Modification And Electrochemical Performance Of MXene-Based Lithium Metal Anode

Thanks to its lowest electrochemical potential and high theoretical specific capacity,lithium metal has been broadly researched as the potent candidate for anode material of high energy density battery.However,several problems of lithium metal anode(LMA)still exist,such as high reactivity,growth of lithium dendrites,unstable interface,large volume change etc.All of these above problems threaten cycling stability and will lead to the failure of LMA.Therefore,building a safe and reliable LMA plays a positive role to a high energy density battery system.Thus,we achieved flexible MXene-based LMA by loading nucleation agents to obtain lithiophilic substrate and construct stable SEI layer.Moreover,we also studied mechanism and electrochemical performance of MXene-based LMA.The main research contents are as follows:(1)Ultrafine and robust Au nanoparticles was deposited on MXene film by ion-sputtering to fabricate flexible Au-MXene substrate.Au nanoparticles,acting as nucleating agents,can naturally alloy with lithium metal to lower nucleation overpotential and finally induce uniform lithium deposition.In addition,the flexible MXene substrate has excellent conductivity and mechanical properties,which can alleviate volume changes.In this paper,the flexible and selfsupporting composite Li-Au-MXene anode we prepared was is applied to full cell with LiFePO4 as the cathode,which shows excellent cycling performance with high-capacity retention ratio at 97.74%after 200 cycles.(2)Dense,lithiophilic indium nucleating seeds were distributed on the MXene substrate using a green,controllable and low-cost electrodeposition method,and finally obtained the flexible In-MXene substrate.The indium nucleation agents on MXene substrate exhibit low nucleation overpotential,which can induce uniform and dense lithium deposition,and finally achieve flexible dendrites-free Li-In-MXene anode.The Li-In-MXene anode was matched with the 5 V-class LNMO cathode to achieve full battery showing good cycling performance and rate ability even in commercial carbonate electrolyte.(3)The stable MXene-based lithium metal anode with stable F-riched SEI interface was designed by introducing a new nonflammable fluorinated carbonated electrolyte system.The flexible MXene host can buffer volume change and lower local current density.The nonflammable fluorinated electrolyte can not only effectively address safety issues,but also generate stable SEI to guide uniform lithium deposition and inhabit the growth of lithium dendrites.Therefore,Li-MXene anode in all-fluorinated nonflammable electrolyte exhibits significantly enhanced reversibility with high average CE at 94.5%after 200 cycles at 1.0 mA cm-2,compared with Li-Cu anode and Li-MXene anode in baseline electrolyte.