Electrode Design for High-Power Sodium-Ion Batteries: Cr Doping into Nasicon-Structured Na3V2(PO4)3 Cathode with Self-Carbon-Coating

Abstract

NASICON-structured Na3V2(PO4)3 (NVP) is one of the most promising cathode material for rechargeable sodium-ion batteries. NVP is characterized by a robust 3D structural framework and a high operating potential; these properties have enabled it to be widely studied as a stable and high-energy density cathode material for sodium-ion batteries (SIBs).1-4 In the present study, we designed a Na3V1.6Cr0.4(PO4)3/C (NVCrP@C) cathode by implanting Cr into the crystal structure of NVP and simultaneously coating the surface of NVP with carbon for realizing high power density SIBs. NVP is fabricated using a low-cost pyro synthesis technique with the advantage of self-carbon-coating and nano sized particles are gained through this facile technique. The substitution of Cr with vanadium in the NVP structure significantly enhanced the structural stability of the electrode while the uniform and thin carbon layer improved the electrical conductivity. Interestingly, the NVCrP@C cathode showed high electrochemical activities with multiple V3+/4+/5+ redox reactions triggered by Cr3+ substitution in a wide voltage range (2.5–4.1 V). Consequently, the NVCrP@C cathode delivered excellent cycling stability over 500 cycles even at 15 C-rate and power capability up to 70 C-rate. References Y. Cao, L. Xiao, W. Wang, D. Choi, Z. Nie, J. Yu, L. V. Saraf, Z. Yang and J. Liu, Mater., 2011, 23, 3155-3160.M. Giot, L. C. Chapon, J. Androulakis, M. A. Green, P. G. Radaelli and A. Lappas, Rev. Lett., 2007, 99, 247211 M. H. Han, E. Gonzalo, G. Singh and T. Rojo, Energy Environ. Sci., 2015, 8, 81-102. H. Liu, J. Xu, C. Ma and Y. S. Meng, Chem. Comm., 2015, 51, 4693-4696