Synthesis And Electrochemical Investigation Of Li-rich Compound Cathodes For Lithium Ion Battery

Nowdays, LiCoO2is the most widely used cathode material in lithium ion batters.However, its high toxicity and poor safety are still issues of great concern as well assuitable alternatives, as a result, it have always been pursued. LayeredxLi₂MnO₃-（1-x-y）LiMn_1/2Ni_1/2O₂-yLiCoO₂and xLi₂MnO₃-（1-x）LiMn_1/3Ni_1/3Co_1/3O₂hasbeen considered as one of the most promising cathode materials for power lithium ionbatteries. It is not only because of layered materials has milder thermal stability, but alsohas the lower cost than commercially used LiCoO₂. This paper mainly discusses that thexLi₂MnO₃-（1-x-y）LiMn_1/2Ni_1/2O₂-yLiCoO₂and xLi₂MnO₃-（1-x）LiMn_1/3Ni_1/3Co_1/3O₂wassynthesized by the co-precipitation, and the best ammonia concentration of precipitantas well as optimum synthesis conditions in order to promote its electrochemicalperformance.First of all, select the best synthetic method to determine for the co-precipitationmethod, which is the carbonate co-precipitation, there is the type of transition metaloxides using carbonate coprecipitation method for lithium-ion battery compositecathode material0.31Li₂MnO₃-0.63LiMn_1/2Ni_1/2O₂-0.06LiCoO₂precipitant is Na₂CO₃.Precipitant of the samples prepared in the shape, structure and electrochemicalproperties of concern. Na₂CO₃as precipitant prepared samples of particles of irregularshape and nonunion particle size, while the sample prepared by using Na2CO3andNH3·H3O composite as precipitator has spherical particle shape and uniform particlesize. Among all the samples, the one prepared with Na2CO3and NH3·H3O compositeexhibits the best hexagonal layered structure, which results in its highest dischargecapacity and best cycling performance. Therefore, ammonia concentration plays animportant role in the co-precipitation reaction and makes a great impact on thecharacteristics of0.31Li2MnO3-0.63LiMn1/2Ni1/2O2-0.06LiCoO2.xLi₂MnO₃-（1-x-y）LiMn_1/2Ni_1/2O₂-yLiCoO₂sample is prepared by coprecipitationmethod, as the cathode material,. The preparation conditions such as precipitant isvaried to optimize the physical and electrochemical properties of the sample. Thestructural, morphological and electrochemical characteristics by XRD, SEM and galvanostatic charge-discharge cycling.The expending demand for high-power and high-energy batteries has motivated thecontinuous research on large-scale lithium-ion batteries with high density.Layeredcathode material yLi₂MnO₃-（1-y）LiMn_0.5-xNi_0.5-xCo₂xO₂has draw much attention.Carboncoating is an effective surface modification method that is widely used to enhance theelectrochemical performance of electrode materials in lithium ion batteries.In thisstudy,we employed the carbon coating on the lithium and manganese-rich material andsynthesized0.5Li₂MnO₃-0.5LiMn_1/4Ni_1/4Co_1/2O₂/C composite.This electrode materialsis characterized by X-ray diffraction,scanning electron microscopy,transmissionelectroscopy and electrochemical tests. Electrochemical and structural resultsdemonstrate that the carbon coating greatly improves the electrochemical property andrate capability of0.5Li2MnO3-0.5LiMn1/4Ni1/4Co1/2O2without destroying its crystalstructure.