Preparationand Electrochemical Properties Of Silver And Nitrogen Graphene Aerogel Lithium Metal Anode

Lithium metal,with the highest specific capacit y(3860 mAh g^-1)and the lowest reduction potential?-3.04 V vs.SHE?,known as the "holy grail" of battery energy storage,is considered as an ideal anode for the next-generation lithium-metal batteries with high energy density.However,the irregular growth of lithium dendrites,the formation of dead lithium,the drastic volume expansion and the poor cycling performance and safet y problems caused by the high reactivity of lithium metal in the process of charging and discharging seriously restrict the commercial application of lithium metal secondary batteries.A three-dimensional li-philic silver-doped and nitrogen-doped graphene aerogel material was constructed to prepare high-performance lithium metal composite anode to slow down the growth of lithium dendrite,aiming to improve the safet y of lithium metal anode.Herein,a three-dimensional?3D?porous silver-doped graphene aerogel?GA-Ag?was prepared by a hydrothermal method followed with lyophilization and high-temperature treatment,and the optimal conditions for the preparation of GA-Ag were explored.On the one hand,the three-dimensional porous structure with high specific surface area reduces the true current density of the electrode and provides a large space for lithium metal deposition;On the other hand,doped silver particles can provide a strong affinit y for uniform lithium metal deposition and reduce the overpotent ial of lithium metal nucleation.Based on the synergist ic effect of the above-mentioned two reasons,the Coulombic efficiency of lithium metal deposition on GA-Ag electrode can remain as high as 99% for over 120 cycles at the test conditions of 0.5 mA cm^-2 and 1 mAh cm^-2.After deposit ion of lithium metal,the Li Fe PO4?LFP?full cells assembled with LFP could keep a high specific capacity of up to 144 mAh g^-1 and cycle for 150 cycles.A three-dimensional nitrogen-doped graphene aerogel?NGA-4?was prepared by hydrothermal method combined with freeze-drying and high temperature treatment with the addition of melamine to guide uniform lithium metal deposition.The hydrogen bond between the amino group on melamine and the oxygen-containing functional group of go in the hydrothermal reaction makes the electrode surface have a more porous fluffy aerogel structure,which can provide more space for the deposition of lithium metal.Doped nitrogen atoms could provide a strong affinit y between lithium metal and NGA-4 substrate,which could increase the nucleation center during the reduction reaction of lithium ion,make the electric field distribution more uniform and guide the uniform deposition of lithium.The Coulombic efficiency of lithium metal deposition on NGA-4 electrode could remain as high as 99% for 160 cycles at the test conditions of 0.5 mA cm^-2 and 1 mAh cm^-2.In addit ion,after deposition of lithium metal,the full cell assembled with LFP also shows excellent cycle performance and rate performance.The results show that silver graphene aerogels and nitrogen doped graphene aerogels could effectively guide the uniform deposition of lithium,alleviate the growth of lithium dendrite.