High-Performance Lithium Metal Rechargeable Battery Using an Ultrafine Porous Polyimide Separator with Three-Dimensionally Ordered Macroporous Structure

It is very important to control the compositional and morphological changes of the lithium metal anode in order to improve the cycle performance of the lithium metal battery (LMB). In this work, we report that the combination of an ultrafine porous polyimide (PI) separator with three-dimensionally ordered macroporous (3DOM) structure and an electrolyte composed of ethylene carbonate (EC) solvent with a high dielectric constant containing LiPF6 can improve the cycle performance of LMB using a Li4Mn5O12 cathode. In LMBs in which depositions of lithium with high reactivity are repeated on the anode at every cycle, undesirable side reactions generating deteriorated products are promoted at the interface between freshly deposited metallic lithium and electrolyte. The reaction of LiPF6 with water and subsequent undesirable side reactions hardly occur in EC solvent with a high dielectric constant. In addition, the size and shape of the deposited lithium particles on the cycled anode in the cell using EC solution are uniform, so EC solvent is suitable for LMBs. The 3DOM PI separator is superior to the conventional polypropylene separator in terms of the uniform current density distribution in addition to high permeability and reservation for electrolytes with low fluidity such as EC solution.