Stable Li Metal Anode Based On Interface Regulation And Structural Design

Lithium metal anode(LMA)is regarded as an ideal candidate for the next generation of high energy density battery because of its ultra-high theoretical specific capacity(3860m Ah·g^-1)and extremely low redox potential(-3.04V).However,before the commercialization of lithium metal battery(LMB),volume expansion,pulverization and dendritic growth are the tricky problems to be solved.At present,building a stable SEI on the surface of lithium metal and designing an independent and stable 3D negative electrode structure are effective methods to improve battery performance and achieve uniform lithium deposition.Similarly,this paper also studied the interface SEI of LMA and design of lithium metal latticed three-dimensional structure,so as to realize high-performance and stable LMA.First of all,starting from the interface SEI of LMA,an organic-inorganic artificial SEI with high dielectric properties is designed to adjust the electric field distribution and Li⁺flux,so as to stabilize the interface of LMA.The addition of inorganic SiO₂enhances the dielectric properties of the interface,which plays an important role in preventing current change,guiding uniform current/potential distribution,uniform the flow of Li⁺in SEI interface and realizing uniform lithium deposition;Organic PDA has the characteristics of high elasticity and lithium affinity which can be used as a strong active site for lithium atom adsorption and reduce the nucleation overpotential.It can assist the migration process of Li⁺.On this basis,the electrochemical stability of LMA is greatly improved.Then,starting from the design of lithium metal latticed three-dimensional structure,a three-dimensional Li-Li Al-Li₃N-Al N-CNT composite anode(LAC)was designed.In order to deposit lithium inside the three-dimensional structural framework rather than its surface,we created lithium nucleophilic sites in the ionic conductive framework.Considering the volume expansion of lithium negative electrode in the cycle process,CNT structure for mechanical support is also added.Dense and smooth lithium deposition was realized based on the in-situ reaction of Li and Al N.The Li Co O₂full cell matched with the composite anode electrode also achieved good electrochemical performance improvement.To sum up,this paper realizes the stable LMA in two aspects:artificial SEI construction and the design of three-dimensional structure.Li⁺transport,migration,deposition and inhibition of dendritic growth are studied.At the same time,it also opens up a new idea for realizing the dendritic free and uniform LMA electrode.