Solid polymer electrolytes rely on ion transport through a polymer matrix without added liquid, composite polymer electrolytes add inorganic or nanostructured fillers to improve conductivity and mechanical strength, and gel polymer electrolytes retain a liquid or plasticiser phase within the polymer network for higher conductivity at the cost of some mechanical rigidity. Patent claims in this corpus typically specify which category applies because the operating temperature range, interfacial adhesion behaviour and mechanical modulus targets differ materially between them. Distinguishing the three matters for freedom-to-operate work, since a composite-specific filler dispersion claim will not usually read onto a pure gel formulation.

The assignee ranking behind this dataset covers 100 companies, with the leading filer holding 346 records and the fifth-placed filer holding 186 — a real but not overwhelming lead. The top five combined account for 18.4% of the 6,911 records in scope, and the top ten reach 26.8%, meaning most of the field sits outside the leading group. Automotive OEMs and battery cell makers dominate the upper part of the ranking, consistent with the fact that 80.9% of records are classified under the batteries and fuel-cells IPC subclass.

Not on the evidence available for complete years: filings rose from 163 in 2021 to 175 in 2024, a 7% increase over that span, following an earlier peak of 311 in 2018. The much lower counts shown for 2025 and 2026 reflect the roughly 18-month lag between when a patent is filed and when it publishes, not a real drop in filing. Anyone reading the trailing two years of a chart like this should treat them as provisional and look instead at the last fully comparable year-over-year comparison.