کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6470642 | 1424111 | 2017 | 7 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Enhancing high-rate capability of MnO2 film electrodeposited on carbon fibers via hydrothermal treatment Enhancing high-rate capability of MnO2 film electrodeposited on carbon fibers via hydrothermal treatment](/preview/png/6470642.png)
- Electrodeposited MnO2 films were firstly subjected to hydrothermal post-treatment.
- The hydrothermal post-treatment in a K2SO4 solution decreases the valence of Mn.
- The K2SO4-treated film keeps the ramsdellite structure and water content.
- The K2SO4-treated film exhibits a good high-rate capability.
- Suitable ratio of Mn4+ to Mn3+ is important for high-rate capability of the films.
MnO2 films electrodeposited on carbon fibers were subjected to hydrothermal treatment in deionized water and a K2SO4 solution. The effects of hydrothermal treatment on the structures and capacitive properties of the films were systematically evaluated. Compared to the as-deposited and K2SO4-treated films, the water-treated film exhibits a much lower capacitance at 2Â mVÂ sâ1 due to the phase transformation from ramsdellite to manganite during the hydrothermal treatment. The K2SO4-treated film maintains the ramsdellite structure although the average oxidation state of Mn in the film is decreased to some extent. At the charge-discharge current density of 1C, the K2SO4-treated and as-deposited films show specific capacitances of 281.9 and 274.7Â FÂ gâ1, respectively. But the K2SO4-treated film displays a capacitance of 135Â FÂ gâ1 at 15C and a good high-rate capability which is more than 3 times as high as that of the as-deposited one. These results and the related kinetic analysis suggest that the suitable ratio of Mn4+ to Mn3+ plays an important role in determination of the high-rate capability of the film.
Journal: Electrochimica Acta - Volume 246, 20 August 2017, Pages 890-896