Li1+x(Fey/2Niy/2Mn1-y)1-xO2正极材料的合成及电化学性能

采用低温共沉淀-水热-煅烧法合成了锂离子电池Fe-Ni-Mn体系正极材料Li1+x(Fey/2Niy/2Mn1-y)1-xO2,并用XRD、SEM、ICP光谱和电化学性能测试对材料进行了表征.XRD测试和ICP分析表明,Fe、Ni取代Li2MnO3中的部分Mn,形成很好的固溶结构yLiFe1/2Ni1/2O2-(1-y)Li2MnO3 (y=0.l,0.2,0.3,0.4,0.5).SEM测试表明,取代量y不同,材料的表观形貌有所不同,y=0.4时材料的颗粒粒径均匀、较小,呈类球形结构.电化学性能测试表明,当y=0.4时,循环稳定性最好,充放电50次后放电比容量仍可维持在195.0 mAh/g,放电中值电压为3.5 V,y=0.4时样品在大倍率放电下的电化学性能表现良好.

Synthesis and Electrochemical Performance of Li1+x(Fey/2Niy/2Mn1-y)1-xO2 Cathode Material

Li1+x(Fey/2Niy/2Mn1-y)1-xO2 was synthesized by a coprecipitation-hydrothermal-calcinations method. The crystal structure and charge/discharge performance of Li1+x(Fey/2Niy/2Mn1-y)1-xO2 were analyzed by X-ray diffraction (XRD), inductively coupled plasma (ICP) and electrochemical performance measurement. The XRD tests and ICP analyses demonstrate that Fe and Ni substitute a part of Mn of Li2MnO3 to form the good solid solution structure yLiFe1/2Ni1/2O2-(1-y)Li2MnO3 (y= 0.1, 0.2, 0.3, 0.4, 0.5). SEM images show that different y values lead to different apparent morphologies of the materials. When y=0.4, the particles are spherical with uniform and small size. The electrochemical tests indicate that when y=0.4, the cathode material has the best electrochemical performance with the discharge capacity of 195.0 mAh/g after 50 cycles