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

In Maxell Ltd. v. Amperex Technology Ltd.,¹  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 U.S. Patent No. 9,077,035 ('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 '035 patent 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 transition metal oxides with