The Application Of A Novel Ternary Molten Salt In The Preparation Of Lini_0.8 Co_0.2o₂ And Lini_1/3co_1/3 Mn_1/3o₂

Lithium-ion battery cathode materials in the current market are high price but low volume, which become the obstacles to enhance the quality of lithium-ion battery and expand the applied scope of it. There are two ways to solve the problem: (1) to develop new cathode material, or to improve the electrochemical properties of existing materials by doping; (2) to improve synthetic methods and optimize the synthesis process in order to get the stoichiometric product with stable quality.Molten salt method is to use eutectic molten salt as reactant and a flux, so that the reaction happens between the solid-liquid, which enhance the ion-diffusion rate significantly and lower the temperature and time of the reaction and also improve the crystal structure and properties of materials. That is to say, molten salt method lies between the solid phase synthesis method and liquid phase synthesis method and is able to synthesize the stoichiometric cathode material with well crystallization. However, due to the introduction of a large number of non-lithium salt or too much lithium salt as a melting agent to promote the micro self-mixing of raw materials in the heating process, so as to achieve the purpose of mixing evenly, the product we get must be separated from molten salt by washing, which may affect the electrochemical activity of the product. In this regard, we think as following: When there exist solid phase and liquid phase at the same time, it is very difficult to achieve the purpose of homogeneous mixing, only relying on the adhesion and infiltration of those liquid reactants. While, if some reactants become liquid phase at a low temperature (<100℃), and we mix all the reactants by mechanical grinding as well as the raw materials mix by themselves at the micro state, then it is easier for us to get the stoichiometric cathode material with well crystallization.Base on the preliminary work of our group, this paper is to improve molten salt method. we explore a novel ternary eutectic molten salt with very well melting state at 80-90℃, and apply it to prepare the cathode material LiNi_0.8Co_0.2O₂ and LiNi_1/3Co_1/3Mn_1/3O₂. Then we study how the different ratios of those lithium salts and the different sintering times and the different sintering temperatures impact the product. The results show that the product has high degree of crystalline, neat layeredα-NaFeO₂ structure, uniform morphology, narrow range of particle size, as well as excellent specific capacity and cycling performance.