POLYMER NANOCOMPOSITES BASED ON CARBON DOTS (CDs): INVESTIGATIONS TOWARD ENERGY STORAGE APPLICATIONS

Project leaders

Marinella Striccoli, Mohammed Essaid Achour

Agreement

MAROCCO - CNRST - Centre National pour la Recherche Scientifique et Technique

Call

CNR/CNRST 2016-2017

Department

Chemical sciences and materials technology

Thematic area

Chemical sciences and materials technology

Status of the project

New

Research proposal

Nowadays, the global economy is projected in the continuous research of sustainable and renewable energy sources, and much of scientific activity is focused on drastically increasing the ability to store electrical energy by chemical (batteries) and capacitive devices (electrochemical capacitors or supercapacitors). In particular, the combination of the right electrode materials with a proper electrolyte, and the development of novel materials effectively integrated in microelectronic devices, are crucial issues for successfully improving energy storage performances [M. Beidaghi, Y. Gogotsi, Energ. Environ. Sci. 2014, 7, 867; P. Simon, Y. Gogotsi, Acc. Chem. Res. 2013, 46, 1094]. The present research proposal aims at the development of dielectric nanocomposites, obtained by the incorporation of carbon quantum dots (CDs) in polymers, as active materials in capacitive energy storage devices.
In recent years, we are witnessing great expansion in the use of polymer-based nanocomposites, consisting in heterogeneous mixtures of materials having different chemical and physical properties. These materials present performances often quite different than those of homogeneous materials, with indeed better optical, electrical, magnetic, thermal, and mechanical properties, thus offering extremely promising prospects for various applications. Among the huge selection of possible nanostructures, carbon-based materials are recently attracting gradually increasing attention. In particular, new carbon materials with sizes below 10 nm, such as graphene quantum dots (GQDs) and CDs represent an emerging class of nanostructures. Indeed, thanks to their biocompatibility, low cytotoxicity, chemical stability, easy dispersibility in both aqueous and organic solvents, bright photoluminescence (PL) and electroluminescence emission (ECL) and resistance to photobleaching, GQDs and CDs are exploited in bioapplication areas (i.e. optical imaging, photodynamic sensor, biosensor, drug delivery, photothermal therapy), optoelectronics (LEDs, electroluminescent devices, down-conversion devices, plasmonic optoelectronic devices), solar technology and photovoltaics. [A. L. Rogach et al., Nano Today 2014, 9, 590; Y. Wang and A. Hu, J. Mater. Chem. C 2014, 2, 6921] Moreover, GQDs and CDs are expected to improve the performances of energy storage devices, such as lithium ion batteries and supercapacitors, thank also to their low cost processing [H Zeng et al., AdV. Funct. Mater. 2015, 25, 4929; H. J. Fan et al., Nano Lett. 2015, 15, 565; C. E. Banks et al., Energ. Environ. Sci. 2013, 6, 3665].
In this perspective, the design and fabrication of novel dielectric nanocomposites based on the incorporation of CDs in suitable polymers could be critically important in the development of devices with high energy density and improved capacitance. In addition, the good processability and flexibility of the dielectric polymer/CDs nanocomposites represent a further advantage for their effective application in storage energy devices. The major challenges in the field of dielectric polymer nanocomposites are to increase the energy density by improving dielectric constant with low dielectric loss and simultaneously retaining high dielectric breakdown strength [J. Vatamanu and D. Bedrov, J Phys Chem Lett 2015 6, 3594]. The proposed CDs/polymer nanocomposites are expected to improve the dielectric properties thanks to the presence of the reinforcing nanofillers, without decreasing the inherent breakdown strength of the polymer. For this purpose, different kinds of polymers can be used as host matrix for the CDs: polypropylene [G. Rizvi et al.,Carbon 2014, 71 206], polycarbonate [W. Zoe et al., J. Appl. Polym. Sci. 2015, 132, 42667], polyurethane [Y. Grohens et al., Composites Sci. Tech. 2014, 104, 18], polystyrene and poly(methyl methacrylate) [X. Huang and P. Jiang, Adv. Mater. 2015, 27, 546]. The right choice of the polymer will be conducted taking into account the affinity of the CDs with the host matrix. Optimal dispersibility, optical transparency, lack of nanoparticle aggregation and retention of physico-chemical properties of both phases are important parameters concerning the nanocomposite preparation. Finally, not only the proper choice of the polymer is crucial, but also understanding the role of the interfaces of polymer/polymer and polymer/CDs in enhancing the energy density is a critical issue. The interfaces of different polymer/nanostructures may contribute to enhance energy density of polymer nanocomposites. In this regard, molecular simulations and modeling approaches will be carried out in order to connect the atomic/molecular scale correlations to the macroscopic composite material and finally predict the device performance.

Research goals

The present proposal aims at engineering advanced materials in order to handle some fundamental issues concerning the energy density for capacitive energy devices. Here the objective is the development of nanocomposites, based on carbon dots (CDs) incorporated into a polymeric host, to obtain materials with improved dielectric constant. CNR-IPCF will set up colloidal chemistry routes for the synthesis of amino-capped CDs. After purification, CDs can be dispersed in various media (weakly polar or polar solvents). Different strategies will be tested for the nanocomposite preparation, to promote the effective interface between the various components, overcome critical issues as risk of phase separation, decreased performances after the incorporation etc. and obtain materials that can be easily manipulated for application. The proper choice of the polymeric host will be addressed by both experimental requirement (chemical affinity between the phases, homogeneous dispersion of nanofillers) and theoretical simulation. Besides the optical and morphological characterization, an extensive study of the dielectric properties of the proposed materials will be performed by the Moroccan team to validate the practical application of nanocomposites in energy storage devices.The present research can lead to significant improvement in the field of innovative technologies for energy storage from sustainable and renewable sources, in view of applying the proposed materials to advanced capacitors

Last update: 08/10/2024