Batteries are an attractive option for gridscale 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.L arge-scale energy storage is poised to play a critical role in enhancing the stability, security, and reliability of tomorrow's electrical power grid, including the support of intermittent renewable resources. 1 Batteries are appealing because of their small footprint and flexible siting; however, conventional battery technologies are unable to meet the demanding low-cost and long-lifespan requirements of this application.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 (Figure 1). Because of density differences and immiscibility, the salt and metal phases stratify into three distinct layers. During discharge, at the negative electrode Mg is oxidized to Mg 2+ (Mg → Mg 2+ + 2e − ), which dissolves into the electrolyte while the electrons are released into the external circuit. Simultaneously, at the positive electrode Mg 2+ ions in the electrolyte are reduced to Mg (Mg 2+ + 2e − → Mg Sb ), which is deposited into the Sb electrode to form a liquid metal alloy (Mg−Sb) with attendant electron consumption from the external circuit (Figure 2 where R is the gas constant, T is temperature in Kelvins, F is the Faraday constant, a Mg(in Sb) is the activity of Mg dissolved in Sb, and a Mg is the activity of pure Mg.Recent work on self-healing Li−Ga electrodes for lithium ion batteries has demonstrated the appeal of liquid components. 2 While solid electrodes are susceptible to mechanical failure by mechanisms such as electrode particle cracking, 3 these are inoperative in liquid electrodes, potentially endowing cells with unprecedented lifespans. The self-segregating nature of liquid electrodes and electrolytes could also facilitate inexpensive manufacturing of a battery so constructed. However, there do not appear to be economical materials options that exist as liquids at or near room temperature.Previous work with elevated-temperature liquid batteries demonstrated impressive current density capabilities (>1000 mA/cm 2 when discharged at 0 V) with a variety of chemistries. 4−7 However, that work generally used prohibitively expensive metalloids (such as Bi and Te) as the positive electrode. The resulting cells exhibited...

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 ͑ORR͒ 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, O͔-based catalyst on carbon powder to 4% ͑wt % Co/C͒, employing the more aromatic 1,2-phenylenediamine ligand, and by using a ligand to Co ratio of 2:1.

PtRu is a promising catalyst for methanol oxidation in direct methanol fuel cells. However, the most active Pt:Ru ratio and oxidation state of the Ru component are still under investigation. PtRu black was obtained from Johnson Matthey, and the as-received catalyst was treated with either hydrogen or oxygen at elevated temperatures to alter the oxidation state. The samples were characterized by cyclic voltammetry (CV), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and X-ray diffraction (XRD) to confirm their redox states and for correlation with their methanol oxidation activity. All of the characterization techniques support successful oxidation and reduction of the PtRu catalyst. The methanol oxidation activity was measured, and the sequence at 25 °C was found to be reduced > as-received > oxidized ≫ strongly oxidized. The effect of the drying regime and the dispersing agent for the catalysts was also investigated, and it was found that samples supported using acetic acid were more active than those supported by Nafion, but were less stable and more susceptible to change in catalyst state from heat gun drying.

A route toward the synthesis of several Pt/Co-based catalysts for the oxygen reduction reaction ͑ORR͒ in proton exchange membrane ͑PEM͒ fuel cells is described here. The composition of these catalysts has been determined by X-ray diffraction studies, while their electrochemical activity was established using slow sweep cyclic voltammetry in 0.5 M H 2 SO 4 at room temperature. We have found that by mixing a Co oxide sol precursor with Pt supported on carbon ͑Pt/C͒, followed by heat-treatment at 700 or 900°C, the active PtCo alloy catalyst is formed. In contrast, when exactly the same procedure is followed but a Co oxide sol-derived Co/N/C catalytic material is employed, Pt 3 Co alloy catalysts, which are somewhat less active toward the ORR, are formed. Catalysts formed by heating at 900°C are more active than those formed at 700°C, and all of our Pt/Co catalysts are more active toward the ORR than pure Pt on carbon.

The feasibility of producing oxygen by direct electrolysis of the molten lunar regolith at 1600 C was investigated and the generation of usable oxygen gas at the anode and concomitant production of iron and silicon at the cathode was successfully achieved from the tightly bound oxide mix. The current efficiency for different melt chemistries, corresponding to different degrees of electrolysis of the regolith, was measured during the course of electrolysis by on steam analysis of oxygen gas and scale-up from thin wire electrodes to plate and disc electrodes was achieved.