Study On The Microscopic Mechanism Of Dendrite Growth On Current Collector Lithium Metal Battery Systems

In recent years,energy storage has attracted widespread attention and led to the emergence of a series of emerging technologies.Since its commercialization in 1991,lithium-ion batteries have played a major role in portable electronic devices.However,in order to meet the growing demand for high energy density,it is necessary to develop next-generation metal-based batteries with the following advantages:high energy density,such as Li-S and Li-O2 batteries.Lithium metal-based batteries(LMBs),which have been extensively studied in recent years,are considered the next gengeration high energy battery systems.The lithium metal anode has a high theoretical capacity of 3860 mAh g-1,a low density of 0.59 g cm-3,and the lowest electrochetical potential.However,current lithium metal batteries have problems in use,such as uneven deposition,low coulombic efficiency,and lithium dendrites,which hinder their commercial application.Therefore,further understanding of the lithium metal deposition process is very important to solve these problemsAt present,the deposition of lithium metal can be mainly divided into two stages,namely,nucleation and growth stages,but the related mechanism is stillcontroversial.Existing research shows that the deposition behavior of lithium metal is closely related to the current collector.In order to further understand the deposition tendency of lithium after initial nucleation on different current collections,we prepared a current collector surface of carbon,copper,and zinc oxide by methods such as magnetron sputtering for experiments.At the same time,the relationship between the binding energy of lithium atoms and atoms of different current collector surfaces,the diffusion energy of lithium atoms on the current collector surface,and the lithium metal deposition morphology were studied using periodic density functional theory calculations(DFT).Relevant experimental characterization and electrochemical tests show that high binding energy and high surface diffusion energy between lithium atoms and current collectors can promote the uniform deposition of lithium metal.Further based on the obtained theory,we proposed a method of alkaline etching of current collectors,which obtained 3D fluffy copper current collectors by adjusting temperature and reaction time,and then magnesium metal was sputtered to the prepared copper by magnetron sputtering Current collector.Finally,no more than 30 ?m lithium metal was deposited on the surface of the reforming fluid by electrodeposition,and it was applied to the Li/LiFePO4 battery system.Electrochemical tests show that the Coulombic efficiency of this type of current collector can still reach more than 95%after 200 cycles,while ordinary commercial current collectors have less than 40%after 60 cycles.