Preparation Of High Safety Gel Electrolyte And Its Application In Lithium Metal/Sodium Ion Batteries

With the energy density of lithium-ion batteries is approaching its limit and the decreasing of lithium ore in the world,lithium metal batteries and sodium ion batteries as the most likely substitutes of lithium-ion batteries gradually come into people’s view.However,lithium metal batteries and sodium ion batteries have more stringent requirements on electrolytes.Two kinds of flame retardant electrolytes based on phosphazene and a single ionic conductor gel electrolyte were designed and synthesized in this work,their structure and properties have also been studied.The main contents are as follows:1.Two crosslinking agents 2,4,6-tris(2,2,2-trifluoroethoxy)-2,4,6-tris(2(2-(vinyloxy)ethoxy)ethoxy)-1,3,5,2λ5,4λ5,6λ5-triazatriphosphinine(TFV)and 2,4,6-tris(2,2,2-trifluoroethoxy)-2,4,6-tris(2-(2-(vinyloxy)ethoxy)ethoxy)1,3,5,2λ5,4λ5,6λ5-triazatriphosphinine(FV)based on cyclophosphazene were synthesized.IR,NMR and other tests were carried out to prove its structure.2.Designed and synthesized a polymerizable monomer((2(acryloxy)ethoxy)carbonyl)(fluorosulfonyl)amide(M)containing carboncarbon double bond and sodium salt group.And it has been tested by IR,NMR and other tests to prove its structure.3.The gel electrolyte(TFV-GPE)was prepared by in-situ polymerization using TFV as the crosslinking agent.Its room temperature ionic conductivity can reach up to 7.78×10-4 S/cm,its electrochemical window is 4.5 V,and its Lithium ion transference number is 0.62.The gel electrolyte(FV-GPE)was prepared by in-situ polymerization using FV as the crosslinking agent.Its room temperature ionic conductivity can reach up to 2.04×10-3 S/cm,its electrochemical window is 4.8 V,and its Lithium ion transference number is 0.57.The ionic conductivity of TFV-GPE and FV-GPE is mainly determined by the content of liquid electrolyte.A single-ion conductor(S-GPE)was prepared by using M for in-situ polymerization of monomers,and its room temperature ionic conductivity can reach up to 7.6×10-5 S/cm.4.The flame retardant properties of TFV-GPE and FV-GPE were characterized.The samples of TFV-GPE were ignited and then self extinguished in 11 to 25 seconds.When the addition of FV in FV-GPE is Greater than or equal to 10 wt%,the sample has the characteristics of self extinguishing.