In this dataset, the search targets records classified under C25B11, C25B13 or B01J23 that also mention electrode material, Raney nickel, diaphragm material or catalyst coating in the title or claims. That combination captures the electrode alloys, separator/diaphragm chemistries and catalyst coatings used inside alkaline water electrolysis (AWE) cells, as distinct from PEM or solid-oxide electrolyzer materials which sit in different IPC groups. Practitioners searching this space should expect the bulk of relevant art to sit in C25B, with secondary art scattered across C25D electroplating and H01M fuel-cell classes.

Patent applications are typically published around 18 months after filing, so any year close to the data cut-off is still missing filings that haven’t published yet. In this dataset the 2026 figure of 4 families is a partial-year snapshot, not a real drop-off, and even 2024–2025 figures should be read as provisional until later data cuts catch up. The reliable comparison point is the 2021 peak of 38 and the 2022 midpoint of 27, both of which are far enough back to be considered essentially complete.

The co-assignee network shows DE NORA PERMELEC and Yokohama National University filing jointly most often, with 54 shared families, followed by DE NORA PERMELEC with Kawasaki Heavy Industries at 40 and Yokohama National University with Kawasaki Heavy Industries at 23. That triangle dominates the most-cited documents in the corpus, including the top-cited diaphragm and bipolar-vessel patents. Beyond that cluster, recent-year momentum across the named assignees is flat or negative, suggesting the leading filers have slowed rather than accelerated their claim activity.