You can freely build on How Lithium-Ion Battery Cathodes Are Made
This patent expired in 2001. Every claim — 0 independent, 1 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
Individual
Patent granted
1982
Expired
2001
Forward citations
41
What this patent covers
This patent describes a chemical process to create stable materials for battery electrodes, specifically those with a layered structure like alpha-NaCrO2. The inventors discovered that you cannot create these materials using high-heat methods because the structure becomes unstable. Instead, the patent claims a method of electrochemical extraction, where you pull positive ions (like Lithium) out of a starting compound at low temperatures to create the final, active electrode material.
What is now free to use
All 1 claims of US 4357215 are in the public domain. Specifically:
The 1 dependent claim add narrowing limitations and are also free.
What is NOT covered
Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.
Does not cover the physical assembly of a complete battery cell.
Does not cover high-temperature manufacturing processes for these materials.
Does not cover the use of materials that do not follow the specific A x M y O 2 layered structure.
Does not cover the specific electrolyte compositions used in the battery.
Who is building on this today
Major battery manufacturers like Panasonic, LG Energy Solution, and CATL build upon these fundamental material science principles. The technology is now industry-standard, and research continues into optimizing these layered oxides for higher energy density.
Products built on expired version of this technology
Lithium cobalt oxide (LiCoO2) cathodes in smartphones
Rechargeable battery packs for electric vehicles
Portable power banks
How to cite this patent in your documentation
Individual. US Patent 4357215. Fast ion conductors. Granted 1982, expired 2001. Now in the public domain.
Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.
PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.