The formation process is the initial controlled charge-discharge cycling step performed on a fresh lithium-ion cell to build a stable solid-electrolyte interphase (SEI) on the electrode surface before the cell is put into service. It is patented separately from cathode material composition because it covers process conditions — voltage profiles, hold times, temperature, electrolyte additive sequencing — rather than the material itself. A cathode composition patent and a formation-protocol patent can both apply to the same physical cell without overlapping, which is why this dataset filters specifically for formation, SEI and aging-process language rather than general NMC cathode claims.

The dataset is fragmented rather than dominated by one company: assignees include Toyota, TNO, both Tesla entities, and Chinese recycling-materials firms such as Guangdong Brunp and Hunan Brunp. Notably, every top assignee tracked for recent-year momentum shows zero filings in the latest tracked year, so current rankings reflect historical filing position rather than active competitive velocity. Anyone assessing this space should treat the leaderboard as a map of prior claims, not a signal of who is currently racing to file more.

Shrinking, on the evidence available. Filings peaked at 7 in 2018 and had fallen to 2 by the 2022 midpoint, with no recovery visible since. Publication lag of roughly 18 months means the very latest year or two is always undercounted, but the multi-year decline from the 2018 peak is too large to be explained by lag alone — this looks like a technology area that filed hard early and has since cooled.

The thinnest coverage sits in sub-areas like formation-cycle voltage profiling tuned for high-nickel NMC chemistries, SEI additive combinations beyond the two-additive systems that dominate the most-cited records, and integration between precursor-material processing and formation-cycle control. Secondary IPC classes such as B60K, B60L and C01G each appear in only 3 of 26 records, indicating that vehicle-integration and precursor-chemistry angles on formation process are rarely claimed together with the core electrochemical process itself.

The United States dominates this dataset with 16 of 26 tracked filings routed through the USPTO, followed by Canada at 5. Europe, the UK, Austria and India each account for only one or two filings, meaning international protection outside North America is comparatively thin. A company planning global formation-protocol protection should treat the US and Canada as the established filing floor and treat European and Indian coverage as an open opportunity rather than contested ground.