纳米LiFePO4材料的制备及性能研究

以FeCl2.4 H2O、(NH4)2HPO4及LiOH·3 H2O和柠檬酸为原料,采用水热模板法制备花形结构的LiFePO4纳米棒。此方法合成的LiFePO4形貌可控,粒径均匀,分散性好,电压平台稳定,具有高于160 mAh/g的比容量。还研究了柠檬酸浓度以及前驱体的煅烧温度对LiFePO4的形貌以及电化学性能的影响。实验表明在柠檬酸浓度为0.1 mol/L、煅烧温度650℃下,样品为分布均匀的纳米"花形棒状"结构,尺寸均匀、晶形稳定,电压平台为3.45 V,且电压平台宽,首次充放电比容量高达162.5 mAh/g,0.5 C充放电50次容量保持率将近100%。

Preparation and mechanism of nano-LiFePO4 materials

The nanoflower-type lithium iron phosphate cathodes was synthesized by hydrothermal template method with FeCl2·4 H2O,(NH4)2HPO4,LiOH·3 H2O and citric acid as raw materials.Through this method,lithium iron phosphate had an ordered nano "flower stick" structure with a high tap density,uniform surface morphology and excellent electrochemical performance.In this paper,it also studied the influence of the change of the concentration of citric acid and calcination temperature on the LiFePO4 morphology and electrochemical performance.The experiments show that when the citric acid’s concentration is 0.1 mol/L and calcination temperature is 650 ℃,the sample has better properties: uniformly distributed as nano "flower stick" structure,uniform size,stable crystal and the wide voltage platform,what’s more,the first charge and discharge specific capacity is up to 162.5 mAh/g,capacity retention rate is nearly 100% after 50 cycles under 0.5 C charge and discharge.