Designed synthesis of LiMn₂O₄ microspheres with adjustable hollow structures for lithium-ion battery applications

Two types of LiMn₂O₄ microspheres with similar sizes but adjustable hollow structures have been synthesized using a new and simple approach. Their performance as cathode materials for lithium ion battery applications has been studied and correlated with the hollow structural parameters. Through a solid state reaction between LiOH and mesoporous MnO ₂ obtained by the complete decomposition of MnCO₃, LiMn₂O₄ hollow spheres with a robust wall and small cavity size are prepared (LiMn₂O₄-A). The fusion of the mesopores and the Kirkendall effect during the lithiation process are responsible for the hollow interior formation. In another approach through partial decomposition and selective etching, LiMn₂O₄ hollow spheres with thin walls are prepared (LiMn₂O₄-B). It is demonstrated that LiMn₂O₄-A shows larger capacity, superior rate capability, and better cycling stability compared to LiMn ₂O₄-B. The former exhibits an initial discharge capacity of ∼120 mA h g^-1, maintains 96.6% of the initial capacity after 105 cycles at 1 C and ∼90% of the capacity at 0.1 C when discharged at 5 C.