摘要
采用ＴＥＭ、ＸＲＤ分析等方法对新型二氧化锰纳米纤维电极材料进行表征，ＴＥＭ观测结果显示这种锰材料是由许多二氧化锰纳米纤维缠绕成巢状，其纤维直径约为１ｎｍ～１０ｎｍ之间；从ＸＲＤ分析表明，它是一种复合结构的锰氧化物，以钡镁锰矿为主体结构，并含有其他钠水锰矿及水羟锰矿结构。从样品电极在１ｍｏｌ／ＬＬｉＣｌＯ４的ＰＣ－ＤＭＥ（１∶１）溶剂中的循环伏安曲线，可以看出在扫描的电压范围内，在３．８Ｖ和２．８Ｖ附近出现一对可逆对称的氧化还原峰，它对应于二氧化锰纳米纤维电极中锂离子的脱出－嵌入反应。通过二氧化锰纳米纤维电极在不同电流密度下的放电，可以看出该电极采用小电流放电（０．２４ｍＡ／ｃｍ２），其容量可达到约１９０ｍＡｈ／ｇ，而且具有３Ｖ的放电平台；而在较大的电流密度（０．９６ｍＡ／ｃｍ２）放电仍具有约１５０ｍＡｈ／ｇ的放电容量。可见，该电极具有良好的负荷特性和较高的放电容量。
A novel cathode material (MnO 2) has been characterized by using transmission electron microscope (TEM) and X ray diffraction (XRD). From the TEM examination, it was found that the MnO 2 has a distinct birds nest shaped nano fiber with the diameter in the range of 1nm～10 nm. XRD data shows that the MnO 2 has a complex structure that is in the form of todorokite (3×3 tunnel) birnessite, and vernadite structure. Cyclic voltammetry has been performed in 1 mol/L LiClO 4的PC DME(1∶1) electrolyte solution. It can be seen that a pair of reversible redox peaks, which mainly occurs in the potential ranged from 2.8 to 3.8 V vs.Li/Li +, it can be described by a lithium intercalation mechanism. The galvanostatic charge discharge experiments at various current density reveal that the MnO 2 nano fiber electrodes have a high electrochemical performance and stability. The reversible capacity can reach 190 mAh/g, 150 mAh/g at lower and higher current density respectively, i.e. 0.24mA/cm 2 and 0.96mA/cm 2.
出处
《电源技术》
CAS
CSCD
北大核心
1999年第3期155-157,共3页
Chinese Journal of Power Sources
基金
国家"863"高技术发展计划课题
中国大洋矿产资源研究开发课题
国家自然科学基金
关键词
锂离子电池
二氧化锰
纳米纤维
锂锰氧化物
lithium ion battery, manganese dioxide nano fiber, lithium manganese oxide
