富锂正极材料0.5Li_2MnO_3·0.5LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2的微波合成及电化学性能研究

Microwave-assisted Preparation of 0.5Li_2MnO_3·0.5 LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2 and the Enhanced Electrochemical Performances

采用共沉淀制备前驱体，微波高温固相烧结制备富锂正极材料0.5Li_2MnO_3·0.5LiNi_1/3Co_1/3Mn_1/3O_2.通过X射线衍射（XRD）、电镜扫描SEM、循环伏安（CV）、充放电性能等材料结构的表征和电化学性能测试，研究了不同烧结时间（微波3 min、5 min、7 min、15 min）对材料结构电化学性能的影响.发现较佳的合成条件所合成的富锂正极材料0.5Li_2MnO_3·0.5LiNi_1/3Co_1/3Mn_1/3O_2结构是α-NaFeO2型，为二维层状结构.在2.0～4.8 V的截止电压范围、17 mAh·g^-1的电流密度，首次放电容量为284.6 mAh·g^-1，20个循环容量的保有率为75.6%.通过微波高温烧结合成正极材料，研究了制备工艺对材料结构和电化学性能的影响，并探讨了该体系的应用前景.

With the increasing global demand for energy, one of the specific requirements is positive electrode material with high capacity, low cost and environmental. Recently, Li-rich cathodes written as Li1＋x[M]1-xO2 （M：Mn, Ni, and Co; x〉0） have caught great attention for the novel electrode materials of lithium ion batteries. 0.5Li_2MnO_3·0.5LiNi_1/3Co_1/3Mn_1/3O_2 has been synthesized by co-precipitation and microwave sintering （MW）. MW time is systematically optimized. The crystal structure and morphology are characterized by XRD, SEM, etc. XRD patterns are refined by two sets of diffraction data （R-3m and C2/m） and indicate that the as-synthesized material is pure and has good crystallinity. 0.5Li2MnO3·0.5 LiNi1/3Co1/3Mn1/3O2 synthesized at 900℃ for 7 min has the best discharge capacity and cyclic performance. Within the cut-off voltage between 2.5 and 4.8 V, the initial discharge capacity is 325 mAg·g^-1 at 0.1 C rate; and after 50 cycles the discharge capacity remains 284.6 mAh·g^-1, with good reversibility （75.6%）. Through the studies of this paper, the authors have a further understanding of the preparation, structure, morphology and electrochemical performance of Li-rich cathode ma-terial, which helps to provide a basic research and practical application for Li-rich cathode material in the fu-ture.