Electro-insertion of Mn2+ions into V2O5•nH2O on MWCNTs coated carbon felt for binder-free Na+ion battery electrodes

In the present article, we report the electrochemical deposition of hydrated and amorphous V2O5 center dot nH(2)O nanostructures and related Mn(2+)cations insertion during anodic polarization. The hydrated phase was synthesized on hydrophilic carbon felt substrates coated by defective multiwall carbon nanotubes (MWCNTs). From the combined data of micro-Raman scattering and X-ray photoelectron spectroscopy (XPS), it was possible to see that the Mn(2+)cations were intercalated into V(2)O(5)under anodic polarization. When MnOOH is inserted between atomic bilayers of V2O5 center dot nH(2)O (V5+), a 3D complex monoclinic-Mn(x)V(2)O(5)system arises. This novel method of Mn doping into V2O5 center dot nH(2)O/MWCNT produces an amorphous MnxV2O5/MWCNT but without hydration. The resulting binder-free MnxV2O5/MWCNT/felt composite electrode provides remarkable Na(+)reversible specific capacities of 400 mA h g(-1)and 224 mA h g(-1)in the 3.5-1.0 V and 3.5-1.5 V ranges, respectively, while the V2O5 center dot nH(2)O/MWCNT/felt provides only 120 mA h g(-1)between the smaller cut-off potential limits. The MnxV2O5/MWCNT nanostructures synthesis onto fibers of graphitic felt does not present a fading capacity during the polarization of 100 discharge/charge cycles.