Among the 26 companies in the ranked field, one assignee leads clearly with 16 of the 70 records in scope, more than double the fifth-place count of 6. The top five assignees together hold 64.3% of all records, and the top ten hold 95.7%, so the field is concentrated among a small group rather than spread evenly. Anyone assessing competitive position should look at that top-ten group first, since almost everything else in the ranking is a single- or few-filing entrant.

Not on the most recent complete data: filing among the leading assignees fell from 7 records in 2021 to 3 in 2024, a 57% decline over that span. Overall filing peaked at 15 records in 2019 and has not returned to that level since. That said, publication typically lags filing by around 18 months, so years after 2024 are still filling in and should not yet be read as a confirmed downward trend.

Cell-and-battery claims under IPC class H01M appear in 94.3% of the 70 records in scope, and metal-extraction claims under C22B appear in 71.4% — the two classes overlap in most filings, meaning claims typically cover both the physical handling of a spent cell and the chemistry used to recover value from it. Smaller classes covering electrolytic production, crushing/grinding, cutting, EV propulsion, solid waste disposal and electrical measurement each sit at 11.4% or below, indicating comparatively less-claimed mechanical and measurement territory around that dense core.

The class-level data points to under-claimed territory in residual capacity assessment automation, non-destructive cell-cutting methods, electrolytic recovery of black mass, and controls for second-life pack repurposing — all of which show lower patent presence than the core H01M/C22B combination. These are process and measurement steps that sit adjacent to the dominant cell-and-chemistry claims rather than replacing them. A freedom-to-operate search focused specifically on these narrower branches is more likely to surface open ground than a general search across the whole field.

US20100146761A1, titled Disassembly of battery, leads the set with 51 citations, notably ahead of the next-most-cited record, WO2020212587A1 on battery precursor preparation, at 31 citations. High citation counts in this kind of searched corpus tend to favour older filings that have simply had more time to be cited, so treat this as a measure of influence on later filers rather than a ranking of which patents matter most commercially today.