Young Wan Ju

Mg–air oxygen shuttle batteries using a ZrO2-based oxide ion-conducting electrolyte

A new concept of an oxygen shuttle type battery for Mg-air solid oxide batteries using a Ca-stabilized ZrO2 electrolyte was proposed and studied. The observed open circuit potential and discharge capacity were 1.81 V and 1154 mA h gMg(-1) (52% of the theoretical capacity), respectively.

A rechargeable Si–air solid state oxygen shuttle battery incorporating an oxide ion conductor

Herein, we report a new type of Si–air rechargeable battery incorporating an oxide ion conducting electrolyte, based on the oxygen shuttle concept. A cell designed in this manner and employing Ca stabilized ZrO2 exhibited stable charge–discharge over 20 cycles at 1073 K and achieved a discharge capacity of approximately 600 mA h gSi−1.

Discharge Performance of Solid-State Oxygen Shuttle Metal–Air Battery Using Ca-Stabilized ZrO2 Electrolyte

The effects of metal choice on the electrochemical performance of oxygen-shuttle metal-air batteries with Ca-stabilized ZrO2 (CSZ) as the electrolyte and various metals as the anodes were studied at 1073u2005K. The equilibrium oxygen partial pressure (Pu2009Ou20092) in the anode chamber was governed by the metal used in the anode chamber. A lower-Pu2009Ou20092 environment in the anode decreased the polarization resistance of the anode. The oxidation of oxide ions to oxygen in the anode is drastically enhanced by the n-type conduction generated in the CSZ electrolyte when it is exposed to a reducing atmosphere. A high discharge potential and high capacity can be achieved in an oxygen-shuttle battery with a Li or Mg anode because of the fast anode reaction compared to that of cells with a Zn, Fe, or Sn anode. However, only the mildly reducing metals (Zn, Si, Fe, and Sn) can potentially be used in rechargeable metal-air batteries because the transport number of the CSZ electrolyte must be unity during charge and discharge. Oxygen shuttle rechargeable batteries with Fe, and Sn electrodes are demonstrated.

Improvement in stability of La0.4Ba0.6CoO3 cathode by combination with La0.6Sr0.4Co0.2Fe0.8O3 for intermediate temperature-solid oxide fuel cells

Improvement in long-term stability and cathodic activity of La0.4Ba0.6CoO3 (BLC) was studied by mixing with La0.6Sr0.4Co0.2Fe0.8O3 (LSCF). LSCF exhibits good long-term stability; however, surface activity is not high like Co-based perovskite. On the other hand, the cathodic activity of BLC is high; however, long-term stability was not so good and large degradation at initial period is observed. Combination of the two oxides shows small overpotential as well as improved long-term stability. Effects of BLC/LSCF ratio on stability and overpotential were studied and it was found that BLC–LSCF (7:3) showed the most stable and small cathodic overpotential among the examined compositions. Although the power density was still slightly decreased over 24xa0h at 0.5xa0V terminal voltage, the maximum powder density of the cell using BLC–LSCF composite oxides for cathode shows 2.5 times larger than that of the cell using LSCF cathode and 1.06 times larger than that of BLC. Degradation rate is smaller than 4xa0% from 5 to 24xa0h on this BLC–LSCF cathode at current density as high as 682xa0mA/cm2 after 24xa0h operation.

A dense La(Sr)Fe(Mn)O3−δ nano-film anode for intermediate-temperature solid oxide fuel cells

To achieve high power density in intermediate-temperature solid oxide fuel cells (IT-SOFCs), we introduce a dense La(Sr)Fe(Mn)O3−δ (LSFM) nano-film anode between a Ni–Fe metallic substrate and a LaGaO3-based oxide electrolyte. Although a three-phase boundary (TPB) is believed to be required for anode active sites, the cell with the LSFM mixed-conductor thin-film anode exhibited much improved power density compared with that of the cell with a simple porous Ni–Fe anode. The maximum power density of the cell with the LSFM film was approximately 3.0 W cm−2 at 973 K. The improved power density was primarily attributed to the enhanced anodic activity. Furthermore, we observed that the dense LSFM thin-film anode is effective in increasing the fuel utilization of a Ni–Fe metallic anode supported cell. This suggests that a two-phase boundary (anode and gas phase) at the LaFeO3 perovskite is highly active towards the anodic reaction.

Mixing effects of Cr2O3-PrBaMn2O5 for increased redox cycling properties of Fe powder for a solid-oxide Fe-air rechargeable battery

Large capacity rechargeable batteries are now strongly required for generating electric power from renewable energy, like solar cells or wind power generators. For this purpose, solid oxide Fe–air rechargeable batteries have been studied. In this study, for increasing the stability of the redox cycling properties of Fe powder at 623 K, mixing effects of Cr2O3 and PrBaMn2O5 catalysts were investigated and it was found that Fe powder mixed with 3 wt% Cr2O3–3 wt% PrBaMn2O5 showed excellent stability against redox cycling at 623 K. When Fe powder mixed with Cr2O3–PrBaMn2O5 was used, stable charge and discharge capacity could be achieved over 50 cycles by using the cell consisting of Ni–Fe/La0.9Sr0.1Ga0.8Mg0.2O3/Ba0.6La0.4CoO3. The discharge capacity of the cell achieved was larger than 770 mA h gFe−1 at 623 K. Increased capacity and cycle performance could be assigned to the deep redox degree of Fe powder.