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

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

Abstract 

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  V 2 O 5   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. 

[전옥성 박사] Dough-type zinc air battery with self-humidifying system

Ok Sung Jeon, Yong Yeol Park, Eun Seo Ko, Se Hun Lee, Dong Pyo Hong, Young Pyo Jeon, Jun Yong Song, Sang Yoon Park*

Abstract

Advances in battery technology have encouraged researchers to develop a suitable source of power. Researchers have recently focused on flexibility and portability to apply versatile fields and devices. While the current most commercial system of the market is based on lithium ion batteries, it has significant limitations to reach to the level of achievement that has never been paralleled due to its mature stages of technology. Furthermore, as known, subsequent battery explosion accidents require the development of next-generation batteries with higher stability. For these reasons, new battery systems of zinc air battery are renewed subjects. It had larger energy density, lower prices and more cost-efficient than post-lithium ion technology. On the other hand, Zn-air batteries still have many problems to solve. One significant barrier is its drying out system. Drying out of electrolyte led to decrease ionic conductivity permanently. While proceeding works has been focused on the electrodes and outward appearance such as flexible type or solid-state batteries to increase performance and application, we focused on solving the problem arising from drying out of electrolyte without external devices or systems. In addition, increasing moldability of zinc-air battery to extend application. Utilizing sodium alginate as electrolyte component, we discovered that gum-type zinc-air battery can be manufactured and show self-humidifying property. It was controlled the composition of electrolyte to optimize the tendencies of water adsorption and drying out to have less impact on performance. It shows new concept of development of zinc-air battery system and possibility of increasing durability.