Synthesis and Electrochemical Properties of Spherical Nano-Structured and Nano-Agglomerated Li_1.2Mn_0.6Ni_0.2O₂ Cathode Materials for Lithium-Ion Batteries

Abstract

Spherical nano-structured and nano-agglomerated Li_1.2Mn_0.6Ni_0.2O₂ cathode materials were prepared by simple blending and mechanical ball-milling process, respectively. The phase structure of Li_1.2Mn_0.6Ni_0.2O₂ cathodes were determined by X-ray diffraction (XRD), and the surface morphology was observed by scanning electron microscopy (SEM). Electrochemical tests of the cathodes were performed to examine the effect of particle morphology on the cycle performance, as well as the rate capability. The results show that spherical nano-structured sample prepared by simple blending process exhibits an initial discharge capacity of ∼234.0 mAh g⁻¹ and remains ∼98.0% of that after 50 cycles. In contrast, the nano-agglomerated cathode synthesized by mechanical ball milling process retains only ∼84.0% of its initial discharge capacity after 50 cycles although it shows a better rate performance than the spherical nano-structured cathode. The good rate performance for the nano-agglomerated cathode can be attributed to the fine nano-scale particles which greatly shorten the lithium-ion diffusion distance. Furthermore, the better structure stability for the spherical nano-structured cathode can be responsible for its superior cycling performance.

Keywords:

• Spherical particle
• nano-structured Li_1.2Mn_0.6Ni_0.2O₂
• cathode materials
• electrochemical performance
• lithium-ion batteries