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Synthesis of Conducting Polymer Intercalated Ammonium Vanadate Nanofiber Composites as a Cathode Material for Aqueous Zinc Ion Batteries

The Korean Electrochemical Society, ICC JEJU, Korea (2022)

Se Hun Lee, Ok Sung Jeon, Young Pyo Jeon, Yong Yeol Park, Sang Yoon Park

The zinc-ion batteries (ZIBs) using aqueous electrolytes are a promising energy storage device. In the field of ZIBs, vanadate-based cathode materials are attracting attention because of their high charge storage capacity by the layered structure and multiple valences, however, in order to have high charge/discharge cycle stability and high-rate capability, obstacles such as low electrical conductivity and trapping of diffusion ions within crystal structure still remain a problem to be solved. Here we report the synthesis of Poly(3,4-ethylenendioxythiophene) (PEDOT) intercalated ammonium vanadate nanofiber (AVNF) composites by oxidative polymerization of 3,4-ethylene dioxythiophene (EDOT) with V2O5 as a host material in intercalation. Morphologies and electrochemical analyses of two different samples AVNF, PEDOT/AVNF (E-AVNF)) were compared. Upon intercalation, the interplanar spacing of AVNF and E-AVNF expand from 7.82Å to 10.27Å respectively. The resulting E-AVNF (1.9ൈ10-2 S/cm) show improved conductivity which compared to the AVNF (5.1ൈ10-3 S/cm). The cation and conducting polymers co-intercalated vanadate nanofiber (E-AVNF) cathode exhibited a reversible capacity of 344 mAh g-1 at a current density of 0.5 A g-1 and 155 mAh g-1 even at an extremely high current density of 20 A g-1, demonstrating excellent rate capability. The E-AVNF cathode also showed high cycle stability, maintaining 92% of its initial specific capacity after 1000 cycles at 20 A g-1. This study can be a steppingstone to take a step closer to the next generation of ZIBs that will replace LIBs.

Keywords: Aqueous zinc-ion battery, Vanadate, Intercalation, Conducting polymer, Nanofiber, Sonochemical method