Within the context of energy shift towards a decrease in the contribution of fossil fuels, the development of new stationary energy storage systems is mandatory. Indeed, the intrinsic intermittent and variable nature of renewable energy sources, such as windmill and photovoltaic, require energy storage. Redox-flow batteries, allowing a decoupling of energy and power, are well adapted to such requirements. As a matter of fact, this technology presents advantages as compared to Li-ion systems presently under development for such applications, in particular for security and recyclability issues. However, the most advanced redox-flow batteries (Vanadium redox-flow batteries, studied since the 80’s) remain expensive with limitations in terms of stability and capacities. The present project aims at developing a full redox-flow battery, based on the flow of redox-mediators based aqueous solutions (pH around 7), using sodium insertion materials immobilized in the battery tanks. The use of these insertion materials will allow an increase in the energy density of these systems, and thus to potentially reduce their size. These materials will be free of toxic or expensive metallic element. To perform these research studies, we created a multidisciplinary team which will allow to break the technological locks related to the development of such innovative and performing systems. The project partners will pursue in particular the study and development of a pilot battery so as to demonstrate the potentialities of this approach for electrochemical energy storage at large scale (coupling with windmill and photovoltaic systems), with storage time of the order of a dozen hours.

Piezoelectric materials represent strategic elements for sensors and energy harvesters with multiple applications, in particular with the emergence of self-powered IoT devices. However, new concepts are required to tackle economic and environmental issues regarding actual lead-based piezoelectric ceramics without compromising final performances. The GENEPI project consequently investigates the spontaneous shear piezoelectricity of poly(L-Lactide) (PLA) as an ideal alternative with many positive benefits. An industrially-relevant and solvent-free extrusion-orientation (MDO) fabrication process is currently under development at IMT Lille Douai to open a straightforward fabrication of PLA-based sensors / harvesters but several scientific challenges need to be overcome to get a full expertise on these technologies and enable faster developments. In this context, the first scientific objective of GENEPI project is to improve the knowledge on shear piezoelectric properties of PLA, in particular on process – structures – properties relationships and the use of (meth)acrylic block copolymers as blending partners to develop high-performance shear piezoelectric films at the laboratory scale. The second scientific objective of the GENEPI project is to convert the peculiar piezoelectricity of PLA into a conventional ferroelectric behavior in order to boost piezoelectric properties of PLA beyond the theoretical limit with electromechanical responses in practical mechanical modes for sensing / actuation / harvesting operations. This challenging task will explore several concepts (high-temperature ferroelectricity of PLA, pseudo-ferroelectricity of nanostructured PLA-based blends and electric field-assisted crystallization of PLA) to reveal long-term research strategies.

Natural fibers reinforced polymers, providing an environmental advantage, are increasingly used in a number of technical applications in which their functionalization (for example flame retardancy) may be required. This is expected to lead in a medium term to an significant amount of end of life functionalized biocomposites waste that have to be valorised. In this context, the objectives of WASABIO is to study and define how to manage the end of life of flame retardant biocomposites in order to ensure their sustainability. Flax/PLA composites obtained from commingled non-woven are considered in the project. Three different flame-retardant treatments will be studied in order to vary the weakness of the interactions (from weak interaction to covalent bonding) between the FR moieties and the flax fibres. Two recycling scenarios will be considered: mechanical recycling (mechanical recycling of plastics refers to the processing of plastics waste into secondary raw material or products without significantly changing the chemical structure of the material) and chemical recycling (chemical recycling, aims to convert plastic waste into chemicals). Innovative technologies including fluid (water and supercritical CO2) assisted-extrusion and catalytic co-pyrolysis will be developed. A life Cycle Analysis will be carried out on both FR treatments and recycling processes in order to evaluate the environmental impact of the different approaches studied in WASABIO. This approach will help to define the best solutions in term of design and recycling of FR biocomposites in order to make them as sustainable as possible. The transdisciplinary approach of WASABIO combining materials science and chemistry should result in fundamental knowledge that could directly benefit to the development of virtuous life cycle of functionalized bio-based materials. The expected impacts of the project are significant and concern at the same time economical, scientific and environmental aspects. The WASABIO project is part of an approach to reduce the environmental footprint of materials both by using bio-sourced materials and by proposing different end-of-life scenarios. The project is focused on two main scientific/technical barriers identified in the field of biocomposites: their functionalization (flame retardancy) and the management of their end-of-life. All the knowledge developed in WASABIO will contribute to the emergence of a sustainable and circular bioeconomy.

Additive manufacturing (or 3D printing) processes has achieved a certain level of industrial maturity. It makes it possible to manufacture parts with complex geometry, personalized in small series, within a reasonable time frame and at a reasonable cost without using specific tooling. However, the additive manufacturing of continuous fiber composite parts remains still limited by the orientation of the fibers in the printing planes. The assembly of 3D printed composite components by laser welding makes it possible, on the other hand, to create functional final 3D parts of large sizes with high mechanical properties (reinforcement fibers in all directions of the space) comparable to those of composite parts which are unfortunately usually limited in shape and geometry, and which are produced by conventional processes requiring expensive tools. Coupling these two processes to produce functionalized and personalized 3D composite parts with very high mechanical performance is unprecedented, and allows the production flexibility and agility with rapid change of product ranges expected by the Industry of the Future. The optimization of this innovative production process implementing a hybridization of technologies will also be based on the development of a simulation tool integrating multi-physics couplings, contributing to the deployment of Industry 4.0. Thus, two types of achievements are expected at the end of the project: a numerical simulation tool of the process, and an optimized functionalized structural part (open source) demonstrator.