MCFC degradation is driven mainly by electrolyte loss, nickel oxide cathode dissolution, and corrosion of cell hardware at high operating temperature. Patent filings in this dataset cluster heavily in IPC subclass H01M (fuel cells generally) and B01J (catalysis and chemical processing), which together cover most of the 212 families addressing these failure modes. Practically, that means the bulk of the patented solutions are electrode and catalyst chemistry fixes rather than mechanical or thermal-management redesigns, so a durability program relying on hardware changes alone is working in a thinner prior-art zone.

The dataset's assignee list is led by a fuel-cell specialist, an energy engineering major, and several chemicals companies including LG Chem and Lanxess Holding, alongside individual named inventors who account for a notable share of filings. Most of these leading assignees show zero filings in the latest reported year, some with a full year-on-year decline, which points to a filing wave that peaked around 2019 rather than one still building. Before assuming any single company dominates, check the co-assignee pairs, since the strongest collaboration links two of these firms directly rather than each filing independently.

Filing activity peaked at 12 in 2019, fell to roughly half that by 2022, and shows no filings recorded yet at either end of the 2017-2026 window in this dataset. Part of that apparent decline is a publication-lag artefact — patents filed in 2024-2026 typically publish 18 months later, so recent years are always undercounted at the time of any snapshot. The rest of the pattern is consistent with an area where the core degradation-mitigation claims were staked out in the late 2010s, leaving later filers to compete for narrower, incremental improvements.

The technology composition data shows dense claiming in H01M and B01J but only single-digit-to-teens family counts in C01B, C01G, C04B, F01K, B01D and C03C — covering inorganic compound chemistry, ceramics, steam-cycle integration, separation processes, and glass/enamel compositions respectively. Ceramic electrolyte retention structures, thermal-cycle fatigue hardware for stack casings, and CO2/water separation membranes stand out as narrower branches with markedly fewer filings relative to the core electrode chemistry space. That does not guarantee the claim space is open — it may simply be technically harder to patent narrowly — but it is where a freedom-to-operate search is likely to turn up less blocking art.

US20250364574A1, filed by Exxonmobil Technology and Engineering Company and published in November 2025, covers cathode collector structures that increase open area at the cathode surface, including surface grooves, specifically to reduce unwanted ion transport when the cell is operated under elevated CO2 utilization. It is the newest record in this dataset, so it represents the current edge of publicly disclosed MCFC durability art rather than an established, widely-cited position. Anyone designing a cathode collector for high-CO2-utilization operation should review its specific claim language before finalising a similar geometry, since it is too recent to have accumulated the citation history that would show how broadly it has been treated by examiners or competitors.