Na4MnV(PO4)3 (NMVP)
is a promising
cathode material for sodium-ion batteries (SIBs) because of its extraordinary
three-dimensional structure that provides plenty of channels for sodium-ion
migration. However, the unsatisfied electrical conductivity of NMVP
limits its utilization in SIBs. Herein, Zn-doped NMVP with a uniform
carbonized polyacrylonitrile (PAN) coating layer, named NMZVP@cPAN,
was synthesized via a sol–gel method, and carbonized PAN was
uniformly distributed on the surface of NMVP. Therefore, the NMZVP@cPAN
cathodes exhibited an outstanding discharge capacity of 70.6 mA·h·g–1 at 30 C and remarkable cycling stability with an
admirable retention of 89.64% after 1000 cycles at 5 C. Rietveld refinement
and ex situ X-ray diffraction analyses were performed to determine
the change in the crystal structure. Density functional theory calculations
were performed to determine the effects of Zn doping on the density
of states and the migration energy barriers. Finally, the NMZVP@cPAN
cathodes were successfully modified and could be used in SIBs as NMVP
cathodes.