【作者】 杨书廷； 赵娜红； 董红玉； 杨金鑫； 岳红云；

【Author】 S. T. YANG, N. H. ZHAO, H. Y. DONG, J. X. YANG, H .Y. YUECollege of Chemistry and Environmental Science, Henan Normal University, Xinxiang, 453007, ChinaHenan New Power Material Research Center Professor of College of Chemistry and Environmental Science, Henan Normal University, Xinxiang 453007, China, Director of Henan New Power Material Research Center

【机构】 河南师范大学化学与环境科学学院；

【摘要】 一种新奇的模板合成材料,聚丙烯酰胺(PAM)模板法合成的LiFePO4正极材料,在室温时即能表现出很好的倍率特性,C/3时放电克容量为109.3mAh/g,C/6时放电克容量为120mAh/g。通过原子力显微镜、长时间超声分散以及透射电镜等手段,我们观察到最终的合成材料中形成了内置螺旋碳导电网络的纳米隧道结构, 30-50nm的LiFePO4活性微晶高度分散在碳网络基底中,且通过碳导电网络相互连接。这种复合材料不同于表面镀碳改性结构,它具有高分散度性LiFePO4,和相对紧凑的交互共生的结构,因而LiFePO4/C接触更加紧密,拥有更加明显的LiFePO4纳米微晶/纳米导电碳界面隧道效应,所以导电性能更加优异。Li+离子的扩散也得到一定促进,这一点可以通过XRD衍射实验及扫描循环伏安证实。另外这种材料在前几周的循环伏安曲线中,呈现出两对氧化还原峰,这一点和传统固相合成法也有很大区别,第一刷的不可逆容量也远远大于Anderson所提出的不可逆容量,这些都说明,模板合成材料中可能存在具有电化学活性的第二相。更多还原

【Abstract】 A novel LiFePO4cathode material was templated by Polyacrylamide (PAM). It had outstanding and fancy electrochemical performances exhibiting 109.3mAh/g capacity at C/3 rate and 120mAh/g capacity at C/6 rate. With the fantastic template, spiral sorbent PAM, nanoprogressional tunnels were designed inside the crystals, which inhabited by spiral carbon discomposed from PAM. These tunnels can be confirmed by TEM. Instead of ‘cover’, those inhabited conductive tunnels formed further intimate interface with that of the active material and fundmentally enhanced the body conductivity, and to a certain degree the diffusion coefficient of the lithium ion was also promoted, which can be proved by diffraction parameters and cyclic voltammetry of this modified material. To our surprise the cyclic voltammograms presented two anodic and two cathodic peaks around 3.5V in the anterior cycles. And the unreversible capacity was much bigger than that reported by Andersson et al [12]. All these proved the existence of the second phase, which had electrochemical activity.更多还原