Study Of Synthesizing Cathode Material LiNi_0.5Mn_0.5O₂ Via Co-Precipititation And Performance

Lithium battery has a rapid development and L1COO2 as the most original cathode material which has been replacing for its expensive, toxic, safety concerns and only 50% of the theoretical capacity can be utilized. LiNi0.5Mn0.5O2 has become one of the most attractive materials for its safe, inexpensive, excellent electrical chemistry properties and without cobalt, which is considered to be one of the most possible materials to replace LiCoO2.LiNi0.5Mn0.5O2 is lithium nickel manganese oxide, which is produced by co-precipitation method to get spherical particles with high tap density and excellent element distribution. In this paper, To find out the best conditions of co-precipitation, more attention is paid on the factors which affect the morphology and size of the particle, such as PH value, concentration, temperature, precipitator, chelating agent, reaction time.There are special advantages to synthesize spherical Ni0.5Mn0.5CO3 via carbonate co-precipitation method. In this paper we used different precipitators such as Na2CO3, NH4HCO3 and NaHCO3. NH4HCO3 was used as the precipitator exhibits good spherical morphology. However, obvious agglomerate of secondary particles is occurred when used NH4HCO3 as the precipitator, the appearance of which can result in inferior physical characteristic. An improved carbonate co-precipitation which used NH4HCO3 doped with different proportion of NaOH/Na2CO3 as a new precipitator is tested in our study. Observed by SEM and Mastersizer, spherical morphology with narrow particle size distribution is synthesized with the proportion of NaOH is 10%. The morphology and size of particle is difficult to control for the rapid speed of nucleate when use NaOH as the precipitator. A new synthesized method was adopted to control the reaction speed, and found when the complex PH value was 8 could get the better particles. The powders line analysis of Electron Probe Micro-analyzer shows symmetrical distributions of Ni and Mn elements via carbonate co-precipitation.Li/Ni disorder is the main reason to affect the performance of LiNi0.5Mn0.5O2. In this paper, we used different ratio of Li/M (M is Ni and Mn) and precursor with different conditions to research the influence of increased lithium content to the crystal structure. We found that the battery exhibited best performance when used the precursor with 4 hours' reaction time and concentration ratio of NiMn and NaHCO3 was 1:2, and Li/M=1.06.