Modification Of Cathode Material And Electrolyte Optimization Of Lithium Ion Battery

At present,emission peak and carbon neutrality have become a global consensus,and the new energy industry is developing rapidly to meet the requirements of the times and continuously contribute to carbon emission reduction.under the trend of comprehensive low-carbon energy and transportation,as a key material of power batteries and energy storage batteries,higher requirements are also put forward for lithium battery cathode materials.Ternary cathode materials have attracted much attention because of their high energy density.In particular,the energy density of lithium manganese rich cathode material(LRNCM)can be as high as 250 mAh·g-1.However,its irreversible phase transition in the cycle process and transition metal ion dissolution caused by electrolyte decomposition under high pressure lead to its poor cycling stability.In order to improve the electrochemical performance of LRNCM,two methods of electrolyte additive modification and cathode material coating modification were proposed in this paper.In this paper,3-Sulfolene was used as an electrolyte additive to study the effect of the electrolyte additive on the electrochemical performance of LRNCM cathode materials during the high pressure cycling(2-4.8 V),and the mechanism of 3Sulfolene was further studied.The results showed that adding 0.5 wt%3-Sulfolene could effectively improve the cycle stability of Li-rich materials,and the capacity reached 179 mAh·g-1 after 200 cycles at 1 C,and the capacity retention rate increased from 60.73%to 72.71%.After characterization analysis,it was found that 3-Sulfolene can participate in the formation of a more stable interface film on the positive electrode surface in the early cycle,so as to reduce the interface impedance,less transition metal ion dissolution,and maintain the structural stability of the positive electrode material.In this paper,the HNTs/LRNCM composites were prepared by coating helloxite nanotube(HNTs)on the surface of LRNCM cathode materials.We studied the electrochemical properties and structural changes of the composites.SiO2 and Al2O3 in HNTs can consume HF,the decomposition product of electrolyte,thus reducing the interface reaction and maintaining the stability of the positive electrode material structure.The results showed that the cyclying stability of the coated composite was significantly improved,and the capacity retention rate increased from 60.09%to 88.15%after 300 cycles at 1 C.However,the capacity of the coated material decreased significantly compared with that of the original material.The characterization results showed that the impedance of the coated material increased significantly,and in the process of sintering at high temperature,the structure of Li-rich materials is damaged,resulting in reduced capacity.