Nanocomposite poly(vynilidene fluoride)/nanocrystalline cellulose porous membranes as separators for lithium-ion batteries

International audienceNanocomposite materials were obtained from poly(vinylidene fluoride) (PVdF) as matrix polymer and a stable DMF suspension of nanocrystalline cellulose (NCC) as the reinforcing phase. Porous and dense nanocomposite membranes were prepared by non-solvent induced phase separation (NIPS) and film casting methods, respectively. The resulting films were characterized regarding their structuration, i.e., the content of crystalline phases, as well as their transport and thermo-mechanical properties. The presence of the fillers led to a mechanical reinforcement, associated with a lower strain at break. For dense nanocomposites, a thermal stabilization at temperatures higher than the melting temperature was highlighted and ascribed to the formation of a rigid cellulosic network within the matrix. The superior electrochemical performances together with the observed reinforcement effect render these porous nanocomposites membranes as interesting candidates for the replacement of commercial polyolefin-based microporous separators in lithium-ion batteries

Improving the quality of micro-nanostructures replication on a polymer surface to confer new functional properties

International audienc

Nanocrystalline cellulose reinforced poly(ethylene oxide) electrolytes for lithium-metal batteries with excellent cycling stability

International audiencePolyethylene oxide (PEO) based polymer electrolytes are still the state of the art for commercial lithium-metal batteries (LMBs) despite their remaining challenges such as the limited ionic conductivity at ambient temperature. Accordingly, the realization of thin electrolyte membranes and, thus, higher conductance is even more important, but this requires a sufficiently high mechanical strength. Herein, the incorporation of nanocrystalline cellulose into PEO-based electrolyte membranes is investigated with a specific focus on the electrochemical properties and the compatibility with lithium-metal and LiFePO 4 -based electrodes. The excellent cycling stability of symmetric Li||Li cells, including the complete stripping of lithium from one electrode to the other, and Li||LiFePO 4 cells renders this approach very promising for eventually yielding thin high-performance electrolyte membranes for LMBs

Towards Extrusion of Ionomers to Process Fuel Cell Membranes

While Proton Exchange Membrane Fuel Cell (PEMFC) membranes are currently prepared by film casting, this paper demonstrates the feasibility of extrusion, a solvent-free alternative process. Thanks to water-soluble process-aid plasticizers, duly selected, it was possible to extrude acidic and alkaline polysulfone ionomers. Additionally, the feasibility to extrude composites was demonstrated. The impact of the plasticizers on the melt viscosity was investigated. Following the extrusion, the plasticizers were fully removed in water. The extrusion was found to impact neither on the ionomer chains, nor on the performances of the membrane. This environmentally friendly process was successfully validated for a variety of high performance ionomers