Improvement of alkali metal ion batteries via interlayer engineering of anodes: from graphite to graphene

Interlayer engineering of graphite anodes in alkali metal ion (M = Li, Na, and K) batteries is carried out based on the first-principles calculations. By increasing the interlayer spacing of graphite, the specific capacity of Li or Na does not increase while that of K increases continuously (from 279 mA h g(-1) at the equilibrium interlayer spacing to 1396 mA h g(-1) at the interlayer spacing of 20.0 angstrom). As the interlayer spacing increases, the electrostatic potential of graphite becomes smoother, and the ability to buffer the electrostatic potential fluctuation becomes poorer in M ions. These two effects jointly lead to minima of the diffusion barrier of M ions on graphite (0.01-0.05 eV), instead of strictly monotonous declines with the increasing interlayer spacing. To perform the interlayer engineering of anode candidates more efficiently, a set of high-throughput programs has been developed and can be easily applied to other systems. Our research has guiding significance for achieving the optimal effect in interlayer engineering experimentally.

Automated summary

Increasing the interlayer spacing of graphite can enhance the specific capacity of K, but not for Li and Na; The increase in interlayer spacing leads to smoother electrostatic potential of graphite, while the ability to buffer electrostatic potential fluctuation becomes poorer; The research findings have guiding significance for experimental interlayer engineering.