Highly porous single-ion conductor gel electrolyte derived from in-situ structural self-assembly for dendrite-free lithium metal batteries

Abstract

Li metal batteries (LMBs) build a potential path for next-generation batteries due to their high theoretical and low redox potential. However, nonuniform deposition of Li⁺ induces hazardous dendrite growth limiting the practical applications of LMBs. In this study, we design a single-ion-transporting porous gel polymer electrolyte (SPPV-13) containing lithiated sulfonated poly (ether ketone) (Li-SPEEK) and polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP). The PVDF-HFP backbone offers SPPV-13 substantial thermal stability and mechanical strength capacity. In parallel, the homogeneous porous structure that arises from in-situ structural self-assembly effectively facilitates the uniform dispersion of Li⁺ and provides a continuously three-dimensionally transportable channel. In addition, Li-SPEEK further immobilizes the anions, regulating facile Li⁺ transport to even deposit on the Li anode. The synergistic effect of the components results in SPPV exhibiting great mechanical strength (26.5 MPa), an excellent Li⁺ transference number (0.75), and high ionic conductivity (1.41 mS cm⁻¹) at room temperature. It is noted that the assembled Li||Li cell produces only 0.13 V polarization voltage after cycling for 2000 h at 2.5 mA cm⁻². The first cycle-specific capacity of the SPPV-13-assembled Li||LiFePO₄ cell at 1 C is 136.3 mAh g⁻¹ and cycles stably. These results indicate that SPPV has great potential for practical applications of LMBs.