Study On The Enhanced Electrochemical Performance Of Li Rich Cathode By Modified With Aluminosilicate Solid Acid

With the shortage of oil energy,new energy has been widely integrated into the development of modern society.As a good energy storage equipment,lithium-ion battery has been widely studied in recent years.With the wide popularization of new energy electric vehicles,the performance requirements of lithium-ion battery have become the mainstream research direction.In order to improve the cycling performance of lithium-ion battery.In this paper,the surface of Li1.18Ni0.15Co0.15Mn0.52O2 cathode material was modified with aluminum silicon solid acid（Al2O3·Si O2）to improve its cycling performance.The lithium rich cathode material Li1.18Ni0.15Co0.15Mn0.52O2 was prepared by sol-gel method,and Al2O3/Si O2 was prepared by ultrasonic impregnation to modify the surface of Li1.18Ni0.15Co0.15Mn0.52O2.In order to have a comparation,three different samples（Al2O3,Al2O3·Si O2 and Si O2）were prepared by controlling the different proportion of Al Si（1:0,1:1and 0:1）.The special Al-O-Si bond of Al2O3·Si O2 can be found by FTIR curve.Through the analysis of electrochemical data,Li1.18Ni0.15Co0.15Mn0.52O2 material with high acid center strength modified by Al2O3·Si O2 has better electrochemical performance.The constant current charge discharge test with current density of 200 m Ah g^-1shows that the maximum capacity retention rate of the material modified by Al2O3·Si O2 coating is 72.5%after 200 cycles,which is much higher than 8.8%of the original sample.When the current density is 1 A g^-1,the discharge specific capacity is 99.2 m Ah g^-1 and the capacity retention rate is 65.7%after 300cycles.DQ/DV curve analysis shows that the strong acid center strength of the coating layer on Li1.18Ni0.15Co0.15Mn0.52O2.cathode material can inhibit the reduction of anions and reduce the side reaction between electrode and electrolyte.In order to reduce the cost of raw materials.Al2O3·Si O2 was prepared by cocurrent precipitation method and its surface was modified by mechanical grinding.The cost of sodium aluminate and sodium silicate for the synthesis of Al2O3·Si O2 by parallel flow precipitation is lower than that of aluminium-iso-propoxide and ethyl orthosilicate.The formation of Al-O-Si bond was also observed by FTIR.The constant current charge discharge curve of the electrochemical test at the current density of 200 m A g^-1 shows that the maximum capacity retention rate of the modified samples with Al2O3·Si O2 is 80.0%after 200 cycles,which is higher than 67%of the original sample.When the current density is 1 A g^-1,the discharge specific capacity is 132.9 m Ah g^-1 and the capacity retention rate is 53.5%after 300 cycles.