Condens. Matter 5(2), 39 (2020) 

Phys. Rev. B 111, 235145 (2025)

With the rising demand for sustainable energy storage, sodium-ion batteries have gained immense attention as a cost-effective and abundant alternative to lithium-ion batteries. A central challenge, however, lies in developing anode materials that simultaneously offer high energy capacity and excellent electronic conductivity.

Our research (Condens. Matter 5(2), 39 (2020)) addresses this by investigating the Na₃BixSb₁₋ₓ alloy series, which bridges Na₃Bi—a topological Dirac semimetal with high conductivity—and Na₃Sb, a high-capacity (660 mAh/g) but poorly conducting anode material. By tuning the Bi/Sb ratio in Na₃BixSb₁₋ₓ alloys, we theoretically predicted a topological semiconductor-to-Dirac semimetal transition that optimizes both capacity and conductivity, unlocking the potential for next-generation high-capacity, highly conductive sodium-ion battery anodes. 

Importantly, this predicted Dirac semimetal–semiconductor transition has now been experimentally observed in our follow-up work using x-ray Compton scattering (Phys. Rev. B 111, 235145 (2025)). Furthermore, it demonstrates how the number of electrons involved in this transition can be estimated, providing a novel descriptor for quantifying the strength of spin-orbit coupling responsible for driving the transition.

This experimental validation strengthens the potential of Na₃BixSb₁₋ₓ alloys as promising anode materials for future applications, enabling faster charging, longer cycling life, and enhanced efficiency, which are critical attributes for advancing renewable energy technologies and electric mobility.

See also Aki Pulkkinen et al, including Wei-Chi Chiu, Probing the semiconductor–Dirac-semimetal transition in Na-Sb-Bi alloys with x-ray Compton scattering, Phys. Rev. B 111, 235145 (2025)