Emulsion Polymerizations for a Sustainable Preparation of Efficient TEMPO‐based Electrodes

Abstract

Organic polymer-based batteries represent a promising alternative to present-day metal-based systems and a valuable step toward printable and customizable energy storage devices. However, most scientific work is focussed on the development of new redox-active organic materials, while straightforward manufacturing and sustainable materials and production will be a necessary key for the transformation to mass market applications. Here, a new synthetic approach for 2,2,6,6tetramethyl-4-piperinidyl-N-oxyl (TEMPO)-based polymer particles by emulsion polymerization and their electrochemical investigation are reported. The developed emulsion polymerization protocol based on an aqueous reaction medium allowed the sustainable synthesis of a redox-active electrode material, combined with simple variation of the polymer particle size, which enabled the preparation of nanoparticles from 35 to 138 nm. Their application in cell experiments revealed a significant effect of the size of the active-polymer particles on the performance of poly(2,2,6,6-tetramethyl-4-piperinidyl-N-oxyl methacrylate) (PTMA)-based electrodes. In particular rate capabilities were found to be reduced with larger diameters. Nevertheless, all cells based on the different particles revealed the ability to recover from temporary capacity loss due to application of very high charge/discharge rates.

Chemical Upcycling of PET Waste towards Terephthalate Redox Nanoparticles for Energy Storage

“…The hydrodynamic and dried-state diameters of the terephthalate polymer nanoparticles were determined by Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM), resulting in average sizes of 115 nm and 71 nm, respectively (Figure 3a,b). As previously mentioned, redox-active nanoparticles with a diameter below 200 nm have demonstrated enhanced rate capability due to the reduced diffusion pathway to access the redox active moieties of the nanoparticles inner core, suggesting fast redox-kinetics can be obtained for the size range of the crosslinked terephthalate nanoparticles [15,16,18,25]. Based on the initial electrochemical results, mono-methacrylate functionalization of the depolymerization product (i.e., bis(2-hydroxyethyl) terephthalate, BHET) was selected for the further development of redox-active polymer nanoparticles.…”

“…Reversible oxidation and reduction peaks are observed at −1.62 V and −2.26 V vs. Fc/Fc + , respectively, confirming their potential use as an ultra-low potential anode material for all-organic batteries. [15,16,18,25].…”

“…Finally, redox polymers can be designed using a wide range of polymerization methods such as free-radical polymerization, controlled radical polymerization or emulsion polymerization, allowing high tuneability of their macromolecular architecture to suit application requirements. Interestingly, the use of redox polymer nanoparticles has been recently shown to have a beneficial impact on the rate capability of redox polymer electrodes, where higher capacity retention was observed at fast (dis-) charge rate with smaller nanoparticles (i.e., <200 nm) [15][16][17][18][19].…”

N‐Substituted Carbazole Derivate Salts as Stable Organic Electrodes for Anion Insertion

“…[12][13][14] Nitroxide, p-type molecules based on other redox centers like aromatic amines, such as phenothia-zine and phenoxazine, have also gained popularity, [15,16] together with conjugates amines. [17,18] In recent years, several reports on a new p-type functional group, based on carbazole moieties, have also been published in the literature. In 2012, Yao and coworkers studied polyvinyl carbazole (PVK) as a high potential positive material.…”

“…Nitroxide based molecules and polymers are the best leading‐contenders [12–14] . Nitroxide, p ‐type molecules based on other redox centers like aromatic amines, such as phenothiazine and phenoxazine, have also gained popularity, [15,16] together with conjugates amines [17,18] . In recent years, several reports on a new p ‐type functional group, based on carbazole moieties, have also been published in the literature.…”