Effective suppression of lithium dendrite growth using fluorinated polysulfonamide-containing single-ion conducting polymer electrolytes

Abstract

The lithium metal anode, which is considered as the “Holy Grail” anode material, possesses extra high energy density and extra low negative electrochemical potential. However, it is hardly applied in lithium batteries owing to lithium dendrite formation and interfacial instability in the electrolyte, resulting in safety problems and poor long-cycle performance. In this work, we designed and synthesized a novel artificial solid electrolyte interface (SEI) layer, which exhibits high ionic conductivity and single-ion conductive characteristics. The SEI layer named LiSFSI-PET4A-PETMP (LFPP) SEI layer was synthesized by a one-step click reaction in situ on the surface of lithium metals using lithium[(4-styrenesulfonyl) (fluorosulfonyl)imide] (LiSFSI), pentaerythritol tetraacrylate (PET), and pentaerythritol tetrakis (2-mercaptoacetate) (PETMP). The formed LFPP-SEI layer has a controllable 3D cross-linked network structure. It also exhibits high ionic conductivity and high lithium ion transference number near to unity, which is beneficial for preventing the nucleation of lithium dendrites, so as to suppress the formation of lithium dendrites from the source. The Li//LFP full cell using LFPP 2%-Li anode exhibits a quite high and stable capacity with a capacity retention of 75.8% and a high coulombic efficiency of 99.0% at 1C after 390 cycles. Moreover, the full battery using an LFPP 2%-Li anode and an LFPP 1%-Li anode at 0.5C for 250 cycles shows a very good coulombic efficiency of 100.0% and capacity retention values of 77.5% and 77.7%, respectively.