The Interface Design And Electrochemical Performance Of Highly Reversible Lithium Metal Anode

In recent years,traditional lithium-ion batteries have been unable to achieve our demands for high specific energy battery systems and long cruising range of electric vehicles.Due to the extremely high theoretical specific capacity(3860 mAh g-1),low density(0.534 g cm-3)and the most negative redox potential(-3.04 V vs.SHE)of metallic lithium,so lithium metal batteries(Li-S,Li-O2,etc.)are a powerful choice for the next-generation of high specific energy battery systems.However,the formation of uncontrollable dendrites/dead Li leads to extremely low utilization of active Li during Li plating/stripping.In addition,the unrestricted volume expansion/contraction cause to continuous rupture/reorganization of the solid-state electrolyte interphase(SEI),resulting in continuously undergoes irreversible reactions.Aiming at the key issues of lithium metal anodes,this thesis proposes and researches the construction of lithophilic interfaces and the effect of pre-reconfigured lithium metal surface on the decomposition of lithium salt from the aspects of functionalized lithiophilic current collectors,lithium composite anodes and additives.The main research contents are as follows:1.High reversible Li metal anode by in-situ construction a multifunctional lithiumpinned array.A multifunctional lithium-pinned array with three effects of lithophilicity,zoning and riveting is constructed by in situ electrochemical reaction.In addition,the synergistic effect of the macroscopic three-dimensional framework structure and micronano zoning effect significantly reduces the local current density and improves the problem of volume expansion during lithium plating/stripping.Based on the above advantages,the functionalized electrode can achieve highly stable electrochemical performance for up to 4000 h at 1 mA cm-2-1 mAh cm-2,which significantly improves the reversibility of lithium plating/stripping.2.A lithium metal anode with ultra-high areal capacity(50 mAh cm-2)by gridding lithium plating/stripping.The functionalized grid-based lithium composite anode can be prepared via streespressing a phosphorized copper mesh on lithium foil,which greatly improves the tedious preparation process of the functionalized lithium composite anode.Therefore,the composite anode possesses the properties of enhancing lithium affinity,alleviating volume expansion,promoting local current distribution,and inducing uniform deposition of lithium ions,which are confirmed by in-situ optical dynamic lithium deposition test and COMSOL simulation.Notably,the concept of gridded lithium plating/stripping is innovatively proposed,and combined with the characteristics of multifunctional lithium-pinned array,a highly reversible behavior of lithium plating/stripping for over 1600 h at a high current density of 10 mA cm-2 with a large areal capacity of 50 mAh cm-2 is achieved.3.A superior solid-state electrolyte interphase via in-situ pre-reconfiguring lithium anode surface.A sulfur-modified Li surface can be successfully constructed via in-situ chemical reaction of guanylthiourea(GTU)molecule on Li.The molecular dynamics simulation results show that the decomposition rate of the LiTFSI salt on the sulfur-modified lithium metal surface is faster than that of the bare lithium surface,and the decomposition of the-CF3 group is particularly prominent,resulting in a robust inorganic-rich solid-state electrolyte interphase.Among them,the interphase is mainly reflected in the higher content of inorganic fluorides,sulfides and nitrides,and its properties of rapid lithium ion conductivity to facilitate the uniform deposition of lithium,while the larger Young’s mode can effectively suppress the piercing of SEI film by lithium dendrites.Therefore,ultra-long Li plating/stripping reversible performances of up to 1 and 0.5 years at 3 mA cm-2-3 mAh cm-2 and 10 mA cm-2-10 mAh cm-2 can be achieved,respectively.More notably,the inorganic-rich solid-state electrolyte interphase can effectively resist the erosion of the lithium metal anode by oxygen in the lithium-air battery,greatly improving the stability of lithium metal anode,and then exhibiting superior electrochemical performance.