Study On The Construction And Air Stability Of The Surface Protective Layer Of Lithium Anode

The lithium metal anode has a very high theoretical specific capacity(3860 m Ah g^-1)and the lowest reduction potential(-3.045 V vs.the standard hydrogen electrode).It has great application prospects in the new generation of high energy density storage and is a lithium battery anode.The final choice of materials.The elemental lithium easily reacts with air,especially humid air,and deactivates,resulting in a sharp increase in the production cost of the battery.The current research is focused on how to improve the cycle life of lithium metal in the battery.Little attention has been paid to the future of lithium metal batteries.The challenges faced by large-scale assembly are lacking economically feasible solutions to improve the air stability of lithium metal at this stage.Therefore,it is very necessary to focus on the air stability of lithium metal.This idea can be used not only for the protection of lithium metal anodes,but also for the protection of other metal anodes(such as sodium and zinc)and the pre-lithium of graphite/silicon-carbon anodes.The process of reformation has meaning for reference.Because polymethyl methacrylate(PMMA)can be dissolved in the electrolyte,and the dissolved PMMA reacts with lithium ions to form a three-dimensional continuous channel in the polymer space,thereby improving the electron transmission efficiency,we first on the surface of the lithium anode Constructed PMMA protective layer to improve its air stability.Through the study of PMMA with different molecular weights(35000,90000,120,000,350,000),it is found that PMMA with a molecular weight of 350,000 has the best protection effect on lithium anode in the air,and the protective layer does not need to be removed before the lithium sheet is used,and has simple operation However,the density of the PMMA protective layer is limited.Even 20%by weight of PMMA(350000)can only protect the lithium anode in the air for about 20 minutes.In order to better improve the air stability of the lithium negative electrode,the combination of PEGDA(Poly(ethylene glycol)diacrylate)polymer film has the characteristics of compactness,and we initiated 400 g mol-1 by ultraviolet irradiation The liquid polymer monomer PEGDA is polymerized to form a PEGDA polymer film,and a protective layer of PEGDA polymer is constructed on the surface of the lithium negative electrode to improve its air stability.The study found that the PEGDA polymer protective layer can protect the lithium negative electrode in the air for up to 10 hours,which is a good protective material,but when assembled with the lithium negative electrode in the battery,the battery impedance will increase by a hundred times,so it is used in lithium tablets Before the protective layer needs to be removed,the process is relatively complicated.In addition to improving the air stability of the lithium negative electrode,we also considered the problem of large interface impedance of the gel electrolyte.Initiation of DOL ring-opening polymerization by 1 m M Al(OTf)₃ under anhydrous conditions,built in situ on the surface of lithium anode A protective layer of polymerized gel electrolyte poly DOL.The study found that the poly DOL protective layer can protect the lithium anode in the air for 1 hour.In addition,the good interface contact between the liquid precursor and the electrode material during in-situ polymerization remains unchanged,which solves the poor physical contact between the gel electrolyte and the electrode material.The problem of large interface impedance.