Self‐Enhancing Gel Polymer Electrolyte by In Situ Construction for Enabling Safe Lithium Metal Battery

TLDR

Lithium metal batteries offer high theoretical capacity but suffer safety and stability issues from dendrite growth and electrolyte leakage. The authors aim to develop a self‑enhancing gel polymer electrolyte by in‑situ polymerizing 1,3‑dioxolane within a nanofibrous skeleton to improve LMB safety. They construct a homogeneous GPE by leveraging the nanofiber membrane’s superior affinity for poly‑DOL, augmenting it with polydopamine‑mediated hydrogen bonding to the bis(trifluoromethyl)sulfonyl)imide anion, which boosts mechanical strength, ionic conductivity, and transference number, and use molecular dynamics to elucidate the underlying conductivity mechanisms. The resulting LiFePO4//Li cells exhibit exceptional cycling stability—800 cycles at 2 C with only 0.021 % capacity fade per cycle—effectively suppressing dendrite growth and demonstrating the potential for high‑performance, safe LMBs compatible with existing production.

Abstract

Lithium metal battery (LMB) possessing a high theoretical capacity is a promising candidate of advanced energy storage devices. However, its safety and stability are challenged by lithium dendrites and the leakage of liquid electrolyte. Here, a self-enhancing gel polymer electrolyte (GPE) is created by in situ polymerizing 1,3-dioxolane (DOL) in the nanofibrous skeleton for enabling safe LMB. The nanofiber membrane possesses a better affinity with poly-DOL (PDOL) than commercial separator for constructing homogeneous GPE with enhanced ion conductivity. Furthermore, polydopamine is introduced on nanofiber membrane to form hydrogen bonding with PDOL and bis((trifluoromethyl)sulfonyl)imide anion, dramatically improving the mechanical strength, ionic conductivity, and transference number of GPE. Besides, molecular dynamic simulation is used to reveal the intrinsic factors of high ionic conductivity and reinforcing effect in the meantime. Consequently, the LiFePO4 //Li batteries using self-enhancing GPE show extraordinary cyclic stability over 800 cycles under high current density of 2 C, with a capacity decay of 0.021% per cycle, effectively suppressing the growth of lithium dendrites. This ingenious strategy is expected to manufacture advanced performance and high safety LMBs and compatible with the current battery production.