1. From the first principles, the geometrical configuration of lithium-intercalated graphite and the voltage platform of lithium-intercalated graphite were studied. Calculations show that when lithium is inserted into the proper six-membered ring center position in graphite, it only causes the overall change of graphite layer spacing, but does not cause changes in the graphite atomic layer, which retains the excellent properties of graphite. This structural model can well simulate the real Structure. We calculated the voltage plateaus of the first-order and second-order lithium-intercalated graphite, which were 0.081V and 0.138V, which were in good agreement with the experimental values of 0.085V and 0.100V.
2. The adsorption behavior of lithium on single-layer graphene was studied by first-principles calculations. First, we discuss the geometric structure of single-layer graphene, and identify the adsorption sites of lithium on single-layer graphene. The calculations show that with the adsorption of lithium on graphene, the corresponding Li-2s state will degenerate on the density of states diagram, which indicates that the charge is transferred from the isolated lithium atom to the graphene, and the electronic energy band of lithium-attached graphene The π* band distortion appears in the figure, which is due to the metallization of semi-metallic graphene due to the adsorption of lithium. At the same time, we found that graphene with different unit cell modes has a certain degree of influence on the adsorption behavior of lithium. , and found that (2×2) is the most suitable mode for graphene to store and release lithium among the three unit cell modes. 3. Using first-principle calculations, the intercalation mechanism of lithium on bilayer graphene was studied, including the effect of lithium intercalation on the structure of bilayer graphene and the effect of isolated carbon atom defects on lithium storage capacity. First, we discuss the bilayer graphene structure. There are two types of interlayer stacking, AB and AA, and most of the AA stacking exists in a metastable state. The calculation results show that AA-stacked bilayer graphene is more suitable for lithium storage from the perspective of system energy and interlayer spacing changes; for AB-stacked bilayer graphene, the system energy and interlayer spacing change drastically after lithium intercalation, which is When lithium intercalates into AB-stacked double-layer graphene to a certain amount, the stacking form of the two graphene sheets changes, and the two sheets will slide along a specific direction and finally transform into the AA stacking form, and it shows that after lithium intercalation The change process from AB stacking structure to AA stacking structure. The real carbon system is defective. In defective double-layer graphene, calculations show that an isolated carbon atom defect can capture 6 lithium, which improves the storage capacity of lithium in double-layer graphene. The defect makes the semiconductor characteristic The bilayer graphene becomes an active metal phase, which increases the electronic conductivity and Li adsorption capacity.