Preparation Of Multifunctional Ionic Liquid Polymer Electrolyte And Its Application In Solid Lithium Batteries

Driven by the urgent need for energy storage and conversion systems with high energy density and long life,the high-safety,green,and practical secondary energy industry is in the ascendant.Solid polymer electrolytes with high safety factor,high electrochemical performance and high mechanical properties are gradually replacing traditional liquid batteries.However,the mechanical properties,rate and cycling performances for the solid lithium batteries are still unsatisfied.Herein,to obtain a solid electrolyte with excellent performance,two different schemes are designed for the polymerization of monomer PEGMA-CH₃ and 1-vinylimidazole ionic liquid,benefiting the solid electrolyte realize its wide application in practical energy storage equipment.More details are as follows.（1）Solid-state electrolytes（PEO@BPIL and PEO@RPIL）with intrinsic self-healing capacity and binary block structure are fabricated via the ATRP of PEGMA-based monomer and the follow-up imidazolium grafting onto the linear structure initiator,incorporated into PEO.The novel GSPEs have more amorphous structure and higher polymer segment migration hybrid power.Besides the decreased crystallinity of PEO,a unique ordered and disordered microphase separation architecture is induced in PEO@BPIL,which provides a“green channel”for fast Li-ion migration.The electrochemical stability window and ionic conductivity of the optimized PEO@BPIL can achieve 5.0 V（vs.Li⁺/Li）and 2.2×10^-4 S cm^-1,respectively.The assembled lithium metal battery has a high discharge capacity of 160 m Ah g^-1 at 0.2 C.The ultra-long and stable polarization cycle test chart further clarifies the excellent synergistic effect of the electrochemical properties of the polymerized ionic liquid and imidazole and the high level of lithium dendritic defense capabilities,making it possible for PEO@PPIL-3-SPE with outstanding interface performance.（2）Using the modified macromolecular brush-like brominated cellulose as the initiator,the monomer PEGMA-CH₃ and 1-vinylimidazole are block-polymerized.A large number of ether bonds on the branch and the introduction of the ionic liquid are carried out,leading to the test results of the performance for electrolytes are quantified.The measured lithium-ion migration number(t _Li+)is 0.32,and the electrochemical window has exceeded 5.0 V vs Li/Li⁺（60°C）.This is due to the fact that the brush-like structure in the polymer facilitates the formation of more and evenly distributed ion channels and reduces ion migration resistance.In addition,the monomer PEGMA-CH₃ and imidazole-type ionic liquid（IL）have a large number of charged groups and ether bonds,which has a beneficial effect on dissociating the lithium salt.The above-mentioned characteristics make the Li Fe PO₄/Li battery assembled based on CB-PEGMA@IL-SPE exhibits excellent long-cycle capability（over 150 cycles）and good rate capacity.CB-PEGMA@IL-SPE with brush-like structure and excellent flexibility provides a feasible channel for the preparation of wearable high-tech electronic devices.