The dataset of 70 patent families shows filing spread across a mix of specialist electrode manufacturers, research institutes and Chinese hydrogen-equipment firms, with no single assignee holding an overwhelming share. De Nora Permelec, Forschungszentrum Jülich and RWTH Aachen appear repeatedly, including in the only recurring co-assignment relationship in the set. The full ranking table on this page lists every assignee by family count, which is the fairer comparison than raw document counts since it neutralises multi-jurisdiction filing.

Filing activity rose from zero in 2017 to a peak of 17 families in 2023 before declining, roughly tracking the broader green-hydrogen investment cycle that drove significant electrolyzer manufacturing capacity announcements through 2022-2023. The pullback since then does not necessarily mean the technology problem is solved; publication lags filing by about 18 months, so recent years understate true filing activity until later applications publish. It is more likely a sign that early movers have already staked out their core claims and follow-on filers are being more selective.

Diaphragm durability claims typically address the separator material's resistance to swelling, cracking or ion-selectivity loss under sustained alkaline exposure and pressure differentials, while electrode degradation claims focus on catalyst coating loss, corrosion of the underlying substrate, and activity decay at the cathode or anode surface. Both problem areas are captured in this dataset's search construction, and the IPC spread suggests electrode and catalyst chemistry claims (reflected in the C25D and B82Y crossover) draw more citation activity than diaphragm-specific mechanical claims. Anyone drafting new claims should check both branches separately since they sit on different prior art bases.

China accounts for 39 of the roughly 70 tracked filings, far more than any other receiving office, which makes it the jurisdiction with the deepest prior art and the highest competitive filing density for this specific technology. That density is a signal of occupied claim space, not necessarily of where commercial value will concentrate — European and PCT filings, while fewer, often correspond to filings intended for broader multi-market enforcement. The practical answer depends on where the applicant intends to manufacture or sell hydrogen equipment, but any China filing strategy here needs to account for a crowded field.

The secondary IPC classes in this dataset are thin relative to the core C25B claiming activity: B01D (separation processes) has only 3 records, B82Y (nanotechnology) has 3, and B05B (spraying/atomising) has just 1, suggesting under-claimed territory around advanced separator membrane materials, nanostructured catalyst adhesion, and coating-application methods for durability. Dynamic operation durability — how electrodes and diaphragms hold up under the load cycling typical of renewable-powered electrolysis — is also referenced in the search terms but appears less densely claimed than static service-life language. These are starting points for a focused prior art search, not confirmed gaps.