| Starting from the late 1970s, solid polymer electrolytes (SPEs) have attracted considerable attention due to their possibility of applications of polymer ionic conductors in high-energy lithium-ion batteries, electrochemical supercapacitors, and fuel cells. To improve electrolyte efficiency, the suitable charge carriers have the key contribution to the ionic conductivity, electrochemical stability, and energy efficiency of SPEs. A novel family of lithium perfluoro-alkoxy (-phenoxy) sulfonylimides based on polyanions and branched-type anion have been characterized in semicrystalline, amorphous and gelled SPEs. The researches based on ab initio quantum-chemical methods for LiN[SO2OCH(CF3)2]2 (LiHFPSI) have revealed the intrinsic relationship between its structure and properties. 1) The conductive behaviors of PEO-polyanion lithium imides SPEs have the character of the classical semicrystalline SPEs. The fluorine groups, aromatic groups, and the length of segments may strongly affect the morphology, ionic conductivity, and electrochemical stability of SPEs. The polyanion lithium imides could induce the amorphization of PEO-based SPEs by slow the re-crystalline process of polymer matrix. As a result, the better ionic conductivity could be obtained. On the other hand, their polyanions with high negative charge delocalization may provide the main contribution for the wider electrochemical windows and the higher cationic transference numbers. The most conductive SPE was the PEO-Lithium poly [4, 4'-(hexafluoroisopropyidene) diphenoxy] sulfonylimide EO/Li=16. The conductivity of this rubbery film was 2.19×10-4 S/cm at 60℃. Its electrochemical window could up to 6 V and the cationic transference number was 0.97. 2) The branched-type lithium imide-LiHFPSI exhibited the better ionic conductivity in PEO-based SPEs. Its conductive behavior agreed with the VTF equation, which was always used to describe the conductive behaviors of amorphous SPEs. The highest ambient ionic conductivity (3.97×10-5 S/cm, 30℃) was obtained when EO/Li=8. The results obtained from a series characterizations suggested that LiHFPSI was a good ionic carrier which have the more plasticizing effect, wider electrochemical window, higher cationic transference number than the traditional lithium imide-LiN(SO2CF3)2 (LiTFSI). 3) A series of methoxy ether-substituted poly(organophosphazenes) (MExP) have been synthesized and used as amorphous polymer matrix for lithium imides doped SPEs. The ambient conductivities of these SPEs have been improved 12 magnitude, and the best conductive SPE was obtained when the length of EO side chains is 4 (ME4P-LiHFPSI Li/rpt unit=3/8, 4.48×10-4 S/cm). The amorphous MExP-LiHFPSI SPEs also exhibited the good electrochemical stability and thermal stability. The Arrhenius-type conductive behaviors could be found in PAN-PC-EC-LiHFPSI gelled polymer electrolytes (GPEs), and their ambient conductivities dramatically increase up to 10-3 S/cm. The proportion of PC to EC would strongly affect the ionic conductivity at different temperature. However, the electrochemical stability of these GPEs decreased on large scale due to the introducing of PC. 4) The optimized geometries, energies, and the charge delocalization of -N[SO2OCH(CF3)2]2 and LiN[SO2OCH(CF3)2]2 have been calculated by ab initio quantum-chemical method with high basis set (HF/6-31+G*). The calculated results showed that the "plasticizing effect"of HFPSI anion was due to the small changes of energy when the large geometrical conversions were occurred. NBO analysis gave the details of the large delocalization of negative charge and the interaction between the molecular orbitals in HFPSI anion. The intrinsic reasons have been elucidated for the more weakly coordinating, the better electrochemical stability and the higher cationic transference number of HFPSI anion than which of TFSI anion.The geometrical studies on LiHFPSI have revealed that the Li cation prefer to coordinate with the O atom on different SO2 groups to form the more stable cyclic geometry. There are no apparent interaction had been found between the Li cation and the molecular negative charge center -N atom. Li cation in LiHFPSI kept the more positive charge than LiTFSI, which indicate that the more weakly coordinating between HFPSI anion and Li cation. In summary, the lithium perfluoro-alkoxy (-phenoxy) sulfonylimides were benefit to the better comprehensive properties of SPEs. Their further application in SPEs and the new catalytical materials could be expected exhilaratingly due to their facile synthesis methods and the large delocalizated structures.
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