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Sodium ion battery (SIB) technology offers an attractive alternative to rechargeable batteries in large-scale applications. To meet the practical demands, it is essential to develop stable electrode materials with a high capacity and high energy density. Herein, we demonstrate a successful activation of the Nb5+/Nb4+, Nb4+/Nb3+, and Cr3+/Cr2+redox couples in NASICON-structured NaCrNb(PO4)3, thus introducing a novel three-electron reaction anode for sodium ion batteries with a high specific capacity. Carbon-coated NaCrNb(PO4)3synthesized using the Pechini sol–gel method demonstrates the reversible capacity of 162 mA h·g–1at the 1C rate and good cycling stability. This is the first example of NASICON-type anode material with the Cr3+/Cr2+reversible transition confirmed by Cr K-edge XANES measurements. Operandopowder X-ray diffraction showed that sodium insertion–extraction in NaCrNb(PO4)3proceeds through a combination of single-phase and biphasic processes. A differential scanning calorimetry study revealed the excellent thermal stability of NaCrNb(PO4)3, exceeding that of hard carbon anodes. Attractive electrochemical properties of NaCrNb(PO4)3, its high thermal and cyclic stability, and the scalable synthesis of this material demonstrate its potential as an anode for use in sodium ion batteries.

NASICON-type NaNbV(PO4)3electrode material synthesized by the Pechini sol–gel technique undergoes a reversible three-electron reaction in a Na-ion cell which corresponds to the Nb5+/Nb4+, Nb4+/Nb3+, and V3+/V2+redox processes and provides a reversible capacity of 180 mAh·g–1. The sodium insertion/extraction takes place in a narrow potential range at an average potential of 1.55 V versus Na+/Na. Structural characterization by operandoand ex situX-ray diffraction disclosed the reversible evolution of the NaNbV(PO4)3polyhedron framework during cycling, while XANES measurements in the operandoregime confirmed the multielectron transfer upon sodium intercalation/extraction into NaNbV(PO4)3. This electrode material demonstrates extended cycling stability and excellent rate capability maintaining the capacity value of 144 mAh·g–1at 10 C current rates. It can be regarded as a superior anode material suitable for application in high-power and long-life sodium-ion batteries.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

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