Preparation And Properties Of Sulfonimide Based Single Lithium-ion Polymer Electrolyte

Single lithium-ion polymer electrolytes（SPEs）have attracted much attention due to its ability to release the anion concentration gradient,inhibit the growth of lithium dendrites and decrease the battery polarization loss.Bis（benzenesulfonyl）imide,due to its strong electron-delocalization,is expected to be used in SPEs.However,currently,the SPEs based on bis（benzenesulfonyl）imide cannot meet the requirements of high ionic conductivity(>10^-4 S cm^-1)and high lithium-ion transference number（>0.90）,simultaneously.In this thesis,aiming at the above problem,two bis（benzenesulf-onyl）imide based single-ion polymer lithium salts with the alternating structure were designed and synthesized:lithium poly[4-styrenesulfonyl（phenylsulfonyl）imide-alt-m-aleic anhydride]（P[SSPSILi-alt-MA]）and P[SSPSILi-alt-MA]modified by ethyl glycinate（EG-P[SSPSILi-alt-MA]）.P[SSPSILi-alt-MA]was selected as the polymer lithium salt and mixed with poly（vinylidene fluoride-co-hexafluoropropylene）（PVDF-HFP）polymer matrix to prepare the gel SPE membrane.The SPE membrane exhibits both high lithium ionic conductivity(2.67×10^-3 S cm^-1)and transference number（0.98）.The full cell with the prepared SPE sandwiched between Li Fe PO₄ cathode（LFP）and Li₄Ti₅O₁₂ anode（LTO）shows the excellent cycling stability and rate capability.The P[SSPSILi-alt-MA]/PEO solid single lithium-ion polymer electrolyte（SSPE）membrane was prepared by combining P[SSPSILi-alt-MA]with PEO matrix.The SSPE membrane presents a high ionic conductivity of 3.08×10^-4 S cm^-1.In addition,the P[SSPSILi-alt-MA]/PEO SSPE membrane shows a high transference number of0.97,which can inhibit the formation and growth of lithium dendrites.When the P[SSPSILi-alt-MA]/PEO SSPE membrane was assembled into a LFP battery,the SSPE membrane shows the good compatibility with electrodes and the LFP battery exhibits the good cycling stability and rate capability.The EG-P[SSPSILi-alt-MA]/PEO SSPE membrane with a compact and uniform surface was prepared by the composite of EG-P[SSPSILi-alt-MA]and PEO matrix.The SSPE membrane shows an ionic conductivity as high as 1.42×10^-4 S cm^-1 and single-ion conducting behavior.The LFP coin cell assembled with the SSPE membrane shows the good rate performance and cycling stability.In addition,the LFP flexible battery using the SSPE membrane exhibits the good practicability and environmental adaptability.