Porous polymer membrane with uniform lithium-ion transport via phase separation for stable lithium metal batteries

Abstract

Lithium metal is considered an ideal anode for lithium batteries due to its high theoretical capacity. However, its industrial applications are limited by the fragile solid electrolyte interphase films and the growth of lithium dendrites. Here, we prepared a polyvinylidene fluoride-lithium poly (acrylamide-2-methyl-1-propane-sulfonate) (PVDF-PAMPSLi) polymer membrane with a porous structure by a one-step phase separation method for stabilizing lithium metal anode. Different from the porous PVDF-protected anode and the unprotected anode, the porous PVDF-PAMPSLi membrane can provide a facile lithium-ion transport pathway and improve the lithium-ion diffusion kinetics in the microchannel structure. In symmetric cell tests, the PVDF-PAMPSLi-protected cell delivers stable cycling over 350 h at 2 mA cm−2 and 1 mAh cm−2. At 5 mA cm−2, it can cycle stably for 125 h, and the overpotential is stable at around 50 mV. As for asymmetric Li/Cu cell tests, the PVDF-PAMPSLi-modified Cu electrode delivers high coulombic efficiency (CE) of 97.43% over 265 cycles at 2 mA cm−2. Moreover, the LFP/Li and NCM811/Li half cells using the PVDF-PAMPSLi-coated Li exhibit significantly improved cycling stability and high discharge capacities under lean electrolyte conditions (10 μL mAh−1).