A major challenge of miniaturized electronics is to improve the energy density of electrostatic capacitors by developing high-performance, ecological and economical materials. In a study published in the journal Advanced Functional Materials, CNRS chemists present a new class of dielectric materials based on colloids complexed with a natural polymer and prepared at low temperature and in water.
At a time of miniaturization where electrical systems are integrated into ever smaller objects, a major challenge is to improve the energy density of dielectric capacitors*, essential components of these circuits. Polymer nanocomposites have great potential as high-energy-density capacitors, but most of them are prepared by high-temperature melt mixing or solution processing in hazardous organic solvents, which poses environmental problems. The development of new high-performance dielectric materials* therefore remains a real economic and ecological challenge.
More concretely, these materials are complexes between chitosan which behaves like a polyeletrolyte in water and a colloid, polyvinylidene fluoride latex. For equal charge mixing, the maximum electric fields that these complex films can sustain are greatly improved while dielectric losses are significantly reduced, leading to greater capacitive energy storage capacity than conventional capacitors. This highly versatile material concept has been validated with several systems, from polymer latexes to suspensions of inorganic colloids, thus offering a new perspective for the design of environmentally friendly energy materials. Fundamentally, the results provide new insights into the mechanisms that control polarization in colloidal nanocomposites under high electric fields.
* A capacitor is an electrical component essential to many circuits and made up of two conductive plates called “electrodes”, very close to each other, separated by an insulator called “dielectric”. Its performance is characterized by its capacitance, dielectric loss and the electrical charge stored by this charge accumulator under the applied high electrical voltage.
** A dielectric material is a non-conductive material (which does not contain free charges), but which can present at the atomic scale electrostatic dipoles which create a polarization when an external electric field is applied. This is what allows the accumulation of opposite charges on the two plates of a capacitor in an electrical circuit.
Reference :
High-Energy-Density Waterborne Dielectrics from Polyelectrolyte-Colloid Complexes
Junjin Che, Cécile Zakri, Isabelle Ly, Wilfrid Neri, Eric Laurichesse, Jean-Paul Chapel, Philippe Poulin & Jinkai Yuan
https://doi.org/10.1002/adfm.202213804
Contact : Jinkai Yuan, chercheur au Centre de recherche Paul Pascal (CNRS/Université de Bordeaux), jinkai.yuan@crpp.cnrs.fr
Figure: dielectric material prepared in water and composed of a natural cationic polymer, chitosan, complexed with negatively charged colloids or polymer latexes.
You can also find this article online on the INC website.