Convenient synthesis and electrochemical performance investigation of nano-sized LiMn₂O₄

Abstract

Nano-sized LiMn₂O₄ materials are synthesized via a simple one-step solid-state reaction using lithium acetate and lithium oxalate as lithium sources, respectively. The physical and electrochemical properties of LiMn₂O₄ materials are investigated by X-ray diffraction, scanning electron microscopy and electrochemical measurements. The results show that both of the as-prepared materials are pure nano-sized LiMn₂O₄ with narrow particle size distribution. Compared with lithium oxalate, lithium acetate is propitious to improve the crystallinity and size distribution of nano-sized LiMn₂O₄. Besides, LiMn₂O₄ synthesized from lithium acetate shows low resistance, good ability to inhibit Mn³⁺ dissolution, long cycle life and excellent rate property. Finally, the adverse effect of nano-sized LiMn₂O₄, which has increased contact area between acid-containing electrolyte and LiMn₂O₄ cathode electrode to aggravate dissolution and corrosion behavior, is treated by Li₂CO₃ additive in electrolyte. Results show that electrochemical performance of nano-sized LiMn₂O₄ is improved, due to the fact that Li₂CO₃ additive can not only consume HF and other Lewis acid in the commonly used LiPF₆-based electrolyte, but also decrease interfacial impedance to promote the migration of Li⁺ ions through cathode surface film.