Multifunctional electrospun PVDF-HFP gel polymer electrolyte membrane suppresses dendrite growth in anode-free li metal battery

Abstract

It is widely accepted that high electrolyte consumption due to decomposition leads to rapid capacity fading in anode-free Li metal batteries (AFLMBs). Here, we report an electrospun gel polymer electrolyte (GPE) membrane, unpeeled-off and integrated with its Cu foil collector (Cu@GPE), prepared using a novel method. The Cu@GPE provides bifunctional applications; as electrolytes and an artificial solid-electrolyte interphase (ASEI). Interestingly, the strong electrostatic interaction between the fiber sheet and the Cu foil collector reconstructs the Cu surface structure, confirmed by grazing angle X-ray diffraction, which positively influences the fluidity of deposited Li. X-ray absorption, depth profile of X-ray photoelectron, Raman and infrared spectroscopies analyses showed the formation of pure β-phase PVDF-HFP as ASEI in which the F elements are aligned toward the Cu surface. These lead to a uniform Li-ion flux and regulate the Li nucleation due to the strong binding between Li and electronegative C-F functional groups promoting uniform Li deposition. The Cu@GPE|Li cell achieved outstanding performance even at a high current density of up to 5 mA cm−2 (coulombic efficiency, 97.14%) after 200 cycles relative to the GPE prepared by the conventional method (cGPE) (90.08%) after 100 cycles. Coupling with LiNi0.33Mn0.33Co0.33O2 (NMC), the Cu@GPE|NMC AFLMB delivered superior performance than Cu|cGPE|NMC.