Outstanding electrochemical performance of sodium vanadium phosphate cathode co-modified by carbon-coating and titanium-doping for Na-ion batteries

As an advanced cathode material, Na3V2(PO4)(3) has received great attention for Na-ion batteries due to the 3D open structure, excellent thermal stability and high-power density. Nevertheless, Na3V2(PO4)(3) has a low electrical conductivity, resulting in bad sodium storage property. In this work, the Na3V2(PO4)(3) nanoparticles co-modified by carbon-coating and titanium-doping have been designed and fabricated. The Na3-xV2-xTi(PO4)(3)@C samples are fabricated via a facile approach. The obtained results demonstrate that the conductive carbon has uniformly coated onto the Na3V2(PO4)(3) nanoparticles and the titanium-ion has doped into the phase of Na3V2(PO4)(3). Among these designed samples, Na2.9V1.9Ti0.1(PO4)(3)@C electrode exhibits the best sodium storage properties with high specific capacity of 106.3 mAh g(-1) at 5C. Meanwhile, the reversible capacity can still be maintained at 95.8 mAh g(-1) after 200 cycles at 10C. These good rate performances are attributed to the doped titanium-ion and coated carbon layer, which can improve the intrinsic and apparent electrical conductivities of Na3V2(PO4)(3).