摘要
以β-Ni0.9Co0.05Mn0.025Mg0.025（OH）2和LiOH·H2O为原料通过高温固相法合成了球形LiNi0.9Co0.05Mn0.025Mg0.025O2。采用热重-差热分析了反应过程，采用X射线衍射和扫描电镜对粉末的结构和形貌进行了表征。采用充放电测试和循环伏安测试对材料电化学性能进行了研究。结果表明：750 ℃煅烧12 h合成的LiNi0.9Co0.05Mn0.025Mg0.025O2为Li原子混排较少的良好层状结构，二次颗粒尺寸在15 μm左右，且具有最高的放电比容量和良好的循环性能，在0.2C，2.8-4.3 V的条件下，首次放电比容量达207 mAh· g^-1，40次循环后容量保持率为92.5%。
Layered structured LiNi0.9Co0.05Mn0.025Mg0.025O2 was successfully synthesized by heating a mixture of β-Ni0.9Co0.05Mn0.025Mg0.025（OH）2 and LiOH·H2O at elevated temperature. Differential scanning calorimetry （DSC） and thermogravimetry analysis （TGA） were employed to study the reaction process. The Ni0.9Co0.05Mn0.025Mg0.025（OH）2 and synthesized LiNi0.9Co0.05Mn0.025Mg0.025O2 were characterized by means of X-ray diffraction （XRD） and scanning electron microscope （SEM）, while the electrochemical properties of LiNi0.9Co0.05Mn0.025Mg0.025O2 were investigated by charge-discharge test and cyclic voltammetry （CV）. Structure analysis shows the LiNi0.9Co0.05Mn0.025Mg0.025O2 synthsized at 750 ℃ for 12 h possess a well-layered hexagonal structure and a low level of the cation-mixing of Li layer. Scaning electron micrographs reveal that the morphology of the samples is characterized by spherical second particles of -15 μm. The analysis from electrochemical test suggests that heating the mixture at 750 ℃ for 12 h is the optimized synthesis condition for highest initial discharge capacity and best cycling performance. The first discharge specific capacity between 2.8 and 4.3 V at 0.2C is tested to be 207 mAh·g-1 and 92.5% of the discharge capacity remained after 40 cycles.The CV result shows that the multi-doping of Co, Mn and Mg has strengthened the cycling capability.
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
2012年第6期1171-1176,共6页
Chinese Journal of Inorganic Chemistry
基金
中南大学中央高校基本科研业务费(No.2010QZZD0101)资助项目
