High Li storage capacity of poorly crystalline porous delta-MnO2 prepared by hydrothermal route

作者：Nayak Prasant Kumar; Penki Tirupathi Rao; Munichandraiah N^*

来源：Journal of Electroanalytical Chemistry, 2013, 703: 126-134.

DOI：10.1016/j.jelechem.2013.05.016

• Porous manganese dioxide
• Poor crystallinity
• Morphology
• High capacity
• Cathode material

Poorly crystalline porous delta-MnO2 is synthesized by hydrothermal route from a neutral aqueous solution of KMnO4 at 180 degrees C and the reaction time of 24 h. The as-synthesized sample and also the sample heated at 300 degrees C have nanopetals morphology with large surface area. On heating at temperatures 400 degrees C, there is a decrease in BET surface area and also a change in morphology from nanopetals to clusters of nanorods. Furthermore, the poorly crystalline delta-MnO2 converts into well crystalline alpha-MnO2 phase. The electrochemical lithium intercalation and de-intercalation studies in a non-aqueous electrolyte provide a high discharge specific capacity (275 mAh g(-1)) at a specific current of 40 mA g(-1) for the poorly crystalline delta-MnO2 samples. The rate capability is also high. There is a decrease in capacity on repeated charge-discharge cycling. The specific capacity values of the crystalline alpha-MnO2 samples are considerably less than the values of poorly crystalline delta-MnO2 samples. Thus, the hydrothermal route facilitates preparation of poorly crystalline electrochemically active porous MnO2.

• 出版日期2013-8-15