Synthesis and comparison of in‐situ carbon‐decorated sodium manganese vanadium phosphate cathode and sodium‐ion full‐cell configurations

Abstract

Carbon‐decorated Na 3.5 Mn 0.5 V 1.5 (PO 4 ) 3 (NMVP@C) composite was synthesized by one‐step solid‐state method. As a cathode material, the as‐obtained material shows a pair of significant redox peaks with highly reversible discharge capacity of 102.8 mAh g –1 at a current density of 100 mA g –1 . More optimistically, when increased to 1600 mA g –1 , a capacity retention of 69.6% (54.7 mAh g –1 ) can still be maintained even after 10000 cycles. The electrochemical performance of full‐cell consisted of NMVP@C as cathode and NaTi 2 (PO 4 ) 3 (NTP) or commercialized hard carbon (HC) as anode was tested. The results show that both full‐cells display a pair of obvious redox peaks whose equilibrium potentials are about 1.29 and 3.35 V, respectively, and exhibit excellent capacity and rate performance. At a current density of 1600 mA g –1 , they deliver high discharge capacities of 75.4 and 78.2 mAh g –1 , respectively. After 2343 cycles, NMVP@C//NTP can achieve a specific capacity of 42.4 mAh g –1 , that is 58.2% of initial specific capacity, and that of NMVP@C//HC is only 35.7%. Overall, whether for half‐ or full‐cell, NMVP@C shows excellent electrochemical performance, demonstrating that our synthesis strategy is effective in improving performance.