Superior Reversibility of NASICON-Na3.5Mn0.5V1.5(PO4)3 Cathode Enabled by Dual-Carbon Conductive Network

Compared to Na3V2(PO4)3, NASICON-typed Na3+xMnxV2-x(PO4)3 with a suitable amount of Mn substitution exhibits higher energy density and low cost due to activation of the V5+/V4+ redox reaction during the electrochemical process. However, the low electrical conductivity severely limits the cycling stability and rate capability. Herein, a combination of dual-carbon coated and Mn2+ doped Na3.5Mn0.5V1.5(PO4)3 (NMVP/C@GO) composite is reported to improve Na storage performance. The dual-carbon conductive network is favorable to electronic and ionic transportation, facilitating the kinetic characteristics and structural stability of electrodes. Consequently, the obtained NMVP/C@GO composite delivers a reversible capacity of 112 mAh g-1 at 2 C and decent capacity retention of 81.3% after 400 cycles. Moreover, it delivers an impressive rate capacity of 88 mAh g-1 at 20 C. This work provides a facile and beneficial strategy to achieve high-energy cathode of SIBs.