Design And Electrochemical Properties Of High Performance Lithium Metal Anode

In order to meet the needs of large-scale energy storage and electric vehicle,it is particularly important to develop lithium batteries with high energy density.Lithium-ion batteries（LIBs）based on intercalation chemistry with the combination of a lithium transition metal oxide（or phosphate）cathode and a graphite anode have been widely used in consumer electronics and are making their way to electric vehicles and grids.However,these conventional LIBs are reaching the limits regarding energy and power density.Therefore,new battery systems such as lithium-sulfur batteries,lithium-air batteries,and high-voltage batteries have entered the field of vision.Lithium metal is considered to be one of the most promising anode materials due to its high theoretical specific capacity and low chemical reaction potential.However,the practical application of lithium metal anode suffers from unsatisfactory cyclability,inferior rate capability and safety issues.Considerable effort has been devoted to tackling the challenges of lithium metal anodes.This paper is mainly aimed at the lithium metal anode.Due to its nearly-infinite volume change and ultra-high electrochemical reactivity,we have designed a new three-dimensional framework,which reduce the volume change of the metal lithium anode during the cycle and the formation of dendrites;at the same time,the protective layer on the surface also reduces the side reaction between lithium metal and high-voltage electrolyte,improve the cycle stability of the high-voltage battery,and achieves an ultra-high energy density.The main results are summarized as follows:1.We uniformly combine layered C₃N₄ and graphene oxide into a three-dimensional framework by simple filtration,and“fill”the lithium metal into the skeleton.After the compounded with lithium metal,the C₃N₄ reacts with the metallic lithium to form Li₃N and carbon flakes.The three-dimensional framework composed of carbon framework and lithium nitride can reduce the volume change of the electrode;and the high lithium ion conductivity of lithium nitride can realize the rapid transmission of ions inside the electrode and reduce the formation of dendrites.the as-achieved LCN nanocomposite delivered ultrahigh rate capability and good stability for long-term lithium stripping/deposition cycling Under an current density of 1 mA cm^-2 and areal capacity of 1 mAh cm^-2,the LCN nanocomposite sustained stable electrodeposition/dissolution over 500 cycles with a very low overpotential.2.We match the LCN anode with a high voltage cathode and a high voltage electrolyte.Due to the Li₃N protective layer on the surface of the LCN electrode,the LCN electrode can be stably cycled in a high voltage battery without causing side reaction with the electrolyte.NCM丨LCN full cell can maintain a reversible specific capacity of 180 mAh/g for more than 100 cycles under the current density of 1 C;and when the current density increases to 4 C,NCM丨LCN battery can still maintain a reversible specific capacity of145 mAh/g.The above work provides a new idea for solving the side reaction between lithium metal battery and electrolyte,low cycle coulombic efficiency,poor cycle stability,serious volume change and safety issue.It is of great significance for developement of high performance lithium metal batteries.