Modeling of Two-Dimensional Anode Materials (Ge–Si)O2 for Alkali Metal (Li,Na,K, Rb,Cs) Incorporation Batteries for Clean Energy-Saving

Alkali metals of rubidium and cesium are studied through doping in lithium, sodium or potassium ion batteries. A vast study on H-capture by LiRb (Ge–Si)O2, LiCs(Ge–Si)O2, NaRb(Ge–Si)O2, NaCs(Ge–Si)O2, KRb(Ge–Si)O2, KCs(Ge–Si)O2, was carried out including using density functional theory (DFT) computations at the Coulomb-attenuating method–Becke, 3-parameter, Lee-Yang-Parr with Dispersion–corrected (CAM–B3LYP–D3/6–311+G (d,p))/6–311+G (d,p) level of theory. The hypothesis of the hydrogen adsorption phenomenon was figured out by density distributions of charge density differences (CDD), total density of states (TDOS) and electron localization function (ELF) for nanoclusters of "LiRb(Ge–Si)O2–2H2, LiCs(Ge–Si)O2–2H2, NaRb(Ge–Si)O2–2H2, NaCs(Ge–Si)O2–2H2, KRb(Ge–Si)O2–2H2, KCs(Ge–Si)O2–2H2. The differences of charge density for these structures are measured as: ΔQLiRb(Ge–Si)O2 = –0.002 , ΔQLiCs(Ge–Si)O2 = –0.005, ΔQNaRb(Ge–Si)O2 = –0.001 , ΔQNaCs(Ge–Si)O2 = –0.004 , ΔQKRb(Ge–Si)O2 = –0.001, ΔQKCs(Ge–Si)O2 = –0.007 coulomb. Therefore, the results have shown that the cluster of KCs(Ge–Si)O2, LiCs(Ge–Si)O2 and NaCs(Ge–Si)O2 may have the most tensity for electron accepting owing to hydrogen grabbing. A small portion of Rb or Cs entered the Ge–Si layer to replace the Li, Na or K sites might improve the structural stability of the electrode material at high multiplicity, thereby improving the capacity retention rate. Among these, potassium-ion batteries seem to show the most promise in terms of Rb or Cs doping. The general tendency that the gap values of these ionic semiconductors are increased as their ionicities are increased and alkali metal incorporation into (Ge–Si)O2 heterocluster will be hopeful to broaden its band-gap.