The Molybdenum Disulfide Interface Layer Adjust The Deposition Behavior And Electrochemical Performance For Lithium Metal Anode

With the increasing demand for energy and the urgent need of new energy storage technologies,the development of energy storage systems with high energy density and long cycle life has received extensive attention.Lithium metal has become a new generation of research hotspot due to its extremely high theoretical specific capacity However,there are serious problems such as dendrite growth on the surface in the practical application process,which limits the application of lithium metal as a negative electrode in the battery system.At present,the sol id electrolyte interface film?SEI?produced by the reaction of the surface with the electrolyte is relatively brittle during the circulation process of lithium metal anode,which cannot effectively inhibit the lithium dendrite problem.This work proposes to use a three-dimensional stainless steel mesh as a current collector,and through the in-situ electrochemical conversion reaction on the surface,a three-dimensional composite array structure with both electron and ion channels is constructed as an artificial SEI film to jointly inhibit the formation and growth of lithium dendrites in this work,the synthetic SEI films were comprehensively characterized by physical and chemical properties,and its electrochemical performance was studied through a series of electrochemical tests to explore its mechanism of action as a metal lithium anode modification.Molybdenum disulfide?MoS₂?nanosheets were loaded on the stainless steel mesh surface by one-step hydrothermal method,and then transformed into Li₂S/Mo structure as artificial SEI film by in-situ electrochemical conversion.The stainless steel mesh with good conductivity has certain mechanical strength and regular network structure,which acts as a three-dimensional fluid collector,is favorable for the fast transmission of electrons and the uniform distribution of surface electric field.It not only can withstand and alleviate the electrode crushing caused by the volume change in the circulation process,but also can fill the lithium metal into the grid space to form a continuous phase,shorten the migration distance between the electrodes,and reduce the ohmic impedance between the electrodes,improve cycle stability.Because of its large specific surface area,the array electrode can provide more electrochemical active centers and large contact area of electrolyte/electrode for ion/electron transport.When the nucleation time and growth rate of lithium dendrites are the same,the vertically arranged nanochannels can effectively regulate the lithium ion?Li⁺?flux.Li₂ S with high ionic conductivity can effectively homogenize ion current and induce lithium to deposit uniformly along the skeleton structure of the substrate.A large number of Mo atoms with uniform distribution have good conductivity,providing electrons for Li⁺ deposition,it allows Li⁺ to be transferred at a minimum over-potential at high current to promote the consistent flow of lithium ions.High-ion conductivity nanosheets layer and stainless steel mesh close together,the two synergistic effect,a good regulation of lithium deposition behavior,from the source to inhibit the growth of lithium dendrite,greatly reduce the lithium deposition potential.MoS₂@SSM can be used as a lithium metal anode under the conditions of 1 m A·cm^-2 and 1 m Ah·cm^-2 for 400 h with a coulomb efficiency of over 96%.At 4.2 V charging voltage and 1C current density,the first cycle discharge capacity of Li Fe PO4 battery is up to 160 m Ah·g^-1,which shows remarkable cycle stability.After 150 cycles,the discharge capacity is still up to 130 m Ah·g^-1.