Maxell, Ltd., the Japanese electronics and intellectual property company, filed suit against Amperex Technology Limited (ATL) on April 8, 2021, in the Western District of Texas before Judge Alan Albright — then the most popular venue for patent plaintiffs in the US. Maxell asserted four patents covering lithium-ion battery technology: US8691446B2, US9166251B2, US9077035B2, and US9350019B2. ATL’s accused cells — including Cell Nos. 465867, 575577N, 785075, 633360, and 2798B7 — were alleged to power devices ranging from Google Pixel 3a smartphones and Huawei MediaPad M5 Lite tablets to DJI Mavic and DJI Spark drones and Dell Alienware notebook battery packs.

The case closed on May 12, 2025, when Maxell and ATL jointly filed a stipulation of dismissal under Fed. R. Civ. P. 41(a)(1)(A)(ii). Critically, all claims asserted by Maxell — and counterclaims by ATL — were dismissed with prejudice, while all affirmative defenses were dismissed without prejudice. Dismissal with prejudice is a final adjudication on the merits: Maxell cannot re-file these specific claims against ATL on the same patents, effectively ending the enforcement action permanently. The without-prejudice carve-out for defenses preserves ATL’s ability to raise invalidity and other defenses in future proceedings involving these patents.

The 1,495-day duration — more than four years — is notable even by complex patent litigation standards, suggesting the parties engaged in substantial claim construction, discovery, and potentially IPR proceedings before reaching resolution. The stipulated dismissal with prejudice, without any public damages award or licensing disclosure, is strongly consistent with a confidential settlement in which ATL took a license or Maxell received consideration. The public record is silent on financial terms. What remains unknown is whether any inter partes review proceedings on these four battery patents influenced the decision to resolve — a common dynamic in multi-patent cases of this complexity and duration.