Adsorption of K Ions on Single-Layer GeC for Potential Anode of K Ion Batteries

Abstract

Potassium ion batteries (KIBs) are considered as promising alternatives to lithium ion batteries (LIBs), following the rapid increase of demand for portable devices, and the development of electric vehicles and smart grids. Though there has been a promising breakthrough in KIB tech niques, exploring the promising anode materials for KIBs is still a challenge. Rational design with first-principle methods can help to speed up the discovery of potential anodes for KIBs. With density functional calculations, GeC with graphene-like 2D structure (g-GeC) is shown to be a desired anode material for applications in KIBs. The results show that the 2D g-GeC with a high concentration of K ions is thermodynamically stable, due to the strong interaction between C and Ge in GeC layer with the proper interaction between K and GeC. The storage capacity can be about 320 mAh/g, higher than that (279 mAh/g) in graphite. The low energy barrier (0.13 eV) of K ions diffusion on the honeycomb structure with proper voltage profile indicates the fast charge transfer. These theoretical finds are expected to stimulate the future experimental works in KIBs.

Twin graphene as an anode material for potassium‐ion battery: A first principle study

“…Hence, based on the stoichiometry of $$$ {\mathrm{K}}_{16}{\mathrm{C}}_{72} $$$, we anticipate a maximum theoretical capacity of $$$ 495.84\ \mathrm{mAh}/\mathrm{g} $$$. Notably, the maximum theoretical capacity of twin graphene for potassium ion is 495.84 mAh/g, surpassing other well‐known anode materials for KIBs such as graphite $$$ \left(273\ \mathrm{mAh}/\mathrm{g}\right), $$$ 60 graphitic carbon nanocage $$$ \left(175\ \mathrm{mAh}/\mathrm{g}\right), $$$ 61 nitrogen‐doped carbon nanofibers $$$ \left(248\ \mathrm{mAh}/\mathrm{g}\right), $$$ 62 nitrogen‐doped graphene $$$ \left(350\ \mathrm{mAh}/\mathrm{g}\right), $$$ 63 graphene‐like 2D structure g‐GeC $$$ \left(320\ \mathrm{mAh}/\mathrm{g}\right), $$$ 64 N‐ and O‐rich carbon nanofiber $$$ \left(170\ \mathrm{mAh}/\mathrm{g}\right), $$$ 53 3D carbon nanofiber (CNF) $$$ \left(270\ \mathrm{mAh}/\mathrm{g}\right) $$$ 1 and apart from the carbon material, others material like …”

Germanium‐based monoelemental and binary two‐dimensional materials: Theoretical and experimental investigations and promising applications

“…Theoretical (C) and experimental (D) capacity of various Ge‐based 2D materials for alkali metal ions storage. Data in (C) were collected from References 157,474–481 Data in (D) were collected from References 223,482–492…”

“…The density functional calculations carried out by Ahuja 475 and Fan 476 revealed that g‐GeC possesses the high stability of graphene as well as the strong interaction between alkali metals and germanene. The single‐layer g‐GeC could be lithiated/sodiated/potassiated on both sides, yielding Li 2 GeC, Na 2 GeC, and KGeC with storage capacities of 633, 633, and 316.7 mAh g −1 , respectively.…”

“…To date, experimental works concerning Ge-based 2D materials as anodes for Naor Li-ion batteries have also been widely reported, and the experimental capacity seems to be higher than the theoretical prediction (Figure 22D). 157,223,[474][475][476][477][478][479][480][481][482][483][484][485][486][487][488][489][490][491][492] This indicates that the electrochemical energy storage of Ge-based 2D materials may involve complex mechanisms.…”