Construction And Properties Of Organic-Inorganic Hybrid Artificial Interface Layer For Lithium Metal Anode

Lithium metal has the advantages of high specific capacity（3860 m Ah/g）and low potential（-3.045 V vs.SHE）,which is one of the key materials to break through the bottleneck of the energy density of secondary battery.However,the low coulombic efficiency,short cycling life and poor safety caused by uncontrolled lithium dendrite growth greatly limit the commercial application of lithium anode.The poor stability of solid electrolyte interface layer（SEI）formed naturally on lithium anode is one of the main reasons for lithium dendrite formation.In this paper,an organic-inorganic hybrid artificial interface layer with high structure stability was constructed on the surface of lithium anode to inhibit Li dendrite growth and improve battery cycle stability.The main research contents and conclusions are shown as follows:（1）An artificial interface layer LAGP-PVDF(Li_1.5Al_0.5Ge_1.5（PO₄）₃)or LATP-PVDF(Li_1.3Al_0.3Ti_1.7（PO₄）₃)was constructed on the surface of lithium anode in advance,and its effect on electrochemical performance and deposition/dissolution behavior of lithium anode was studied.It was found that the interfacial layers regulate lithium deposition/dissolution behavior and inhibit lithium dendrite growth.Based on these,LATP-PVDF@Cu foil electrode can stably cycle for nearly 500 cycles at2.0 m Ah/cm²and 1.0 m A/cm²,and the capacity retention rate of Li Fe PO₄/Li full battery with modified Li electrode is 92.6%at 3.0 C for300 cycles,which is far higher than that of the ordinary lithium electrode fabricated on flat copper foil.（2）Aiming at the problems that 3D porous carbon lithium anode is prone to dendrite growth under high current and high circulation surface capacity,The LATP-PVDF@porous carbon lithium composite lithium anode was constructed.The LATP-PVDF interfacial layer can adjust the deposition behavior of lithium metal,realize the deposition of lithium metal in 3D porous carbon,and improve the electrode cycling stability.The LATP-PVDF@porous carbon lithium anode possesses a stable cycle for more than 700 cycles at 0.5 m Ah/cm²and 0.5 m A/cm²,which is better than that of the conventional porous carbon/lithium anode.The Li Fe PO₄/Li full battery assembled with this electrode exhibits a specific discharge capacity of 133.6 m Ah/g at the first cycle with a rate of 2.0 C,and a capacity retention rate of 80.3%after 400 cycles,while the common porous carbon lithium full battery only has a cycle of 250 cycles under the same conditions.