A new high voltage alluaudite sodium battery insertion material

P. Barman, P. K. Jha, A. Chaupatnaik, K. Jayanthi, R. P. Rao, G. Sai Gautam, S. Franger, A. Navrotsky, P. Barpanda

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Large-scale stationary storage forms a key sector that can be economically served by sodium-ion batteries. In realizing practical sodium-ion batteries, discovery and development of novel cathodes is essential. In this spirit, alluaudite-type Na2Fe2(SO4)3 was reported in 2014 to have the highest Fe3+/Fe2+ redox potential (∼3.8 V vs. Na). This finding led to reports on various PO43− and SO42− based alluaudite compounds exhibiting high energy densities. In 2017, MoO42− based alluaudite, Na2.67Mn1.67(MoO4)3, was found as a 3.45 V cathode material. Exploring molybdenum chemistry further, this work reports alluaudite type Na3.36Co1.32(MoO4)3 (NCMo) as a novel versatile electroactive cathode for Li-ion and Na-ion batteries. It was synthesized by a wet solution-combustion route with a restricted annealing duration of 1 min at 600 °C. Calorimetric study revealed the formation enthalpy from component oxides (ΔH°f,ox = −575.49 ± 7.75 kJ/mol) to be highly exothermic. Unlike the sulfate class of alluaudites, this material is highly stable in air and moisture (ΔHds = 537.42 ± 0.78 kJ/mol). Having an ionic conductivity of 6.065 × 10−8 S/cm (at 50 °C), it offers a pseudo two-dimensional Na+ migration pathway. Without any material optimization, NCMo was found to work as a high-voltage insertion cathode (ca. 4.0 V vs. Na/Na+ and 4.1 V vs. Li/Li+) in sync with theoretically predicted potential of 3.98 V (vs. Na/Na+). Ex-situ X-ray diffraction and photoelectron spectroscopy studies revealed the occurrence of solid-solution redox mechanism solely involving Co3+/Co2+ redox centre. It benchmarks Na3.36Co1.32(MoO4)3 as a novel electrochemically active Mo-based alluaudite-type polyanionic cathode insertion material.

Original languageEnglish (US)
Article number101316
JournalMaterials Today Chemistry
StatePublished - Jan 2023


  • Alluaudite
  • Batteries
  • Cathodes
  • High-voltage
  • Ionic conductivity
  • Molybdates

ASJC Scopus subject areas

  • Catalysis
  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Polymers and Plastics
  • Colloid and Surface Chemistry
  • Materials Chemistry


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