How to Enhance Graphite Anode Material Safety for Li-Ion Batteries
Graphite is an important material for commercial lithium-ion batteries (LIBs) due to its unique properties, such as high electrochemical potential and storage capacity. Nevertheless, the safety of graphite anode materials is still a major concern, and a significant research effort is required to solve this issue. Moreover, the overall performance of graphite electrodes must be enhanced to meet the demand of high energy density and coulombic efficiency for LIBs in electric vehicles and grid scale energy storage.
Several physicochemical approaches to enhance anode materials have been recently proposed. One approach relies on pre-lithiation of graphite-based anode compounds to enhance their reversible electrochemical cycling ability. Such lithiation is achieved by introducing a reversible electrolyte additive. This approach is also applicable to other active materials. However, it requires the installation of relatively large space with a protected atmosphere (either noble gases or at least dry air), which adds another processing step to the cell assembly.
Aside from lithiation, other approaches to enhance anode materials are also possible, such as surface engineering. By modifying the graphite morphology and surface properties, anode materials are prevented from forming diffusion-induced stresses (DISs) during Li-ion insertion/extraction within the active particles. These DISs can eventually lead to mechanical degradation of graphite-based anode materials and bring about their deterioration during battery operation.
Aside from lithiation, a new approach to boost anode materials is to control graphite's crystal and electronic structure to increase Li ion intercalation, storage, and diffusion. This can be done by regulating the Li-GIC intercalation pathway in graphite.
