Study on the Process of Citric Acid-Assisted Alkaline Liquid Phase Metal Cation Doping for Ni-Rich Ternary Materials AITranslate

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Chinese Library Classification Number:TM911.1[电气工程—电力电子与电力传动]

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Metal cation doping can significantly improve the structural stability of Ni-rich ternary material.However,in liquid-phase co-precipitation doping process,metal cations are prone to hydrolysis,which complicates the influences of dopants on material properties.To address this problem,this study took Ni_0.83Co_0.11Mn_0.06(OH)₂ precursor as the research object,and conducted Al doping modification via alkaline liquid-phase co-precipitation using two approaches:with and without citric acid.The effects of Al doping and citric acid addition on the phase composition and micromorphology of precursors were studied.The precursors before and after modification were subjected to lithium blending and sintering to prepare Ni-rich ternary materials,and the electrochemical performance of their positive electrodes was investigated.The results show that doping Al without citric acid easily results in the formation of aggregates between Al³⁺and ions in the alkaline solution,forming a coating layer on the surface of Ni_0.83Co_0.11Mn_0.06(OH)₂ particles and preventing Al³⁺from entering the interior of the particles.After adding citric acid as a chelating agent with a molar ratio of 0.25∶1 to Al³⁺,the prepared Ni-rich ternary cathode material has a sphericity that is basically consistent with the precursor,and the secondary spherical particles are composed of fine primary particles.Under the conditions of 1 C current density,2.8~4.3 V voltage,and 25℃temperature,after 100 cycles,the capacity retention rate of the Al-doped Ni-rich ternary cathode material with 25%citric acid added increases from 67.9%(without citric acid)to 83.3%,exceeding the 71.6%of the unmodified material.When the Ni-rich ternary precursor is doped with metal cations in the alkaline liquid phase,an appropriate amount of citric acid is beneficial for the incorporation of metal cations into the particles,thereby improving the electrochemical performance of the Ni-rich ternary cathode material.However,excessive citric acid can cause the particles to grow too large,leading to a decrease in electrochemical performance.