The main objective of the project is to widen the possibilities of creating new chemical structures from oligosaccharide blocks. Polysaccharides are very abundant natural polymers, inexpensive, renewable, stable, and modifiable hydrophilic biopolymers that have biological and chemical properties such as non-toxicity, biocompatibility, biodegradability, polyfunctionality, high chemical reactivity, chirality, chelation and adsorption capacities. However, natural polysaccharides often exhibit solubility, processability, and feasibility issues with variable extends depending on the type of polysaccharide, causing difficulty in employing them in a wide variety of applications. In this project, we will prepare and study the properties of a new class of multiblock copolymers based exclusively on the assembly of oligosaccharides carrying different functionalities and thus varying properties. Structurally defined diazido (AA) and dipropargyl (BB) oligosaccharide monomers will be synthesized from cyclodextrins by selective ring opening followed by terminal modification. Side-chain functionalization will be performed on diazido or dipropargyl blocks, in order to obtain and combine hydrophobic/hydrophilic blocks, and anionic/cationic/neutral blocks especially through the introduction of biosourced side-groups. Complementary diazide and dialkyne oligosaccharide-based monomers containing different side-chain functionalization will be copolymerized by AA + BB copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) mediated step growth polymerization. Post-polymerization modifications will also be performed through N-alkylation of the resulting poly(1,2,3-triazole)s to yield the corresponding poly(1,2,3-triazolium)s. Besides, anion exchange with biosourced salts will be an additional mean to provide highly functional biosourced saccharide-based materials with original structures and properties. After preparation and thorough characterization, we will relate the structure of the obtained multiblock copolymers with their physical and physico-chemical properties in solution and in bulk as well as their mechanical and processing properties. The preparation of most promising polymers will be scaled-up using green routes for monomer synthesis and functionalization to investigate the most relevant applications based on their peculiar properties, i.e. formation of nanoparticles, encapsulation/release properties, stabilizers for cosmetics, stabilizers/dispersants of renewable colloids, e.g. nanocellulose, chitin or starch nanoparticles.

Li-ion batteries are indispensable elements of our daily life, especially through our phones and laptops. To improve the capacities of these batteries, substitute part of the carbon graphite by silicon in the negative electrode is a promising way to improve their performance. The polymer binder is then, one of the essential constituents of this composite electrode. It helps to retain the capacity of the silicon by controlling the volume expansion during charge/discharge cycles. Various macromolecular parameters allow to obtain a stable electrode with good electrochemical performances. If the reference polymer remains carboxymethylcellulose, other polysaccharides have since been tested and showed very attractive binding properties. Unfortunately, these different studies did not lead to a sufficiently precise structure/property relationship to create the ideal polysaccharide for this application. The objective of this project is to modify cellulose, in a very original way in the field of batteries, by simple chemical and enzymatic reactions: oxidation, esterification, amidation with lipophilic chains or cyclodextrins. The idea is to modulate their physico-chemical properties, hydrophilic/hydrophobic character in particular, and thus the interactions with the surface oxides of electrochemically active silicon. The contribution of enzymatic chemistry is relevant here with regard to the usual chemical reactions by being a much more specific, greener synthesis method, but also much less harmful to the macromolecular skeleton. One objective will thus be to determine the structural parameters conferring optimal binding properties to the polysaccharide. This will allow us to synthesize a cellulose based binder, not only bio-sourced by an innovative method but also inducing an excellent preservation of the cohesion of the silicon anode in the Li-ion battery.

The basic research project, DEOSS, aims at developing the use of Solid-State Electrolytes together with Electroactive Organic Materials (EOMs) as electrodes in organic batteries. The DEOSS project is therefore at the crossroads of different issues, namely: i) research for efficient, safe, eco-compatible means for reversibly storing electrical energy, ii) the implementation, for these purposes, of organic electrodes and iii) the use of solid electrolytes. Basically, the implementation of Electroactive Organic Materials (EOMs) in secondary batteries has recently (since the 2000’s) attracted renewed interest. EOMs’ properties differs firmly from the ones of their inorganic counterparts and their use feet well with today’s energy and environmental issues. In fact, EOMS are composed of abundant elements (C, H, O, N), they present usually multi-electrons reactions, multiple cell designs are possible and some physical flexibility of the cells are reported. It has also been recognized that use of EOMs could lower environmental impact of the cells and offer a better recyclability. However, reports on full organic batteries are still scarce in the literature without speaking of their absence on the market. Particularly the use of low molecular weight EOMs presenting the highest specific capacities is still hampered by their solubility issues in common liquid battery electrolytes. On the other hand researches concerning Solid-State Electrolytes for safer secondary batteries rise rapidly. Not to mention that such a technology give the possibility to use lithium as the anode. The originality of the DEOSS project is to promote both researches areas. We will exploit properties of promising low molecular weight EOMs through the use of solid electrolytes. In order to tackle such an ambitious goal we gather French specialists of EOMS and Solid-State Electrolytes: LG2A (Amiens), IMN (Nantes), LRCS (Amiens), IPREM (Pau). Our scientific approach will allow the evaluation of multiple cell configurations using organic electrodes. We will evaluate the use of EOMs together with classical sulfide Solid-Electrolytes with both EOM/Li and EOM/EOM configuration. Simultaneously our efforts will be also devoted to the preparation and assessment of new organic materials like ionic-Covalent Organic Frameworks or lamellar compounds, able to act as solid electrolytes. Then EOM/Li and EOM/EOM cells will be assembled with the best organic ionic conductor materials and evaluated. These strategies will be associated with a systematic interphase study using crossed technics at our disposition through our consortium (SEM, XPS, ToF-SIMS, STEM-EELS). Thus, the insights gained will guide us toward improvement of the first cells. Finally, our working plan should offers us the possibility to assemble an organic all-solid-state Li-battery characterized by an energy density of ~ 50 Wh/kg, before loading optimization.

Li-ion batteries are indispensable elements of our daily life, especially through our phones and laptops. To improve the capacities of these batteries, substitute part of the carbon graphite by silicon in the negative electrode is a promising way to improve their performance. The polymer binder is then, one of the essential constituents of this composite electrode. It helps to retain the capacity of the silicon by controlling the volume expansion during charge/discharge cycles. Various macromolecular parameters allow to obtain a stable electrode with good electrochemical performances. If the reference polymer remains carboxymethylcellulose, other polysaccharides have since been tested and showed very attractive binding properties. Unfortunately, these different studies did not lead to a sufficiently precise structure/property relationship to create the ideal polysaccharide for this application. The objective of this project is to modify cellulose, in a very original way in the field of batteries, by simple chemical and enzymatic reactions: oxidation, esterification, amidation with lipophilic chains or cyclodextrins. The idea is to modulate their physico-chemical properties, hydrophilic/hydrophobic character in particular, and thus the interactions with the surface oxides of electrochemically active silicon. The contribution of enzymatic chemistry is relevant here with regard to the usual chemical reactions by being a much more specific, greener synthesis method, but also much less harmful to the macromolecular skeleton. One objective will thus be to determine the structural parameters conferring optimal binding properties to the polysaccharide. This will allow us to synthesize a cellulose based binder, not only bio-sourced by an innovative method but also inducing an excellent preservation of the cohesion of the silicon anode in the Li-ion battery.

Photo2Batt aims at the emergence of innovative energy-related technologies situated at the frontier research between material sciences and supramolecular chemistry. It is a proposal offering a good balance between fostering new fundamental knowledge and a disruptive concept applied to solar energy. It integrates a number of leading concepts in the fields of electrochemistry and photo-electrochemistry in association with robust expertise in both dye-sensitized solar cells and lithium-ion batteries. At the meeting point between these two, the core of this proposal targets the utilisation of light-induced charge separation in the space charge layer of n and p-semi-conducting insertion materials to onset a quantitative battery photorecharge reaction (1st pillar research) and the tailoring of smart hybrid conversion/storage molecular assembly through the development of very specific donor/acceptor chromophores suited to n and p-type insertion materials (2nd pillar research). These two research pillars will be supported by a more fundamental oriented workpackage aiming at improving community knowledge about the (photo)electrochemical interface between redox active semi-conductor and ionic conductive electrolyte, free of any redox couple. Photo2Batt intends to develop a new box into the research panorama, embracing fundamental research in semi-conductor physics and the tailoring of smart materials. The combination of conversion and storage functionality at a molecular level will offer a robust key to one of the main energetic challenge Human needs urgently to tackle, making use and stabilize technologically the electricity output from intermittent sun power. With its multidisciplinary approach, we strongly believe Photo2Batt gathers a perfect cocktail to cultivate totally new fundamental and technological concepts which will allow France closing the technological and scientific gap in nanoscience and photoelectrochemistry while establishing a new scientific world-lead in renewable energy exploitation.