Volatile Single-Source Molecular Precursor for the Lithium Ion Battery Cathode

The first single-source molecular precursor for a lithium–manganese
cathode material is reported. Heterometallic β-diketonate LiMn2(thd)5 (1, thd = 2,2,6,6-tetramethyl-3,5-heptanedionate)
was obtained in high yield by simple one-step solid-state reactions
employing commercially available reagents. Substantial scale-up preparation
of 1 was achieved using a solution approach. The crystal
structure of the precursor contains discrete Li:Mn = 1:2 trinuclear
molecules held together by bridging diketonate ligands. The complex
is relatively stable in open air, highly volatile, and soluble in
all common solvents. It was confirmed to retain its heterometallic
structure in solutions of non-coordinating solvents. The heterometallic
diketonate 1 was shown to exhibit clean, low-temperature
decomposition in air/oxygen that results in nanosized particles of
spinel-type oxide LiMn2O4, one of the leading
cathode materials for lithium ion batteries.