Hydrothermal preparation and the capacitance of hierarchical MnO2 nanoflower

Facile synthesis of hierarchical hollow ε-MnO2 spheres and their application in supercapacitor electrodes

“…The distinctive semicircle of the MnO 2 sample after charge-discharge cycles in the medium frequency region is small as compared to that before the cycles sample suggesting lower diffusion resistance during insertion/de-insertion of H + and Na + ions inside the matrix of porous MnO 2 sample. A major difference is the slope of the 45° portion of the curve called the Warburg resistance (Z W ), which is a result of the frequency dependence of ion 13 diffusion/transport in the electrolyte to the electrode surface [40]. Moreover, the increased Warburg resistance after 500 cycles is attributed to the increased diffusion and migration pathways of electrolyte ions during the charge/discharge processes.…”

“…As one of the most attractive hierarchical architectures, on the other hand, porous hollow manganese oxide nanostructures have displayed the enhanced interfacial area for electron/ion adsorption and unhindered mass transport during electrochemical process. However, most of the reported synthesis methods are either hydrothermal mediated [12][13][14][15] or tedious and expensive combinations of procedures such as use of noble metals [16,17] and electrochemical deposition [18][19][20], which are employed to generate bulk nanostructures and films of MnO 2 for supercapacitor applications.…”

Long Cyclic Life in Manganese Oxide-Based Electrodes

“…20,22 It is exciting that there are several groups reporting manganese oxide electrodes with very good cycling stability. [23][24][25][26] For example, Sun et al. reported that a todorokite-type manganese oxide electrode can remain stable up to more than twenty thousands.…”

“…23 Zhu et al reported the birnessite-type MnO 2 hierarchical nanoflower exhibiting capacitance retention of 97.5% over 10,000 cycles. 25 It suggests that good electrochemical stability could be achieved in different manganese oxides electrodes. However, the key factor(s) dominating the cycling performance is still unknown.…”

Synthesis of MnO 2 /C composite nanotubes as advanced cathode of supercapacitors

“…To date, numerous MnO2 nanostructures (e.g., nanotubes [17], nanoflowers [18], nanowires [19]) have been prepared and improved performance are demonstrated due to their increased active sites and enlarged surface area. In particular, nanotube structure possesses much more advantages among these nanostructure design because of more transfer space for ions/electrons.…”