Preparation And Microstructure Properties Of Spinel LiNi_0.5Mn_1.5O₄ Cathode Material

In 1991,the world's first commercial lithium-ion battery was brought to market by Sony,which opened the prelude to the rapid development of the lithium-ion battery industry.Research and development of a new generation of high-capacity,high-rate,high-security,and long-life lithium-ion batteries has become the most important task at this stage.As an important part of batteries,cathode materials play a decisive role in battery performance.Therefore,the research and development of cathode materials is also one of the most popular topics.Among them,the spinel-type LiNi_0.5Mn_1.5O₄cathode material has a high working voltage platform(?4.7V vs.Li/Li⁺),has a high energy density?680Wh/kg?,good cycle performance,resources The advantages of richness and low cost have attracted extensive attention and research.However,there are still some problems in its application,such as poor cycle stability,especially the electrolyte is easily decomposed under high temperature conditions,and the elution of manganese and nickel ions directly affects the electrochemical performance of the active material and hinders its Large-scale commercial production.In this paper,the effects of sintering time,sintering temperature and annealing time on the micro-morphology,line structure and electrochemical performance of LiNi_0.5Mn_1.5O₄cathode material are studied to achieve the purpose of improvement.Spherical Mn₂O₃ was prepared by chemical method,which was used as template to prepare LiNi_0.5Mn_1.5O₄ cathode material by solid phase sintering.By comparing LiNi_0.5Mn_1.5O₄ cathode materials prepared at 700�C for 10h,12h,and 14h,it was found that the three samples are all P4₃32 space structures,and LiNi_0.5Mn_1.5O₄cathode materials prepared at a sintering time of 12h have more regular The spherical secondary morphology and the electrochemical performance are also excellent.The initial specific capacity reaches 108m Ah/g at a rate of 0.5C,the capacity retention rate after 100 times is 95.1%,and the specific discharge capacity at 5C can reach77m Ah/g.LiNi_0.5Mn_1.5O₄cathode materials were prepared by comparing different sintering temperatures?700�C,750�C,800�C,and 850�C?for 12 hours.It was found that all four samples had a regular secondary morphology,750�C,The samples prepared by sintering at 800?and 850?showed a transformation from P4₃32 space structure to Fd3m space structure.The comprehensive performance of LiNi_0.5Mn_1.5O₄ cathode material prepared by sintering at 800?for 12h was excellent.121.2 m Ah/g,the capacity retention rate after 100 laps is 94.3%,and the specific discharge capacity at5C is 84m Ah/g.annealing treatment was carried out at 650?by annealing at 650?for 0h,15h,10h,15h and 20h.The comparison of the prepared LiNi_0.5Mn_1.5O₄ cathode material revealed that the LiNi_0.5Mn_1.5O₄ cathode material obtained by annealing at 650?had undergone a transition from Fd3m space structure to P4₃32 space structure,and the order of the sample increased.The LiNi_0.5Mn_1.5O₄ cathode material prepared by annealing at 650?for 5h has regular micro-morphology distribution and more excellent comprehensive performance.The specific discharge capacity at the first cycle at 0.5C was 124.7m Ah/g,and the specific discharge capacity at 5C was as high as 92m Ah/g.