Effects of ionothermal and hydrothermal methods on structure and electrochemical performance of LiNi1/3Co1/3Mn1/3O2 cathode materials

Two different liquid-phase synthetic methods both ionothermal and hydrothermal methods were used for preparation of LiNi1/3Co1/3Mn1/3O2 cathode materials successfully. It was found that the LiNi1/3Co1/3Mn1/3O2 polycrystalline particles synthesized by ionothermal method were composed of single crystals, which lie on (003) plane with the same preferred orientation. 1-ethyl-3-methylimadozolium tetrafluoroborate was selected as reaction medium for ionothermal method. However, the sample prepared by hydrothermal method shows a nanobrick structure with high percentage of exposed {010} facets along the c-axis orientation before calcination and then these nanobricks pile up along the orientation perpendicular in the c-axis to form larger single crystal during calcination process. The LiNi1/3Co1/3Mn1/3O2 synthesized by hydrothermal method possess a higher percentage of exposed {010} facets than that prepared by ionothermal synthesis. Thus as cathode material for Li+ batteries, the LiNi1/3Mn1/3Co1/3O2 materials synthesized by hydrothermal method show higher discharge capacity, better rate capability, better cyclic performance and lower impedances. Compared to ionothermal method, the discharge capacities of material synthesized by hydrothermal method are improved by 2.5%, 3.1%, 8.1% and 14.8% after 20, 40, 60 and 80 cycles at 0.5, 1, 5, and 10C rates, respectively.