纳米K-MnO2嵌入化合物的制备与电化学性能研究

The Preparation and Electrochemical Performance of Nanostructured K-MnO_2 Intercalation Compound

在冰浴条件下,以KMn O4、KOH和Mn Cl2为反应物,采用液相化学共沉淀法制备了层状δ-MnO_2宿主,然后以KOH为嵌入离子源,采用水热沉淀法,制备了纳米K-MnO_2嵌入化合物.分别采用X-射线衍射光谱和扫描电子显微镜等物理方法对试样的晶体结构和表面形貌进行表征;用循环伏安、恒流充放电和交流阻抗等电化学方法研究其电化学性能.结果表明,纳米K-MnO_2嵌入化合物在1 mol·L-1的KOH、Na OH和Li OH电解液中发生了相互协同的氧化-还原反应和嵌入-脱嵌反应,在相同的扫描速率或电流密度下比电容的大小关系分别为KOH>Na OH>Li OH,在600次循环充放电中展现出了良好的循环稳定性,意味着这种嵌入化合物K-MnO_2是一种很有前途的水系混合超级电容器的正极材料.

In this paper,layered δ-MnO2 host was synthesized with liquid chemical coprecipitation method by using KMnO4,KOH and MnCl2 reactants at 0 ℃.Nanostructured K-MnO2 intercalation compound was prepared by hydrothermal method treated the mixture of δ-MnO2 as host and KOH as intercalation ion scourse at 180 ℃ for 2 day.X-ray diffraction,scanning electron microscopy were used to investigate crystal structure,morphology of the K-MnO2 intercalation compounds,respectively.The electrochemical properties were evaluated by cyclic voltammetry,galvanostatic charge/discharge and electrochemical impedance spectroscopy,etc.The results show that nanostructured K-MnO2 intercalation compound presents the synergistic effects of oxidation-reduction reaction and insertion-deinsertion reaction in 1 mol·L-1 KOH,NaOH and LiOH electrolyte,and the specific capacitance of K-MnO2 is in the order of KOH〉NaOH〉LiOH at same scan rate or current density,respectively.Exhibiting excellent 600-cycle charge-discharge in 1 mol·L-1 KOH electrolyte,which indicate that the as-prepared K-MnO2 intercalation compound would be as a promising cathode materials for aqueous hybrid supercapacitors.