Constructing 3D porous network channel on PP-based separator to achieve homogeneous deposition of lithium ions for lithium metal battery

Abstract

Lithium metal anode is broadly regarded as one of the most promising anode materials for batteries due to its extremely high specific capacity, very low redox potential, and mass density. Nevertheless, non-uniform deposition of lithium ions hinder the practical application of lithium metal batteries (LMBs). Herein, it was essential to design a separator with high electrolyte affinity to inhibit the non-uniform deposition of lithium ions. In this work, the wettability and electrolyte uptake of the polypropylene (PP) separator were remarkably improved by introducing reduced graphene oxide (rGO) and polyvinylidene fluoride (PVDF) to the surface of the separator through one-sided coating. The composite separator resulted in lithium ion with high conductivity (1.35 × 10-3 S cm-1) and transfer number (0.63). After assembling the rGO/PVDF@PP separator into the LiFePO4||Li battery and conducting the test, it was found that the specific discharge capacity could still reach 136 mAh g-1 after 100 cycles at 1C. Furthermore, After 1000 hours of cycling in the assembled Li‖Li symmetric battery, there is no obvious generation of lithium dendrites on the surface of the lithium metal, indicating the successful suppression of lithium dendrites by the composite separator. This study offers a promising pathway for producing large quantities of new composite separators with high levels of safety.