Preparation And Modification Of LiNi_0.8Co_0.1Mn_0.1O₂ Cathode Materials For Enhanced Performances Of Lithium-ion Batteries

With the miniaturization and lighting of the portable electronic products,and the rapid development of electric vehicles and grid energy storage devices,lithium ion batteries with higher energy density and higher performances are increasingly demanded.High-nickel ternary cathode material,such as LiNi_0.8Co_0.1Mn_0.1O₂,owing to higher energy density and lower cost,has becoming the first choice for next-generation commercial batteries.It is of great significance to the coating modification and structural design for LiNi_0.8Co_0.1Mn_0.1O₂ cathode materials with better cycle performance and enhanced thermal stability.The main points are summarized as follows:1?A near-equilibrium deposition tactic has been presented to achieve uniform Li₂TiO₃ coating on LiNi_0.8Co_0.1Mn_0.1O₂.With a simple pH control and usage of BO₃^3-scavenger in the?NH₃?₂TiF₆ precursor solution,the hydrolysis reaction chemistry can thus be manipulated at a near-equilibrium condition and a uniform coating layer of Li₂TiO₃ with the thickness of about 4 nm can be successfully deposited on the LiNi_0.8Co_0.1Mn_0.1O₂ cathode material,As a result,the Li₂TiO₃ coating layer can significantly improve the cycling stability and initial coulomb efficiency of the LiNi_0.8Co_0.1Mn_0.1O₂ cathode materials by increasing the capacity retention from 67.2%?0.5 C,200 cycles?for the bare sample to 93.5%for the Li₂TiO₃-coated sample,delivering 204.1 mAh g^-1 at 0.2 C.The ionic conductive nature of Li₂TiO₃ layer also enhances the rate capability of the LiNi_0.8Co_0.1Mn_0.1O₂ cathode materials.Moreover,the thermal stability of the Ni-rich cathode material could be enhanced by 7 ^oC.2?A co-precipitation route has been utilized to synthesize the precursor of Ni_0.8Co_0.1Mn_0.1?OH?₂,which was mixed with MnCO₃ and Li₂CO₃ afterwards in a certain proportion.After post-heat treatment in the oxygen atmosphere,Li₂MnO₃-LiNi_0.8Co_0.1Mn_0.1O₂ composite material has been obtained.The electrochemical performance of the material was tested by galvanostatic charge/discharge measurements and electrochemical impedance spectroscopy.The results show that the 3wt%Li₂MnO₃ composite material exhibit higher initial discharge capability(183 mAh g^-1 at 0.5 C),more stable cycle performance?with capacity retention of 85.7%after 120 cycles at 0.5 C?and better rate performance,compared with unmodified cathode.