Written By Dr. Mallika Bohm and Dr. Siva Bohm
Ceylon Graphite (CYL) deposits in Sri Lanka are the highest-grade in situ underground vein graphite on the planet, with more than 90% Cg. Therefore, CYL has exceptionally low operating costs mining Vein Graphite.
The sp2 hybridized graphene layers are linked by weak van der Waals forces of the delocalized electron orbitals. This weak interaction between layers contributes to the easy intercalation of ions into graphite, forming GIC (Graphite Intercalating Compound). Natural graphite particles show flake-like morphology with two different surfaces. The basal planes are generally parallel to the graphene layer and edge planes expose the end face of the graphene layer. Accordingly, the edge planes show a higher intercalation/deintercalation reactivity than the basal planes. This difference results in the anisotropy of graphite, including electronic, mechanical, and other physicochemical properties. The graphite layers are stacked in three different modes: hexagonal, Bernal, and rhombohedral, marked as AA, AB, and ABC-stacking, marked as AA, AB, and ABC-stacking.
The layer-layer distance (Iz) is 3.35 Å. The unit cells are indicated by dark shadows for three structures, where the symbols α, β, and γ represent the interlayer and intralayer hopping integrals.
The first Brillouin zone shows below, where symmetric points are defined as Γ, M, K, A, L and H. Calculations of the Brillouin zone properties of graphite or graphene anodes are helpful for the elucidation of their stability and anisotropic transport properties. The electronic conductivities of graphite depend on their band structures and density of states (DOSs), and will have a close relationship with the rate capability (power performance) and utilization ratio (capacity).
The stacking pattern of graphite layers influences the conductivity and the related electrochemical performance of graphite, the relationship between crystal structure and physical/electrochemical properties of graphite anode has not been paid enough attention. Regardless of the stacking configurations, graphite presents weak van der Waals forces between the graphene layers and allows for an expansion of the interlayer distance, enabling the intercalation of ionic and molecular species. This intercalation usually accompanies by a re-stacking of the graphene layers.
As announced in Nov 2021 explain, why we had exceptionally high discharge capacity compared to average commercial synthetic samples.
Ceylon’s vein graphite anode material far exceeded comparable anodes made with industry-standard commercial synthetic graphite. This is the first time in battery research history that commercial spherodized vein graphite materials were tested in a lithium-ion battery in a full cell.
Results came in at 161 and 165 mAh/g for specific discharge capacity (SDC) for our vein graphite materials, which is beyond what is expected for the best current commercially used synthetic graphite with a specific capacity of 153 mAh/g. These data were produced repeatedly in a certified UK battery testing organization.