Aislinn H. C. Sirk

Magnesium−Antimony Liquid Metal Battery for Stationary Energy Storage

Batteries are an attractive option for grid-scale energy storage applications because of their small footprint and flexible siting. A high-temperature (700 °C) magnesium-antimony (Mg||Sb) liquid metal battery comprising a negative electrode of Mg, a molten salt electrolyte (MgCl(2)-KCl-NaCl), and a positive electrode of Sb is proposed and characterized. Because of the immiscibility of the contiguous salt and metal phases, they stratify by density into three distinct layers. Cells were cycled at rates ranging from 50 to 200 mA/cm(2) and demonstrated up to 69% DC-DC energy efficiency. The self-segregating nature of the battery components and the use of low-cost materials results in a promising technology for stationary energy storage applications.

Oxygen Reduction by Sol Derived [Co, N, C, O]-Based Catalysts for Use in Proton Exchange Membrane Fuel Cells

Two Co oxide sol-derived catalysts, one based on ethylenediamine and one on 1,2-phenylenediamine, were synthesized and examined for their oxygen reduction reaction (ORR) behavior in 0.5 M H 2 SO 4 . Supporting the catalyst on carbon powder significantly improved the catalyst performance, while heat-treatment of the carbon-supported catalysts at 650-900°C for 2 h under nitrogen dramatically improved its activity and selectivity. The ORR activity was further improved by increasing the concentration of the [Co, N, C, O]-based catalyst on carbon powder to 4% (wt % Co/C), employing the more aromatic 1,2-phenylenediamine ligand, and by using a ligand to Co ratio of 2:1.

Oxygen Reduction by Sol-Derived Pt ∕ Co -Based Alloys for PEM Fuel Cells

“© The Electrochemical Society, Inc. 2005. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in Journal of Electrochemistry, 2005, Vol. 152(10).”

Direct Electrolysis of Molten Lunar Regolith for the Production of Oxygen and Metals on the Moon

The feasibility of producing oxygen by direct electrolysis of molten lunar regolith at 1600 oC was investigated. Oxygen gas at the anode was generated concomitantly with production of iron and silicon at the cathode from the tightly bound oxide mix. Current efficiencies for oxygen evolution from different melt compositions were determined during the course of electrolysis by on-stream analysis of oxygen gas. Scale-up from thin wire (ca. 0.3 cm 2 ) electrodes to plate and disc electrodes (ca. 10 cm 2 ) was achieved.

Effect of Preparation Conditions of Sol–Gel-Derived Co–N–C-Based Catalysts on ORR Activity in Acidic Solutions

Using a Co oxide ethanol-based sol as a precursor solution, nitrogen (N)- and carbon (C)-containing ligands [1,2 phenylene diamine (phen) and ethylene diamine (en)] were added to produce an oxygen reduction reaction (ORR) catalyst precursor. After adsorption on carbon powder, heat-treatment in an inert atmosphere at 500-900°C, and the addition of Nafion as a binder, the powdered mixture was coated on a glassy carbon electrode and evaluated for its ORR activity in 0.5 M H 2 SO 4 . The catalyst-carbon powder ratio, heat-treatment temperature, ligand type, and ligand:Co ratio were optimized, and the effect of increased catalyst layer thickness, particle size, and C support was also determined. It was concluded that a phen-based catalyst with a metal to ligand ratio of 1:2, a heat-treatment at 900°C, and a concentration of 4 wt % Co was the most active, selective, and stable ORR catalyst material of the materials developed in the present work. X-ray photoelectron spectroscopy and X-ray diffraction analysis showed the formation of both Co metal and CoN 4 units upon heat-treatment, with the most active catalyst having a 5.3:1 overall N-Co ratio.

Recent Advances in Scale-up Development of Molten Regolith Electrolysis for Oxygen Production in support of a Lunar Base

Previously, we have demonstrated the production of oxygen by electrolysis of molten regolith simulants at temperatures near 1600oC. Using an inert anode and suitable cathode, direct electrolysis (no supporting electrolyte) of the molten silicate is carried out, resulting in the production of molten metallic products at the cathode and oxygen gas at the anode. Initial direct measurements of current efficiency have confirmed that the process offer potential advantages of high oxygen production rates in a smaller footprint facility landed on the moon, with a minimum of consumables brought from Earth. We now report the results of a scale-up effort toward the goal of achieving production rates equivalent to 1 metric ton O2/year, a benchmark established for the support of a lunar base. We previously reported on the electrochemical behavior of the molten electrolyte as dependent on anode material, sweep rate and electrolyte composition in batches of 20-200g and at currents of less than 0.5A. In this paper, we present the results of experiments performed at higher currents (several Amperes) and in larger volumes of regolith simulant (500g) for longer durations of