Influence of Roasting Temperature on Electrochemical Performance of LiNi0.5Mn1.5O4 Cathode for Lithium-Ion Battery

Nanomicro spheres of LiNi0.5Mn1.5O4 materials are prepared by carbonate coprecipitation method. The effect of calcination temperatures on morphology and electrochemical property is explored. Results show that the structure of the material becomes more compact with the increase of the temperature, which is propitious to the improvement of electrical conductivity and activation level of the material. The charge–discharge tests show that the sample obtained at 850 °C (LNMO850) exhibits optimal rate capability and cyclic stability, due to the fact that LNMO850 has a high diffusion coefficient, which is propitious to the improvement of electrical conductivity and activation level of the material.

Low-temperature preparation of dense 10 mol%-Y2O3-doped CeO2 ceramics using powders synthesized via carbonate coprecipitation

A carbonate coprecipitation method was used for the facile synthesis of highly reactive 10 mol%-Y2O3-doped CeO2 (20YDC) nanopowders, employing nitrates as the starting salts and ammonium hydrogen carbonate (AHC) as the precipitant. The AHC/RE3+ (RE = Ce + Y) molar ratio (R) and the reaction temperature (T) significantly affect the final yield and precursor properties, including chemical composition and particle morphology. Suitable processing conditions are T = 60 °C and R = 2.5 to 10, under which precipitation is complete, and the resultant precursors show ultrafine particle size, spherical particle shape, and good dispersion. The thus-processed precursors are basic carbonates with an approximate formula of Ce0.8Y0.2(OH)CO3 · 2H2O, which directly yield oxide solid solutions upon thermal decomposition at a very low temperature of approximately 400 °C. The 20YDC solid-solution powders calcined at 700 °C show excellent reactivity and were densified to >99% of theoretical via pressureless sintering at a very low temperature of 950 °C for 6 h.