Yanglin Zhang,Xi'an Fan,Wentao Hu,Zigui Luo,Zhenjia Yang,Guangqiang Li,Yawei Li
In this paper, Fe soft magnetic composites (SMCs) coated with MnO 2 were prepared successfully by ball milling and following spark plasma sintering. The effect of MnO 2 content on microstructure and magnetic properties for the Fe/MnO 2 SMCs was investigated in detail. The analysis results show that a uniform MnO 2 coating layer can be formed on the surface of the Fe particles via low speed ball milling with agate balls. When the MnO 2 content increases from 0.0 wt% to 10.0 wt%, the thickness of the MnO 2 coating layer exhibits a growth trend. As a consequence, the increased nonmagnetic phase leads to the magnetic dilution, finally resulting in the reduced saturation magnetization and deteriorated coercivity. Moreover, the enhanced resistivity induced by the increased thickness, significantly reduces the generation of the inter-particle eddy current, which leads to more stable permeability and lower total core loss at high frequencies. This study provides a novel insulating coating layer to reduce total core loss and is advantageous for the development of iron-based SMCs.
Xin Guo,Li-Na Cong,Qin Zhao,Ling-Hua Tai,Xing-Long Wu,Jing-Ping Zhang,Rong-Shun Wang,Hai-Ming Xie,Li-Qun Sun
LiNi 1/3 Co 1/3 Mn 1/3 O 2 is successfully coated with MnO 2 by a chemical deposition method. The X-ray diffraction (XRD), scanning electron microscope (SEM) and high resolution transmission electron microscope (HRTEM) results demonstrate that MnO 2 forms a thin layer on the surface of LiNi 1/3 Co 1/3 Mn 1/3 O 2 without destroying the crystal structure of the core material. Compared with pristine LiNi 1/3 Co 1/3 Mn 1/3 O 2 , the MnO 2 -coated sample shows enhanced electrochemical performance especially the rate capability. Even at a current density of 750 mA g −1 , the discharge capacity of MnO 2 -coated LiNi 1/3 Co 1/3 Mn 1/3 O 2 is 155.15 mAh g −1 , while that of the pristine electrode is only 132.84 mAh g −1 in the range of 2.5–4.5 V. The cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) curves show that the MnO 2 coating layer reacts with Li + during cycling, which is responsible for the higher discharge capacity of MnO 2 -coated LiNi 1/3 Co 1/3 Mn 1/3 O 2 . Electrochemical impedance spectroscopy (EIS) results confirmed that the MnO 2 coating layer plays an important role in reducing the charge transfer resistance on the electrolyte–electrode interfaces.
危险品化学品经营许可证（带存储）