ZnO包覆LiNi_(0.5)Mn_(1.5)O_4正极材料的制备及其电化学性能

Preparation and Electrochemical Properties of ZnO Coated LiNi_(0.5)Mn_(1.5)O_4 Cathode Materials

通过共沉淀法合成了锂离子电池正极材料LiNi_(0.5)Mn_(1.5)O_4,并使用Zn O对其表面进行包覆改性。通过X射线衍射(XRD)、激光拉曼光谱(Raman)、场发射扫描电镜(FESEM)、透射电子显微镜(TEM)、电化学阻抗图谱(EIS)、恒流充放电循环测试分析技术对所得材料进行测试与表征。结果表明:包覆未改变基体结构并且适量的ZnO包覆可以提高LiNi_(0.5)Mn_(1.5)O_4的电化学性能。当包覆量为1. 5%时,材料的电化学性能提升最为明显,室温0. 1C倍率和1C倍率下首次放电比容量分别为133. 15,132. 66 m Ah/g,充放电循环100次后容量保持率分别为96. 1%,90. 1%;在55℃高温1C倍率下首次放电比容量为126. 96 m Ah/g,充放电循环100次后容量保持率仍能达到77. 2%,而未包覆的LiNi_(0.5)Mn_(1.5)O_4在相同条件下容量保持率仅为42. 9%。

The cathode material LiNi0.5Mn1.5O4 of lithium-ion battery was synthesized by co-precipitation method,and coated by ZnO.The prepared materials were tested and characterized by X-ray diffraction (XRD),laser Raman spectroscopy (Raman),field-emission scanning electron microscopy (FESEM),transmission electron microscope (TEM),electrochemical impedance spectrometry (EIS),and galvanostatic charge-discharge measurements.The results show that the coating does not change the matrix structure,while an appropriate amount of ZnO coating can improve the electrochemical performance of LiNi0.5Mn1.5O4as well.When the amount of ZnO is 1.5%,the electrochemical performance of the material is improved obviously.The first discharge specific capacity at 0.1 C and 1 C current rate is 133.15 mAh/g and 132.66 mAh/g at room temperature,and after 100 times of charge-discharge cycle the capacity retention ratio remains at 96.1% and 90.1%,respectively.At 55 ℃ and 1 C current rate,the first discharge specific capacity is 126.96 mAh/g,and the capacity retention ratio can still reach 77.2% after 100 times of charge-discharge cycle,while the capacity retention ratio of uncoated LiNi0.5Mn1.5O4 is only 42.9% under the same condition.