The chemical structure of lithium salts is believed to play a pivotal role on the intrinsic properties of solid polymer electrolytes (SPEs), which are considered as an important element for accessing safe and reliable lithium batteries. Herein, we propose the use of lithium (fluorosulfonyl)(pentafluoroethylsulfonyl)imide (LiFPFSI), an isomer of the widely used lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt, as a conducting salt for building high-performance SPEs. The physicochemical and electrochemical properties of the LiFPFSI/poly(ethylene oxide) (PEO) electrolytes are comparatively studied with the reference LiTFSI/PEO electrolytes, in terms of phase transition, ionic conductivity, lithium-ion transference number (T_Li⁺), electrochemical stability and the interfacial behavior between lithium metal (Li°) and SPEs. Compared to the LiTFSI/PEO electrolytes, the LiFPFSI/PEO electrolytes exhibit lower glass transition temperatures and higher ionic conductivities, and in particular, better stability against Li° electrode. These results suggest that LiFPFSI would be a promising salt for improving the performance of SPE-based solid-state Li° batteries.

锂盐的化学结构被认为对固体聚合物电解质（SPE）的内在特性起着关键作用，固体电解质被认为是访问安全可靠的锂电池的重要元素。本文中，我们建议使用锂（氟磺酰基）（五氟乙基磺酰基）酰亚胺（LiFPFSI）（一种广泛使用的双（三氟甲磺酰基）酰亚胺锂（LiTFSI）盐的异构体）作为导电盐来构建高性能SPE。LiFPFSI /聚环氧乙烷（PEO）电解质的物理化学和电化学性质与参考LiTFSI / PEO电解质在相变，离子电导率，锂离子转移数（T _Li ⁺，电化学稳定性以及锂金属（Li°）和SPE之间的界面行为。与LiTFSI / PEO电解质相比，LiFPFSI / PEO电解质具有较低的玻璃化转变温度和较高的离子电导率，尤其是对Li°电极的稳定性更好。这些结果表明，LiFPFSI将是改善SPE基固态Li°电池性能的有希望的盐。