Ion Flux Self-Regulation Strategy with a Volume-Responsive Separator for Lithium Metal Batteries

Lithium metal batteries (LMBs) are regarded as one of the most promising next-generation energy storage devices due to their high energy density. However, the conversion of LMBs from laboratory to factory is hindered by the formation of lithium dendrites and volume change during lithium stripping and deposition processes. In this work, a volume-responsive separator with core/ shell structure thermoplastic polyurethane (TPU)/polyvinylidene fluoride (PVDF) fibers and SiO2 coating layers is designed to restrict dendrite growth. The TPU/PVDF-SiO2 separator can accommodate the volume change like an artificial lung and keep intimate contact with the electrodes, which leads to the formation of a uniform and high-density solid-electrolyte interphase. Meanwhile, the separator can regulate the transport channels and diffusion coefficients (D) of lithium ions with the change of porosity from both experimental and ab initio molecular dynamic analysis. The Li symmetric cells assembled with the TPU/ PVDF-SiO2 can run for 1000 h at the current of 1.0 mA cm-2 without a short circuit. Moreover, the low melting point of PVDF can shut the ionic conduction down at 170 degrees C, guaranteeing the thermal safety of the batteries. With the above advantages, the TPU/PVDF-SiO2 separator presents great potential to promote the commercial and industrial of LMBs.

Automated summary

This study presents the design of a volume-responsive separator with a core/shell structure for inhibiting the growth of lithium dendrites in lithium metal batteries (LMBs). The separator can accommodate volume change, maintain intimate contact with the electrodes, and facilitate the formation of a uniform and high-density solid-electrolyte interphase. Additionally, the separator can regulate the transport channels and diffusion coefficients of lithium ions. The Li symmetric cells assembled with this separator demonstrate long-term stability and thermal safety, showing great potential for promoting the commercialization and industrialization of LMBs.