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

Cage-like MnO 2 -Mn 2 O 3 hollow spheres with high specific capacitance and high rate capability as supercapacitor material

“…This pattern matched that of the CV results, and in comparison with previous reports on hollow-structured manganese oxides, the specific capacitance for CMHS produced via CV and galvanostatic cycling are quite competitive. Previously reported values include: hollow MnO2 spheres of 115 F g -1 at 0.5 A g -1 in 1 M Na2SO4 electrolyte 14 ; double-shelled MnO2 hollow spheres of 210.2 F g -1 at 0.2 A g -1 in 1 M Na2SO4 electrolyte 22 ; hollow α-MnO2 of 167 F g -1 at 2.5 mA cm -2 in 1 M Na2SO4 electrolyte 18 ; and nano-structured MnO2 hollow spheres of 147 F g -1 at 0.2 A g -1 in 1-butyl-3-methylimidazolium hexaurophosphate in DMF electrolyte 41 . However, MnO2 hollow paramecium of 554.3 F g -1 at 1 A g -1 21 and hollow tubular MnO2 of 315 F g -1 at 0.2 A g - 1 19 are the exceptionally high examples in the field.…”

“…Furthermore, different synthesis strategies have managed to achieve hollow spheres [5][6][7] , cubes 8 , polyhedrons 2 and bowls 9 , and their manipulation into double-layer shells 10,11 and multi-layer shells 12,13 . Hollownanostructured manganese oxides are attractive due to the high abundance, environmental friendliness and high theoretical specific capacity of manganese oxides 2,[14][15][16][17] . Various studies have reported hollow MnO2 structures such as spheres [14][15][16]18 , tubes 19 , urchin 20 , and paramecium 21 , prepared using methods employing oxidationetching and hard-templates.…”

“…Hollownanostructured manganese oxides are attractive due to the high abundance, environmental friendliness and high theoretical specific capacity of manganese oxides 2,[14][15][16][17] . Various studies have reported hollow MnO2 structures such as spheres [14][15][16]18 , tubes 19 , urchin 20 , and paramecium 21 , prepared using methods employing oxidationetching and hard-templates. These hollow-structured MnO2 crystals have a specific capacitance range of ~100 to 300 F g -1 at current densities lower than 2 A g -1 .…”

“…S8). For both CHMS and MHS, increasing scan rates decreased the specific capacitance due to limitations in the Na + diffusion rate 14 . At a scan rate of 1 mV s -1 , CMHS and MHS produced Csp,CV specific capacitances of 239.8 F g -1 and 178.3 F g -1 respectively.…”

A novel Ni@Ni(OH)2 coaxial core-sheath nanowire membrane for electrochemical energy storage electrodes with high volumetric capacity and excellent rate capability

“…From the cycling tests, it can be seen that the capacity decreases gradually before 400 cycles and becomes stable from 400 to 1500 cycles. After 1500 cycles CD at a high current density, the capacity can still retain about 78% of initial value with high coulombic efficiency, this is competitive to those of most works reported [14,35,36], indicating the excellent electrochemical stability of our material. The electrochemical performance of Ni-H3 is also compared with other materials previously reported, as listed in Table 1.…”