| 摘要 |
A straightforward and scalable solid-state synthesis at 975° C. used to generate cathode materials in the system Li(3+x)3Ni(1-x-y)CoyMn2x/3O2 {a combination of LiNiO2, Li2MnO3, and LiCoO2 as (1-x-y)LiNiO2.xLi2MnO3.yLiCoO2} is described. Coatings for improving the characteristics of the cathode material are also described. A ternary composition diagram was used to select sample points, and compositions for testing were initially chosen in an arrangement conducive to mathematical modeling. X-ray diffraction (XRD) characterization showed the formation of anα-NaFeO2 structure, except in the region of compositions close to LiNiO2. Electrochemical testing revealed a wide range of electrochemical capacities with the highest capacities found in a region of high Li2MnO3 content. The highest capacity composition identified was Li1.222Mn0.444Ni0.167Co0.167O2 with a maximum initial discharge capacity of in the voltage range 4.6-2.0 V. Differential scanning calorimetry (DSC) testing on this material was promising as it showed an exothermic reaction of 0.2 W/g at 200° C. when tested up to 400° C. Cost for laboratory quantities of material yielded $1.49/Ah, which is significantly lower than the cost of LiCoO2 due to the low cobalt content, and the straightforward synthesis. Li1.222Mn0.444Ni0.167Co0.167O2 is thought to be near optimum composition for the specified synthesis conditions, and shows excellent capacity and safety characteristics while leaving room for optimization in composition, synthesis conditions, and surface treatment.
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