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化学学报
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化学学报 ›› 2005, Vol. 63 ›› Issue (3): 229-233. 上一篇    下一篇

研究论文

水溶液中掺铬层状二氧化锰可充性研究

朱新功，吴智远*，王敏，赵勇   

  1. (武汉大学化学与分子科学学院 武汉 430072)
  • 投稿日期:2004-01-31 修回日期:2004-11-05 发布日期:2010-12-10
  • 通讯作者: 吴智远

Investigation of the Rechargeability of the Cr-birnessite in Aqueous Solution

ZHU Xin-Gong,WU Zhi-Yuan*,WANG Min,ZHAO Yong   

  1. (College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072)
  • Received:2004-01-31 Revised:2004-11-05 Published:2010-12-10
  • Contact: WU Zhi-Yuan

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1229

被引次数

38

由高温分解KMnO4制备层状K-birnessite前驱体, 再经过离子交换反应制备Cr-birnessite. 在2.5 mol/L LiOH水溶液中研究了Cr-birnessite电极的可充性. 据AAS测试和锰的价态分析得Cr-birnessite的分子式为Cr0.26Mn0.84O2＋0.04. SEM显示Cr-birnessite为片状颗粒, XRD分析表明其层状结构在充放电前后没有明显变化. 恒电流充放电实验表明在2.5 mol/L LiOH水溶液中以1 C大电流速率对Cr-birnessite进行全充全放循环可达70次而保持初始容量的93%, 显示了良好的循环可逆性. AAS表明在充放电过程中材料中的铬离子没有脱嵌, Li＋脱嵌/嵌入. 循环伏安曲线表明在大约 －0.3和0 V出现两个氧化峰, 在－0.1 V左右出现一个还原峰, 循环20周电流大小没有明显变化. 利用恒电位阶跃法测得Li＋在Cr-birnessite 中的扩散系数平均值为1.57×10－10 cm2·s－1 .

关键词: 层状二氧化锰, 铬掺杂, 水溶液体系, 可充性, 锂离子嵌入

The Cr-birnessite was prepared by ion exchange from K-birnessite, which was synthesized by calcination of KMnO4. Measurement methods of scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), atomic absorption spectrometry (AAS), slow-scanning cyclic voltammetric and galvanostatic discharge/charge characteristics of the Cr-birnessite were applied. Potentiostatic method was used for the determination of a chemical diffusion coefficient D. XRD patterns indicate that Cr-birnessite has layered structure. Slow-scanning voltammograms exhibit single peak occurring in the range of －0.2 to 0 V on discharge and two peaks at about －0.3 and 0 V on charge. The galvanostatic discharge/charge curves indicate that the Cr-birnessite has better rechargeability at a high discharge/charge rate. Li＋can reversibly intercalate into and de-intercalate from the Cr-birnessite during discharge and charge. The average value of the chemical diffusion coefficient D of Li＋ intercalated into the Cr-birnessite is 1.57×10－10cm2·s－1.

Key words: birnessite, Cr3＋-doped, aqueous rechargeable battery, cycling ability, lithium intercalation