锂二次电池新型正极材料BiO_(0.1)F_(2.8)的制备及性能研究

The synthesis and electrochemical performance of BiO_(0.1)F_(2.8) as a new positive electrode for rechargeable lithium battery

通过液相反应合成了BiO0.1F2．8，且在合成过程中加入活性炭，制备了BiO0.1Fz．8／C。用X射线衍射（XRD），扫描电镜（SEM），充放电测试等对两种材料的结构和电化学性能进行了研究。XRD和SEM测试结果表明，合成的BiO0.1F2．8和BiO0.1F2．8／C均为简单六方晶型，属P63／mmc空间群，并且两种材料的颗粒分布均匀、结晶规则，呈棱柱形结晶，加入活性炭能使BiO0.1F2．8颗粒尺寸减小。将两种材料作为正极，与金属锂组装成锂二次电池，在1～4．5V电压范围内，以不同放电倍率充放电测试，发现BiO0.1F2．8／C电化学性能有明显的改善，在0．05C放电时其质量比能量高达613Wh／kg。

The BiO0.1F2.8 was synthesized via a liquid phase precipitation method, and the BiO0.1F2.8/C composite was prepared by adding active carbon （AC） during the synthesis process of BiO0.1F2.8. The structure and electrochemical performance of these materials were characterized by X-ray diffractometer （XRD）,scanning electron microscope （SEM） and the constant current charge/discharge method. The results showed that the BiO0.1 F2.8 and BiO0.1F2.8/C belonged to primitive hexagonal P63/mmc space group. The gains of the BiO0.1F2.8and BiO0.1 F2.8/C were homogeneous and prismy,and the grain size could be decreased by doping AC material during the synthesis process of BiO0.1F2.8. The electrochemical performance of these materials as cathode for the lithium secondary battery was tested with lithium as anode at different charge/discharge rate and the voltage range of 1- 4.5V. The results showed that the doped AC material would evidently improve the electrochemical performance of BiO0.1F2.8. The energy density of the BiO0.1F2.8/C composite was up to 613Wh/kg at 0.05C rate.