Synthesis Optimization And Characteristics Research On Spherical High Tap-density LiNi_1/3Co_1/3Mn_1/3O₂

Nowadays, the conventional LiCoO2 cathode material for Lithium-ion batteries (LIB) was losing the momentum for its safety hazard and high cost. People were looking for a suitable substitute for LiCoO2 to meet the development demands of lithium ion battery for years. Recently, a multi-element compound LiNi1/3Co1/3Mn1/3O2 attracted widely attention and investigation. As the most promising candidate, LiNi1/3Co1/3Mn1/3O2 has excellent electrochemical performance, superior thermal stability and relatively low cost, which can be widely used in not only small-type high energy density battery, but also high power source systems, such as hybrid electric vehicle (HEV), satellite and so on. In this paper, hydroxide co-precipitation method was employed to synthesize precursor powders Ni1/3Co1/3Mn1/3(OH)2 and high temperature calcination was followed to produce active material LiNi1/3Co1/3Mn1/3O2. The as-prepared samples were investigated by scanning electron microscopy (SEM), X-ray drffraction (XRD), and galvanostatic charge/discharge test and so on.In this paper, three experimental routes were designed to prepare Ni1/3Co1/3Mn1/3(OH)2 and the most proper method of producing regular spherical powders with uniform morphology and high tap-density was successfully obtained. During co-precipitation process, chelating agent NH4OH plays a significant role to induce spherical morphology and generate homogeneous sediment, which usually led to well-crystallized LiNi1/3Co1/3Mn1/3O2 with good physicochemical characteristics. In this paper, a lot of work was done to investigate (optimize) the effect of depositing conditions on the morphology of Ni1/3Co1/3Mn1/3(OH)2 powders, and some experimental parameters such as: the amount and concentration of chelating agent, pH value, the concentration of transition metal ions and NaOH solution, feeding rate and stirring speed were well studied and optimized.At last, kinds of LiNi1/3Co1/3Mn1/3O2 powders were synthesized by high temperature calcination under various calcination temperatures; different sinter time and Li/M value, and the morphology, crystal structure and electrochemical performance of the final products were all systematically discussed and optimized. LiNi1/3Co1/3Mn1/3O2 synthesized under the optimum condition delivered an initial discharge capacity of 155.7 mAh·g-1 and retained 154.1 mAh·g-1 after 50 cycles, with a superior capacity retentivity of 99.0%. At the same time, the tap-denstiy of the as-prepared LiNi1/3Co1/3Mn1/3O2 reached 2.23 g·cm-3 and well met the demand of industrialization.