TiO2包覆对LiCo1/3Ni1/3Mn1/3O2材料的表面改性(英文)

Surface Modification of LiCo_(1/3)Ni_(1/3)Mn_(1/3)O_2 by TiO_2-Coating

为了提高材料LiCo1/3Ni1/3Mn1/3O2的循环性能,采用浸渍-水解法对其进行TiO2包覆.用X射线衍射(XRD)、电化学交流阻抗谱(EIS)、电感耦合等离子体发射光谱(ICP-OES)和恒流充放电测试研究包覆材料的结构和电化学性能.TiO2仅在材料表面形成包覆层,并未改变材料的结构.TiO2包覆能提高材料LiCo1/3Ni1/3Mn1/3O2的倍率性能和循环性能,TiO2包覆后的材料在5.0C(1.0C=160mA·g-1)下的放电容量达到0.2C下的66.0%,而包覆前的材料在5.0C下的放电容量仅为其0.2C下的31.5%.包覆后的材料在2.0C下循环12周后的容量没有衰减,而未包覆的材料容量保持率仅为94.4%.EIS测试表明包覆材料性能的提高是由于循环过程中材料的界面稳定性得到了提高.循环后材料的XRD和ICP-OES测试表明,包覆层能提高材料LiCo1/3Ni1/3Mn1/3O2的结构稳定性.

A method to improve the cycling performance of LiCo1/3Ni1/3Mn1/3O2 in lithium-ion batteries by coating with TiO2 using an in-situ dipping and hydrolyzing method was presented in this work. The effect of the TiO2 coating on the structure and electrochemical properties of LiCo1/3Ni1/3Mn1/3O2 was investigated using X-ray diffraction （XRD）,electrochemical impedance spectroscopy （EIS）,inductively coupled plasma-optical emission spectroscopy （ICP-OES）,and galvanostatic charge/discharge testing. TiO2 forms a layer on the surface of LiCo1/3Ni1/3Mn1/3O2 without destroying the structure of the core material. The TiO2-coated LiCo1/3Ni1/3Mn1/3O2 possesses better rate capability and cyclability than the uncoated material. The capacity of the TiO2-coated material at 5.0C （1.0C=160 mA·g-1） reaches 66.0% of that achieved at 0.2C,while the capacity of the uncoated LiCo1/3Ni1/3Mn1/3O2 obtains a value of only 31.5%. The rate of capacity retention after 12 cycles at 2.0C for the coated sample is about 100%,which is much better than that of the uncoated material （94.4%）. EIS shows that the reason for this improvement in the capacity of the coated material is the enhanced interface stability during cycling. XRD and ICP-OES tests taken after cycling indicate that the TiO2-coating can enhance the structural stability of LiCo1/3Ni1/3Mn1/3O2.