Recent experimental study shows that the pre-lithiated MoS 2 monolayer exhibits an enhanced electrochemical performance, coulombic efficiency of which is 26% higher than the pristine MoS 2 based anode. The underlying mechanism of such significant enhancement, however, has not yet been addressed. By means of density functional theory (DFT) calculations, we systematically investigated the adsorption and diffusion behavior of lithium (Li) atoms on the MS 2 (M = Mo, W, V) monolayers. on the pre-lithiated MS 2 monolayers, the adsorption energy of extra Li ions are not significantly changed, implying the feasibility of multilayer adsorption. Of importance, the Li diffusion barriers on pre-lithiated MS 2 are negligibly small because of the charge accumulation between the diffusing Li ions and the pre-lithiating Li layer. correspondingly, we report that the pre-lithiation should be a general treatment which can be employed on many transition-metal di-chalcogenides to improve their storage capacities and charge-discharge performance in Li ion batteries. in addition, we propose that the pre-lithiated VS 2 may serve as an outstanding anode material in LIBs.The Lithium-ion battery (LIB) has been regarded as one of the most indispensable and promising devices in the fields of telecommunications, electric automobiles and electric power grids 1,2 . Today, graphite is widely used as the anode material of commercial LIBs owing to its layered structure, good electric conductance and excellent chemical stabilities 3,4 . Nevertheless, the maximum specific capacity of lithium ions of graphite (LiC 6 ) is only 372 mA•h • g −1 . As a result, numerous researches have been devoted to the searches of new anode materials with higher energy densities 1,5-7 . In addition to the specific capacity, columbic efficiency has also been employed to evaluate the performance of electrodes in LIBs. Thus, an ideal anode material, should not only accommodate densely packed Li ions, but also allow for fast Li diffusions to promote the charge-discharge rate 1,8-10 . In the past decade, a number of two-dimensional (2D) materials, including transition-metal oxides, di-chalcogenides (MO 2 and MS 2 ) and BN, have been successfully synthesized [11][12][13] . Their electronics properties and potential applications in devices have also been explored and proposed as electrode material for LIBs 14-20 . Very recently, Yang et al. report that the coulombic efficiency of MoS 2 can be significantly improved by the pre-lithiation treatment, in which the MoS 2 is on direct contact with lithium foils 21 . Despite the improved performance of MoS 2 upon pre-lithiation, the underlying mechanism however, has not yet been addressed. Herein, systematic Density Functional Theory (DFT) calculations have been conducted to explore (i) the chemical insights of the enhanced performance after pre-lithiathion, and (ii) the effect of pre-lithiathion on other MS 2 nanosheets. Our results revealed that the pre-lithiathion allows for multilayer adsorption and fast diffusion of Li ions on ...
