Sodium sits just below lithium on the periodic table, and the resemblance is the whole pitch: a sodium-ion battery works much like a lithium-ion one, but with an element that is vastly cheaper and available almost everywhere. No lithium price exposure, no cobalt, no geopolitically fraught supply line. The catch is physics — sodium ions are bigger and heavier, so the cells store less energy per kilogram.The 2022 grants show the chemistry being built out in earnest. Nippon Electric Glass's US11515534B2 claims a positive-electrode active material for a sodium-ion cell. The Research Foundation for the State University of New York's US11289700B2 claims a specific KVOPO4 cathode for sodium-ion batteries. Korea-linked work in US11251426B2 claims a sodium composite transition-metal oxide cathode. These are cathode patents — the same battleground as lithium-ion, refought for sodium.Does it pencil? Not for a long-range EV, where energy per kilogram is king and sodium's lower density is disqualifying. It pencils for the opposite case: stationary grid storage, where the battery sits on the ground, weight is free, and the only number that matters is cost per kilowatt-hour over the asset's life. There, sodium's cheap, stable, abundant inputs are a genuine advantage.The assignee data around sodium-ion in this period is the real headline: CATL, the largest cell maker on earth, shows up heavily, alongside specialist Natron Energy. When the volume leader patents a 'lower-performance' chemistry, it is not slumming — it is segmenting. CATL can serve premium EVs with high-nickel lithium and cost-sensitive grid and entry-level applications with sodium, from the same factories.There is a safety bonus that does not show up in the energy-density number. Sodium-ion cells tolerate being fully discharged to zero volts, which simplifies shipping and storage, and many formulations are less thermally touchy than high-nickel lithium. For grid applications where a fleet of cells sits for years, that durability has real value.The CPC code H01M 10/054, the office's label for sodium secondary cells, is the one to track. Its climb through 2022, concentrated among cathode filings, is the signal that sodium-ion had crossed from curiosity to a chemistry that serious players intended to ship — just not into the applications where lithium already wins.
“The present invention provides a novel positive electrode active material for a sodium-ion secondary battery having a high voltage and a high capacity.”— U.S. Patent No. 11,515,534 source