锂离子电池正极材料Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2的碳包覆研究

The Effect of Carbon Coating on the ElectrochemicalPerformance of Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2 Positive Electrode Material for Lithium Ion Battery

以过渡金属乙酸盐和氢氧化锂为原料，采用共沉淀方法制备了锂离子电池富锂正极材料Li[Li0.2Mn0.54Yi0.13Co0.13]O2并对该材料进行表面包碳．X射线衍射技术（XRD）、扫描电子显微技术（SEM）实验数据表明，该材料具有层状α—NaFeO2结构．包碳后材料结构没有变化，表面覆盖上一层纳米级别的颗粒．电化学性能测试结果表明该材料包碳后在0．1C（1C=180mA／g），2．0—4．8V电位范围内首次放电比容量高达259．0mAh／g．包碳后首次放电比容量，倍率性能，循环性能均得到提高．采用电化学阻抗谱（EIS）研究包碳前后该材料的传荷阻抗，结果显示碳包覆材料的传荷阻抗明显减小，电子电导率得到提高，从而提高电化学性能．

Li [ Li0.2 Mn0.54 Ni0.13 Co0.13 ]O2 cathode material was successfully prepared by co-precipitation method using transition metal ace-rate and lithium hydroxide as starting materials.The surface ＆cathode material was modified with carbon.The cathode material was charac terized by XRD and SEM techniques.The results showed that Li[Li0.2Mn0.54Ni0.13Co0.13]O2 has α-NaFeO2 layered structure and that carbon coating did not cause structure change.Electrochemical measurements showed that the carbon-coated material was able to deliver higher initial discharge specific capacities of 259.0mAh/g in the voltage range 2.0-4.8V at 0.1C（1C=180mA/g）rate.Besides the rate capability,the cycling performance was also improved after carbon coating.EIS technique was utilized to investigate the charge transfer resistance of the pristine and carbon-coated materials.The results showed that the carbon-coated material displaied lower charge transfer resistance,which contributed to the improved electrochemical performance.