论文部分内容阅读
采用溶胶凝胶及高能球磨制得Li3Fe2(PO4)3/C材料,利用多种物理及其电化学技术观察材料形貌,表征材料结构及电化学性能,用电化学原位XAFS等初步研究Li3Fe2(PO4)3/C超理论容量电化学反应机理.结果显示,Li3Fe2(PO4)3/C的结构为单斜晶系,空间群P21/n.2.0~4.0 V电位区间,10 m Ah·g-1电流密度,Li3Fe2(PO4)3/C电极的首周期放电比容量为129 m Ah·g-1,达到其理论容量.若电位区间拓宽至2.0~4.95 V,其首周期放电比容量高达165 m Ah·g-1,超出理论的“额外”容量30%.电化学原位XAFS测试未观察到明显的Fe3+/Fe4+氧化还原对参与电化学反应,初步推测“额外”容量可能来自于该复合材料的高浓度表面缺陷.
Li3Fe2 (PO4) 3 / C materials were prepared by sol-gel and high-energy ball milling. The morphology of the material was observed by various physical and electrochemical techniques, and the structure and electrochemical properties of the material were characterized. (PO4) 3 / C. The results show that the structure of Li3Fe2 (PO4) 3 / C is monoclinic and the space group P21 / n is 2.0-4.0 V, -1 current density, the first cycle discharge capacity of Li3Fe2 (PO4) 3 / C electrode is 129 m Ah · g-1, reaching its theoretical capacity.If the potential range broadened to 2.0 ~ 4.95 V, the discharge capacity of the first cycle was as high as 165 m Ah · g-1, which is 30% more than the theoretical “extra” capacity.Electrochemical in-situ XAFS did not show obvious Fe3 + / Fe4 + redox couples involved in the electrochemical reaction, and presumed the “extra” capacity Probably from the high concentration of surface defects of the composite.