LiTi_2(PO_4)_3表面包覆LiNi_(0.05)Mn_(1.95)O_4及其性质

Surface Coating of LiNi_(0.05)Mn_(1.95)O_4 with Lithium Ion Conductor LiTi_2(PO_4)_3 and Its Properties

采用湿化学法在LiNi0.05Mn1.95O4表面包覆锂离子导体LiTi2(PO4)3。采用X射线衍射、扫描电子显微镜、恒电流充放电、电位阶跃、交流阻抗技术对合成产物进行物相、形貌和电化学分析。结果表明:LiTi2(PO4)3包覆LiNi0.05Mn1.95O4与未包覆LiNi0.05Mn1.95O4具有相似的X射线衍射结果,LiNi0.05Mn1.95O4包覆LiTi2(PO4)3前后的锂离子扩散系数变化不大,但包覆LiTi2(PO4)3后的LiNi0.05Mn1.95O4颗粒边界和轮廓变得模糊。LiTi2(PO4)3包覆LiNi0.05Mn1.95O4的比容量略低于未包覆LiNi0.05Mn1.95O4,且随着LiTi2(PO4)3包覆量的增加而减小,但包覆LiTi2(PO4)3后的LiNi0.05Mn1.95O4循环性能得到了大幅提高。

LiNi0.05Mn1.95O4 powders coated with a lithium ion conductor of LiTi2（PO4）3 were prepared by a wet chemical route. The phase, surface morphology, and electrochemical properties of the prepared powders were characterized by X-ray diffraction, scanning electron microscopy, galvanostatic charge-discharge experiments, potential step technique, and electrochemical impedance spectros- copy, respectively. The LiNio.05Mn1.9504 powders coated with different mass fraction of LiTi2（PO4）3 have the similar X-ray diffraction patterns as LiNio.05Mnl.9504. The coating of LiTi2（PO4）3 has little influence on the lithium diffusion coefficient of LiNio.05Mn1.9504. However, the particle boundary and comer of LiNio.05Mnl.9504 powders become blurring after being coated with LiTi2（PO4）3. The specific capacity of LiTi2（PO4）3 coated with LiNi0.05Mn1.9504 decreases with the increase of the LiTiz（PO4）3 coating, and is slightly smaller than that of LiNio.05Mn1.9504. However, the cycling behavior of the LiTi2（PO4）3 coated with LiNi0.05Mn1.9504 is much better than that of LiNi0.05Mn1.9504.