Ab Initio Study of Graphite Intercalation Compounds for Dual-carbon Battery Application
DescriptionLithium-ion batteries (LIBs) have been at the center of the portable electronics development since their first commercial production in 1991. However, the rapid technological advances and the demands for efficient, low-cost energy storage solutions in new applications have constantly pushed the rechargeable battery technology to their limits in terms of cost, cycle life, charge/discharge rate, energy density and safety. The need for the development of better rechargeable batteries to overcome these new challenges is compelling.In this regard, dual-carbon batteries (DCBs) has attracted great attention in recent years. In DCBs, the active materials in both the anode and cathode are graphite or other carbonaceous materials. The charge/discharge of DCBs proceeds via reversible intercalation/extraction of the cations and anions in their respective electrode. This new class of battery systems has shown several potential advantages over conventional LIBs like the faster charge/discharge rate due to different ion dynamics and higher working voltage for high-power applications. Moreover, the replacement of transition metal oxides with graphite as the cathode materials also highlights the promises of DCBs as the next-generation economical, safe and environmental-friendly energy storage devices for large-scale applications.The charge and discharge of DCBs relies on the reversible formation of the graphite intercalation compounds (GICs). There have been a long history in the study of GICs on problems like lithium intercalation in LIBs, hydrogen storage, catalysis and superconductivity. However, it was only recently that the GICs involving anion intercalation in DCBs have gained significant interest. Despite the increasing attention, the systematic understanding of these anionic GIC materials is still limited. On the other hand, in DCBs, the electrolyte serves as the cation and anion reservoir for GICs formation and needs to be considered as part of the battery active materials. Different performance parameters like the energy density, the charge/discharge rate and the voltage depend strongly on the properties of the electrolyte and of its interface with the electrode. Taken together, the anions and the electrolyte solvent are expected to play crucial roles in determining the performance of the DCBs. However, many aspects in DCBs including the fundamental properties the anionic GICs, the kinetics and mechanisms of the intercalation process, and the roles of the electrolyte solvent are still not fully understood.In this project, we will carry out systematic ab initio study of the structural, energetic and electronic properties of the anionic GICs in DCB applications. Our study will also reveal the microscopic details of lithium salt solvation and of the liquid structures at the electrolyte-cathode interface. The kinetic and mechanistic details of the intercalation processes will also be investigated using both static and dynamic ab initio techniques. Focus will be placed on the GICs with anions of common lithium salts including LiBF4, LiPF6and LiTFSI due to their high solubility in carbonate-based solvents and promising intercalation behavior for DCB applications. Through these studies, the key roles of the anions and the electrolyte solvents on the performance of the DCBs will be examined closely. Throughout this project, there will be close collaboration with the experimental collaborators who will provide continuous verification, guides and insights into our theoretical studies. The results from this project will aid the development of economical, efficient and durable next-generation rechargeable battery systems. The success of this project will also demonstrate a systematic scheme for future study of GICs in battery applications.
|Effective start/end date||1/09/18 → …|