Polymeric ionic liquid nanoparticles as binder for composite Li-ion electrodes

Abstract

1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide (VEIMTFSI) monomer was polymerized by dispersion polymerization in water in presence of an imidazolium-based ionic liquid crosslinker, leading to crosslinked polymeric ionic liquid nanoparticles. These nanoparticles were used as nanolatex binder to process Li-ion battery electrodes. Graphite electrodes were tested in half-cells vs lithium and showed excellent cycling performance for more than 7 months, although the irreversible capacity remained high in the initial cycles as compared with commercial electrodes. Sub-micrometric particles of ca. 200–300 nm of both carbon coated LiFePO4 (LFP) and Li4Ti5O12 (LTO) were also processed, leading to high coulombic efficiencies, although only the LTO electrodes allowed very stable cycling as well as practical performances.