The start-ups hoping to return battery making to the US
Batteries based on sodium-ion technology could be made in the US with locally sourced materials.
As heatwaves scorched Europe this summer, workers at a US battery company noticed an uptick in demand.
San Diego-based Unigrid sells a nine kilowatt hour battery for people's homes. Sweltering European homeowners were apparently looking for ways of storing power when it was available from the grid at lower rates. They could then run air conditioners more cheaply, off the battery, during the worst heat of the day.
"We have requests coming from Spain, France, Germany, The Netherlands," says Darren Tan, co-founder and chief executive. "We've shipped the first 100 units and [expect to ship] 1,000 before the end of the year."
The choice of cathode material, or how the electrolyte – which separates cathode and anode – is formulated are key details influencing the performance and longevity of sodium ion batteries. Some manufacturers are not using chromium for their cathode but hard carbon instead, or sodium iron phosphate pyrophosphate (NFPP).