ИСТИНА

NASICON-type Na3V2(PO4)3 cathode materials are considered as promising candidates for high-performance Na-ion batteries due to extremely long cyclic stability and an outstanding ability to operate at high (dis)charge rates. However, its cost-effectiveness can still be improved using transition metals cheaper than vanadium, which could also increase the energy density compared to that in Na3V2(PO4)3. The replacement of V with Mn and Cr in Na3V2(PO4)3 lowers the cost of the materials and enhances the operation voltage. Substitution of V by electrochemically inactive Mg and Sc allows studying vanadium redox processes without contributions from other transition metals. Figure 1 Comparison of galvanostatic charge curves of NASICON compounds with different composition In order to link electrochemical features with the phase transformations in NASICON samples operando X-ray powder diffraction was carried out. The evolution of the transition metal oxidation states during charge and discharge was studied by operando X-ray absorption spectroscopy [1]. The experimental results indicate the benefits of vanadium-substituted compounds and ability to outperform the unsubstituted materials in terms of rate-capability. Therefore they should be preferred for high-power applications. This work was supported by the Russian Science Foundation (Grant No. 17-73-30006-P). References: 1. Buryak, N.S.; Anishchenko, D.V.; Levin, E.E.; Ryazantsev, S.V.; Martin-Diaconescu, V.; Zakharkin, M.V.; Nikitina, V.A.; Antipov, E.V. // Journal of Power Sources 2022, 518, 230769-230780.