Swedish sodium-ion battery developer Altris presented a pure Prussian White cathode material with a capacity of 160 mAh/g, making it the highest capacity declared to date. This marks an important milestone on Altris’ commercialization journey, as the capacity of cathode materials is crucial to increase the energy density and deployment of sodium-ion batteries. (Earlier post.)

Prussian White is a framework material consisting of sodium, iron, carbon and nitrogen (Na_xFe[Fe(CN)₆] with x>1.9). The large pores inside the material enable the capture and storage of a range of atoms or molecules making the compound highly interesting for a range of applications.

Altris, spun out of Uppsala University in 2017, has developed a patented low-temperature and pressure synthesis method to produce Prussian White in a form ideal for use as a positive electrode material in sodium ion batteries.

Since its founding in 2017, Altris has developed Prussian White cathodes, electrolytes, battery cells and blueprints to create sodium-ion batteries. The new Prussian White cathode material is sustainable, made from abundant raw materials, and free from toxic elements and conflict minerals such as nickel and cobalt.

High-capacity cathodes are crucial for increasing the energy density of sodium-ion batteries. Following the development of its Prussian White cathode, Altris also measured its highest energy density to date in a commercial-sized sodium-ion battery cell, amounting to 150 Wh/kg. This makes the battery cell commercially viable for applications such as grid energy storage connected to renewable energy production.

The world is in desperate need of batteries to accelerate electrification and the transition to a sustainable energy system. At Altris, we are ready to play our part. With our latest achievement, we have placed ourselves at the very forefront of Prussian White cathode development. But this is only the beginning. The cathode will enable us to increase the energy density of our sodium-ion battery cells. I am confident that we will achieve 160 Wh/kg and beyond in the near future.

—Björn Mårlid, CEO of Altris

Transitioning from a society built on fossil fuels to renewable energy requires a massive number of batteries. There are not enough readily available raw materials to produce lithium-ion batteries to make this happen in time,Altris says. Sodium-ion batteries have outstanding performance in terms of longer life, more flexible working temperatures, and safety, making them a competitive complement to lithium-ion—and a superior alternative for applications such as grid energy storage and commercial transport.