Seung Wook Eom

Studies on Suppression of Hydrogen Evolution Reaction for Zinc/Air Fuel Cell

We studied the electrochemical behavior of a zinc oxide anode in the presence of succinic acid as an organic additive. This additive was added to the electrolyte, which is 8.5 M KOH solution containing 25g of ZnO and 3000 ppm of polyethylene glycol in 1 liter of water. The modified electrolyte was newly attempted to improve the main problems namely the hydrogen overpotential and dendrite formation during cycling in Zn/Air energy system. The results obtained in the presence of succinic acid were compared with the behavior of the electrolyte 8.5 M KOH in the absence of the additive. It has been concluded that the hydrogen overpotential is raised enormously, shifting to the more negative potential side as -4.19 V vs. Hg/HgO while zinc oxide electrode was at -1.399 V. Similarly, we found that dendrite formation on the surface of zinc oxide anode is reduced to some extent by scanning electron micrographs.

Preparation and electrochemical evaluation of La1- xSrxMnO3 cathode material for zinc air secondary batteries application

We prepared nano-sized La1-xSrxMnO3 (x=0.2~0.5) cathode catalyst for the zinc air secondary batteries by citrate method and measured cathode’s electrochemical characteristics according to content of strontium compose the cathode catalyst. We heat treated the prepared precursor at various calcination temperature (500~900), and examined the optimum calcinations temperature by XRD analysis and electrochemical evaluation. We examined the ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) performance of the prepared La1-xSrxMnO3 catalyst powder. La0.7Sr0.3MnO3 and La0.8Sr0.2MnO3 catalyst has shown the best performance in the ORR. But in the OER, La0.7Sr0.3MnO3 catalyst has shown better performance. When we consider ORR and OER performance simultaneously, La0.7Sr0.3MnO3 catalyst has shown the best performance because of its lowest voltage difference between charge and discharge.