Fabrication of ZnV₂O₄ Nanoparticles Embedded in Carbon Nanofibers as a Cathode Material for High-Performance Aqueous Zn-Ion Batteries

Recently, lithium-ion batteries have led the related market. However, the price of Li is expected to increase continuously, leading to unbalance of demand and supply for LIBs used for electric vehicles (EVs) and energy storage systems (ESS). For replacing LIBs, electrically rechargeable aqueous zinc-ion batteries (ZIBs) have been spotlighted due to Zn's attractive properties, such as being environmentally friendly, low price, and high stability. Nevertheless, the low capacity of ZIBs is attributed to low-capacity cathode material, restricting their practical utilization. To increase the capacity of ZIBs, ZnV₂O₄ containing the Zn element has recently been considered. However, the ZnV₂O₄ cathode developed so far shows various problems of low electronic conductivity and low surface area limiting reactionsites. Here, we suggest ZnV₂O₄ nanoparticles embedded in carbon nanofibers (ZVO@CNFs) as a promising cathode material for ZIBs. The ZVO@CNFs were synthesized using the electrospinning process and heat treatments, including stabilization and carbonization. The fabricated ZVO@CNFs were investigated by SEM, TEM, XRD and XPS to confirm how can the ZVO nanoparticles form inside. In addition, Raman analysis was conducted to know the composition of ZVO@CNFs and crystal lattice information and EA analysis was carried out to obtain wt% of ZVO in the CNFs. The ZIB cell with the ZVO@CNFs was evaluated for its feasibility. Charge and discharge tests and rate tests were conducted and CV(Cyclic Voltammetry) test was conducted to determine the voltage window, reversibility, and impurities in the system where the redox reaction occurs.