In Maxell, Ltd. v. Amperex Technology Limited, [2023-1194] (Fed. Cir. 2024), the Federal Circuit reversed the finding of indefiniteness of the claims of U.S. Patent No. 9,077,035 were not indefinite.

The ’035 patent, titled “Nonaqueous Secondary Battery and Method of Using the Same,” describes and claims a lithium-ion battery with a positive electrode, a negative electrode, and a nonaqueous electrolyte. Claim 1 contained the limitation “wherein M1 represents at least one transition metal element selected from Co, Ni and Mn,” and further “wherein the content of Co in the transition metal M1 of the formulae (1) and (2) is from 30% by mole to 100% by mole,”

The district court found the claims invalid for indefiniteness, noting t reasoned that “the
plain language of the claim recites a contradiction, ”because the first limitation does not require the presence of cobalt (nickel or manganese suffices), so cobalt is “optional,”
whereas the second limitation does require cobalt.”

The Federal Circuit concluded that the district court’s rationale, was incorrect, but
not because a contradiction in a claim cannot produce indefiniteness. Rather, there is no contradiction in the claim language at issue in this case. The Federal Circuit explained:

The first of the two limitations at issue regarding M1– limitation [c]—states one requirement a transition metal element must meet to come within the claim: It must contain cobalt, nickel, or manganese. The second limitation at issue—limitation [f]—states a second requirement: The transition metal element must contain 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. 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 Federal Circuit said that 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. And the record provides a readily discernible explanation for the placement: The second requirement for the M1 term was added during
prosecution to overcome a prior art reference that primarily used nickel as a transition metal. That there were other ways of drafting the claim does not render the claim language contradictory or indefinite.