In-Situ Grafting Strategy Enables Functional Separator for Advanced Lithium-Sulfur Batteries

A functional separator is developed by in-situ grafting nickel tetraaminophthalocyanine (NiTAPc) onto the surface of polypropylene (PP). It is applied to inhibit the shuttle effect of polysulfides (PSs) in lithium-sulfur(Li-S) batteries. The characterization results showed that NiTAPc is highly dispersed and uniformly grafted onto PP separator. In-situ grafting strategy effectively mitigates the self-agglomeration issue associated with NiTAPc and enhances the exposure of catalytically active Ni-N4 sites. These sites exhibit excellent adsorption and conversion capabilities for PSs. This is consistent with the results of theory calculations, which indicate that the presence of NiTAPc can reduce the delithiation energy barrier associated with Li2S conversion. Owing to the excellent inhibition ability of NiTAPc on the shuttle effect of PSs, the Li-S battery employing a PP-NiTAPc separator demonstrates excellent cycle stability. It shows an initial specific capacity of 1256.5 mAh g-1 at 0.1 C, and a capacity retention of 582.4 mAh g-1 after 500 cycles at 1 C, showcasing a minimal decay rate of 0.0547% per cycle. The strategy adopted in this study offers valuable insights for the development of modified separators for rechargeable batteries and other energy storage fields.