Preparation And Modification Of Lithium-rich Solid Solution Cathode Materials Li_1.2Ni_0.13Co_0.13Mn_0.54O₂

Lithium-rich layered oxides have been a research focus in the lithium ionbattery cathode material due to their extremely high reversible capacity, high energydensity and low cost. In this paper, the main content is to study the effect of thesurface NH4HF2modification, Li3PO4/C composite coating layer and Mg/Cr bulkdoping on the structure and electrochemical performance of Lithium-rich layeredoxides Li1.2Ni0.13Co0.13Mn0.54O2.we designed and prepared a novel heterostructured Li1.2Ni0.13Co0.13Mn0.54O2material with mosaic spinel nanograins and surface coating, which is synthesized bya facile one-step solid phase process. It is proposed that the chemical Li leachingfrom Li2MnO3induces the formation of fluorite coating and the layer-to-spinel phasetransformation simultaneously at high temperatures. The fluorite coating protects thelithium-rich oxides from being directly exposed to the highly active electrolyte. Thespinel phase provides an efficient path for Li+mobility, and also faciliatessuppressing the initial irreversible capacity loss. Therefore, such uniqueheterostructured Li1.2Ni0.13Co0.13Mn0.54O2material exhibit an outstanding initialCoulombic efficiency, superior rate capability and excellent cyclability.we prepared Li3PO4coated Li1.2Ni0.13Co0.13Mn0.54O2Via sinteringLi1.2Ni0.13Co0.13Mn0.54O2and NH4H2PO4under450℃, and then through the carboncoating prepare Li1.2Ni0.13Co0.13Mn0.54O2with the Li3PO4/C composite coating layer.The Li3PO4/C composite coating layer provides faster lithium ion transportcoefficient and high electrical conductivity, and effectively restrain active materialdirectly contact with the electrolyte, therefore Li1.2Ni0.13Co0.13Mn0.54O2with theLi3PO4/C composite coating layer shows the excellent rate performance and cyclestability.Mg/Cr bulk doped Li1.2Mn0.52Ni0.13Co0.13Mg0.01Cr0.01O2shows no obviouslayered to spinel phase transition after200cycles under25℃and100cycles under60℃, which is caused by Mg/Cr hindering of transition metal Mn migration to thelithium vacancy...