An anode-free cell is one built without a pre-installed anode host material, where lithium plates directly onto a bare current collector during the first charge. This search captures filings that address the practical problems this creates, including uneven plating, first cycle efficiency losses and electrolyte consumption at the collector surface. It is distinct from silicon-dominant designs, which retain an anode host but replace most of the graphite with silicon, though many records in this dataset address both approaches together.

Filing is concentrated: five assignees hold 45.0% of the 855 records in scope, and the leading filer alone holds 109 records against 50 for the fifth-placed company. Beyond the top ten, which together hold 60.7% of records, filing volume drops off quickly across a long tail of single- or few-filing entrants. This pattern suggests a small group of specialists and battery majors are driving most of the technical development, while the wider field experiments at the margins.

Filing rose steadily from 71 records in 2017 to a peak of 113 in 2022, then eased slightly to 85 by 2024 — a -4% move from 2021’s 89 records, essentially a plateau rather than a decline. Figures for 2025 and 2026 appear lower still, but that reflects publication lag of roughly 18 months rather than a genuine slowdown, since recent filings have not all published yet. Treat any apparent drop in the last one to two years with caution for this reason.