Preparation And Modify Of LiNi_0.5Mn_1.5O₄as Cathode Material For High-Voltage Lithium-ion Battery

The greatest characteristics of spinel structure LiNi0.5Mn1.5O4is the high charging and discharging voltage platform, high power performance and low-cost, which is known as one of the most potential positive electrodes in power Lithium-ion battery. But the preparation of LiNi0.5Mn1.5O4material has some difficulty, it also can easily be dissolved by electrolyte,and oxidative decomposition of electrolyte under high voltage lead to the bad cycle performance of battery, these limited the practical application of LiNi0.5Mn1.5O4material. Goal of this paper is to modify the cycle performance of cell assembled with LiNi0.5Mn1.5O4, LiNi0.5Mn1.5O4and its doped samples are prepared by sol gel self-propagating method. Then the morphology, structure and electrochemical performance of the samples are tested systematic.First, research progress of the anode materials of Li ion battery is reviewed, and the preparation condition of LiNi0.5Mn1.5O4by sol gel self-propagating method is studied. The morphology and its phase of samples in this paper are investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that samples heated at800℃for12h and then annealed at600℃in air reveal uniformity particles in appearance and no miscellaneous phase materials. Charging and discharging test at constant current of cell with these samples as the anode material shows this cell is of more stable cycle performance, higher median voltage and higher discharge efficiency.Secondly, based on the commonly used electrolytic and solvent, a number of potential electrolytes are prepared. Conductivity test and electrochemical window show0.7mol/L lithium bis(oxalato)borate (LiBOB)-propylene carbonate (PC)/dimethyl carbonate (DMC) is appropriate for5V high voltage Li-ion battery. Compared with electrochemical performance of cell with1.0mol/L LiPF6-ethylene carbonate (EC)/DMC electrolyte, cell with0.7mol/L LiBOB-PC/DMC electrolyte emerges superior cycle performance, higher median voltage and higher discharge efficiency.Besides, doping of LiNi0.5Mn1.5O4is introduced in this paper. And effect of the doping of rare-earth element on electrochemical performance of LiNi0.5Mn1.5O4is studied. The doped samples LiNi0.45La0.1Mn1.45O4modify electrochemical performance of LiNi0.5Mn1.5O4obviously. Once more, LiNi0.45La0.1Mn1.45O4/Li cell shows longer cycle life, higher median voltage and efficiency.Finally, innovations and inadequacy of this paper are summarized, and then the outlook of the study is raised.