Fluorine-free polysiloxane-based single-ion-conducting polymer electrolyte for lithium–metal batteries

Abstract

Herein, the synthesis and comprehensive characterization of a new, completely fluorine-free single-ion-conducting polymer electrolyte (SIPE) for lithium–metal batteries are reported. For this new SIPE, lithium(4-styrenesulfonyl)(dicyanomethide) has been grafted onto a polysiloxane backbone. Self-standing membranes additionally containing non-toxic polyacrylonitrile and propylene carbonate exhibit suitable mechanical properties, a high ionic conductivity of more than 10⁻⁴ S cm⁻¹, and good anodic stability up to more than 4.1 V vs. Li⁺/Li at 40 °C. Symmetric Li∥Li cells show an excellent cycle life with more than 1000 h of lithium stripping and plating, thanks to the formation of a stable and low-resistive interphase. As a result, completely fluorine-free Li∥LiFePO₄ cells provide stable cycling for more than 500 cycles, rendering this new electrolyte system very promising for the realization of more sustainable and safer lithium batteries.