| Recently, as the Cobalt resources were expensive, high toxicity, high pollution, the LiCoO2which was commercial and popular had exposed its drawbacks gradually. The layered LiNi1/3Co1/3Mn1/3O2which had its advantages of high capacity, cheap, hypotoxicity, less pollution catched the attention of the researchers rapaidly. And the researchers thinked that the layered LiNi1/3Co1/3Mn1/3O2could take place of the LiCoO2.In this paper, Ni1/3Co1/3Mn1/3(OH)2and Li2CO3were used as the raw materials. The single factor experiment and the response surface methodology were carried out in the atmosphere of microwave-heating for optimizing the preparation of LiNi1/3Co1/3Mn1/3O2. Meanwhile, the pilot which was carried out in a continuous way was studied in this paper. The preparation of the Li(Ni1/3Co1/3Mn1/3)1-xMxO2was also studied in this paper. All above work was used to find out the best process of the preparation. The content of the above work as follows:(1) The effect of microwave-heating temperature, Li/(Ni+Co+Mn) and holding time on the electrochemical performance of the LiNi1/3Co1/3Mn1/3O2were studied in this chapter. Based on this work, the optimized process was obstained, as follows: Ni1/3Co1/3Mn1/3(OH)2mixed with Li2CO3(Li/(Ni+Co+Mn)=1.075), then the mixture was calcined at940℃for60min. The discharge capacities of LiNi1/3Co1/3Mn1/3O2were155.51mAh/g and141.33mAh/g at the rates of0.2C and1C, respectively. The cycle retention of LiNi1/3Co1/3Mn1/3O2was91.40%and90.97%after30cycles.(2) Microwave-heating temperature, Li/(Ni+Co+Mn) and holding time were selected as independent variables. The initial discharge capacity and the capacity retention of LiNi1/3Co1/3Mn1/302after30cycles were selected as dependent variables affected by these factors. Response surface methodology and central composite design were implemented to optimize the technological parameters for preparating the LiNi1/3Co1/3Mn1/3O2by microwave roasting directly, then the mathematical model was found to explain the dependent variables affected by the independent variables. The optimum experimental parameters could obtained by solving and analyzing the model, these parameters were microwave temperature of955℃, Li/(Ni+Co+Mn) of1.105, and holding time of72min. The discharge capacities of LiNi1/3Co1/3Mn1/3O2was156.843mAh/g at the rates of0.2C. Meanwhile, the cycle retention of LiNi1/3Co1/3Mn1/3O2was93.56%after30cycles. The experimental values were close to predicted values, showing less error rate and high reliability.(3) A continuously pilot synthesis by microwave-heating was used in preparing the cathode material LiNi1/3Co1/3Mn1/3O2for Li-ion battery. In the continuous preparing process, the time of material pushing was adjusted in order to control the formulated time that the material stayed in the roasting stage. By controlling the above step, the continuous prepartion of LixNi1/3Co1/3Mn1/3O2could be realized. The XRD pattern of the Li1.075Ni1/3Co1/3Mn1/3O2shows that the Li1.075Ni1/3Co1/3Mn1/3O2had a highly ordered layered structure. Meanwhile, the Ni2+/Li+almost didn’t exist in Li1.075Ni1/3Co1/3Mn1/3O2. The discharge capacities of Li1.045Ni1/3Co1/3Mn1/3O2were156.6mAh/g and147.3mAh/g at the rates of0.1C and0.2C, respectively. Meanwhile, the cycle retention of Li1.075Ni1/3Co1/3Mn1/3O2could be as high as98.55%and99.46%after10cycles.(4) In this chapter, a doping method was used to improve the electrochemical performance of LiNi1/3Co1/3Mn1/3O2. The XRD pattern showed that Li(Ni1/3Co1/3Mn1/3)1-xMxO2(M=Mg, Al, x=0.01-0.05) had a highly ordered layered structure. The SEM pattern showed that the morphology of Li(Ni1/3Co1/3Mn1/3)0.95Mg0.05O2was the same as LiNi1/3Co1/3Mn1/3O2, while an agglomerate phenomenon was appeared in the structure of Li(Ni1/3Co1/3Mn1/3)0.95Al0.05O2. The electrochemical performances of Li(Ni1/3Co1/3Mn1/3)0.96Mg0.04O2and Li(Ni1/3Co1/3Mn1/3)0.98Al0.02O2were the best. The discharge capacities of Li(Ni1/3Co1/3Mn1/3)o.96Mg0.04O2and Li(Ni1/3Co1/3Mn1/3)0.98Al0.o2O2were151.96mAh/g and154.53mAh/g at the rates of0.2C, respectively. Meanwhile, their cycle retentions was98.94%and96.78%after30cycles. |
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