锂离子电池正极梯度材料的制备及电性能研究

采用金属离子混合硫酸盐溶液分次共沉淀法制备前躯体,混锂后通过高温固相反应得到具有镍、钴和锰浓度梯度的层状LiNi0.56Co0.22Mn0.22O2锂离子电池正极材料。通过x射线衍射(XRD)、扫描电子显微镜(SEM)及恒电流充放电测试对合成的材料进行了表征。结果表明,750～900℃焙烧15h下合成的产物均具有典型的α-NaFeO2型层状结构特征,晶型结构完整,粒度均匀。800℃合成的正极材料具有较好的电化学性能。在充放电倍率0.4C、2.75-4.2V电压范围内,材料的首次充放电比容量分别为170.0mAh/g和131.8mAh/g,放电效率为77.5%;第51次循环的充放电比容量分别为131.3mAh/g和130.5mAh/g,放电效率为99.4%,容量保持率达到99.0%。

Electrochemistry synthesis and characterization of cathode gradient material for lithium-ion batteries

Layered gradient cathode material of lithium ion battery,LiNi0.56Co0.22Mn0.22O2,which had concentration grads of Ni,Co,Mn,was synthesized by mixing precursor with excess LiOH·H2O followed by heat treatment.The precursor was prepared via multiple co-precipitation of sulphate solutions with different compositions of Ni,Co,Mn.The cathode material was characterized using X-ray diffraction(XRD),scanning electron microscope(SEM),galvanostatic chargedischarge test.The results showed that all the samples prepared at 750~900℃ for 15 hours were layered materials with typical α-NaFeO2 structure.The crystal structure was orbicular and the particle size was well-proportioned.The sample prepared at 800℃delivered the higher discharge capacity and better cycling performance.At the current density of 5C and in the voltage range 2.75~4.2V,this powder had the initial charge capacity of 170.0mAh/g and discharge capacity of 131.8mAh/g,the initial discharge efficiency was 77.5%.After 51 cycles,it still had the charge capacity of 131.3mAh/g and discharge capacity of 130.5mAh/g,and the capacity retention was 99.0%.