Effectively suppressing lithium dendrite growth via an es-LiSPCE single-ion conducting nano fiber membrane

Abstract

Lithium metal is a potential candidate for next-generation anode materials. However, the practical application of a lithium metal anode has been hindered by uncontrolled dendrite formation. Herein, a cost-effective single lithium ion conducting polymer electrolyte membrane based on a highly porous lithium sulfonated polyether ether ketone electrospun nanofiber membrane (es-LiSPCE) is designed to serve as both a separator and a lithium ion conductor. Impregnation of the ethylene carbonate (EC)/dimethyl carbonate (DMC) (v/v = 1 : 1) solvent mixture and 1 M LiFP₆ in EC/PC (v/v = 1 : 1) yields gel pure es-LiSPCE and es-LiSPCE/1 M LiFP₆ in an EC/PC (v/v = 1 : 1) membrane, respectively, which display high ionic conductivity, low interfacial compatibility and a high lithium ion transference number. Combined scanning electron microscopy (SEM) images and the long-term stripping/plating cycling test of lithium foil confirm that such a membrane is greatly favorable for inhibiting the formation of a concentration gradient and thus suppressing lithium dendrite growth. In addition, the fully aromatic polyether ether ketone backbone enables high thermal dimensional stability and high polarity and high polarity enables fast electrolyte wetting of the es-LiSPCE membrane. Notably, Li/LiFePO₄ cells fabricated using es-LiSPCE membranes demonstrate promising rate capacity at 6C, and excellent electrochemical stability for 1500 cycles even at 6C. Therefore, it is believed that such an electrolyte can serve as an alternative to conventional polyolefin-based separators for high energy density lithium metal batteries.