Theoretical prediction of germanium selenium nanosheet as a potential anode material for high-performance alkali-metal based battery

Alkali-metal (AM) ion batteries have been attracting great attention due to the high specific capacity, fast charging rate, and good reversibility. In this work, the adsorption and diffusion of Li, Na, and K atoms on a twodimensional (2D) group-IV monochalcogenide, germanium selenium nanosheet (GeSeNS), have been systematically investigated by first-principles calculations. The considered AM atoms could form strong binding and exist in stable configuration with GeSeNS. A semiconducting to metallic transition induces an excellent electrical conductivity after AM intercalation on GeSeNS, that is essential for an optimal anode material. Our results show that the low energy barriers of AM atoms diffusion along zigzag direction are 0.329 (Li), 0.175 (Na) and 0.132 (K) eV, respectively, which are lower than values of the commercial graphite anode material and corresponding to ultrafast charge/discharge capability. The average voltages are about 1.82, 1.45 and 1.28 V for the LixGeSe, NaxGeSe and KxGeSe systems, respectively. Hence, our results suggest that GeSeNS could be a potential electrode material for application in low-cost AM ion batteries with a high rate capability and high charging voltage, thus encouraging further experimental work.