Patent Owner Alert: Unconventional Claim Language May Complicate Enforcement/Litigation

In Maxell Ltd. v. Amperex Technology Ltd., the Federal Circuit held a claim that reciting two limitations of different scope for the same element was not indefinite since it was possible for the element to meet both limitations, and thus there was no contradiction. The court explained that there is no difference between reciting a narrowing limitation in a dependent claim and reciting a narrowing limitation in the independent claim itself.

Maxell, Ltd. owned (‘035 patent), which is related to a rechargeable lithium-ion battery. Amperex Technology Limited was a producer of lithium-ion batteries. Maxell asserted infringement of the ‘035 patent, and Amperex challenged its validity. The disclosed a lithium-ion battery as having a positive electrode, a negative electrode and a nonaqueous electrolyte. All claims of the ‘035 patent recited a positive electrode that had at least two lithium-containing metal oxides with distinct average particle sizes. The transition metal oxides were recited in the claims using formulas that included a transition metal element M. Claim 1 recited the following:

1. A nonaqueous secondary battery comprising:
   • [a] a positive electrode having a positive electrode mixture layer, a negative electrode, and a nonaqueous electrolyte,
   • [b] wherein the positive electrode comprises, as active materials, at least two lithium-containing metal oxides having different average particle sizes, and the lithium-containing metal oxide having the smallest average particle size is a lithium-containing metal oxide represented by the formula (1): LixMyMzMvO2,
   • [c] wherein M represents at least one transition metal element selected from Co, Ni and Mn, M represents Mg and at least one metal element selected from the group consisting of Ti, Zr, Ge, Nb, Al and Sn, M represents at least one element selected from the group consisting of Na, K, Rb, Be, Ca, Sr, Ba, Sc, Y, La, Hf, V, Ta, Cr, Mo, W, Tc, Re, Fe, Ru, Rh, Cu, Ag, Au, B, Ca, In, Si, P and Bi, and x, y, z and v are numbers satisfying the equations respectively: 0.97≤x<1.02, 0.8≤y<1.02, 0.002≤z≤0.05, and 0≤v≤0.05, and has an average particle size from 2 μm to 10 μm, and the lithium-containing metal oxide having the largest average particle size is a lithium-containing metal oxide represented by the formula (2): LiaMbMcMdO2,
   • [d] wherein M, M and M are the same as defined in the formula (1), and a, b, c and d are numbers satisfying the equations respectively: 0.97≤a<1.02, 0.8≤b<1.02, 0.0002≤c≤0.02, and 0≤d≤0.02, and has an average particle size from 5 μm to 25 μm,
   • [e] wherein said electrolyte contains a fluorine-containing organic solvent,
   • [f] wherein the content of Co in the metal M of the formulae (1) and (2) is from 30% by mole to 100% by mole,
   • [g] wherein the content of said lithium-containing metal oxide having the smallest average particle size in the lithium-containing metal oxides is from 5% by weight to 60% by weight,
   • [h] wherein the content of said lithium-containing metal oxide having the largest average particle size in the lithium-containing metal oxides is from 40% by weight to 95% by weight, and
   • [i] wherein an amount of said fluorine-containing organic solvent is 0.1% by weight to 30% by weight based on the whole weight of the electrolyte.

The district court construed the claims and held the claims to be indefinite and invalid because of the following claim language: “M represents at least one transition metal element selected from Co, Ni and Mn, ... wherein the content of Co in the transition metal M of the formulae (1) and (2) is from 30% by mole to 100% by mole.” The court reasoned that the claim language recited a contradiction, because a first claim element did not necessitate the existence of cobalt, whereas a second claim element required cobalt.

Maxell appealed, and the Federal Circuit reversed. , ¶ 2 states that a patent specification “shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.” When “claims, read in light of the specification delineating the patent, and the prosecution history, fail to inform, with reasonable certainty, those skilled in the art about the scope of the invention,” they are indefinite.

The Federal Circuit observed the district court and concluded that the claim language was contradictory and indefinite because claim 1 recited a Markush group where cobalt was not required, while the second part of claim 1 recited that cobalt was required. The Federal Circuit disagreed and held that there was no contradiction in the language of claim 1.

The court also observed that the M—element [c]—recited first that a transition metal element must contain cobalt, nickel or manganese. The claim then recited—limitation [f]—which stated that the transition metal element must include cobalt at a content of 30% to 100% by mole. “It is perfectly possible for a transition metal element to meet both requirements. The two limitations are therefore not contradictory,” the court explained.The court reasoned:

It makes no difference, at least here, that the two requirements are placed in separate limitations—rather than both appearing in limitation [c]. Such placement does not alter the logical point that it is possible to meet both requirements, meaning that there is no contradiction. . . .

The placement of the two requirements does not create an otherwise-nonexistent contradiction. That is so even if there was a more artful way of stating the two requirements within the same claim.

The court also noted that there was an obvious explanation why the second requirement for the M term was separate, because it was added during prosecution to overcome a prior art reference. According to the court: “That there were other ways of drafting the claim does not render the claim language contradictory or indefinite.”

The court noted that if there are two conditions in the same claim, and it is possible to satisfy both conditions, there is no contradiction. The court reasoned:

That there is no contradiction here is confirmed by the fact that it is the ordinary role of dependent claims to add narrowing limitations to the independent claims to which they refer.. . . . But there is no difference material to the indefiniteness inquiry between a narrowing limitation recited in a dependent claim and the situation here, where the further narrowing limitation is recited in the independent claim itself.

Therefore, the district court’s indefiniteness holding was reversed, and the claims were held definite.

Important Considerations:

This decision highlights the potential perils of poor or unconventional claim drafting. While the Federal Circuit found the claims definite, it is still important for practitioners to draft and amend claims in a clear manner, especially when adding claim features to overcome rejections during prosecution, to reduce the risk of later dispute. For example, instead of adding element [f] later in the claim to further define the claim language --

• wherein M represents at least one transition metal element selected from Co, Ni and Mn,

the claim could have been drafted as follows (bolded language indicates the added language) :

• wherein M represents at least one transition metal element selected from Co, Ni and Mn, with the content of Co in the metal M from 30% by mole to 100% by mole,

This decision also reveals that patent owners and practitioners must be careful when drafting the appropriate scope of patent claims. A variety of claims should be prepared that describe the different inventive features, and claims that range from broad to narrow in scope should also be included. As mentioned in previous articles, patent claims define the legal boundary of an invention, much like property boundaries define the legal bounds of land/real property. If you have an incorrect description of your property boundaries, you could end up owning less property than you think. The same applies to patents and inventions—an overly narrow or incorrect set of claims can result in an unnecessarily narrow or limited protection for an invention.

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is a Partner in Manatt, Phelps and Phillip’s Intellectual Property Protection and Enforcement practice and is the author of Patent Prosecution: Law, Practice, and Procedure, 2024 Edition, and Constructing and Deconstructing Patents (2d Edition 2016).

Maxell Ltd. v. Amperex Technology Ltd., 94 F.4th 1369, 2024 USPQ2d 433 (Fed. Cir. 2024).

Id., 94 F.4th at 1371 (emphases added) (letters added to label the claim elements).

Id., 94 F.4th at 1372.

Id., 94 F.4th at 1372 (quoting 35 U.S.C. § 112, ¶ 2 (2006)).

Id., 94 F.4th at 1372 (quoting Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898, 901, 134 S.Ct. 2120, 189 L.Ed.2d 37 (2014)).

Id., 94 F.4th at 1373.

Id., 94 F.4th at 1373.

Id., 94 F.4th at 1373.

Id., 94 F.4th at 1373-74.