Magnetic structure of some battery materials and why it matters

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International Battery Materials Association
Operation of batteries with insertion cathodes is typically based on a redox reaction Mn+/Mn+p (p=1,2) of transition metals. The motivation to increase gravimetric energy density and reduce cost naturally drives research to the light, i.e. 3d, transition metals M=V-Ni, which in turn are also paramagnetic ions and may order magnetically. Using neutron diffraction and magnetometry we explored magnetic structure and properties of some materials recently synthesized in search of better cathode materials: Na2CoP2O7, maricite- and triphylite-NaFePO4, Na2FePO4F, M(OH)xF2-x (M=Co,Fe), Li2MnSiO4, Li2CoSiO4, LiNaCoPO4F, LiNaFePO4F. The detailed magnetic structures will be presented and features of crystal structures affecting the type of magnetic ordering will be discussed. Although polyanionic materials (phosphates and silicates) are magnetically low density systems and thus order at low temperature (< 50 K), the information on magnetic structure is important for accurate DFT calculations. The effect of neglecting magnetic order on the DFT based quantitative predictions will be illustrated.
Neutron diffraction, Transition elements, Gravimetric analysis, Energy density, Redox reactions, Electric batteries, Cathodes, Magnetic properties, Temperature range 0065-0273 K
Avdeev, M., Ling, C. D., Mohamed, Z., Barpanda, P., Yamada, A., Ben Yahia, H., & Shikano, M. (2014). Magnetic structure of some battery materials and why it matters. Paper presented at the International Battery Association 2014, Brisbane Convention & Exhibition Centre, Brisbane, Australia, 3 - 7 Mar 2014.