Controlling the Crystallographic Orientation of Graphite Electrodes for Fast-Charging Li-Ion Batteries.

Abstract

In this study, we report a new design paradigm for an electrode preparation method that drastically improves the fast-charging capabilities of a graphite (Gt) anode by controlling the crystallographic orientation. The crystallographic orientation of the Gt electrode is achieved under a dynamic magnetic field using commercially available neodymium magnets. When the slurry of the Gt electrode is tape casted using the conventional method with no magnetic field, the crystallographic orientation is dominated with (002) planes along with other random planes. However, once the slurry of the Gt electrode is casted and dried under a magnetic field, the Gt particles tend to orient themselves along the (100), (101), and (110) planes which are all aligned vertically to the current collector. This striking difference allows the oriented Gt electrode to reach 80% state of the charge in only 50 min at 1C charge rate, whereas the randomly distributed Gt electrode reaches 80% state of the charge in 138 min at 1C charge rate using a constant current-constant voltage charging protocol. The outstanding electrochemical performance of the oriented Gt electrodes was characterized by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, electrochemical cycling, and electrochemical impedance spectroscopy techniques.