A Polar and Ordered-Channel Composite Separator Enables Antidendrite and Long-Cycle Lithium Metal Batteries.

Abstract

Lithium (Li) metal as an anode replacing the traditional graphite could largely enhance the specific energy density of Li batteries. However, the repeated formation of solid electrolyte interfaces on the surface of Li metal upon plating/stripping leads to a low Coulombic efficiency, and the growth of Li dendrites upon cycling probably causes the short circuit or even explosion of the batteries, both of which block the commercial application of Li metal in lithium metal batteries (LMBs). Herein, we report an antidendrite AAO@PVDF-HFP composite separator fabricated by a two-step method, which features the ordered pore channels and the polar groups in the channels. This novel composite separator has a good wettability to the electrolyte, high mechanical properties, and high ionic conductivity. Expectedly, the assembled batteries based on our novel composite separator show many impressive performances. In Li-Li cells, the cycling life up to 1600 h at an areal current density of 2 mA/cm2 can be realized; in Li-Cu cells, the cycling life of more than 1000 h with a high Coulombic efficiency of 99.9% at 1 mA/cm2 can be achieved. More interestingly, the Li/LiFePO4 full batteries constructed by the novel AAO@PVDF-HFP composite separators show a high discharge capacity of 140 mAh/g and weak capacity decays even after 360 cycles. The novel design of the separator with ordered channels and polar groups presents an effective route for developing the next-generation LMBs.