Separators Based on the Dynamic Tip-Occupying Electrostatic Shield Effect for Dendrite-Free Lithium-Metal Batteries

Lithium-metal batteries (LMBs) have long been considered the “holy grail” of next-generation energy storage systems due to the unique advantages of Li metal, such as having a high specific capacity and the lowest potential. Unfortunately, the practical application of LMBs is seriously hindered by the uncontrollable growth of dendritic Li. To address this issue, a positively charged layer (PCL) with freely moving multication sidechains is successfully polymerized on a commercial polypropylene (PP) separator. The cationic groups on the sidechains of the polymer realize dendrite-free Li deposition based on the “dynamic tip-occupying electrostatic shield” effect. LMBs with improved cycling stability and rate performance can be achieved by using a PP-N,N,N,N”,N”-pentamethyldiethylenetriamine (PP-PMDT) separator. All the results demonstrate that this strategy for constructing a flexible “electrostatic shield layer” can successfully eliminate the formation of Li dendrites while retaining the desired performance.