合成方法对富锂锰基正极材料Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)电化学性能的影响

Effect of Synthesis Methods on the Electrochemical Performance of Lithium-Rich Manganese-Based Cathode Material Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)

采用共沉淀法、溶胶凝胶法和固相法合成了富锂锰基正极材料Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2),并通过XRD、SEM、EDS等对所合成材料的物相结构和微观组织等进行了表征,采用电池测试系统对由合成材料组装的CR2032纽扣式半电池进行电化学性能测试。研究表明,三种合成方法都成功合成了具有层状结构的富锂锰基正极材料,其中共沉淀法制备的样品阳离子混排程度最低,元素分布和颗粒大小均匀,晶界边缘清晰,并且无明显团聚。从电化学性能来看,在2.0~4.8 V的电压范围内,0.1 C倍率下共沉淀法合成样品的首圈放电比容量最高,在充放电循环100圈后,仍保持195.8 mA·h/g的放电比容量,容量保持率为87.3%。相较而言,溶胶凝胶法和固相法制备的样品容量保持率较低,分别为84.5%和83.8%。与溶胶凝胶法和固相法制备样品相比,共沉淀法可有效提高Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)正极材料中Li^(+)的传输效率,进而提高样品的倍率性能。

Lithium-rich manganese-based cathode material Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)was prepared by co-precipitation,sol-gel,and solid phase methods,and the phase composition and microstructure of the synthesized material were characterized by XRD,SEM,EDS,etc.The electrochemical performance of the CR2032 button type half cell assembled from the synthesized material was tested using a battery testing system.The results indicate that lithium-rich manganese-based cathode materials with a layered structure have been successfully synthesized by the three synthesis methods.Among them,the sample prepared by co-precipitation method exhibits the lowest degree of cation mixing,and has uniform elemental distribution and particle size,clear grain boundary edges,and no obvious agglomeration.In terms of electrochemical performance,the first cycle discharge specific capacity of the sample synthesized by co-precipitation method at a rate of 0.1 C reaches the highest within the voltage range of 2.0~4.8 V.Moreover,after 100 cycles,the prepared sample still maintains a discharge specific capacity of 195.8 mA·h/g,with a capacity retention rate of 87.3%.Comparatively,the samples prepared by sol-gel method and solid phase method has lower capacity retention rates of only 84.5%and 83.8%,respectively.And compared with the samples prepared by sol-gel method and solid phase method,the co-precipitation method can effectively improve the Li^(+)transport efficiency of Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)cathode material,thereby improving the rate performance of the sample.