Sustained cycling of metallic lithium negative electrodes is possible without dendrite failure in the convection battery due to the ability to effectively lower concentrations within the separator region during charge by flowing electrolyte through the negative electrode first, where lithium ions are consumed, prior to entering the separator. Consumption of lithium ions prior to entering the separator region results in a lowered concentration and reduced electrochemical potential. Additionally, convective flow reduces overall concentration gradients therefore lowering concentration overpotentials. At these lowered concentrations, dendrite formation is not thermodynamically favored as shown through the relationship between concentration, electrochemical potential and Gibbs free energy. This work presents theory, experimental validation, and autopsy (visual) verification of how the pumping of electrolyte between counter-electrodes eliminates dendrite short-circuit through the separator. Experimental validation included establishing a control using lithium particles as the negative electrode. The control consistently failed due to dendrite-based short circuit when operated without the flow of electrolyte. For the same experimental system operated with flow, the battery operated for 10 cycles (limit of study), exhibiting characteristic capacity fade at these rates. Imagery confirmed that dendrite crystals were not forming in the separator when operated during flow and that crystals did form without flow.

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Highly nanoporous carbon with surface areas in excess of 3,000 m 2 /g can be produced via potassium hydroxide (KOH) activation of a high surface area (1,150 m 2 /g) carbon intermediate. These materials have exhibited methane storage capabilities in excess of 20 wt % at ambient temperature with interest toward commercial production. In preparation for commercial production, detailed mass balances are needed to quantify yield and waste streams, understand the propensity to recycle the KOH, and to provide a benchmark for further optimization. Analytical processes used to evaluate produced carbon performance are detailed in addition to a mass balance on the reaction of KOH with carbon and a KOH balance. Carbon balances revealed that increasing activation time and activation temperature produce lower yields of carbon.

Current battery technology relies on thin materials in order to limit the overpotential losses due to diffusion within the cell, which generally leads to increased cost and lower energy densities. This study analyzes the use of sonication as a means to reduce losses associated with diffusion using Electrochemical Impedance Spectroscopy (EIS) for Zinc-Manganese Oxide (Zn-MnO 2 ) cells. Impedance changes in the Warburg diffusion controlled regions are compared for different membrane materials.A growing interest in recent years has been to develop batteries which have higher capacities, higher power density, and shorter charge times. While it is important to study novel chemistries and materials, this paper focuses on using sonic energy to overcome some of the limitations inherent in diffusion-based cells. The optimization of battery technology has led to thin materials as a means to significantly reduce distances within the cell in order to reduce diffusion times, and therefore voltage losses due to diffusion limitations.Batteries rely on diffusion and migration for mass transfer of ions between electrodes. It is hypothesized that sonic energy waves can enhance this ionic mass transfer. Previous studies have shown that flow induced by peristaltic pump has shown to reduce overpotential losses. 1 Zinc-alkaline chemistry is used in this study, due to the chemistry's resilience outside controlled atmospheres such as are required for many battery chemistries.Previously, it has been shown that sonication can enhance mixing of solutions. 2 A growing field has emerged using sonic energy to enhance electrochemical systems called sonochemistry. Within this field, it has been shown that electrochemical reactions in Galvanictype cells experience an increase in mass-transfer limited currents under sonication. 3,4 Sonication can induce several phenomena that result in enhanced ion movement: acoustic streaming, acoustic cavitation (even bubble collapse), and microjet formation (uneven bubble collapse). 3 Acoustic streaming is an effect experienced on the scale of the electrodes that induces flow and is initiated and maintained by sonic waves. 5 Bubble formation occurs when pressure drops due to the sonic waves moving through solution. After the wave has passed, the bubble collapses leading to microjet and/or acoustic cavitation. However, intense cavitation may also cause erosion of electrodes. 6 The research reported in this paper uses electrochemical impedance spectroscopy (EIS) to provide insight into mass transfer mechanisms of a battery subjected to sonication. EIS applies alternating voltage at varying frequencies between electrodes to obtain an impedance related to the mass transfer processes. This impedance is composed of real and imaginary components due to the sinusoidal nature of the applied voltage. Plotting negative imaginary impedance vs. real impedance gives a Nyquist plot, which can be broken down into kinetic controlled regions and mass-transfer controlled regions. Previously, analysis of phase angles for high to ...

Soybean flakes were extracted using supercritical carbon dioxide at 48.3 MPa and 80 °C, which is a higher temperature than previously reported. Several operational parameters were explored to determine their effect on extractions. Flakes, as typically used in this industry, provided the best extraction performance. Particle size distributions were created through grinding. Reducing average particle diameters smaller than 0.069 mm had no appreciable effect on increasing extraction efficiencies. Exploration of flow rate indicated that a residence time of less than 60 s for the supercritical carbon dioxide would be sufficient for complete extractions. A solvent mass to load mass ratio of 10:1 was found to be sufficient for extraction of oils from soybean flakes. Increasing moisture in the soybeans led to decreasing extraction efficiency of oils. Finally, soybean hulls had no effect on extraction efficiency. Thus, the de-hulling procedure can be removed from the extraction process without decreasing extraction efficiency.