The pursuit of sustainable energy utilization arouses increasing interest in efficiently producing durable battery materials and catalysts with minimum environmental impact. As green, safe, and cheap eutectic mixtures, deep eutectic solvents (DESs) provide tremendous opportunities and open up attractive perspectives as charge transfer and reaction media for electrochemical energy storage and conversion (EESC). In this review, the fundamental properties of DESs are first summarized. Then, the important roles that DESs play in various EESC technologies including advanced electrolytes for batteries/supercapacitors, media for the preparation of electrode materials and catalysts, and extracting agents for battery recycling are systematically reviewed. A particular focus is placed on the fundamental understanding of structure-composition-property-performance relationships. Finally, the challenges for the controllable design of DESs for EESC applications and future developments are presented. This review is expected to shed light on developing advanced DESs for next-generation EESC systems.

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A new nanocomposite, lignosulfonate–graphene oxide–polyaniline (LS-GO-PANI), was prepared from aniline via an in situ polymerization in the presence of lignosulfonate and graphene oxide. The morphology and structure of the LS-GO-PANI ternary nanocomposite were characterized by FE-SEM, TEM, FTIR, and UV–vis spectroscopy. Furthermore, the adsorption property of Pb­(II) ions onto the nanocomposite was studied. The effects of adsorption time, initial pH value, adsorbent concentration, and initial adsorbate concentration on the adsorption of Pb­(II) ions in aqueous solution were investigated by batch experiments. The LS-GO-PANI ternary nanocomposite showed an adsorption capacity as high as 216.4 mg g–1 for Pb­(II) ions at 30 °C. Moreover, the adsorption kinetic and equilibrium data were described well with the pseudo-second-order and Langmuir isotherm models for the Pb­(II) ions adsorption process. The results showed that the LS-GO-PANI ternary nanocomposite has great potential application in removal of Pb­(II) ions from industrial wastewater.

A hierarchical polyaniline-lignin (PANI-EHL) composite was facilely prepared from aniline and enzymatic hydrolysis lignin in an aqueous solution of ammonia. The morphology, FTIR, UV-vis spectra, thermogravimetric analysis, and wide-angle X-ray diffraction analyses of the composite were systematically investigated. Furthermore, the sorption property of the PANI-EHL composite for silver ions in aqueous solution was studied via a static sorption technique. The result demonstrated that the PANI-EHL composite possessed a strongly reactive sorption characteristic for silver ions. Serrated silver threads with length up to 10 mm were obtained by using the PANI-EHL composite as a low-cost adsorbent. Moreover, the role of EHL and polyaniline in the PANI-EHL composite for silver ions sorption was investigated. The investigation indicated that the EHL unit could play a vital role in the chelation of silver ions, whereas the polyaniline unit played a leading role in redox sorption.

Novel copolymer nanoparticles with inherent self-stability, narrow size distribution, and high electrical conductivity are facilely and productively synthesized by the oxidative precipitation polymerization of 5-sulfonic-2-anisidine and aniline in acidic medium without any external stabilizer. The structures of the copolymer particles are systematically characterized by IR and UV/Vis spectroscopy, X-ray diffraction, laser particle-size analysis, atomic force microscopy, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy. The comonomer ratio, oxidant/monomer ratio, and polymerization temperature and medium can be used to optimize the size and conductivity of the nanoparticles. It is found that the nanoparticles exhibit a minimal size and polydispersity index of around 53 nm and 1.045, respectively. Nanocomposite films of the nanoparticles with diacetyl and ethyl celluloses show good thermostability and a low percolation threshold of 0.08 wt%, at which the films retain 89% of the transparency, 96-98% of the strength, and 10(8) times the conductivity of the matrix film. The synthesis of sulfoanisidine copolymer nanoparticles is thus achieved without the use of external stabilizer, which opens up a simple and general route to the fabrication of nanostructured polymer materials with controllable size, narrow size distribution, intrinsic self-stability, strong dispersibility, high purity, and optimizable electroconductivity.