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Ionic liquids, low temperature molten salts, have various advantages manifesting themselves as durable and environmentally friendly solvents. Their application is expanding into various fields including hydrometallurgy due to their unique properties such as non-volatility, inflammability, low toxicity, good ionic conductivity, and wide electrochemical potential window. This paper reviews previous literatures and our recent results adopting ionic liquids in extraction, synthesis and processing of metals with an emphasis on the electrolysis of active/light, rare earth, and platinum group metals. Because the research and development of ionic liquids in this area are still emerging, various, more fundamental approaches are expected to popularize ionic liquids in the metal manufacturing industry.

Water‐responsive (WR) materials that strongly swell and shrink in response to changes in relative humidity (RH) have shown a great potential to serve as high‐energy actuators for soft robotics and new energy‐harvesting systems. However, the design criteria governing the scalable and high‐efficiency WR actuation remain unclear, and thus inhibit further development of WR materials for practical applications. Nature has provided excellent examples of WR materials that contain stiff nanocrystalline structures that can be crucial to understand the fundamentals of WR behavior. This work reports that regenerated Bombyx (B.) mori silk can be processed to increase β‐sheet crystallinity, which dramatically increases the WR energy density to 1.6 MJ m−3, surpassing that of all known natural muscles, including mammalian muscles and insect muscles. Interestingly, the maximum water sorption decreases from 80.4% to 19.2% as the silk's β‐sheet crystallinity increases from 19.7% to 57.6%, but the silk's WR energy density shows an eightfold increase with higher fractions of β‐sheets. The findings of this study suggest that high crystallinity of silk reduces energy dissipation and translates the chemical potential of water‐induced pressure to external loads more efficiently during the hydration/dehydration processes. Moreover, the availability of B. mori silk opens up possibilities for simple and scalable modification and production of powerful WR actuators.

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Room temperature ionic liquids (RTILs) containing bis­(trifluoromethylsulfonyl)­imide [NTf2]− anion are attractive electrolytes due to their preferable properties such as extremely wide electrochemical stability window and superior ionic conductivity. We study electrochemical behavior of [NTf2]-based RTILs with four types of cations, 1-butyl-1-methylpyrrolidinium [BMPyr]+, 1-butyl-2,3-dimethylimidazolium [BDMIm]+, 1-ethyl-3-methylimidazolium [EMIm]+, and 1-butyl-3-methylpyridinium [BMPy]+ in neat conditions and in the presence of lithium salts. Cyclic voltammetry shows bulk lithium reduction peaks in all RTILs, and surface characterization confirms the presence of Li metal and LiOH on the electrodeposits. The least stable [BMPy] [NTf2] shows a large cathodic peak at a potential more positive than the bulk lithium reduction peak indicating RTIL decomposition, whereas the other RTILs do not have apparent decomposition peaks.

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Bombyx (B.) mori silk’s water-responsive actuation correlates to its high β-sheet crystallinity. In this research, we demonstrated that stiff silica nanoparticles can mimic the role of dispersed β-sheet nanocrystals and...

An electrochemical series of pyrrolidinium-based ionic liquids is established by designing a redox system where only one kind of anion is present in the electrolyte and metal ions are supplied by anodic dissolution.