Novel nanomaterials and concepts for advanced rechargeable lithium- ion batteries

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Evaluation of the Physicochemical Properties and Active Response of Piezoelectric Poly(vinylidene fluoride-co-trifluoroethylene) as a Function of Its Microstructure

Publication . Gonçalves, R.; Cardoso, V. F.; Pereira, Nelson; Oliveira, Juliana; Nunes-Pereira, João; Costa, C. M.; Lanceros-Mendez, Senentxu

Poly(vinylidene fluoride-trifluoroethylene), P(VDF-TrFE), microstructures have been produced using different solvents, including green ones, by different techniques, such as solvent casting, screen-printing, replica molding, electrospray, and electrospinning. The obtained microstructures span from simple porous and dense films to spheres, fibers, and patterned three-dimensional architectures, with no significant variation in their physicochemical and electrical properties. The simplicity, low cost, and reproducibility of the processing techniques allied to their versatility to adapt to other materials to produce controlled and tailored microstructures with specific properties demonstrate their potential in a wide range of technological applications, including biomedical, energy storage, sensors and actuators, and filtration.

2018Journal article

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Mesoporous poly(vinylidene fluoride-co-trifluoroethylene) membranes for lithium-ion battery separators

Publication . Costa, C. M.; Kundu, Manab; Dias, J. C.; Nunes-Pereira, João; Botelho, Gabriela; Silva, M. M.; Lanceros-Mendez, Senentxu

Mesoporous separator membranes based on poly(vinylidene fluoride-co-trifluoroethylene), PVDF-TrFE, were prepared through the removal of ZnO nanoparticles from the polymer matrix composite. Different filler concentrations were used, and the evaluation of the morphology, mechanical properties, uptake and ionic conductivity of the membranes were demonstrated that they depend on initial ZnO content in the composite. On the other hand, the vibration peaks characteristics of PVDF-TrFE and the thermal properties are independent on initial filler content. The membrane with the best ionic conductivity, 1.6 mS/cm, is the one prepared after 70 wt.% ZnO removal. The separator membranes were assembled in Li/C-LiFePO4 half-cells exhibiting good rate capability and cycling performance, the best battery performance being obtained for the PVDF-TrFE after 70 wt.% ZnO removal. The good performance of the developed separators was also demonstrated in full battery cells. Thus, a way to tailor membrane mesoporosity is presented and it is shown that the obtained membranes represent suitable separators for lithium-ion battery applications.

2019Journal article

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Surface wettability modification of poly(vinylidene fluoride) and copolymer films and membranes by plasma treatment

Publication . Correia, Daniela M.; Nunes-Pereira, João; Alikin, Denis; Kholkin; Carabineiro, S.A.C.; Rebouta, Luis; Rodrigues, Marco S.; Vaz, F.; Costa, C. M.; Lanceros-Mendez, Senentxu

This manuscript reports on the modification of the surface wettability of poly (vinylidene fluoride) (PVDF) and PVDF copolymer films and membranes by plasma treatments at different conditions, under oxygen and argon atmospheres. It is shown that a more pronounced decrease of the contact angle after O2 plasma treatments is obtained, with a decrease of ∼20-30° for PVDF and its copolymers films, leading also to superhydrophilic membranes. This effect is related to a defluorination process, followed by the incorporation of oxygen atoms onto the surface of membranes that occurs during the surface modification. The influence of plasma treatments on surface morphology and topography was studied by atomic force microscopy, showing a decrease in the mean surface roughness with the plasma treatments, being more noticeable for Ar treatments. Finally, it is also shown that plasma treatments under Ar and O2 did not induce modifications in the physicochemical and thermal properties of PVDF and PVDF copolymers. The chemical reaction mechanism after plasma treatment is proposed for the different copolymers.

2019Journal article

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Synthetic polymer-based membranes for lithium-ion batteries

Publication . Martins, Pedro; Nunes-Pereira, João; Lanceros-Mendez, Senentxu; Costa, C. M.

Efficient energy storage systems are increasingly needed due to advances in portable electronics and transport vehicles, with lithium-ion batteries standing out among the most suitable energy storage systems for a large variety of applications. In lithium-ion batteries, the porous separator membrane plays a relevant role as it is placed between the electrodes, serves as a charge transfer medium, and affects the cycle behavior. Typically, porous separator membranes are comprised of a synthetic polymeric matrix embedded in the electrolyte solution. The present chapter focus on recent advances in synthetic polymers for porous separation membranes as well as on the techniques for membrane preparation and physicochemical characterization. The main challenges to improve the synthetic polymer performance for battery separator membrane applications are also discussed.

2020Book part

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