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The trend of research towards more sustainable materials is pushing the application of biopolymers in a variety of unexplored fields. In this regard, hydrogels are attracting significant attention as electrolytes for flexible electrochemical devices thanks to their combination of ionic conductivity and mechanical properties. In this context, we present the use of cellulose-based hydrogels as aqueous electrolytes for electrochemical devices. These materials were obtained by crosslinking of hydroxyethyl cellulose (HEC) with divinyl sulfone (DVS) in the presence of carboxymethyl cellulose (CMC), creating a semi-IPN structure. The reaction was confirmed by NMR and FTIR. The small-amplitude oscillatory shear (SAOS) technique revealed that the rheological properties could be conveniently varied by simply changing the gel composition. Additionally, the hydrogels presented high ionic conductivity in the range of mS cm&minus, 1. The ease of synthesis and processing of the hydrogels allowed the assembly of an all-in-one electrochromic device (ECD) with high transmittance variation, improved switching time and good color efficiency. On the other hand, the swelling ability of the hydrogels permits the tuning of the electrolyte to improve the performance of a printed Zinc/MnO2 primary battery. The results prove the potential of cellulose-based hydrogels as electrolytes for more sustainable electrochemical devices.

Redox polymers with high energy storage capacity are searched in order to diminish the weight to the actual batteries. Poly(anthraquinonyl sulfide) PAQS is a popular redox polymer which has shown a high performance cathode for lithium, sodium and magnesium batteries. Although PAQS cathodes show high cycling stability it has a relatively low theoretical specific capacity of 225 mAh/g. In this paper we show the synthesis and characterization of new poly(anthraquinonyl sulfides) PAQxS in an attempt to improve the specific capacity of PAQS. Thus, a series of PAQxS polymers with different polysulfide segment lengths (x between 2 and 9 sulfur atoms) have been synthesized in high yields by reacting in situ formed sodium polysulfides with 1,5-dicholoroanthraquinone. The poly(anthraquinonyl sulfides) powders were characterized by ATR-FTIR, solid state 13C NMR for the organic part and Raman spectroscopy for the chalcogenide part. This characterization confirmed the chemical structure of the PAQxS based on an anthra...

Lithium-sulfur batteries are among the most promising next-generation battery systems due to the high capacity of sulfur as cathodic material. Beyond its interesting intrinsic properties, sulfur possesses a very low conductivity and complex electrochemistry, which involves the high solubility of the lithium sulfides in the electrolyte. These two characteristics are at the core of a series of limitations of its performance as active cathode material, which leads to batteries with low cyclability. Recently, inverse vulcanized sulfur was shown to retain capacity far better than elemental sulfur, leading to batteries with excellent cyclability. Nevertheless, the diene co-monomers used so far in the inverse vulcanization process are man-made molecules. Herein, a tentative work on exploring inverse vulcanization using two naturally available monomers, diallyl sulfide and myrcene, is presented. The inverse vulcanization of sulfur was successfully completed, and the resulting polymers were characterized by FTIR, NMR spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Afterwards these polymers were tested as cathodic materials in lithium-sulfur cells. The sulfur-natural dienes materials exhibited high capacity at different C rates and high lifetime over 200 cycles with very high capacity retention at a moderate C rate of C/5. Altogether, these materials made from inexpensive and abundant chemicals are an excellent option as sustainable materials for electrochemical energy storage.

Lithium-Sulfur (Li-S) battery technology is one of the promising candidates for next generation energy storage systems. Many studies have focused on the cathode materials to improve the cell performance. In this work we present a series of poly (S-DVB) copolymers synthesised by inverse vulcanization of sulfur with divinylbenzene (DVB). The poly (S-DVB) cathode shows excellent cycling performances at C/2 and C/4 current rates, respectively. It was demonstrated poly (S-DVB) copolymer containing 20% DVB did not influence the electrochemical performance of the sulfur material, compared to elemental sulfur as high specific capacities over ∼700 mAh g −1 at 500 cycles were achieved at C/4 current rate, comparable to conventional carbon-based S cathodes. However, the use of copolymer network is assumed to act firstly as sulfur reservoir and secondly as mechanical stabilizer, enhancing significantly the cycling lifetime. The Li-poly (S-DVB) cell demonstrated an extremely low degradation rate of 0.04% per cycle achieving over 1600 cycles at C/2 current rate.

Sulfur-containing polymers and poly(ionic liquid)s are emerging macromolecules with unique properties and applications. This article shows the first integration of these two polymer families, leading to materials with a unique combination of properties. The synthetic strategy toward sulfur-containing poly(ionic liquid)s involves first the copolymerization of elemental sulfur with 4-vinylbenzyl chloride and subsequent quaternization of the alkyl chloride group using N-methyl imidazole. The synthetic pathway is completed by the anion exchange reaction of the poly(sulfur-co-4-vinylbenzyl imidazolium chloride) by a sulphonamide anion. The obtained polymers are fully characterized by NMR, FTIR, SEC, DSC, and TGA. The sulfur poly(ionic liquid)s combine some properties related to its poly(ionic liquid) nature, such as anion-dependent solubility (water vs organic solvents) and high ionic conductivity as well as properties related to its sulfur content, such as redox activity.

Lithium-sulfur (Li-S) batteries are the most promising candidates for succeeding lithium ion batteries. However, they present some challenges which should be faced to increase its commercial possibilities as detrimental mechanisms during operation (e.g. shuttle effect, low capacity retention, anode corrosion, and so on) and sulfur cathode processing limitations (e.g. poor mechanical stability of S cathodes, defects, low S loading, and so on). Atomic layer deposition (ALD) with alumina (Al2O3) has been extensively applied to sulfur cathode surfaces to improve the electrochemical behavior of Li-S technology as it minimizes discharge product dissolution and hence, it reduces detrimental mechanisms during operation. However, the improvement of sulfur cathode processing still remains unsolved even high-cost approaches have been proposed in the state of the art which unfortunately are not viable for realistic applications. In the present work, for first time, ALD in a fluidized bed reactor (FBR) is carried out to coat sulfur-carbon (S/C) composite particles with Al2O3 before electrode manufacturing. The present approach provides a precise control of S/C composite agglomeration, which improves sulfur cathode processing while maintaining the well known satisfactory operational mechanisms related to Al2O3 coating. We reported on the economic FBR-ALD technique in a promising strategy for high specific energy density Li-S battery with an increased sulfur loading being, double of that obtained for a standard sulfur cathode (3.6 vs. 1.8 mgsulfur cm−2).