A supramolecular interaction strategy enabling high-performance all solid state electrolyte of lithium metal batteries

Abstract

In general, solid polymer electrolyte suffers from relatively low ionic conductivity and inferior oxidation stability. Herein, these issues can be effectively addressed by a supramolecular strategy based on the intermolecular interaction between a novel amorphous comb polymer of poly[propylene oxide-co-2-(2-methoxyethoxy)ethyl glycidyl ether] [P(PO/EM)] and highly fluorinated anion based lithium salt of lithium trifluoro(perfluoro-tert-butyloxyl)borate (LiTFPFB). The supramolecular solid state polymer electrolyte exhibits superior lithium ion transference number (0.59). It is noted that this polymer electrolyte presents enlarged electrochemical window up to 4.6 V (vs. Li/Li+ at 70 °C), which is resulted from the powerful supramolecular interaction between polymer skeleton and lithium salt. The supramolecular interaction was confirmed by Fourier transform infrared spectroscopy (FT-IR) analysis, solid state nuclear magnetic resonance (NMR) spectroscopy, stripping and self-healing tests. More bracingly, high voltage LiFe0.2Mn0.8PO4/Li cell based on this polymer electrolyte exhibits improved cycling performance (capacity retention is 88.7% after 100 cycles at 0.1C). Meanwhile, this well-designed electrolyte endows LiFe0.2Mn0.8PO4/Li cell pouch cell excellent safety characteristic even under deformation and truncation procedures. This supramolecular strategy paves a new way for boosting high energy density all solid state lithium metal batteries.