Surface Coated Polyethylene Oxide Solid Electrolyte:Fabrication And Performance Study

The development of future energy storage systems requires the of batteries with higher energy densities.However,the current state-of-the-art lithium-ion batteries still have bottlenecks in further increasing energy density,making it difficult to break through in the short term.A battery using lithium metal as an anode can greatly increase the energy density of the battery.Whereas,the growth of the lithium dendrite during cycling is inevitably,which may pierce the separator and induce a short circuit in the battery to cause the battery to burn or explode.The application of solid electrolyte in lithium metal batteries can solve the safety issue.Among them,the solid polymer electrolyte has been extensively studied for its good flexibility,excellent processability and low interfacial resistance with lithium metal anodes.However,the ionic conductivity of solid polymer electrolyte at room temperature is very low,and the battery must be operated at high temperatures.In this case,the mechanical strength of the solid polymer electrolyte is very low,and it is difficult to prevent the growth of lithium dendrites.In recent years,it has been found that the increase of the mechanical strength of the solid polymer electrolyte can inhibit the growth of lithium dendrites and improve their cycle performance in lithium metal batteries.The main purpose of this paper is to enhance the mechanical strength of the polymer electrolyte by surface modification.The modified solid polymer electrolyte can inhibit the growth of lithium dendrites and improve the cycle performance of the lithium metal battery.Firstly,it is reviewed the main problems and solutions in the application of high-energy lithium metal batteries.Secondly,the classification of solid electrolytes and the current status of research are described.Based on the previous work,this paper provides a new way to improve the performance of solid polymer electrolytes in lithium metal batteries through the surface design of solid polymer electrolytes.The results of this research obtained are as follows:1.Two-dimensional boron nitride nanosheets coated polyethylene oxide(PEO)polymer electrolytes was explored.The boron nitride nanosheets coated PEO polymer electrolyte was prepared by a hot-pressing method.The boron nitride nanosheets layer affords an excellent interfacial protection and also stabilizes the interface between electrolyte and Li mental.This reduces the tip effect and enable es homogeneous lithium ion flux distribution at the interface of PEO electrolyte/Li metal anode to inhibit the growth of lithium dendrites.As a result,all solid state Li/LiFePO4 cell with the boron nitride nanosheets coated PEO polymer electrolyte show a higher the specific discharge capacity and a better cycle stability.2.MAPbCl3 perovskite film coated stainless steel sheet was prepared by spin coating and annealing,and then transferred to the PEO polymer electrolyte by hot-pressing method.The MAPbCl3 perovskite film enhances the mechanical strength of the PEO polymer electrolyte and ensures the stability of the lithium metal and electrolyte interface.The obtained PEO electrolyte showed largely improved resistance capability to the dendritic growth of lithium metal in comparison to pristine PEO electrolyte.The proposed perovskite film coating strategy for the protection of solid polymer electrolyte will open a new avenue to improve the performance of solid state Li metal batteries.