inorganic particles in the active layer are interconnected among themselves and are fixed by the binder polymer, and interstitial volumes among the inorganic particles form a pore structure,	The inorganic particles in the ATL Cell 844297’s active layer are interconnected among themselves and are fixed by the binder polymer, and interstitial volumes among the inorganic particles form a pore structure.	¶21	col. 4:50-54
and the inorganic particles have a size between 0.001 µm and 10 µm...	The inorganic particles in the ATL Cell 844297’s active layer have a size between 0.001 µm and 10 µm.	¶21	col. 8:56-60
and are present in the mixture of inorganic particles with the binder polymer in an amount of 50-99 wt % based on 100 wt % of the mixture,	[The inorganic particles] are present in the mixture...in an amount of 50-99 wt % based on 100 wt % of the mixture.	¶21	col. 8:1-4
and wherein the separator has uniform pore structures both in the active layer and the polyolefin-based separator substrate.	The separator in the ATL Cell 844297 has uniform pore structures both in the active layer and the polyolefin-based separator substrate.	¶21	col. 4:34-38

’241 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
An organic/inorganic composite separator comprising: (a) a porous substrate having pores;	The ATL Cell 844297 includes a porous separator substrate made from polyethylene.	¶31	col. 2:36-37
and (b) a porous active layer containing a mixture of inorganic particles and a binder polymer with which at least one surface of the porous substrate is coated,	The ATL cell also includes an active layer made from a mixture of aluminum oxide (inorganic particle) and PVDF-HFP (binder polymer).	¶31	col. 2:37-40
wherein the porous active layer shows heterogeneity of composition morphology toward a thickness direction...	The ATL Cell 844297’s active layer exhibits heterogeneity of composition morphology toward a thickness direction.	¶31	col. 2:40-42
...in which a content ratio of the binder polymer/inorganic particles present in a surface region of the porous active layer is higher than that of the binder polymer/inorganic particles present inside the porous active layer.	[T]he content ratio of the binder polymer/inorganic particles present in a surface region of the porous active layer is higher than that of the binder polymer/inorganic particles present inside the porous active layer.	¶31	col. 2:42-46

Identified Points of Contention

• Technical Questions: A primary factual dispute may center on the physical evidence required to prove the claimed microstructures. For the ’241 patent, demonstrating the "heterogeneity of composition morphology" will likely require sophisticated materials analysis (e.g., cross-sectional SEM/EDX) to prove a higher binder-to-particle ratio at the surface versus the interior. The complaint makes this allegation without presenting such evidence.
• Scope Questions: For the ’517 patent, the meaning of "uniform pore structures both in the active layer and the polyolefin-based separator substrate" raises a question of claim scope. The dispute may focus on whether this requires strict geometric uniformity in pore size and shape across both distinct layers, or if it allows for functional uniformity related to consistent ion permeability.

V. Key Claim Terms for Construction

Term 1: "uniform pore structures" (’517 Patent, Claim 1)

• Context and Importance: This term is critical because infringement depends on the structural relationship between the coating and the underlying substrate. Defendant may argue its product lacks the claimed "uniformity" across both layers. Practitioners may focus on this term because its definition—whether geometric or functional—will dictate the type of evidence needed to prove or disprove infringement.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The specification describes the purpose of the pores as allowing ion movement and containing electrolyte, suggesting a functional definition where "uniform" means sufficient and consistent permeability rather than a specific geometric arrangement (’517 Patent, col. 10:8-14).
  • Evidence for a Narrower Interpretation: The patent repeatedly contrasts its invention with prior art having "non-uniform" pores, and emphasizes that its active layer has a "uniform pore structure" formed by the interstitial volumes between particles (’517 Patent, col. 4:11-13; col. 5:11-13). This emphasis on the uniformity of the active layer itself could be used to argue that the claim requires a high degree of structural regularity.

Term 2: "heterogeneity of composition morphology toward a thickness direction" (’241 Patent, Claim 1)

• Context and Importance: This term represents the central inventive concept of the ’241 patent. The infringement analysis for this patent will turn entirely on whether the accused product exhibits this specific structural gradient. Practitioners may focus on this term because it is not a standard materials science term and its meaning is defined entirely by the patent.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The claim itself provides the definition: a structure "in which a content ratio of the binder polymer/inorganic particles present in a surface region of the porous active layer is higher than that of the binder polymer/inorganic particles present inside the porous active layer" (’241 Patent, Claim 1). This language could be read to cover any non-uniform distribution that meets this relative condition, regardless of how it is formed.
  • Evidence for a Narrower Interpretation: The specification describes achieving this heterogeneity through a specific manufacturing process involving phase inversion controlled by moisture levels (’241 Patent, col. 11:4-29). A defendant could argue that the term should be limited to structures resulting from such a process or exhibiting the specific physical characteristics that result from it.

VI. Other Allegations

• Indirect Infringement: The complaint alleges both induced and contributory infringement for all three patents. Inducement is based on allegations that ATL sells its battery cells to customers for incorporation into end-products sold in the U.S. and provides "materials and instructions" for their operation (Compl. ¶¶ 24-25, 34-35, 44-45). Contributory infringement is based on the allegation that the accused separators are especially made for an infringing use and are not staple articles of commerce with substantial non-infringing uses (Compl. ¶¶ 26, 36, 46).
• Willful Infringement: Willfulness is alleged based on pre-suit and post-suit knowledge. The complaint asserts that ATL had actual notice of the patents and its infringement no later than May 11, 2017, when Plaintiffs allegedly sent a letter with claim charts, and that infringement has continued despite this knowledge (Compl. ¶¶ 25, 35, 45).

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

• A central issue will be one of structural verification: what level of physical evidence will be required to prove the existence of the claimed microscopic and compositional structures? This is particularly acute for the "heterogeneity of composition morphology" of the ’241 patent, which appears to necessitate complex, quantitative cross-sectional analysis that is alleged but not yet shown.
• A key legal battle will likely be one of claim construction: how will the court define functionally-oriented terms like "uniform pore structures" from the ’517 patent? The outcome will determine whether infringement requires proof of strict geometric regularity or merely consistent functional performance.
• A third core question will be one of quantitative proof: for the ’152 patent, can Plaintiffs prove through testing that the accused separators meet the specific numerical thresholds for peeling force (≥5 gf/cm) and thermal shrinkage (≤50%) defined in the claim, and how will those test methodologies themselves be scrutinized?