Investigating Na_3V_2(PO_4)_3 @C/CNF Hybrid Cathode in Aqueous Zinc-Ion Battery

摘要

With the rapid development of new energy storage technologies, aqueous zinc-ion batteries (AZIBs) gaining significant attention as one of the most promising candidate due to its lower cost and enhanced safety aspects. The key to the development of full batteries lies in suitable high-performance electrode materials. A NASICON type material, Na_3V_2(PO_4)_3 (NVP) has a high ion conductivity and an open three-dimensional structure, which can accommodate zinc-ion intercalation, reversibly. Here, we developed a hybridcarbon coated NVP interconnected with carbon nanofibers (NVP@C/CNF) as cathode in AZIBs. The cyclic voltammogram analysis shows that after adding CNF, electrode material owns higher diffusion coefficient of Zn~(2+) with lower electrochemical polarization. The as-prepared NVP@C/CNF composite exhibits discharge capacity of 95.1 mAhg~(-1) at 1 C, larger than that of the NVP@C composite (77.3 mAhg~(-1) at 1 C). The capacity retention of NVP@C/CNF is 75.6% after 100 cycles, superior to NVP@C without incorporation of CNF (63.1%). The uniform carbon layer on the surface of NVP alleviates the vanadium dissolution during cycling, while the CNF network further improves the electrical conductivity and structural stability of the hybrid, which can effectively suppress material expansion caused by insertion and extraction of Zn~(2+). As verified, NVP@/C/CNF is expected to be a great potential electrode in safer ZIBs.