Scalable Self-Assembly\nof Composite Nanofibers into\nHigh-Energy-Density Li-Ion Battery Electrodes

The application of nanosized active particles in Li-ion\nbatteries\nhas been the subject of intense investigation, yielding mixed results\nin terms of overall benefits. While nanoparticles have shown promise\nin improving rate performance and reducing issues related to cracking,\nthey have also faced criticism due to side reactions, low packing\ndensity, and consequent subpar volumetric battery performance. Interesting\nprocesses such as self-assembly have been proposed to increase packing\ndensity, but these tend to be incompatible with scalable processes\nsuch as roll-to-roll coating, which are essential to manufacture electrodes\nat scale. Addressing these challenges, this research demonstrates\nthe long-range self-assembly of carbon-decorated V<sub>2</sub>O<sub>5</sub> nanofiber cathodes as a model system. These nanorods are\nclosely packed into thick electrode films, exhibiting a high volumetric\ncapacity of 205 mA h cm<sup>–3</sup>at 0.2 C. This surpasses\nthe volumetric capacity of unaligned V<sub>2</sub>O<sub>5</sub> nanofiber\nelectrodes (82 mA h cm<sup>–3</sup>) under the same cycling\nconditions. We also demonstrate that these energy-dense electrodes\nretain an excellent capacity of up to 190.4 mA h cm<sup>–3</sup>(<2% loss) over 500 cycles without needing binders. Finally, we\ndemonstrate that the proposed self-assembly process is compatible\nwith roll-to-roll coating. This work contributes to the development\nof energy-dense coatings for next-generation battery electrodes with\nhigh volumetric energy density.