Zhuhai CosMX Battery Co Ltd v. Ningde Amperex Technology Ltd

1. Case Identification

• Case #: IPR2025-00432
• Patent #: 11,575,148
• Filed: January 10, 2025
• Petitioner(s): Zhuhai CosMX Battery Co., Ltd.
• Patent Owner(s): Ningde Amperex Technology Limited
• Challenged Claims: 1-19

2. Patent Overview

• Title: Porous Film, Preparation Method Thereof, Separator, and Electrochemical Device
• Brief Description: The ’148 patent discloses a porous film for use in lithium-ion batteries, typically as part of a separator. The film comprises a binder and inorganic particles characterized by specific cumulative particle size distribution ranges (Dv10, Dv50, and Dv90), which were added during prosecution to secure allowance.

3. Grounds for Unpatentability

Ground 1: Obviousness over Murakami - Claims 1, 2, 5-11, and 14-19 are obvious over Murakami.

• Prior Art Relied Upon: Murakami (Application # 2017/0162849).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Murakami, which teaches a porous layer for a lithium-ion battery separator, discloses every limitation of the independent claims. Murakami explicitly describes a porous film made of a binder resin and inorganic filler particles (alumina). Crucially, Petitioner asserted that Murakami’s general disclosure and specific examples teach inorganic particle size ranges for Dv10, Dv50, and Dv90 that either overlap with or fall squarely within the ranges recited in the ’148 patent claims. Petitioner contended that the limitation "pores at least comprises a part of the inorganic particles" is inherently disclosed in Murakami due to the high filler-to-binder ratio (97:3 by weight) and the large size of the filler particles relative to the film thickness, making it inevitable that particles protrude into the pore spaces.
  • Motivation to Combine (for §103 grounds): This ground is based on a single reference. Petitioner argued a person of ordinary skill in the art (POSITA) would be motivated to implement Murakami’s specific working examples because they exhibited the best performance (smallest voidage variability and highest capacity retention), providing a clear reason for their selection.
  • Expectation of Success (for §103 grounds): A POSITA would have an expectation of success in using Murakami's teachings as it directly addresses improving the cycle characteristics of non-aqueous electrolyte secondary batteries.

Ground 2: Obviousness over Beard in view of Akiike - Claims 1-3, 5-12, and 14-19 are obvious over Beard in view of Akiike.

• Prior Art Relied Upon: Beard (Application # 2012/0228214) and Akiike (Application # 2016/0013465).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Beard discloses a microporous membrane for a battery separator comprising a polymer binder and a high concentration of inorganic filler particles. Beard's manufacturing process, which uses a pore-forming agent that is later removed, was alleged to teach pores "formed by the binder." Petitioner also argued Beard discloses pores comprising a part of the inorganic particles, as its figures show filler tightly packed into the pore walls. However, Beard does not specify the claimed particle size distributions. Akiike, an analogous reference, was argued to supply these missing limitations by disclosing porous membranes with inorganic particles having Dv10, Dv50, and Dv90 values that fall within the claimed ranges.
  • Motivation to Combine (for §103 grounds): Petitioner asserted that a POSITA, seeking to implement Beard’s general disclosure of a filler-based separator, would have looked to a similar reference like Akiike for guidance on appropriate particle size distributions. Akiike provides explicit technical reasons for its preferred particle size ranges—such as improving high-temperature cycle properties, mechanical strength, and heat resistance—which would motivate a POSITA to apply these known, beneficial distributions to Beard's system.
  • Expectation of Success (for §103 grounds): A POSITA would have a reasonable expectation of success because both Beard and Akiike disclose separators using common polymer binders and inorganic fillers (both identify TiO2 as suitable). This compatibility would lead a POSITA to expect that incorporating Akiike's optimized particle sizes into Beard's membrane structure would result in a separator with the combined benefits described in the references.

Ground 3: Obviousness over Murakami in view of Honda - Claims 3 and 12 are obvious over Murakami in view of Honda.

• Prior Art Relied Upon: Murakami (Application # 2017/0162849) and Honda (WO 2015/178351).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground builds on Ground 1, asserting that while Murakami discloses the base invention, it does not expressly disclose the "average wall thickness between the pores" limitation of dependent claims 3 and 12 (20 nm to 500 nm). Petitioner argued that Honda, which also relates to battery separators, discloses a porous layer with a "honeycomb structure" having a partition wall thickness of 0.1 µm to 2 µm (100 nm to 2000 nm), a range that overlaps the claimed range.
  • Motivation to Combine (for §103 grounds): Honda explained that its disclosed wall thickness allows for micropores that interconnect larger pores, thereby increasing overall porosity. As Murakami taught a preference for high porosity (up to 90% voidage), a POSITA would have been motivated to incorporate Honda's thin-walled structure into Murakami's porous layer to help achieve this desired high porosity and improve ion permeability.
  • Expectation of Success (for §103 grounds): Petitioner argued success would be expected because both references describe analogous solvent-based phase inversion processes to form their porous layers. The similarity in manufacturing techniques would give a POSITA confidence that Honda’s honeycomb structure and wall thickness could be readily achieved in Murakami’s system.
• Additional Grounds: Petitioner asserted additional obviousness challenges based on combining Murakami or Beard/Akiike with Tanaka (for its teachings on pore size distribution coefficients) and further combinations involving Beard.

4. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §325(d) is inappropriate because the primary references asserted (Murakami and Akiike) are substantially different from the prior art considered by the Examiner during prosecution. Specifically, these references allegedly disclose the very particle size distribution limitations that were the basis for allowing the ’148 patent claims over the cited art.
• Petitioner also argued against discretionary denial under Fintiv, noting that the petition was filed very early in the parallel district court litigation, before significant resources had been invested. Further, Petitioner stipulated that if the IPR is instituted, it will not pursue the same grounds or any grounds that it reasonably could have raised in the parallel litigation.

5. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-19 of the ’148 patent as unpatentable under 35 U.S.C. §103.