  Existence of van der Waals gaps renders two-dimensional (2D) materials ideal
passages of lithium for being used as anode materials. However, the requirement
of good conductivity significantly limits the choice of 2D candidates. So far
only graphite is satisfying due to its relatively high conductivity. Recently,
a new polymorph of layered germanium selenide (Gamma-GeSe) was proven to be
semimetal in its bulk phase with a higher conductivity than graphite while its
monolayer behaves semiconducting. In this work, by using first-principles
calculations, we examined the possibility of using this new group-IV
monochalcogenide, Gamma-GeSe, as anode in the Li-ion battery (LIBs). Our
studies revealed that Li atom would form an ionic adsorption with adjacent
selenium atoms at the hollow site and exist in cationic state (lost 0.89 e to
Gamma-GeSe). Results of climbing image-nudged elastic band show the diffusion
barrier of Li is 0.21 eV in the monolayer limit, which can activate a
relatively fast diffusion even at room temperature on the Gamma-GeSe surface.
The calculated theoretical average voltages range from 0.071 to 0.015 V at
different stoichiometry of LixGeSe with minor volume variation, suggesting its
potential application as anode of LIBs. The predicted moderate binding energy,
a low open circuit voltage (comparable to graphite) and a fast motion of Li
suggests that Gamma-GeSe nanosheet can be chemically exfoliated via Li
intercalation and a promising candidate as the anode material for LIBs.
