14-Oct-2022 - Osaka Metropolitan University

New cheaper positive electrode material improves all-solid-state sodium batteries

Expected to improve high-capacity rechargeable batteries and make them cheaper by using common materials

The demand for high energy density rechargeable batteries, such as lithium-ion batteries, increases every year, as society shifts toward becoming carbon neutral. Sodium-ion batteries—which have a resource advantage over lithium-ion batteries—are attracting more attention, as cheap new high-performance materials continue to be developed.

A research group led by Associate Professor Atsushi Sakuda, President Masahiro Tatsumisago, and Professor Akitoshi Hayashi, at the Graduate School of Engineering, Osaka Metropolitan University, has successfully developed a new positive electrode, made of Na2FeS2, for all-solid-state sodium batteries. The batteries have a high energy storage capacity, high reversibility and use inexpensive elements that are readily available.

Furthermore, the batteries using the Na2FeS2 as a positive electrode can be charged and discharged for more than 300 cycles, due to the unique crystal structure of the Na2FeS2 that gives the electrode a long lifespan. Most high-capacity metal sulfide electrodes rely on conversion-type reactions, during which large rearrangements—during charging and discharging—are associated with inhomogeneous reactions and degradation. The Na2FeS2, on the other hand, achieves a high degree of reversibility during charging and discharging, by undergoing insertion-type reactions, which allow the electrode to retain its crystal structure over many cycles.

“The new Na2FeS2 positive electrodes are well balanced in terms of materials, cost, and lifetime; we expect them to be put to practical use in all-solid-state sodium batteries,” Professor Sakuda concluded. “In the future, we will continue our research to develop cheaper all-solid-state sodium batteries with even higher performance, by examining high input and output for rapid recharging, as well as making and testing of superior anode materials.”

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  • sodium batteries
  • all-solid-state batteries
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