片层纳米结构磷酸铁制备及对磷酸铁锂电性能的影响

Preparation of the Lameller Nanostructure Iron Phosphate and Its Effect on the Electrochemical Performance of Lithium Iron Phosphate

采用液相反应结晶法,在磷源及铁源中添加NaAlO_2,利用在结晶过程中生成的Al(OH)3胶体对结晶面的作用,合成出具有片层纳米结构纺锤体状磷酸铁前驱体,并通过高温固相法进一步制备成磷酸铁锂。采用XRD、FT-IR、SEM、TEM、比表面及孔隙率分析、激光粒度分析和电化学性能测试等手段对样品进行表征分析。结果表明,由具有片层纳米结构的磷酸铁前驱体制备的磷酸铁锂比由无片层纳米结构的磷酸铁前驱体制备的磷酸铁锂在0.1C下的首次放电容量提升了20%,达到151.48mAh/g,电极电荷转移电阻降低了约75%,仅为27.23Ω;0.1C倍率下循环50次后容量保持率可达96%。同时,对Al(OH)3胶体影响片层纳米结构磷酸铁生成机制进行了分析和讨论。

Using liquid phase reactive crystallization,NaAlO 2 was added to phosphorus source and iron source and the lamellar nanostructure of spindle shaped iron phosphate precursor was synthesized by the effect of Al(OH)3 colloid on the crystal surface during crystallization.It was used to prepare LiFePO 4 through high temperature solid state method.The samples were characterized by means of XRD,FT-IR,SEM,TEM,analysis of BET surface area and porosity,laser particle size analyzer and electrochemical performance test.The results showed that the initial discharge capacity of the LiFePO 4 that prepared by the lameller nanostructure FePO 4 precursor at 0.1C increased by 20%,reaching 151.48 mAh/g,and the electrode charge transfer resistance was reduced by 75%,just 27.23Ω,compared with the LiFePO 4 that prepared by non lameller nanostructure FePO 4,and the retention rate of capacity reached 96%after 50 cycles at 0.1C rate.Meanwhile,the mechanism of Al(OH)3 colloid affecting the formation of lamellar nanostructured iron phosphate was analyzed and discussed.