New material boosts sodium-ion batteries in bid to be alternative to expensive lithium

With lithium prices much higher than a year ago, researchers from Skoltech and Lomonosov State University have developed a sodium-ion battery material that offers an alternative to the lithium-ion technology of more and more expensive.

The the new material is sodium vanadium phosphate fluoride powder with a particular crystalline structure. Used in the battery cathode, it provides record energy storage capacity, removing one of the bottlenecks of emerging sodium ion technology.

Lithium-ion batteries are everywhere: they power portable electronic devices and electric vehicles, among other things, and they store the energy produced by wind farms to balance erratic winds.

However, relying solely on lithium is riskybecause its chemicals are getting more and more expensive, its production is quite dirty, and ore deposits are unevenly distributed around the world.

A notch lower in the periodic table, sodium, a much more abundant alkali metal presents itself as a possible alternative to lithium.

Until now, sodium-ion battery technology is relatively newand although the basic battery cell architecture is the same, different materials must be used for the main components.

Between them, the cathode is crucial for the characteristics of the battery. Skoltech and MSU researchers present a new cathode material that provides 10-15% higher battery energy density than today’s best competitor.

Our new material and the one recently used by industry are called sodium vanadium phosphate fluoride: they are made from atoms of the same elements. What differentiates them is the arrangement of these atoms and the proportion in which they are contained in the compound.

Our material also compares well to the class of layered cathode materials: it provides nearly the same battery capacity and greater stability, which translates to longer battery life and profitability.

Surprisingly, even the theoretical predictions of competing materials fall short of the practical performance of ours, and this is not trivial, as the theoretical potential is never fully realized.

Stanislav Fedotov, Skoltech University.

According to the scientists, once more research is done on efficient materials for sodium-ion batteries, they could dethrone lithium-ion batteries in heavy electric vehicles such as buses and trucks, as well as in the storage of electricity. stationary energy in wind farms, solar parks and other places.

The greater energy storage capacity is just one of the advantages of this material. It also allows the cathode to operate at lower ambient temperatures, which is particularly important for Russia.

Stanislav Fedotov

In fact, the battery community tends to research new materials empirically, through trial and error, or with high-throughput studies testing large sets of materials. We take a different approach and favor the rational design of solid-state chemistry. This means that we rely on hard science, using the fundamental laws and principles of solid state chemistry to arrive at the material with the desired properties.

Theoretical considerations led us to the basic formula for a material that could provide high energy storage capacity. Next, we had to determine which crystal structure would release this potential. The one we have chosen is known as the KTP-like structure, and it comes from nonlinear optics; is not very common in battery engineering. After careful consideration and theorizing, we realized that this particular compound with this particular crystal structure should work. We then succeeded in synthesizing it by ion exchange at low temperature. And there it is, with its superior characteristics now confirmed by experience.”

Semyon Shraer, researcher at Skoltech and lead author of the article.

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