| LiCoO2 has excellent comprehensive performances and has a high request for mainly-used precursor material, battery-grade Co3O4. However, traditional processing technology can't content with the continuously improved request. Therefore, it has the extremely vital significance to systematically study and develop the process technology of battery-grade Co3O4. The layered LiNixCoyMn1-x-yO2 is a new type of cathode material and probably one of most possible alternate material of LiCoO2. To improve its processing and electrochemical performance, the methods of carbonate co-precipitation and hydroxide co-precipitation have been applied to obtain spherical NCM precursor. By optimization of the processing, a series of LiNixCoyMn1-x-yO2 cathode materials have been obtained. The influence of doping and anion on the performance of LiNixCoyMn1-x-yO2has been studied.The precuosors have great influence on the performance of cathode materials.The Co3O4 materials which fit to different requirements have been prepared by using wet precipitation method and high-temperature sintering technique. The thermal decomposition process destroyed the morphology model of cobalt oxalate by sintering twice. It made cobalt oxalate change morphology from the appearance of knitting needle to sphere and the obtained quasi-sphere Co3O4 with uniform particle size distribution and high density which is 3.1g·cm-3. The chloride in the cobalt oxalate is helpful to sinter. By analyzing the system of Co(Ⅱ)-NH3-CO32--H2O, pure-phase cobalt carbonate was prepared using CoCl2 solution to add into NH4HCO3 solution with anti-addition method. The performance of anti-oxidation is very well and the precipitation rate of cobalt was up to 99.7%. The Content of Cl- and Na+ can be controlled below 0.01% and 0.005% respectively. It has solved the problem of the higher content of Cl" and Na+ and lower precipitation rate when use NH4HCO3 as precipitating agent for cobalt carbonate obtained by traditional method. The Co3O4, with adjustable morphology, particle size and tap density, can be obtained by sintering and thermal-decomposition. Additionally, by analysis of Co(Ⅱ)-NH3-H2O system and using chelating-precipitation method, spherical Co(OH)2 was prepared under the condition of optimize processing. Spherical Co3O4 with large specific surface area could be obtained by optimized sintering processing.To simplify the processing and cut the cost, by analyzing the systems of Co-Cl-O and Co-S-O, Co3O4 was prepared by directly solid-pyrolysis of CoCl2·6H2O and CoSO4·7H2O. The products of Co3O4 which use CoCl2·6H2O as materials have typical octahedral morphology. Calcinations after dehydration and under oxygen-enriched atmosphere are helpful to obtain Co3O4 with uniform particle size distribution. Temperature is a key factor for Co3O4 which has been prepared by calcination of cobalt sulphate. By controlling the calcination conditions, two type of Co3O4 could be obtained. One is of agglomerate morphology; the other is single-crystal morphology. LiCoO2 was synthesized by using different types of Co3O4 as the precursor materials and all the synthesized LiCoO2 materials have excellent performance. In comparison, the preparing method of Co3O4 using Co(OH)2, cobalt chloride and cobalt sulphate, is more suitable in future.To improve the processing and electrochemical performance, using the carbonate co-precipitation method, spherical Ni1/3Co1/3Mn1/3CO3 precursor could be obtained with tap density of 2.0g·cm-3. The tap-density of spherical LiNi1/3Co1/3Mn1/3O2 powders can reach 2.32g·cm-3. The test results of LiNi1/3Co1/3Mn1/3O2 indicated that the LiNi1/3Co1/3Mn1/3O2 delivered 170.1 and 158.7 mAh·g-1 at the rate of 0.2C and 1C in the voltages of 2.7-4.3V respectively, and the capacity retention rates were 93.4% and 91.5% after 30 cycles. With the same method, the tap-density of spherical LiNi0.5Co0.3Mn0.2CO3 can reach 2.56g·cm-3 and the spherical LiNi0.5Co0.3Mn0.2CO3 delivered 174.5 and 163.8mAh·g-1 at the rate of 0.2C and 1C, in the voltages of 2.7-4.3V. The capacity retention rates were 94.2% and 92.6% after 30 cycles. Otherwise, surface modification of LiNi1/3Co1/3Mn1/3O2 by coating with Al2O3 was applied using heterogeneous nucleation method. The LiNi1/3Co1/3Mn1/3O2 samples coated with 0.5% Al2O3 delivered initial discharge capacity 150.1 and 172.6mAh·g-1 respectively at 2.7-4.3V and 2.7-4.6V at 1C rate. The capacity retention was 99% and 88% after 30 cycles respectively. The cycle performance and thermal stability have been greatly improved.To further cut the cost and improve the processing performance, the spherical low-cobalt LiNi0.5Mn0.3Co0.2O2 and LiNi0.4Mn0.4Co0.2O2 with high density were synthesized by the co-precipitated spherical hydroxide precursor whose tap-density is as high as 2.2 g·cm-3. The additive A was combined with ammonia to be used as double chelating agent. The tap density of spherical cathode materials can reach 2.74 and 2.68g·cm-3。The results indicated that the initial discharge specific capacities of LiNi0.5Mn0.3Ni0.2O2 are 173.2mAh·g-1,161.0mAh·g-1respectively, under the conditions of 0.2C and1 Crate in voltages of 2.7-4.3V. The capacity retention rates were 97.8% and 94.7% after 30 cycles respectively.The LiNi0.4Mn0.4Co0.2O2 delivered 171.3mAh·g-1 and 159.5 mAh·g-1 under the conditions of 0.2C and 1C rate, in voltages of 2.7-4.3V. The capacity retention rates were 96.6% and 94.2% after 30 cycles respectively. Otherwise, the preparation of LiNixCoyMn1-x-yO2 using chloride as starting materials has been applied. The oxidation of Co2+ and Mn2+ will cause the high content of Cl- which is more than 1.5% in the hydroxide precursor. The Cl- anion played the role of fluxing agent and accelerate the sintering. LiNi0.5Mn0.3Co0.2O2 material with large single crystal(5-10μm) and high tap density which was as high as 2.74g·cm-3 could be obtained.
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