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Probing Quantum Capacitance of Typical Two-Dimensional Lattices Based on the Tight-Binding Model

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journal contribution
posted on 14.01.2022, 22:13 by Wenting Li, Jintao Cui, Maokun Wu, Lijing Wang, Yahui Cheng, Hong Dong, Hui Liu, Feng Lu, Weichao Wang, Wei-Hua Wang
The quantum capacitance (Cq) of two-dimensional (2D) electrode materials is closely connected with the 2D lattice symmetry and the electronic structures. Understanding the correlation between the 2D lattice structures and their Cq, in particular, unveiling the function of ferromagnetic spin polarization on Cq, enables one to design highly efficient capacitive materials. Herein, the electronic structures, the specific Cq, and the effect of the spin polarization in 2D square, triangular, and hexagonal lattices have been explored to access the origin and the modulation of Cq based on the single-orbital tight-binding model at half-filling. Compared with the nonmagnetic states, it is found that the range of the specific Cq with considerable values is evidently extended in spin-polarized states. Moreover, the specific Cq near the zero bias is greatly improved in the graphene-like hexagonal lattice under the spin-polarized state owing to the improved density of states near the Fermi level. Compared with only considering the nearest neighboring hopping interaction t1, the next-nearest neighboring hopping interaction t2 further increases the specific Cq near zero bias, which results from the more localized density of states near the Fermi level. Therefore, the specific Cq of 2D systems could be manipulated through modulating magnetic properties and different electron hopping interactions. These findings would provide a route to design 2D electrode materials with high quantum capacitance.

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