Graphite Anode for Lithium Ion Battery (LIB)
As a key component for lithium ion battery (LIB) for electric vehicles, graphite is and will remain the main anode material in the medium to long term. The graphite used for LIBs comes either in the form of natural flakes that need to be converted to a spherical state or synthetically produced with a special process. Increasing the energy density of graphite-based anodes is one of the most important targets for improving the performance of LIBs, which are expected to reach significant market penetration in the near future.
Several strategies are currently being pursued to improve the anode performance, including pre-lithiation and modification of the electrode/electrolyte interface. These approaches aim at reducing the first cycle irreversible capacity loss (Cirr) and optimizing cycling behavior.
To this end, researchers have studied the impact of varying the microstructure of graphite anodes for EV applications by introducing nanoparticles into the original structure. For example, a porous silicon@graphite composite has been successfully developed through ball milling to achieve a high capacity of 1178 mA h g-1. Moreover, the addition of Si nanoparticles into the graphite microstructure resulted in an improved Cirr of 86% after 150 cycles.
However, it remains challenging to fully understand the underlying mechanisms that influence the electrochemical intercalation and extraction of lithium ions in graphite anodes during cell operation. In this study, the surface and structure morphology of graphite anodes dismantled from fresh and degraded cells was analyzed by XRD, SEM, and TEM. The evolution of radial, tangential and shear stresses in the active particles, as well as the volume changes that occur during cycling were characterized.
