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Technology & Innovation

Celgard and Farasis Settle, Celgard Adds Senior-China to the California Patent Case, and Celgard Moves the North Carolina Trade Secret Case Back to California


Celgard, LLC (Celgard), a subsidiary of Polypore International, LP, was successful in settling its patent litigation against several Farasis defendants in the United States (U.S.) District Court for the Northern District of California (NDCA). Celgard and all Farasis entities listed in the lawsuit have settled the outstanding disputes between Celgard and Farasis.

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Effective December 31, 2021, Celgard and Farasis entered into an agreement that settles the U.S. patent infringement litigation and the global disputes between the two companies. In the agreement, Celgard will supply product to Farasis and Farasis agreed to assist Celgard in the protection of its patents and trade secrets. The other terms of the settlement are confidential.

In the public NDCA litigation filings on January 7, 2022:

1. Celgard voluntarily dismissed all claims against the Farasis
defendants asserted in its Fourth Amended Complaint in the NDCA patent
case. The Farasis defendants voluntarily dismissed all counterclaims
against Celgard asserted in their Answer to The Fourth Amended
Complaint and Counterclaim.

2. Celgard filed a Fifth Amended Complaint that added Senior-China back
in as a defendant in Celgard’s ‘520 and ‘867 patent case and moved the
U.S. District Court for the Western District of North Carolina (WDNC)
trade secret case back to the NDCA court.

Celgard also alleges brazen theft of Celgard’s trade secrets, proprietary information, and confidential information by defendants Senior-China, Senior-California, Sun Town, Global Venture, and Dr. Steven Zhang (the “Trade Secret Defendants”) — which includes a competitor and an ex-employee who changed his name to conceal the Trade Secret Defendants’ unlawful conduct — and who Celgard believes conspired together to hijack Celgard’s confidential, proprietary, and trade secret information, copy Celgard’s products, and take business from Celgard. This lawsuit also concerns defendant Dr. Steven Zhang’s breach of his nondisclosure agreement with Celgard, and Senior’s inducement of that breach.

Celgard has active cases in both the UK and U.S. against Senior-China and/or one or more of its subsidiaries or related companies. Celgard intends to fully pursue its trade secret case against Senior in the UK and in the U.S.

The UK Court of Appeal win (See Release ( )), the UK High Court interim injunction (See Release ( )), and the successful outcome of the Targray (See Release ( )), MTI (See Release ( )) and Farasis cases further solidifies the integrity of Celgard’s intellectual property (IP) regarding coated and uncoated separators for lithium-ion batteries. Celgard will continue to prevent the unfair exploitation of its technology and IP to safeguard its assets and customers.

About Celgard and Polypore

Celgard specializes in coated and uncoated dry-process microporous membranes used as separators that are a major component of lithium-ion batteries. Celgard’s battery separator technology is important to the performance of lithium-ion batteries for electric drive vehicles, energy storage systems and other applications.

Celgard, LLC is a wholly-owned subsidiary of Polypore International, LP, an Asahi Kasei Company.

Polypore is a global company with facilities in nine countries specializing in microporous membranes used in electric and nonelectric vehicles, energy storage systems and specialty applications. Visit: and

SOURCE: Polypore International, LP

PRESS CONTACT: Beth Kitteringham