LiCo_(1-x)Al_xO_2包覆MgO的改性研究

Study on modification of MgO-coating LiCo_(1-x)Al_xO_2 material

采用溶胶-凝胶法合成了掺杂改性的锂离子电池正极材料LiCo1-xAlxO2,并在此基础上对其进行包覆MgO的改性研究。通过X射线衍射和扫描电镜对材料的晶体结构和表观形貌进行了分析。通过恒电流充放电、循环伏安以及电化学阻抗技术对材料的电化学性能进行了分析。试验结果表明,所制备的正极材料LiCo1-xAlxO2和MgO-LiCo1-xAlxO2均为α-NaFeO2型层状结构,形貌近似为球型,且颗粒分布均匀。包覆后的材料充放电电压提高,充放电循环性能得到明显改善。其中以包覆量为1.0%wt左右时性能最好,首次放电容量为120.17mAh.g-1,30次循环后容量保持率为89.3%。

LiCo1-xAlxO2 cathode materials Of lithium-ion baterry were synthesized by sol - gel method, and its surface was coated with a thin layer of MgO. The LiCo1-xAlxO2 and the MgO coated LiCo1-xAlxO2 powders were characterized by means of X- ray diffraction（XRD） and scanning electron microscopy （SEM） . The electrochemical properties of LiCo1-xAlxO2 and MgO coated LiCo1-xAlxO2 were examined by the galvanostatic charge-discharge tests, cyclic vohammogram, electrochemical impedance spectroscopy（EIS） . The result showed that LiCo1-xAlxO2 and the MgO coated LiCo1-xAlxO2 particles possessed spherical morphology and uniform particle size with the α - NaFeO2 layered structure. The voltage of charge - discharge was increased after coating . Also the cyclic properties for charge - discharge was improved evidently. The best electrochemical performance is gotten when the coating amount of MgO is 1.0%. The discharge capacity at initial cycle was 120. 17 mAh · g^-1 and remained 89.3% after 30 cycles.