When two fluids of different composition are mixed, mixing energy is released. This holds true for both liquids and gases, though in case of gas, no technology is yet available to harvest this energy source. Mixing the CO 2 in combustion gases with air represents a source of energy with a total annual worldwide capacity of 1570 TWh. To harvest the mixing energy from CO 2 containing gas emissions, we use pairs of porous electrodes, one selective for anions and the other selective to cations. We demonstrate that, when an aqueous electrolyte, flushed with either CO 2 or air, alternately flow between these selective porous electrodes, electrical energy is gained. The efficiency of this process reached 24% for deionized water as aqueous electrolyte

Silicon is a promising candidate to substitute or complement graphite as anode material in Li-ion batteries due, mainly, to its high energy density. However, the lithiation/delithiation processes of silicon particles are inherently related to drastic volume changes which, within a battery's physically constrained case, can induce significant deformation of the fundamental components of the battery that can eventually cause it to fail. In this work, we use non-destructive time-lapse X-ray imaging techniques to study the coupled electrochemomechanical phenomena in Li-ion batteries. We present X-ray computed tomography data acquired at different times during the first lithiation of custom-built silicon-lithium battery cells. Microstructural volume changes have been quantified using full 3D strain field measurements from digital volume correlation analysis. Furthermore, the extent of lithiation of silicon particles has been quantified in 3D from the grey-scale of the tomography images. Correlation of the volume expansion and grey-scale changes over the silicon-based electrode volume indicates that the process of lithiation is kinetically affected by the reaction at the Si/Li x Si interface.

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The growth of electrodeposited lithium microstructures on metallic lithium electrodes has prevented their use in rechargeable lithium batteries due to early performance degradation and safety implications. Understanding the evolution of lithium microstructures during battery operation is crucial for the development of an effective and safe rechargeable lithium-metal battery. This study employs both synchrotron and laboratory X-ray computed tomography to investigate the morphological evolution of the surface of metallic lithium electrodes during a single cell discharge and over numerous cycles, respectively. The formation of surface pits and the growth of mossy lithium deposits through the separator layer are characterised in threedimensions. This has provided insight into the microstructural evolution of lithium--metal electrodes during rechargeable battery operation, and further understanding of the importance of separator architecture in mitigating lithium dendrite growth.

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Highlights• Self-produced H2 from electrodialytic treatment of environmental matrices collected • Collected H2 average purity (% mol/mol) of ≈ 98%• A fuel cell used to produce electricity from the self-produced H2 (~1 V)• Experimental self-generated energy promotes savings on electroremediation (≈ 7%) AbstractElectrodialytic technologies are clean-up processes based on the application of a low-level electrical current to produce electrolysis reactions and the consequent electrochemically-induced transport of contaminants. These treatments inherently produce electrolytic hydrogen, an energy carrier, at the cathode compartment, in addition to other cathode reactions. However, exploring this by-product for self-energy generation in electroremediation has never been researched. In this work we present the study of hydrogen production during the electrodialytic treatment of three different environmental matrices (briny water, effluent and mine tailings), at two current intensities (50 and 100 mA). In all cases, hydrogen gas was produced with purities between 73% to 98%, decreasing the electrical costs of the electrodialytic treatment up to ≈ 7%. A protonexchange membrane fuel cell was used to evaluate the possibility to generate electrical energy from the hydrogen production at the cathode, showing a stable output (~1 V) and demonstrating the proof of concept of the process.