新型负极材料LiTi_2(PO_4)_3的合成及电化学性能研究
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摘要
以碳酸锂(Li2CO3)、二氧化钛(Ti O2)、磷酸二氢铵(NH4H2PO4)为主要原料,采用流变相反应法成功地合成了Li Ti2(PO4)3,并探讨不同合成温度对Li Ti2(PO4)3结构及电化学性能的影响。采用X射线衍射光谱法(XRD)、扫描电子显微镜法(SEM)技术对合成材料的晶体结构和形貌进行了表征,采用恒流充、放电系统及交流阻抗测试法对合成材料的电化学性能进行了测试,结果表明:在小电流密度下两种温度合成的产物电化学性能差别不大,但在较高倍率下充、放电时,600℃下合成的样品具有较高的比容量和较好的循环性能,还对合成温度影响Li Ti2(PO4)3性能的原因进行了初步探讨。
Polyanionic compounds [Li Ti2(PO4)3] were synthesized by rheological phase reaction method, using lithium carbonate, titanium dioxide and ammonium dihydrogen phosphate as raw materials. The effects of different sintered temperatures on the properties were studied. The crystal structure and microstructure were characterized by XRD and SEM techniques. And the electrochemical properties of the samples were investigated by constant-current charge-discharge system and AC impedance spectroscopy testing method. The results show that although there are little differences in electrochemical properties between the samples synthesized at 600 and 800 ℃, the sample synthesized at 600 ℃ exhibits higher charge/discharge specific capacity and better cycle performance than that of the sample synthesized at 800 ℃. The related reasons were also discussed.
Polyanionic compounds [Li Ti2(PO4)3] were synthesized by rheological phase reaction method, using lithium carbonate, titanium dioxide and ammonium dihydrogen phosphate as raw materials. The effects of different sintered temperatures on the properties were studied. The crystal structure and microstructure were characterized by XRD and SEM techniques. And the electrochemical properties of the samples were investigated by constant-current charge-discharge system and AC impedance spectroscopy testing method. The results show that although there are little differences in electrochemical properties between the samples synthesized at 600 and 800 ℃, the sample synthesized at 600 ℃ exhibits higher charge/discharge specific capacity and better cycle performance than that of the sample synthesized at 800 ℃. The related reasons were also discussed.
引文
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[8]郑威.锂离子电极材料Li Fe PO4和Li Ti2(PO4)3固相合成及表面改性[D].杭州:浙江大学,2010.
[2]郭晓伟,贾晓琳,户赫龙,等.溶胶-凝胶微波加热合成Li Ti2(PO4)3超细粉[J].材料导报,2007,11(21):68-84.
[3]TAKADA K,TANSHO M,YANASE I,et al.Lithium ion conduction in Li Ti2(PO4)3[J].Solid State Ionics,2001,139:241-247.
[4]KOSOVA N V,OSINTSEV D I,UVAROV N F,et al.Suitable doped lithium titanium phosphates as cathodes,anodes and electrolytes for rechargeable lithium ion battery[J].Chemistry for Sustainable Development,2005,13(2):253-260.
[5]娄太平,王家良.Li Ti2(PO4)3的Na Li离子交换特征[J].物理化学学报,2007,23(10):1642-1646.
[6]张学广,张旭东,何文,等.聚阴离子型正极材料磷酸钛锂的研究进展[J].山东轻工业学院学报,2011,25(1):28-30,40.
[7]张克立.固体无机化学[M].武汉:武汉大学出版社,2005:125-127.
[8]郑威.锂离子电极材料Li Fe PO4和Li Ti2(PO4)3固相合成及表面改性[D].杭州:浙江大学,2010.