Carbon nanotube wiring of electrodes for high-rate lithium batteries using an imidazolium-based ionic liquid precursor as dispersant and binder: a case study on iron fluoride nanoparticles

To meet the energy and power demands of lithium-based batteries, numerous nanostructured and -decorated material prototypes have been proposed. In particular for insulating electrodes, a decrease of grain size coupled with wiring by a conductive phase is quite effective in improving the electroactivity. In this work, we report a novel electron-wiring method using single-wall carbon nanotubes in an imidazolium-based ionic liquid precursor, which enables them to be well disentangled and dispersed, even unzipped. As a case study, in situ formed iron fluoride nanoparticles (∼10 nm) are collected into micrometer-sized aggregates after wiring of merely 5 wt % carbon nanotubes in weight. These composite materials act as cathodes and exhibit a remarkable improvement of capacity and rate performances (e.g., 220 mAh/g at 0.1C and 80 mAh/g at 10C) due to the construction of mixed conductive networks. Therein, the ionic liquid remainder also serves as an in situ binder to generate a nanographene-coated fluoride, which can even run well without the addition of extra conductive carbon and binder. This nanotechnological procedure based on an ionic liquid succeeds without applying high temperature and pressure and is a significant step forward in developing high-power lithium batteries.