Volatile heterometallic precursors for the low-temperature synthesis of prospective sodium ion battery cathode materials

Abstract

Heterometallic single-source precursors with a proper sodium:transition-metal ratio for nonoxide sodium ion battery cathode materials are reported. Heterometallic fluorinated β-diketonates NaM(hfac)3 (M = Mn (1), Fe (2), Co (3), and Ni (4); hfac = hexafluoroacetylacetonate) have been obtained on a large scale, in high yield using a one-step reaction that employs commercially available reagents. The complexes are stable in open air and highly volatile. The mass spectrometric investigation indicates the existence of heterometallic molecules in the gas phase. The presence of heterometallic species in solutions of several solvents has been unambiguously confirmed. Heterometallic precursors were shown to exhibit clean, low-temperature decomposition in argon atmosphere that results in phase-pure perovskite fluorides NaMF3, the prospective cathode materials for sodium ion batteries.