Narrow Results

The carbothermal reduction and nitridation has been used to synthesize composite ceramic powders from rice husk ash (RHA) with alumina addition of 0.02, 0.1, 0.5 and 1 (Al₂O₃/SiO₂) respectively. The phase composition of products after calcining at high temperatures was almost sensitive to the Al₂O₃ content. The sequence of phase-formation except for SiC and Si₃N₄ with alumina addition was followed by Si₂N₂O→Si_1.62Al_0.38 N_1.62O_1.38→Si₃Al₃O₃N₅ for 1500 °C, and Si₃Al₃O₃N₅→AlN for 1550 °C. The results highlighted that effects of alumina impurity on the synthesis of composite ceramic powders from rich husk ash were significant.

Spinel LiMn₂O₄ was synthesized by solid-state method, using different manganese sources and industrial electrolytic manganese dioxide as the raw materials. Structure and properties of the samples were determined by X-ray diffraction, scanning electron microscope and electrochemical measurements. In the experiment, Mn₂O₃ was selected as the optimal manganese source. And Mn₂O₃ with various impurity content was prepared to study the effects of impurity in manganese sources on the electrochemical performance of spinel LiMn₂O₄. The results showed that the LiMn₂O₄ samples containing various impurity content had spinel structure, and there was not the existence of impurity phase in samples; the particle size and morphology of LiMn₂O₄ had no obvious differences, and particle size was uniform; with the increase of impurity content in the LiMn₂O₄ samples, it had little effect on the initial charge capacity , when the impurity content was too high, the initial charge capacity reduced slightly; the initial discharge specific capacity increased first and decreased later; at the same time, the increase of the impurity content was helpful to improve the cycle performance of the LiMn₂O₄ battery.